Master‘s thesis
Loss of longline-bait to northern fulmars
Economic balance between damage from bait-loss and costs of measures to reduce seabird bycatch on the Faroe Islands
Susanne Kühn
Advisor: Dr. Jan Andries van Franeker
University of Akureyri Faculty of Business and Science
University Centre of the Westfjords Master of Resource Management: Coastal and Marine Management
Ísafjörður, February, 2016
Supervisory Committee Advisor: Jan Andries van Franeker, Dr Marine Biologist, Institute for Marine Resources & Ecosystem Studies (IMARES), The Netherlands Reader: Ögmundur H. Knútsson, Ph.D. Dean of the School of Business and Science at the University of Akureyri, Iceland Program Director: Dagný Arnarsdóttir, MSc.
Susanne Kühn Loss of longline-bait to northern fulmars. Economic balance between damage from bait-loss and costs of measures to reduce seabird bycatch on the Faroe Islands.
45 ECTS thesis submitted in partial fulfilment of a Master of Resource Management degree in Coastal and Marine Management at the University Centre of the Westfjords, Suðurgata 12, 400 Ísafjörður, Iceland
Degree accredited by the University of Akureyri, Faculty of Business and Science, Borgir, 600 Akureyri, Iceland
Copyright © 2016 Susanne Kühn All rights reserved Printing: Háskólaprent, Reykjavík, February, 2016
Declaration
I hereby confirm that I am the sole author of this thesis and it is a product of my own academic research.
__________________________________________ Student‘s name
Abstract
On the Faroe Islands, longline fishermen experience a loss of bait to scavenging
seabirds. This Master thesis evaluates the economic impact of bait-stealing by a
seabird, the northern fulmar (Fulmarus glacialis), in the longline fisheries. Baits found
in stomachs of northern fulmars, caught accidentally in longline fisheries around the
Faroe Islands, were used to estimate the bait loss. From this an estimate was made of
the potential economic loss experienced by fishermen due to seabirds. Possible
mitigation measures were discussed regarding their suitability for the Faroese fisheries
and their economic viability. The results show that the economic loss for the fishermen
can range between 600 and 88,000 Danish Krona (DKK) per trip for one vessel,
depending on the fishing efficiency and the number of birds surrounding the vessel. As
a mitigation measure, tori lines are proposed to keep the birds out of the reach of bait. It
became clear that direct observer data is necessary to evaluate the situation on the Faroe
Islands and to make a realistic picture of the extent of the fisheries-seabird interaction.
Unfortunately the collection of data on board of fishing vessels was beyond the scope
of this thesis. Nevertheless a useful tool is provided for fishermen to calculate the
individual economic loss they suffer from seabirds and weigh the financial loss of
seabirds stealing baits against the costs of mitigation measures that might reduce
seabird fatalities and therefore create a situation where both, fishermen and seabirds
benefit.
A Faroese Fisherman speaks of drowning
But you can’t let fear cripple your will
When you are in the waves well above your neck
Or else your limbs will get heavier still
And then who’d dare risk pulling you on deck?
Guðrið Hansdóttir
xi
Table of Content
Abstract .............................................................................................................................. vii
List of Figures ................................................................................................................... xiii
List of Tables .......................................................................................................................xv
Acknowledgements .......................................................................................................... xvii
1 Introduction .....................................................................................................................1
2 State of Knowledge ..........................................................................................................5 Fishing technique .....................................................................................................5 2.1
2.1.1 Effects of longline fisheries on the environment ........................................... 6 Fishing on the Faroe Islands ....................................................................................9 2.2
2.2.1 Associated birds ........................................................................................... 12 General mitigation strategies ..................................................................................15 2.3
2.3.1 Fishing gear adaptations .............................................................................. 16 2.3.2 Operational adaptations ............................................................................... 18 2.3.3 Management options .................................................................................... 19
3 Methods ..........................................................................................................................21 Stomach content analysis .......................................................................................21 3.1 Analysis of the economic loss, simulations and costs of mitigation ......................23 3.2
3.2.1 Value of a fish .............................................................................................. 23 3.2.2 Costs of mitigation ....................................................................................... 24
Ethical issues ..........................................................................................................25 3.3
4 Results .............................................................................................................................27 Stomach content analysis .......................................................................................27 4.1
4.1.1 Catch rates per tour ...................................................................................... 27 4.1.2 Seabird mortality ......................................................................................... 28 4.1.3 Bait in seabird stomachs .............................................................................. 28
Calculation of economic loss .................................................................................31 4.2 Simulation of different scenarios ...........................................................................34 4.3 Costs of mitigation .................................................................................................36 4.4
5 Discussion .......................................................................................................................41 Catch rates ..............................................................................................................41 5.1 Economic loss calculations ....................................................................................43 5.2 Mitigation measures ...............................................................................................44 5.3
6 Conclusions .....................................................................................................................49
References ...........................................................................................................................51
xii
xiii
List of Figures
Figure 1: Demersal longline fisheries. (Drawing: U. Kühn) ............................................ 6
Figure 2: Bycatch of seabirds in demersal longline fishery (Drawing: U. Kühn) ............ 7
Figure 3: Map showing the Faroe Islands between Scotland and Iceland and a detailed map of the Faroe Islands (Created by Google Maps 2015) ............. 9
Figure 4: A haddock (Melanogrammus aeglefinus) caught on a longline vessel on the Faroe Islands. Northern fulmars are surrounding the vessel searching for food opportunities (Photo: J.A. van Franeker) ...................... 11
Figure 5: Northern fulmars following a longline vessel on the Faroe Islands and fighting for food (Photo: J.A. van Franeker) ............................................... 12
Figure 6: Northern fulmars in flight (left), in portrait (with clearly distinguishable tube on the bill; centre) and northern fulmars feeding around a fishing vessel (right; Photo‘s: S. Kühn) ................................................................... 13
Figure 7: Short term trends of the breeding population of northern fulmars in Europe (adapted from BirdLife International, 2015a) ................................. 15
Figure 8: Examples of bait found in the stomachs of northern fulmars, accidetally bycaught on the Faroe Islands (Photo‘s: J.A. van Franeker) ....................... 22
Figure 9: Number and distribution of fishing trips where northern fulmars were caught and collected between 2004 and 2012 ............................................. 27
Figure 10: Distribution of northern fulmars caught in Faroese longline fisheries per month and year ...................................................................................... 28
Figure 11: Count of baits found in northern fulmar stomachs between 2004 and 2012 ............................................................................................................. 29
Figure 12: Distribution of bait types found in the stomachs of northern fulmars caught accidentally in longeline fisheries .................................................... 29
Figure 13: Average number of baits per month in northern fulmar stomachs in comparison with the number of seabirds caught in this month ................... 30
Figure 14: Average bait loss and caught northern fulmars between 2004 and 2012 ..... 31
Figure 15: Species distribution in percentage caught by Faroese longline fisheries in 2014 (Hagstova Føroya, 2015b) .............................................................. 33
Figure 16: Comparison of the economic costs of mitigation measures and their efficiency in reducing bait loss and seabird bycatch ................................... 40
xiv
xv
List of Tables
Table 1: Wet mass of different fish species and their percentage of the total landed longline catch on the Faroe Islands in 2014 (Hagstova Føroya, 2015b) .......................................................................................................... 10
Table 2: Sample size and distribution of northern fulmars caught accidentally during longline fishing operations on the Faroe Islands between 2005 and 2012 ...................................................................................................... 21
Table 3: Data on the average size of different fish species when caught, the calculated mass per individual fish, the average prices (in DKK) per kilogram fish and the calculated price per individual fish and species ....... 32
Table 4: Calculation of the average price per individual fish, considering the proportion of each species in longline fishery catches ................................ 33
Table 5: The price of the fish and the average number of baits found in northern fulmars has been calculated before, the number of birds searching for food around the vessel (x) and the fishing efficiency (y) can vary. ............ 35
Table 6: Simulation of different scenarios. Variables x and y (see Table 3) have now been replaced by numbers that estimate the number of birds searching for food around the vessel and a varying fishing efficiency. ...... 35
Table 7: Table of mitigation measures, their efficiencies and costs (if data available) and references ............................................................................. 37
xvi
xvii
Acknowledgements
First I want to thank my supervisor Jan van Franeker. I am extremely grateful for the
opportunities you are creating for me. Your dedication for this work and these beautiful
birds is inspiring and I am glad you are sharing your knowledge with me. Your
patience, your honesty and your support are impressive and I want to thank you for all
of this! Thanks to Ögmundur Knútsson, the external reader of this thesis, your
comment and advise were very valuable.
I want to thank the staff of the University Centre of the Westfjords; you created a
unique opportunity in this magical Ísafjörður-world for students. We’ve learned so
much, not only about Coastal and Marine Management, but about this beautiful place,
the life under special (winter) conditions and particularly about ourselves. Thanks for
the support and assistance during this awesome time. In Ísafjörður there is also a very
special club of people, the Kayak Center, thanks for the endless hours of teaching,
kayaking in the fjords, rolling in the pool and under ice, I had an awesome time! I also
want to thank the 2014/2015 student cohort, what an incredible group of passionate,
strong and beautiful people. I am glad that I was a part of this group; I loved (almost)
every minute we spent together, on land, at sea and in the helicopter. I also want to
thank my little sister Ulrike Kühn for the provision of the drawings in this thesis and
my presentation, your talent and your sense of humour are amazing!
xviii
1
1 Introduction
Longline fishery is a fishing technique that is used on a global scale. Even though this
type of fisheries is regarded as relatively environmentally friendly, seabirds all over the
world have been observed to target the baits on the hooks while the fishing lines are
deployed, often at the risk of their own life.
Fisheries therefore experience an economic loss, as stolen bait can result in reduced
gear efficiency, up to a level where trips become unprofitable (Sánchez & Belda, 2003).
In Norwegian longline fisheries a bait loss of up to 70% caused by seabirds has been
reported (Løkkeborg, 1998). Beside the direct loss of baits, entangled birds can also
impact the fisheries through changes in the buoyancy of the lines, resulting in an
unwanted and unpredictable change in depth and position of the fishing lines (Sánchez
& Belda, 2003). In Argentinian longline fisheries for example, Gandini & Frere (2012)
estimate a loss of 1.5 million and 2 million US Dollar (US$) in a ten year period
respectively, due to the loss of bait to seabirds.
At the same time, the birds get entangled or swallow the hook and subsequently drown
when the lines sink to the bottom (e.g. Anderson et al., 2011, Croxall et al., 2012).
Anderson et al. (2011) estimate that on a global scale between 160,000 and 320,000
seabirds die annually, due to longline activities. The effect of longline mortality can
even be a threat for whole populations of seabirds as described for various species of
the Southern Ocean (Cherel et al., 1996). The Faroe Islands belong to the Top 10 of
fishing fleets with the highest estimated seabird bycatch rates (Anderson et al. 2011).
The rate of seabird bycatch in longline fisheries has been studied intensively, especially
in the Southern Ocean; however the economic loss for the fisheries has often been
neglected (Sánchez & Belda, 2003; Ward et al., 2012). Another problem of these
studies has been described by Brothers et al. (2010). The authors state that the usual
approach of collecting bycaught birds might underestimate the loss of birds and
therefore also the loss of bait.
2
Many different approaches to reduce bait loss and seabird mortality have been
developed and tested. As mitigation measures can be expensive in acquisition or during
use, incentives are necessary to convince fishermen to use these measures, to their own
benefit and that of the seabird.
This master thesis is intended to provide data to show that mitigation measures might
not only contribute to seabird conservation, but at the same time can ultimately reduce
the economic loss of the fishermen by increasing the fishing efficiency of their gear. To
achieve this, the following questions need to be evaluated:
1) What are the pitfalls of using the approach of stomach content analysis of
bycaught seabirds to estimate bait loss rates and how can this approach be
improved?
2) What is the economic loss a fisherman on the Faroe Islands might
experience due to bait loss by seabirds?
3) What are suitable mitigation measures to reduce seabird bycatch and
consequently the economic loss experienced by Faroese fishermen?
This thesis intentionally focuses on the economic consequences of bait loss and not on
the biological and ecological implications that occur when a long living seabird species
loses an unknown number of individuals to the longline fishery. The reasons are on one
hand the lack of data on the severity of this impact on the Faroe Islands and on the
other hand the idea that a report on the economic consequences of bait loss might be of
higher interest and utility to Faroese fishermen.
As an initial part of this thesis, scientific literature was searched for information on
longline fishery practices in general and specifically on the Faroe Islands, the
interaction of seabirds with this fishery and general mitigation measures to reduce
harmful interaction (Chapter 2).
To answer the research questions mentioned above a set of methods was combined. The
stomach content of 634 northern fulmars (Fulmarus glacialis) was analysed and bait
was identified, counted and weighed. In a second step literature research and modelling
is used to find out important information on the costs of bait loss. Finally the mitigation
measures are tested for their suitability in the Faroese fisheries including their
3
efficiency in reducing bait and the general costs of implementation. All methods used
during this research are described more in detail in Chapter 3. Results evaluating the
bait loss by seabirds use an innovative approach by analysing bait found in stomachs of
northern fulmars, bycaught in longline fisheries around the Faroe Islands (Chapter 4).
This approach has been used once before in the Southern Ocean by Gandini & Frere
(2012), however they solely used the number of baits found in a few stomachs to
estimate bait loss as a secondary source of information and did not go much into detail
with this data. In a second step this data and additional literature research leads to an
estimation of the economic loss a fisherman on the Faroe Islands experience using
simulated scenarios. In a third step the mitigation measures introduced earlier are
analysed, regarding their suitability and the economic viability for the Faroese longline
fisheries. In the discussion (Chapter 5) the approach and the data are evaluated.
Alternative approaches are discussed to gain a deeper insight in the Faroese fisheries
and recommendations are made how in future research could support policy discussions
and how fisheries could benefit economically from this research. The conclusions of
this research and recommendation for further research as well as recommendations for
implementation are presented in Chapter 6.
4
5
2 State of Knowledge
Seabird-fishery interaction is a well-known phenomenon. There are various scenarios
wherein seabirds either suffer or benefit from fishery activities. Negative impacts on
seabirds include bycatch and disturbance in their habitat as well as competition for food
(mainly smaller fish). However, especially scavenging seabird populations can benefit
from discarded fish as an additional source of nutrition and the human-induced
depletion of competitive predatory fish species, that forage on the same fish as seabirds,
can also be beneficial to some seabird species (Montevecchi 2002). On the other hand
also fisheries can be influenced by seabirds. As seabirds concentrate on fish-rich areas
they may lead fishermen to these places and therefore might be economically
advantageous for the fisheries, even though it is impossible to express this effect in
money (Suazo et al. 2013). However, at the same time seabirds and fisheries are
competing for food. In 2004 the total annual consumption of fish by seabirds was
estimated at 70 million tonnes, while the commercial fishing activity was estimated to
catch around 80 million tonnes a year (Brooke 2004). Fishing down the food web also
occurs in the North Sea where the depletion of cod (Gadus morhua) and the
introduction of aquaculture led to an increasing commercial interest in the smaller sand
eel (Ammodytes marinus) (Furness 2002). By focussing on smaller fish species, the
fishery and seabird competition becomes more direct and obvious and in this case can
lead to economic disadvantages for the fishery (Brooke 2004). Another problem occurs
in the longline fishery where seabirds decrease the fishing efficiency by stealing the
bait from the deployed hooks. In this thesis it was the attempted to investigate whether
there is a method to indirectly gain more knowledge on the impact seabirds have on
fisheries and vice versa.
Fishing technique 2.1
Longline fishery is one of the largest fisheries for consumption fish worldwide. Bjordal
& Lokkeborg (1996) report that between 15 and 90% of the fish worldwide was caught
by longline boats. It is seen as a passive fishing technique, where fish is attracted to
static lines with baited hooks by odour or vision (Brothers et al., 1999). The fisheries
6
use lines up to kilometres in length. On these main lines, at intervals of a few metres up
to thousands of branch lines are connected with baited hooks (Figure 1). Fishes can be
caught at all water depths, pelagic, semi-pelagic and demersal (Bjordal & Lokkeborg,
1996).
Figure 1: Demersal longline fisheries. (Drawing: U. Kühn)
Large ships can operate in deep sea environments down to 3,000 meters depth
(Brothers et al., 1999). Pelagic longlining mainly targets large species as tunas
(Thunnus spec.) and tuna-related species in the water column while demersal longliners
often focus on the continental shelf with species living at, or close to, the seafloor such
as e.g. gadoids (Brothers et al., 1999). The hooks vary in size and shape, depending on
the target species. As bait, fish, squid or whelk are commonly used (Collins et al.,
2010).
2.1.1 Effects of longline fisheries on the environment
Compared to other fisheries longlining has been described as a relatively
environmental-friendly fishing technique. As there are species- and age-specific
differences in habitat choice, longlines can be deployed on specific areas or a specific
7
type or size of bait can be chosen to avoid non-target fish species and to select for fish
of the right size or age, other than other fishing techniques (Brothers et al., 1999).
Another advantage is, that in general longlining is not destructive to bottom structures
(Dunn & Steel, 2001).
The fishery is not totally free of environmental impacts as unintended bycatch of sharks
turtles and marine mammals and damage to cold water corals in deep sea longlining
occur (Hinman, 1998; Durán Muñoz et al., 2010). However, the fisheries main problem
concerns the unintentional bycatch of a range of seabirds. Furness (2003) described the
problem as one of the most urgent issues for seabird conservation.
Figure 2: Bycatch of seabirds in demersal longline fishery (Drawing: U. Kühn)
In the northern hemisphere more surface-feeding seabirds occur, while in the southern
hemisphere many seabird species forage while diving and therefore problems not only
occur in the very first phase of deployment when the baited hooks are close to the water
surface, but also in a later phase, as e.g. shearwaters (Procellariidae) are known to dive
8
down to considerable depth (Bull, 2007). As surface foraging seabirds often feed
indiscriminate and are known for scavenging, they are described as “preadapted” for
bait stealing and offal foraging (Camphuysen et al., 1995). Another factor playing a
role in vulnerability to longline entanglement is the size of the seabird. Seabirds as for
example storm petrels (Hydrobatidae) are too small to forage on baits used in longline
fisheries (Brothers et al., 1999). Larger birds also can benefit in competition and have
been found to be more aggressive when competing for bait, at the same time increasing
the vulnerability of getting caught by hooks (Brothers, 1991).
The exact extent of this problem is difficult to estimate, but it is evident that hundreds
of thousands of seabirds die annually worldwide, while trying to forage on bait
(Anderson et al., 2011). Brothers et al. (1999) made an extensive overview of different
bycatch rates over the world. They list 61 seabird species that have been recorded as
bycatch in longline fisheries, many of them are regarded as threatened species by IUCN
(International Union for Conservation of Nature).
It is difficult to prove a correlation between longline fisheries and impacts on seabird
population levels as many interconnected factors may play a role (Løkkeborg, 2011).
Indications for effects on population level are given by a few studies. Lewison &
Crowder (2003) for example estimate that in the Northern Pacific Ocean 5,000 to
10,000 black-footed albatrosses (Phoebastria nigripes) are killed annually in longline
interactions. As albatrosses are long-lived and slow in reproduction, this will result in a
population decline throughout the next 60 years. Also the rare Amsterdam Albatross
(Diomedea amsterdamensis) is likely to be negatively affected by longline fishing
activities around their breeding range (Inchausti & Weimerskirch, 20010). Belda &
Sanchez (2001) provide data on shearwaters in the Mediterranean, they link the
decrease in shearwater population to longline fisheries bycatch. In the Southern Ocean,
Ryan & Watkins (2002) estimated the mortality of more than 5,000 white-chinned
petrels (Procellaria aequinoctialis) in a four-year period, equalling 10-20% of the
breeding population. Most of these birds were caught during illegal fishing activities.
Tasker et al. (2000) calculate great negative impacts by longline mortality on
population levels for albatrosses in the southern hemisphere and moderate negative
impacts on petrels and shearwaters worldwide.
9
Fishing on the Faroe Islands 2.2
The Faroe Islands are a group of 18 small islands, located in the North East Atlantic,
between Scotland and Iceland (62º00’ N; 6º47’ W; Figure 3). About 48,000 people live
on the islands, that fall under the territory of Denmark (Føroya Landsstýri, 2015).
However, as they are self-governing, they decided to not become a member of the
European Union (EU) and therefore have their independent fisheries management
Figure 3: Map showing the Faroe Islands between Scotland and Iceland and a detailed map of the Faroe Islands (Created by Google Maps 2015)
10
regime. Their economy solely relies on fisheries, fish processing and aquaculture, 95%
of the Faroe exports since 1920 are fishery products (FAO, 2005). 240 fishing vessels
above 20 GRT (Gross Register Ton) are registered; furthermore the Faroese fleet
includes more than 1,000 smaller fishing vessels (Vinnhusid, 2015).
Longline fishing is a big contributor to the national income. In 2003, 92 longline
vessels of different sizes were registered (Løkkegaard et al., 2007). The main species
caught by longline fisheries are cod, haddock (Melanogrammus aeglefinus) (see Figure
4), tusk (Brosme brosme) ling (Molva molva) and saithe (Pollachius virens), which in
2014 generated an income of around 200 million DKK (Hagstova Føroya, 2015b).
Since 1993 fish is auctioned electronically and is owned by the fish suppliers. Often
more than 80% of the fish is sold even before the vessel reaches land (Fiskamarknadur
Foroya, 2015). Inside longline fisheries the species distribution caught in 2014 is
shown in Table 1 (Hagstova Føroya, 2015b).
Table 1: Wet mass of different fish species and their percentage of the total landed longline catch on the Faroe Islands in 2014 (Hagstova Føroya, 2015b)
Species Wet mass (kg) % Longline Cod 95,635 40.0 Haddock 42,547 17.8 Tusk 16,486 6.9 Ling 57,494 24.0 Saithe 3,296 1.4 Other 23,785 9.9 Total 239,243 100
The main tool to manage the harvest of fish on the Faroe is the effort control. This
policy was implemented in 1996, after a Total Allowable Catch system (TAC) failed,
due to high discard rates (Jákupsstovu et al., 2007). Therefore the focus lies on input
control rather than on output control as it is usually implemented in the EU, where they
focus mainly on landed fish (Hegland & Hopkins, 2014). The effort control based
system is known for being less bureaucratic and less expensive. However the biggest
advantage is, that especially in mixed demersal fisheries, a TAC leads to high bycatch
level of fish species with different quotas (Hegland & Hopkins, 2014). The main
components of the effort control policy are summarized by Hegland & Hopkins (2014).
They include a limit of fishing days for each type of fishing vessels (these days are
11
transferable in the same fishing category; Zeller & Reinert, 2004), fleet segmentation to
make sure not all types of fishing vessels are fishing in the same area at the same time
and capacity regulation to keep the number and capacity of the fleet to the level of
1997. Another regulation playing a big role in Faroe fisheries are spatial and temporal
closures. They were originally established to avoid gear conflicts and regulate access
rights, but later the protection of vulnerable habitats, species and stocks also became an
important issue. Technical
measures as mesh size
regulation, sorting grids etc.
were implemented to
decrease bycatch of too small
or non-target fish species
(Hegland & Hopkins, 2014).
As applicable as it appears for
the Faroese fishing to use this
kind of effort control, also
disadvantages have been
documented. The annual limit
of fishing days is decided by
the Faroese Ministry of
Fisheries and Natural
Resources. They get input
from the Faroe Marine
Research Institute and from
the Committee on Fishing Days, which is represented by the fishing sector. It appeared
that in the past, the minister tended to go with the recommendations the committee
made, rather than finding a compromise between the scientists and the fishery sector to
ensure sustainable fishing (Hegland & Hopkins, 2014). Other concerns regard the
difficult enforcement and the fact that there is actually no fishing management plan in
place (Jákupsstovu et al., 2007).
Figure 4: A haddock (Melanogrammus aeglefinus) caught on a longline vessel on the Faroe Islands. Northern fulmars are surrounding the vessel searching for food opportunities (Photo: J.A. van Franeker)
12
2.2.1 Associated birds
Bycatch of seabirds is common on the Faroe Islands. Anderson et al. (2011) estimate
that the Faroe Islands belong to the Top 10 of longline fleets with the highest estimated
seabird bycatch rate worldwide. Data regarding the species composition of longline
bycatch is not directly available from the Faroe Islands. Norwegian data by Dunn &
Steel (2001) shows that northern fulmars are the very dominant species which is caught
in longlines with more than 99% of the total bycatch. Personal observations from the
Faroe Islands by J.A. van Franeker confirm this picture (also see: Figure 5). Other bird
species associated in small numbers with longline fishing vessels are gull species
(Larus spec.), great skuas (Stercorarius skua), that use kleptoparasitic foraging
techniques to steal food from other birds and a few northern gannets (Morus bassanus)
which dive around the vessels, but were not observed to be caught.
Bycatch of seabirds in Faroese longline fisheries hasn’t been monitored yet. There are
no reliable numbers available. More recent estimates of bycatch in saithe longline
fishing in Faroese waters have been made by the Marine Stewardship Council (MSC,
2012). They estimate that 5,000 to 25,000 northern fulmars might get caught annually
Figure 5: Northern fulmars following a longline vessel on the Faroe Islands and fighting for food (Photo: J.A. van Franeker)
13
by longline vessels that catch saithe. Following their calculations this might be equal to
5% of the Faroese northern fulmar population. Tasker et al. (2000) argue that,
regarding the range of northern fulmars and the sheer number of breeding pairs, the
northern fulmar population might not be threatened by longline fishing mortality (also
see Brothers et al., 1999).
As northern fulmars seem to be the most affected species in the northeast Atlantic
Ocean (Dunn & Steel, 2001; Løkkeborg, 1998), this report will focus on them.
Northern fulmars (Figure 6) are seabirds that occur in all parts of the northern Atlantic,
from the Arctic to the North Sea and another population is found in the North Pacific.
Northern fulmars are members of the tubenose order (Procellariiformes), which for
example also includes the albatrosses. They are a long-lived species, can live up to 35
years and have a slow reproduction cycle as they start breeding when they are on
average 9.2 years old (Ollason & Dunnet, 1978). They breed in great numbers on rocky
cliffs but most of the year they spend on the ocean (BirdLife International, 2015c).
Northern fulmars forage exclusively at sea on fish, crustaceans, squid, jellyfish and
scavenge all sort of dead animals or fishing offal (Phillips et al., 1999; Ojowski et al.,
2001; Garthe et al., 2004). They are known to ingest large numbers of marine debris
(e.g. Van Franeker et al., 2011). Regularly they are found to follow fishing vessels day
and night, waiting for discards or bait (e.g. Thompson et al., 1995; Furness & Todd,
1984; Dunn & Steel, 2001).
The first record of northern fulmars following ships reaches back to 1671 on
Spitzbergen where they were observed to follow whalers (Fisher, 1952). Fisher (1952)
Figure 6: Northern fulmars in flight (left), in portrait (with clearly distinguishable tube on the bill; centre) and northern fulmars feeding around a fishing vessel (right; Photo‘s: S. Kühn)
14
also cites the fisherman, Henry Fitzler, who described the determined search for baited
hooks in 1946 as follows:
“The fulmar brain probably contains no innate mechanism whereby its owner is apt to
respond distrustfully with regard to human beings. The birds are apparently so
constituted that, when suitable food is available, they are incapable of associating the
manner in which it is presented – in this instance on hooks- with possible hazard to
themselves” (Fisher, 1952, p. 420).
The northern fulmar population estimate for the entire North Atlantic is more than
2,800,000 breeding pairs, on the Faroe Islands there are 600,000 breeding pairs found,
the population has been regarded as being secure (BirdLife International, 2015c),
however recent numbers show decreasing population trends. There have been
observations showing a slight decrease in Canada (Gaston et al., 2012) and an decrease
in most parts of the UK (except Wales; Mavor et al., 2005) as well as moderate
decreases on the Faroe Islands (See Figure 7; BirdLife International, 2015a). While the
IUCN keeps the northern fulmar in the “Least Concern” list (BirdLife International,
2015c) in 2012, in the European Red List assessment the fulmar is categorized as
“Endangered” (BirdLife International, 2015b).
15
Figure 7: Short term trends of the breeding population of northern fulmars in Europe (adapted from BirdLife International, 2015a)
General mitigation strategies 2.3
Even though the northern fulmar population seems not to be affected at the moment,
the Food and Agriculture Organization of the United Nations (FAO) Conduct for
Responsible Fisheries obliges member states to reduce non-target bycatch (FAO,
1995). Many measures to mitigate seabird mortality have been tested. However,
avoiding seabird bycatch is not enough. At the same time, the methods must be safe for
fishermen during operation, it must not or only marginally decrease fishing efficiency
and in best case even provide operational and economic benefits (Gilman et al., 2005).
To avoid bait loss by seabirds, three theoretic approaches are proposed by Brothers et
al. (1999): decrease the visibility of the bait, decrease the access to the bait and
decrease the chance of mortality when hooked.
16
The baited hooks are most prone to be taken by seabirds during setting operations. The
lines with baited hooks can float on the surface for a while, depending on the vessels
speed and tension of the line, weights used and the turbulence caused by the propeller
as most lines are set on the back of the ships (Brothers et al., 1999). As soon as the
lines sink, they get out of the reach of seabirds, depending on the seabird species and its
diving capacity. However, once hooked, birds themselves can decelerate the sinking
speed, as they struggle against the entanglement and change the floating behaviour of
the lines, attracting even more birds to steal bait (Barnes et al., 1997; BirdLife
International, 2014). Therefore most mitigation strategies focus on the setting process.
Hereafter the main strategies to avoid bait loss by seabirds are introduced. They are
split into adaptations of either fishing gear, fishing operation or management strategies.
2.3.1 Fishing gear adaptations
Underwater setting tubes: Underwater setting tubes are used in demersal and pelagic
longlining to bring the lines out of the reach of seabirds, preventing them from hunting
for bait. These are fixed tubes on the stern of the boat, which lead the lines with baited
hooks directly a few meters under the water surface. The tubes can be attached on an
vessel already in use but there are also systems that are integrated in the ship during
construction (Brothers et al., 1999). Significant seabird bycatch reduction has been
proven in several studies. For example, research by Gilman et al. (2003) shows that
20% more bait can be retained when using under water setting tubes in comparison
with the control situation without tube. Costs to install the tubes are expected to be high
initially but low once it is installed (Brothers et al., 1999; Gilman et al., 2003; Dunn &
Steel, 2001). Problems in handling can occur when the line tangles (Dunn & Steel,
2001). Another disadvantage can be observed when the lines still can reach the surface
due to high waves pulling up the stern with the fixed tube (Løkkeborg, 1998; Gilman et
al., 2003).
A comparable type of funnel is the chute. Here only the branch line with the baited
hooks are sent through the tunnel, decreasing the risk of tangling during deployment
activities (Bull, 2007). In pelagic longline fisheries a reduction of 95% of seabird
bycatch was achieved and fishing efficiency was increased by 15 to 30% (Gilman et al.,
2007).
17
Bird Scaring Lines (BSL): Bird Scaring Lines (sometimes also called tori lines) are a
group of different methods where colourful and fluttering lines, are attached on the
back of the ship flying above the actual fishing lines, preventing seabirds to reach the
baited hooks. These lines are hanging above the main lines and protect them from
seabirds during setting of the line (Bull, 2007; Brothers et al., 1999). The efficiency
depends on the sinking rate of the fishing line and the height of the scaring lines as this
defines the distance before the lines reach the water surface and loses its bait protection
ability. A significant reduction in seabird mortality and an increase in fishing efficiency
has been observed in several studies in the northeast Atlantic Ocean (e.g. Løkkeborg,
1998, 2003) and elsewhere (e.g. Boggs, 2001) with a reduction in seabird bycatch
ranging from 30-70% in pelagic longline fisheries (Brothers et al., 1999) and 90-98%
in demersal fisheries (Løkkeborg, 1998). Sometimes these lines can tangle with the
fishing gear and at those instances clearly decrease fishing efficiency (Weimerskirch et
al., 2000). The scaring lines (including the mounting pole) are regarded as relatively
cheap initially and during the use (Brothers et al., 1999).
Laser Deterrent: A newly developed method is the Seabird Saver laser method,
combined with a deterring sound system (SaveWave, 2014; AFMA, 2014). The laser is
attached on the stern of the vessel, pointing backwards in a line with the longline itself.
According to the producers, as soon as turned on in a test, all seabirds took off from the
water surface and kept distance to the laser light and the baited hooks. Added bird
stress sounds increased the deterring effect. Until now, this system has only been tried
in unpublished trials conducted by the developer SaveWave, who claim good results in
dark, foggy or rainy circumstances. However, as potential negative effects of laser
beams on birds have not been tested by independent scientists yet, the claimed
efficiency rate cannot be used in tabulated or graphical representations of mitigation
methods.
Weighted Lines: The time, fishing lines need to sink depends on the speed of the ship,
the tension on the line and its weight. Added weights on the lines or integrated heavy
lines ensure a fast sinking rate, out of reach for most seabirds (Robertson, 2000;
Robertson et al., 2006). The efficiency of weighted lines to reduce seabird bycatch
depends increases with the sinking rate and can reach 100% reduction (Robertson et al.,
18
2006). In demersal fisheries it is less complicated to add weights as they sink to the
seafloor anyway. In some cases even an increase of target species catch has been
observed, because the hooks are better positioned on the sea floor (Brothers et al.,
1999) or at least have shown no reduction in target species catch (Robertson et al.,
2006). However, as the tension of the line gets stronger, there is a higher risk for crew
members when the line snaps unintentionally (Brothers et al., 1999).
2.3.2 Operational adaptations
Offal discard: In many fisheries, discarding bycatch has been prohibited, including
fisheries on the Faroe Islands, However, when processing the fish on board, offal is still
discarded immediately. It has been proven to reduce the bait loss due to seabirds when
the discard of fishing offal (either intestines or other bycatch) is adapted time- and
place wise to fishing operations. As the lines are set on one side of the boat, it helps
when the offal is discarded on the opposite side of the ship as it leads the birds away
from the deployment. Also timing can be crucial, when deployed and discarded at the
same time, birds tend to steal much more bait as when setting the lines and discard take
place at the same time but opposite sides of the ship (Collins et al., 2010). So there are
two ways of thinking, either use the discard to distract birds from the setting or hauling
operations or retain all discard, including offal on board. In the latter case, fishermen
might be worried about the additional storage space needed for the offal (Bull, 2007).
The first option however, has been criticized as discarding of alleged edible items may
attract higher numbers of seabirds which may increase the initial number of entangled
birds (Brothers et al., 1999).
Dyed bait: In longline fisheries there have been some trials done to colour bait blueish
and therefore decrease the contrast with seawater and camouflage the bait to the
seabird`s eye (Gilman et al., 2007). Studies have been proven a bait loss reduction in
pelagic fisheries up to 95% (Boggs, 2001) however, in comparison with side setting
and chutes it was the least efficient measure (Gilman et al., 2007).
Smell distraction: There have been trials in distracting seabirds during the setting of
the fishing lines with a smell and therefore mislead them from the hooks. This smell
was created by fish oil retrieved from non-target fish bycatch (Pierre & Norden, 2006).
19
However the uncertain effects on the marine ecosystem, the effect of oil in bird feathers
and the chance of habituation seemed to make this mitigation strategy not suitable for a
larger scale of fishing operations.
2.3.3 Management options
Area closures: Area closures try to avoid overlap of areas of special importance to
seabirds and high fishing pressure. It is a commonly used method also to protect
spawning fish stock, or vulnerable habitats. Therefore areas where seabirds accumulate
could be closed to fisheries. This can be a very effective strategy in reducing bait loss
by seabirds, however, the fishermen might lose income as high densities of fish
naturally attract also high densities of birds, taking away important fishing grounds
(Brothers et al., 1999). Area closures are closely related to time closures, described
below.
Time closures: Temporal closures concern either diurnal or seasonal fishing
limitations and as spatial closures they try to prevent the overlap of seabirds and fishing
vessels in high densities (Bull, 2007). For example in the Southern Ocean toothfish
(Dissostichus eleginoides) fisheries, fishing during breeding season of seabirds
(September-April) is restricted as seabirds abundance around fishing boats seemed to
be higher during the breeding season and the birds are highly vulnerable throughout the
breeding season. Furthermore the fishermen are only allowed to set their lines during
night, when fewer seabirds are following the boats (Collins et al., 2010). Managing
area and time closures demand a high level of knowledge of the environment and the
ecology (e.g. breeding and migration patterns) of the particular target and non-target
species (Bull, 2007).
20
21
3 Methods
Stomach content analysis 3.1
Data on the frequency and quantity of bait in stomachs of bycaught northern fulmars on
the Faroe Islands has been recorded since 2004. A total of 634 northern fulmars have
been accidentally caught and collected during longline fishing operations between 2004
and 2012 (Table 2). The stomach contents were sorted as natural food, bait and non-
food as marine debris. The original reason for the collection is a research project on
marine debris ingested by northern fulmars. This research is conducted by Dr. Jan
Andries van Franeker, working for IMARES (Institute for Marine Resources and
Ecosystem Studies) in the Netherlands. As for this research a spreading over the
seasons was necessary, the fishermen did not necessarily collect all birds they caught
on a single trip. Unfortunately it is therefore impossible to calculate the average number
of birds that is caught during one fishing trip.
Table 2: Sample size and distribution of northern fulmars caught accidentally during longline fishing operations on the Faroe Islands between 2005 and 2012
The northern fulmars were dissected following the standard protocol for plastic in
seabird monitoring, described by Van Franeker (2004). As I am involved in the projects
searching for plastics in northern fulmars since 2011, I joined the dissection of all the
birds from the Faroe Islands, many of the birds I dissected myself, in other cases I
assisted the dissections. Before that time, dissections and analyses were performed by
Van Franeker and colleagues. We collected details on morphometric data such as the
length of the head, bill, wings and tarsus. We also noted the state of moult and down
feathers, visible fractures or wounds, as well as signs of entanglement and the colour
phase, as it can give us an indication of the origin of the birds. During the dissection we
removed the stomachs and store them frozen at -20 degree Celsius for later analysis.
Year 2004 2005 2006 2007 2008 2009 2010 2011 2012 Total Number of birds 43 238 47 0 46 38 11 198 13 634
22
For the stomach content analysis the stomachs were thawed again. Since 2011 the
content analysis of all the Faroese northern fulmar stomachs was done by a colleague
and me. We rinsed the stomach contents over a 1 millimetre sieve with cold water. The
wet stomach content was weighed and the number of bait items was counted, weighed
and categorized as fish, squid or whelk.
Bait is easily distinguished from natural food as being clearly cut pieces of fish, squid
or whelk (Figure 6). As the birds drown while scavenging on bait, bait pieces are very
fresh and show little signs of digestion. An exception forms the opercula of whelks, the
hard, calcareous “house door” which is attached to the foot of the gastropod and
protects it against desiccation and predation (Figure 8, bottom row centre). This part of
the snail body takes much longer to be digested in seabirds and therefore might stay
longer in the gastrointestinal tract than softer, fleshy parts. As whelk does not belong to
the natural prey of northern fulmars all opercula found in stomachs have been assigned
as being bait.
Figure 8: Examples of bait found in the stomachs of northern fulmars, accidetally bycaught on the Faroe Islands (Photo‘s: J.A. van Franeker)
23
Analysis of the economic loss, simulations 3.2
and costs of mitigation
From market and literature research, data is collected to estimate the financial loss of
Faroese fishermen due to bait-stealing seabirds. Therefore information on catch rates,
market prices and the number of birds following a vessel was collected. With the data
collected, different simulations were developed to create a broad range of scenarios
with minimum-maximum estimations. Different mitigation measures were evaluated
and recommendations were made concerning their suitability regarding costs and
fishing efficiency.
3.2.1 Value of a fish
To calculate the financial loss experienced by a Faroese fisherman, it is important to
know what a single lost piece of bait means to the success of catching a fish. In general
it can be assumed that every single piece of bait that is scavenged by a seabird means a
lost chance for the fishermen to catch a fish on this specific hook. Therefore the
reduction of bait loss is crucial to increase the fishing efficiency of each individual set
of line that is deployed. On the market (and in literature), catches are normally counted
in kilograms per species and catch. However for this research it is necessary to know
what the loss of an individual fish means to the fisherman in economic terms. The
landings, expressed in kilogram have to be transformed in the numbers of fish caught
per landing. The average size of the fish when caught can be found in the literature.
Furthermore the value per kilogram fish and species is needed to calculate the price per
individual fish. When no information on the relation of size to kilogram was available,
standardized regressions were used to calculate from fish length to mass. It is important
to note that these numbers represent the size and weight when most fish is caught, not
the numbers of general fish assemblages in the ocean. So first the price per fish species
has to be calculated. The following formula combines the factors mentioned above:
𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑃𝑃𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴 𝑝𝑝𝐴𝐴𝐴𝐴 𝑓𝑓𝑃𝑃𝑓𝑓ℎ (𝐷𝐷𝐷𝐷𝐷𝐷) = 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑚𝑚𝐴𝐴𝑓𝑓𝑓𝑓 (𝑘𝑘𝐴𝐴) ∗ 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑝𝑝𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴 𝑝𝑝𝐴𝐴𝐴𝐴 𝑘𝑘𝐴𝐴 (𝐷𝐷𝐷𝐷𝐷𝐷)
24
The Faroese longline fishery is a multispecies fisheries, meaning that fishermen target
not a single species but normally try to catch different species of the same size and
habitat. The average price per fish must be related to the percentage of the share per
fish species caught by longliners. Therefore the following formula is used correcting
for the different market prices per species:
𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑝𝑝𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴 𝑝𝑝𝐴𝐴𝐴𝐴 𝑓𝑓𝑃𝑃𝑓𝑓ℎ = 𝑆𝑆𝑆𝑆𝑚𝑚 𝑜𝑜𝑓𝑓 (𝑝𝑝𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴 𝑝𝑝𝐴𝐴𝐴𝐴 𝑓𝑓𝑝𝑝𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴𝑓𝑓 (𝐷𝐷𝐷𝐷𝐷𝐷) ∗ 𝑝𝑝𝐴𝐴𝑜𝑜𝑝𝑝𝑜𝑜𝐴𝐴𝑝𝑝𝑃𝑃𝑜𝑜𝑝𝑝 𝑜𝑜𝑓𝑓 𝑃𝑃𝐴𝐴𝑝𝑝𝑃𝑃ℎ)
Knowing the average number of baits that northern fulmars scavenge and the economic
loss of a single fish, simulations can be made with additional data from literature
research regarding the estimated abundance of seabirds and different fishing
efficiencies that might occur. Therefore the data were combined in the following
formula
𝑃𝑃𝑜𝑜𝑝𝑝𝐴𝐴𝑝𝑝𝑝𝑝𝑃𝑃𝐴𝐴𝑃𝑃 𝑃𝑃𝑜𝑜𝑓𝑓𝑓𝑓 (𝐷𝐷𝐷𝐷𝐷𝐷; 𝑝𝑝𝐴𝐴𝐴𝐴 𝑝𝑝𝐴𝐴𝑃𝑃𝑝𝑝) = �(𝑥𝑥 ∗ 𝐴𝐴) ∗ 𝑏𝑏� ∗ 𝑦𝑦
whereby x is the variable number of birds around a vessel and y the fishing efficiency
defined as the percentage of hooks that actually catch a fish. In this formula, a is the
average number of bait that is found in bird stomachs and b is the average price per
fish. The two latter ones are calculated in this research while x and y are variable.
These simulations display the economic loss an individual vessel experiences during
one single trip.
3.2.2 Costs of mitigation
The costs for various mitigation measures were, when available, collected from
literature research or by contacting industrial producers and collected in one
overviewing Table. Here, when the information was available, several factors are
summarized:
• the type of mitigation measure
• the fishery (demersal or pelagic longlining)
• the reduction in seabird mortality or bait loss noted (varying per reference)
• the costs (numbers or descriptions)
• the region where the fishery takes place
• the seabirds associated
25
• the reference
As often no exact number was given, all identified estimations regarding the costs of
the mitigation strategy were categorized into five categories from 1=low to 5=high.
This data, together with the efficiency of reducing bycatch (in percentage) was put into
a graph to visualize the trade-offs of the different methods and to identify the most
efficient mitigation strategy regarding costs and efficiency. This analysis is to identify
all advantages and disadvantages, resulting in recommendations for the most suitable
mitigation measures for the Faroe Islands.
Ethical issues 3.3
All birds collected were accidental bycatch from longline boats; none of them was
killed intentionally for this study. The dissections were conducted by IMARES in the
Netherlands under permission by the Dutch Ministry of Economic Affairs (Permission
FF/75A/2013/22).
26
27
4 Results
Stomach content analysis 4.1
4.1.1 Catch rates per tour
During 81 fishing trips between 2004 and 2012, 634 birds were collected for research
purposes. Fishing vessels are mostly out at sea for a single day sometimes a few
consecutive days. As the date is the only data collected in this thesis trips are defined as
one day. Figure 9 shows the distribution of trips throughout the years and months. Most
trips when birds were collected were during the first half of the year. January was
sampled during 6 years while in the second half of the year most months were only
sampled once or twice (June to December), mainly in the year 2005. This year has the
best coverage over all the month except for November. No birds were sampled in
November during 2004 and 2012. In 2006 and 2012 only January was sampled and in
2009 March was the only month when birds were collected.
0
2
4
6
8
10
12
14
16
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Num
ber o
f trip
s (n=
81)
Month
2012
2011
2010
2009
2008
2006
2005
2004
Figure 9: Number and distribution of fishing trips where northern fulmars were caught and collected between 2004 and 2012
28
4.1.2 Seabird mortality
As mentioned in the methods, we cannot assume that the birds collected during one trip
equals the number of birds caught on this day by this vessel or on the other hand that
fishermen started collecting birds only when they caught sufficient birds. Therefore an
average number of birds caught during these trips cannot be defined. The numbers in
Figure 10 present the birds that were collected by the fishermen. In October 2005, a
maximum of 44 birds were collected during one trip. Most of the birds were collected
during winter and spring reflecting the high numbers of fishing trips presented above.
4.1.3 Bait in seabird stomachs
In 5 out of 634 northern fulmars collected there is no data available about the amount of
bait in the stomach, so they were excluded from the bait calculations. In total, 1,308
pieces of bait were recorded in the remaining 629 birds. At the point they got
entangled, the birds had an average of 2.1 baits in their stomach weighing in average
32.2 gram. The maximum number of bait found in one bird was 11 pieces, weighing
168.6 gram. 142 birds did not have any identifiable bait in their stomachs. The
distribution of the number of baits per bird is shown in Figure 11. For modelling
0
20
40
60
80
100
120
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Num
ber o
f bird
s (n=
634)
Month
2012
2011
2010
2009
2008
2006
2005
2004
Figure 10: Distribution of northern fulmars caught in Faroese longline fisheries per month and year
29
purposes in this study it is assumed that the average of 2.1 pieces bait per bird is
representative for all northern fulmars associated with a longlining fishing vessel.
Figure 11: Count of baits found in northern fulmar stomachs between 2004 and 2012
Baits were defined as either fish, squid or whelk. In most cases the identification to
species level was impossible. In many cases there was a combination of different bait
types found in individual birds. The main bait that was found in stomachs was fish,
followed by squid and a low percentage of whelk, see Figure 12.
0
20
40
60
80
100
120
140
160
none 1 2 3 4 5 6 7 8 9 10 11
Num
ber o
f bird
s (n=
629)
Number of bait in stomachs (n=1308)
Fish 65%
Squid 28%
Whelk 7%
Figure 12: Distribution of bait types found in the stomachs of northern fulmars caught accidentally in longeline fisheries
30
During the 81 trips, 1,308 pieces of bait were collected in the stomachs of the birds
caught. This equals a minimum of 16.1 baits per tour that are lost to seabirds. The
average number of baits stolen varies per month (Figure 13) and was high during the
breeding season with a maximum of an average of 3.9 and 3.8 baits per bird in June and
August respectively even though sample size was low in this period of time. For
November no birds were available.
Figure 13: Average number of baits per month in northern fulmar stomachs in comparison with the number of seabirds caught in this month
The average bait loss from 2004 to 2012 is presented in Figure 14. Over the whole
period a slightly upward trend can be observed, however in 2012 a sharp increase of the
average number of baits ingested is recorded.
0
20
40
60
80
100
120
00.5
11.5
22.5
33.5
44.5
Jan Feb Mrt Apr Mei Jun Jul Aug Sep Okt Nov Dec
Num
ber o
f bird
s cau
ght
Aver
age
num
ber o
f bai
ts
Month
Average number of bait Number of birds
31
Figure 14: Average bait loss and caught northern fulmars between 2004 and 2012
Calculation of economic loss 4.2
The economic loss of the fishermen is difficult to calculate, it has been tried only once
before by Gandini and Frere (2012). It is a combination of several factors that need to
be considered when approaching this issue and that can vary during every single fishing
trip conducted. First of all, there is the piece of bait that gets lost. In the worst case
every lost piece can equal a lost fish. However, also the behaviour of the line can play a
role when birds get entangled. Every bird attached to the lines can change the weight
and the sinking rate of the lines. When this leads to a suboptimal deployment on the
seafloor, a decrease in the catch rate of the target species can be the consequence.
Calculating the costs of a lost fish
From literature research the five most important fish species (in wet mass) have been
identified (Hagstova Føroya, 2015b) and are used in Table 3. The size of the fish is the
average size of fish in longline catches described in the literature. Together with the
data collected on individual size and mass per species and the prices for fish the
following formula was applied for each species separately:
𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑝𝑝𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴 𝑝𝑝𝐴𝐴𝐴𝐴 𝑓𝑓𝑃𝑃𝑓𝑓ℎ (𝐷𝐷𝐷𝐷𝐷𝐷) = 𝑚𝑚𝐴𝐴𝑓𝑓𝑓𝑓 (𝑘𝑘𝐴𝐴) ∗ 𝑝𝑝𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴 𝑝𝑝𝐴𝐴𝐴𝐴 𝑘𝑘𝐴𝐴 (𝐷𝐷𝐷𝐷𝐷𝐷)
0
50
100
150
200
250
00.5
11.5
22.5
33.5
44.5
5
2004 2005 2006 2007 2008 2009 2010 2011 2012
Num
ber o
f biir
ds c
augh
t
Aver
age
num
ber o
f bai
ts
Years
Number of birds Average number of bait
32
The results of these calculations are also presented in Table 3 as “Price (DKK) per fish”
Table 3: Data on the average size of different fish species when caught, the calculated mass per individual fish, the average prices (in DKK) per kilogram fish and the calculated price per individual fish and species
The percentage of fisheries catch data is provided in Table 1 and summarized in Figure
15. This is important as the Faroese fisheries is a multispecies fishery and therefore the
caught proportion of each species should be considered.
Species Size
range (cm)
Mass per ind.
(kg)
Price per kg (DKK)
Price (DKK) per fish
References
Cod 45-85 4 14.3 57.2 Valtýsson, 2015; Magnussen, 1996; Syntesa, 2014; Hagstova Føroya, 2015a
Haddock 50-65 2 14.6 29.2 Valtýsson, 2015; Syntesa, 2014; Hagstova Føroya, 2015a
Saithe 70-110 7¹ 8 56 Valtýsson, 2015; Hagstova Føroya, 2015a
Ling 60-100 5² 10³ 50 Cohen et al., 1990; Magnússon et al., 1997; Hagstova Føroya, 2015a
Tusk 40-65 2² 7.5 15 Cohen et al., 1990; Valtýsson, 2015; Hagstova Føroya, 2015a
¹average weight calculated, using Leopold et al. (2001) regressions ²average weight calculated using Magnússon et al. (1997) regressions ³data by Hagstova Føroya, 2015a) from 07.10.2015 as no long term average was available
33
Figure 15: Species distribution in percentage caught by Faroese longline fisheries in 2014 (Hagstova Føroya, 2015b)
Considering the factors mentioned above the following formula is used and applied in
Table 4.
𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑝𝑝𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴 𝑝𝑝𝐴𝐴𝐴𝐴 𝑓𝑓𝑃𝑃𝑓𝑓ℎ = 𝑆𝑆𝑆𝑆𝑚𝑚 𝑜𝑜𝑓𝑓 (𝑝𝑝𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴 𝑝𝑝𝐴𝐴𝐴𝐴 𝑓𝑓𝑝𝑝𝐴𝐴𝑃𝑃𝑃𝑃𝐴𝐴𝑓𝑓 ∗ 𝑝𝑝𝐴𝐴𝑜𝑜𝑝𝑝𝑜𝑜𝐴𝐴𝑝𝑝𝑃𝑃𝑜𝑜𝑝𝑝 𝑜𝑜𝑓𝑓 𝑃𝑃𝐴𝐴𝑝𝑝𝑃𝑃ℎ)
Table 4: Calculation of the average price per individual fish, considering the proportion of each species in longline fishery catches
Species Price (DKK) per fish (mass*price/kg)
% share of the catch Sum
Cod 57.2 40.00 22.88
Haddock 29.2 17.80 5.2
Saithe 56 1.40 0.78
Ling 50 24.00 12
Tusk 15 6.90 1.04
Average price per fish (in DKK) 41.9
COD 40%
HADDOCK 18%
TUSK 7%
LING 24%
SAITHE 1% Other
10%
34
The average price is therefore 41.9 DKK per fish. This is the monetary value that a
fisherman potentially loses for each piece of bait ingested by a seabird and will be used
in further calculations.
Simulation of different scenarios 4.3
As there is no reliable data available on the extent of bait loss by seabirds on the Faroe
Islands, different scenarios are presented to show the ranges of impact that different
numbers of birds can have on the fishing efficiency. We have minimum numbers of
birds caught in longline fisheries and the amount of bait ingested by them. In addition
the average price of fish has been calculated. What remains unknown is the amount and
variation of hooks deployed, this would be necessary to calculate the rate of
entanglement per set of hooks. Another factor playing role is the assumption that each
lost bait equals a lost fish (equalling a fishing efficiency of 100% in undisturbed
conditions). Firstly it is not clear, how efficient longline fishing is in reality, regarding
the average use of baited hooks by the target species, however this can be changed in
different scenarios. In contrast to autoliners, where baiting occurs automatically on
board (with a baiting efficiency of ca. 90-95%; Dunn & Steel, 2001), on the Faroe
Islands hooks are baited manually ashore on a daily base, resulting in a 100% baiting
efficiency, so this factor can be neglected in further calculations. Something that cannot
be corrected for is the assumption that the specific chunk of bait which was stolen by a
bird is the one which would have attracted a target-species fish. So we have to play
with different scenarios, as we might have to assume different percentages of fishing
efficiencies. This influences the economic loss of bait to seabirds. From literature, the
number of birds following a longline fishing vessel were taken into account. Dunn &
Steel (2001) observed an average of 300 seabirds, mainly northern fulmars around
longline fishing vessels in Norway, but also reported a maximum number of 1000
birds. Also in Norway, Løkkeborg & Robertson (2002) reported 70 to 600 northern
fulmars that were following the ship.
35
Table 5: The price of the fish and the average number of baits found in northern fulmars has been calculated before, the number of birds searching for food around the vessel (x) and the fishing efficiency (y) can vary.
Therefore, taking into account the number of birds around the ship, the average number
of bait in their stomachs, the fishing efficiency and the price of one fish we can
calculate different scenarios of individual trips, where two factors are fixed (price per
fish and the average number of bait per bird) and the two other factors are variable
(number of birds around the ship and the fishing efficiency; see Table 5).
The formula to calculate the potential economic loss looks like:
𝑃𝑃𝑜𝑜𝑝𝑝𝐴𝐴𝑝𝑝𝑝𝑝𝑃𝑃𝐴𝐴𝑃𝑃 𝑃𝑃𝑜𝑜𝑓𝑓𝑓𝑓 (𝐷𝐷𝐷𝐷𝐷𝐷; 𝑝𝑝𝐴𝐴𝐴𝐴 𝑝𝑝𝐴𝐴𝑃𝑃𝑝𝑝) = �(𝑥𝑥 ∗ 2.1) ∗ 41.9� ∗ 𝑦𝑦
Now we can simulate different scenarios using the numbers that were found in
literature. The number of birds varies between 70 and 1000 and the fishing efficiency
ranges from 100% to 10% (Table 6).
Table 6: Simulation of different scenarios. Variables x and y (see Table 3) have now been replaced by numbers that estimate the number of birds searching for food around the vessel and a varying fishing efficiency.
Price of fish (DKK)
Number of birds
Average nr. bait
Fishing efficiency
Potential Loss (DKK)
41.9 70 2.1 1.0 6.159 41.9 300 2.1 1.0 26.397 41.9 600 2.1 1.0 52.794 41.9 1000 2.1 1.0 87.990 41.9 70 2.1 0.5 3.080 41.9 300 2.1 0.5 13.199 41.9 600 2.1 0.5 26.397 41.9 1000 2.1 0.5 43.995 41.9 70 2.1 0.3 2.053 41.9 300 2.1 0.3 8.799 41.9 600 2.1 0.3 17.598 41.9 1000 2.1 0.3 29.330 41.9 70 2.1 0.1 616 41.9 300 2.1 0.1 2.640
Price of fish (DKK) Number of birds Average bait/bird Fishing efficiency 41.9 x 2.1 y
36
41.9 600 2.1 0.1 5.279 41.9 1000 2.1 0.1 8.799
Following such calculation models, the possible economic impact during a fishing trip
or a part of it without any mitigation measures can range from 616 DKK assuming only
70 birds surround the vessel and a low fishing efficiency (10% of the hooks will catch a
fish) up to 88,000 DKK when 1,000 birds follow the boat and a fishing efficiency is
100%. The real economic loss will be somewhere in between these numbers and may
vary per trip, season, type of fish caught and other external factors.
Costs of mitigation 4.4
Worldwide many studies have been performed to find the best mitigation measure to
reduce seabird bycatch in longline fisheries without compromising safety and
efficiency of fishing operations. From the different studies it becomes clear that all
measures only can work under specific circumstances, such as the type of boat, gear
and fisheries, target and seabird species, weather and geographic environments. In the
North East Atlantic, northern fulmars are the seabird species most affected by
accidental longline bycatch. Beside the fact that the northern fulmar population is
supposed to be decreasing, fishermen can experience severe economic loss from bait
loss to northern fulmars. Therefore a solution for this problem is necessary. Analysing
the literature (Table 7) shows that there are many ways to reduce seabird mortality and
bait loss, however many factors as the type of fishery, the region and the associated
birds can play a role.
37
Table 7: Table of mitigation measures, their efficiencies and costs (if data available) and references
Mea
sure
Pela
gic
(P),
Dem
ersa
l (D
)
Red
uctio
n (in
bir
ds
per
1000
hoo
ks)
befo
re a
nd a
fter
Red
uctio
n in
bai
t lo
ss (%
)
Red
uctio
n bi
rd
mor
talit
y (%
)
redu
ctio
n de
scri
ptio
n
Cos
t des
crip
tion
Loc
atio
n
Seab
ird
spec
ies
Ref
eren
ces
BSL (Bird Scaring Line)
P 76 N Pacific, Hawaii Alb Boggs, 2001
BSL D very high
1,500 AU$, low ongoing
n/a Brothers et al., 1999
BSL 1.06 to 0/0.03
20/30 to 15
NE Atlantic, Norway
N. fulmar
Løkkeborg, 1998
BSL P 52 79 N Pacific, Hawaii n/a McNamara et
al., 1999
BSL D 88-100 N Pacific, Alaska
N fulmar
Melvin et al., 2001
BSL D 71-94 N Pacific, Bering Sea
N fulmar
Melvin et al., 2001
BSL D 98-100 NE Atlantic, Norway
N fulmar
Løkkeborg, 2003
BSL D cheap n/a BirdLife International, 2014
Dyed bait P 94 N Pacific, Hawaii Alb Boggs, 2001
Dyed bait 68% for squid
S Pacific, Australia n/a Cocking et
al., 2008
Dyed bait P 60 63
max 15 US$ per set. rel. inexp.
N Pacific, Hawaii Alb Gilman et al.,
2003
Dyed bait P 77 95 N Pacific, Hawaii McNamara et
al., 1999 Strategic offal dumping
D 98 great reduction
S Atlantic, Kerguelen
WC Petrel
Cherel et al., 1996
Strategic offal dumping
D 54 Indian Ocean
WC Petrel
Weimerskirch et al., 2000
Night setting P 93 98 N Pacific,
Hawaii Alb Boggs, 2003
Night setting DP 60/96 very
high widely none n/a Brothers et
al., 1999
Night setting 97 N Pacific,
Hawaii n/a McNamara et al., 1999
38
Mea
sure
Pela
gic
(P),
Dem
ersa
l (D
)
Red
uctio
n (in
bir
ds
per
1000
ho
oks)
be
fore
and
aft
er
Red
uctio
n in
ba
it lo
ss (%
)
Red
uctio
n bi
rd
mor
talit
y (%
)
redu
ctio
n de
scri
ptio
n
Cos
t des
crip
tion
Loc
atio
n
Seab
ird
spec
ies
Ref
eren
ces
Night setting D 41/85 Indian
Ocean WC Petrel
Cherel et al., 1996
Night setting D 100 S Atlantic,
S. Georgia Alb, G petrels
Ashford et al., 1995
Night setting D 100 S Atlantic,
Falklands BB Alb
Reid & Sullivan, 2004
Night setting D 81-99 Indian
Ocean
WC petrel, Alb
Weimerskirch et al., 2000
Night setting + Blue bait
P 99 100 N Pacific, Hawaii Alb Boggs, 2003
Reduce offal D mod. Initially n/a Brothers et
al., 1999
Side setting + curtain P
? To 0.01-0.002
most effective
1,000 US$ / 50US$ (bird curtain), cheap
N Pacific, Hawaii Alb Gilman et al.,
2007
Side setting D negligible Sullivan,
2004
Smell distraction
Sign. decrease
S Pacific, New Zealand
Pierre & Norden, 2006
Sp./temp. closures D unknown n/a Brothers et
al., 1999
Strategic discard P 53 86 no extra
costs N Pacific, Hawaii n/a McNamara et
al., 1999
Tube + scaring line D 0.022
3 times lower
S Ocean, Pr. Edw. Isl.
WC Petrel
Ryan & Watkins, 2002
Underwater setting tube D 0.03/0.04
to 0.01 40,000 B£ (in 1997)
NE Atlantic, Norway
N fulmar
Dunn & Steel, 2001
Underwater setting tube P 0.06 to 0 95 100
recouped after 2 trips, 4,000 US$
N Pacific, Hawaii L Alb Gilman et al.,
2003
Underwater setting tube D Rel. exp.,
5,000 US$ N Pacific, Hawaii Alb Gilman et al.,
2007
Underwater setting tube D 1.75 to
0.49 72-92 NE Atlantic, Norway
N fulmar
Løkkeborg, 1998
Underwater setting tube D 37/76
Significant decrease
N Pacific, Alaska
N fulmar
Melvin et al., 2001
39
Mea
sure
Pela
gic
(P),
Dem
ersa
l (D
)
Red
uctio
n (in
bir
ds
per
1000
ho
oks)
be
fore
and
aft
er
Red
uctio
n in
ba
it lo
ss (%
)
Red
uctio
n bi
rd
mor
talit
y (%
)
redu
ctio
n de
scri
ptio
n
Cos
t des
crip
tion
Loc
atio
n
Seab
ird
spec
ies
Ref
eren
ces
Underwater setting tube D
considerable, 20,000 US$
n/a BirdLife International, 2014
Weighted lines P 92 N Pacific,
Hawaii Alb Boggs, 2001
Weighted lines D 0.4 to
0.05 93-98 14-23% more exp. Than UW
S Pacific, New Zealand
petrels, shearw.
Robertson et al., 2006
Weighted lines D
91-100 N Pacific, Bering Sea
fulmar, gulls, shearw.
Dietrich et al., 2008
Weighted lines D 80 S Atlantic,
S Georgia
BB Alb, WC Petrel
Agnew et al., 2000
Weighted lines D 61/94-
99 S Pacific, New Zealand
WC Petrel, Sooty Shw.
Robertson et al., 2006
Weighted lines P
18 times lower
S Africa petrels, Alb
Melvin et al., 2013
It is about to find the best trade-off between the costs that the fishermen have to pay for
a specific mitigation strategy and the economic gain they can reach on a longer term
with reducing the bait loss (is this case expressed as the reduction in seabird bycatch).
The trade-off between costs and efficiency is summarized in Figure 16 showing that
most mitigation measures do have a high efficiency between 75 and 100%, except for
the line shooter that showed a low efficiency of reducing bycatch. More differences can
be observed in the costs of mitigation measures where offal regulations and Bird
Scaring Lines seem to be the cheapest variations to reduce bycatch while closures
(either temporal or spatial), the laser and tubes are placed in the higher cost categories.
As the information on costs of mitigation measures in literature is scarce the lacking
data has been estimated to provide an overview of expected costs. There is no
estimation in the literature of how much spatial and temporal closures might cost.
Therefore the costs are assumed to be high (5) as fishing areas might become closed
40
and the fishing effort has to increase to keep up with the same amount of catch.
Consequently fishing might be more time-consuming and more fuel might be
necessary. Night setting might have an serious impact on the lifestyle of Faroese
fisherman as normal fishing trips occur over day and therefore has been nominated as
being relatively high (4) in costs. Underwater tubes have been described as “relatively
expensive” (Gilman et al., 2007) or “considerable” (BirdLife International, 2014) in
costs as they urge construction adaptions on the hull of the ship. Weighted lines have
been categorized as moderate costly (3), as the single source of information states an
additional cost of 14-23% (Robertson et al., 2006). Dyed bait has been described as
relatively inexpensive by Gilman et al. (2003). Bird Scaring Lines are “cheap”
(BirdLife International, 2014) or „low ongoing“ in costs (Brothers et al., 1999), while
offal management is expected as being almost cost-free.
Figure 16: Comparison of the economic costs of mitigation measures and their efficiency in reducing bait loss and seabird bycatch
BSL
weights
closures
tubes night
offal
dyed
shooter
side
0
1
2
3
4
5
0 10 20 30 40 50 60 70 80 90 100
Cost
s (1=
low
, 5=h
igh)
Seabird bycatch reduction (%)
41
5 Discussion
In the framework of this master thesis, the suitability of stomach contents to identify
bait loss in longline fisheries was evaluated. The potential economic loss to fishermen
due to bait stealing by seabirds was simulated using various scenarios. In addition
possible mitigation measures to increase fishing efficiency and decrease seabird
mortality on the Faroe Islands were discussed.
Catch rates 5.1
Many factors influence bait loss and the suitability of different methods to avoid
seabird-fisheries interaction. Much more information is necessary to estimate a realistic
numbers of seabirds that scavenge on longline bait and the rate at which they remove
baits from hooks. In this research we calculated minimum numbers of stolen bait, but
for a realistic number, experienced fisheries observers are unavoidable, to collect data
on:
a. the number of birds around the ship during setting and hauling
b. turn-over rate (or fluctuation) of birds throughout a trip
c. the species distribution of the birds
d. the rate of stolen baits (including attempt and success rates)
e. the rate of entangled (and killed) birds
Almost all studies consulted for this thesis base their information on observers that are
on board of the vessels. Although model scenarios can be calculated, predictions would
certainly benefit from field observations.
We were also interested in the bait types and possible implications regarding a
preference for a specific bait type, however, again a lack of detailed information made
this attempt not more than a general description of what we found in our specific birds.
The mixed type of bait in single birds shows that all three bait types must have been
used during a single fishing trip. As there is no data available how the availability of
bait during the specific fishing trips was, we cannot conclude whether the northern
fulmars show selectivity in baits or the general abundance of different bait types. Again
42
fishery observers on board of the vessels could help to get a better insight in the type of
baits used on the Faroe Islands and which one are preferred by the seabirds.
During the breeding month the numbers of baits per stomach were much higher than
outside the breeding season, even though sample sizes were low in June and August.
The seasonal trend shows a pattern that also has been observed by Dunn & Steel (2001)
and can be explained by a more urgent and higher need for food during chick-rearing
times (Furness, 1987).
The annual differences however are much more difficult to analyse. The average
amount of baits in stomachs increases slightly throughout the time from one to two
pieces between 2004 and 2011, in 2012 however the number rises sharply to an average
of more than four pieces of bait per stomach. In the literature there is no data on trends
between years and many factors might influence these findings. Unfortunately 2012 is
the last year of collection so this could be either an establishing trend or an outlier.
However when looking at the dataset it appears that the 2012 data were collected in
only one trip that took place in January, so an outlier seems to be likely. Cold weather,
storms or other environmental impacts might have caused a more desperate search for
easily available food by seabirds (Camphuysen et al., 1999; Schreiber et al., 2001).
With the exception of one study, no data is available from literature regarding the
amount of baits in stomachs. Gandini & Frere (2012) found in average four pieces of
bait in black-browed albatrosses (Thalassarche melanophris) and white-chinned
petrels, so higher than in our birds (average 2.1) however their range was much smaller
(0-6) while in our birds the range was 0 to 11. Seabirds may not only steal bait during
setting of the lines, but may also ingest baits removed from lines at hauling in, and
possibly discarded together with other offal. This could lead to overestimation of the
amount of stolen baits at setting of the lines. To estimate the extent of this effect,
observational or experimental approaches on board vessels would be necessary.
However other factors may indicate an underestimation of the bait loss. It is unclear,
whether young and unexperienced birds have a lower average of baits in their stomachs
before they get entangled accidentally. Successful older birds may steal more bait
without being caught as often as young ones. It has been described that mainly young
non-breeding birds attend fishing vessels in the North Sea (Camphuysen et al., 1995).
43
Studies have shown that seabirds and especially northern fulmars rely on the fisheries,
as discards can be a major part of their summer diet (Phillips et al., 1999; Camphuysen
& Garthe, 2000). Another underestimation of bait loss which we cannot properly
account for, is that the model assumption of a ‘fixed’ group of birds around the vessel
is in fact not very realistic. We had to assume this for our ‘per trip’ modelling but in
fact it is more realistic to expect that birds come and go all the time. Thus substantially
more birds have stolen an average of 2.1 pieces of bait than the number of birds seen to
surround a vessel at a given moment.
There is concern regarding the contradictory estimates of population size and status of
northern fulmars in the North Atlantic. As mentioned in the introduction, published
qualifications for the status of fulmars range from “Least Concern” up to
“Endangered”. This might have to do with the lack of recent data of most northern
fulmar breeding populations and trends. As the population trends of northern fulmars
are under discussion at the moment, the high number of birds killed in longline
fisheries should be of concern to conservationists and policy-makers. As northern
fulmars are slow in reproduction and long-lived, Buckland (1982) indicates that 96%
adult survival is crucial to maintain the population stable. Therefore the estimation of
the MSC (2012) of 5% of northern fulmars being caught in saithe longline fishery on
the Faroe islands should be of serious concern. Changes in food availability, climate or
habitat shifts caused by policy changes (e.g. discard bans) will all have impacts on
seabird populations (Grosbois & Thompson, 2005). Therefore different effects can
influence the population size and then, bycatch can put accumulative pressure on
northern fulmars and other seabirds.
Economic loss calculations 5.2
As mentioned above, a lot of data is lacking to properly calculate the economic loss,
caused by seabirds. This might be in so far realistic, as there are many different factors
influencing the circumstances on board. Therefore a broad range of scenarios has been
provided with the least realistic minimum and maximum start and ending points, where
1,000 birds follow a vessel and the fishermen can catch a fish on literately every hook
deployed or the opposite only 70 birds that follow a vessel and a bad efficiency of the
44
hooked baits where only every tenth baited hook catches a fish. The real numbers will
be somewhere in this broad range of the loss calculated and are heavily dependent of
external circumstances as weather, season, fish availability, use of gear, habitat where
the lines are deployed, etc. The only other study that used stomach content analysis as a
tool to estimate bait loss (Gandini & Frere, 2012), used fisheries observer data in
addition to calculate the economic loss. However with the consideration of all
circumstances, this thesis might provide a useful tool for Faroese fishermen to calculate
their personal economic loss as they have a much deeper insight to the two variables
fishing efficiency and seabird abundance on a daily level.
Mitigation measures 5.3
From literature research it can be shown that there are several ideas and methods to
reduce bait loss and bycatch at the same time, some of them are still in their developing
phase, many have been tested under different circumstances and others have been
successfully implemented and enforced by policy makers.
Bird Scaring Lines have reduced the bycatch of seabirds reliably over various studies,
areas and species, especially in northern fulmars (Melvin et al., 2001; Løkkeborg,
2003). Problems with tangling of the scaring lines and the main fishing lines can be
avoided by increasing the distance of the Bird Scaring Lines and fishing lines by
increasing the height on where the Bird Scaring Line is fixed (Brothers et al., 1999).
Being relatively cheap in purchase and maintenance, they do not have any negative
influences on the target species. In Norway, fishermen used old fishing gloves to hang
on lines above the baited longlines. Their movement in the air and on the water surface
resembles the traditional tori lines and seem to have a deterrent effect on northern
fulmars that constantly stayed behind the gloves. The costs of this method are
negligible and might be a cheap and convenient alternative to other bird scaring lines
(M. Langset, personal information).
The measures proposed range in the low cost level and therefore promise an economic
gain especially on a longer term. Bird Scaring lines have been described as “cheap” by
45
BirdLife International (2014) or as initial cost of 1,500 Australian Dollars (ca. 7,600
DKK; Brothers et al., 1999) but low in ongoing costs. Even cheaper is the version of
scaring lines proposed by Norwegian fishermen, the “gloveline”. Thus using the costs
of 7,600 DKK that has been paid in Australia, even with a lowest bait loss rate
calculated here (616 DKK per trip) might pay off almost immediately after only 12
trips and much faster when seabird abundance or fishing efficiency increases.
Strategic offal discard does not create any costs (e.g. McNamara et al., 1999) and
therefore should be considered as a very cheap measure that can be implemented
immediately. The strategic discard of offal could be considered for the Faroe Islands as
it is a cheap and convenient method to reduce seabird bycatch. Different options of
either completely retain offal on board or to distract seabirds during the deployment by
discarding offal on the opposite side of the fishing operation on board are some of the
options. The first option could create problems regarding storage space and additional
weight of the boats. Distraction at the same time as deployment has been discussed
controversially, as it might attract more seabirds in general. However, it might be an
option to restrict offal dumping to times when there is no setting or hauling, not
compromising operations on board. Hooks however should be removed in any of the
options.
Weighted lines have shown good results in areas with low abundance of deep-diving
seabirds and are especially suitable for demersal longline fisheries as weight plays a
minor role in deploying the lines. Robertson et al. (2006) estimate the costs of weighted
longlines at being 14-23% higher than conventional lines, but they expect lower costs
when the demand and therefore industrial production increases. Løkkeborg (2011)
calculated that increased sinking rates not only reduce bait loss, but the time of the lines
they need to reach the bottom is much shorter than in conventional unweighted lines.
As the smell of the bait attracts most fishes during the first two hours, the short sinking
time increases the attraction of the bait to fishes and therefore the fishing rates have
been observed to be increasing.
Dyed bait showed a variable outcome in reducing bait loss to seabirds. The method
seems to be less efficient compared to other mitigation measures (Gilman et al., 2007)
and reduction in target species catch has been observed (Minami & Kiyota, 2004). This
46
method has been tested for pelagic fisheries but not in demersal, due to the higher
number of hooks used (Bull, 2007) and might therefore not be a suitable mitigation
measure for the Faroese longline fisheries.
The laser deterrent is a new method, therefore more independent trials are necessary to
test it under various circumstances. Producers claim that the system operates on its
optimum in darkness, twilight, fog and rain as the laser becomes more visible to the
birds. This could be suitable for Faroe weather circumstances, especially during the
long-lasting winters. In clear daylight weather the producers suggest spraying seawater
in the laser line to increase its visibility. However it needs to be researched whether
habituation of birds can take place after a period of time and how harmful the effects of
the lasers are to the eyes of seabirds.
Underwater setting tubes could be a good protection against bait stealing birds, even
though the literature shows varying results in efficiency. A lower efficiency was caused
by diving seabirds and these birds are not commonly known as bait scavengers around
the Faroe Islands. However the initial construction prices for the tubes are high and
procedures can get slower, decreasing the fishing efficiency.
The relative high initial costs are also apparent in side setting, laser deterrents and
weighted lines. Side setting would need some construction work and the crew members
would have to adapt to the new situation, however, Gilman et al. (2003) observed an
increased catch of the target species and after habituation by the crew, side setting did
not create any ongoing costs or discomfort for the crew.
While the line shooter seems not to be realistic because of its low efficiency, other
measures are also high in costs. For example substantial or additional temporal and
spatial closures have been recorded as being very efficient in reducing bait steal,
however, it might diminish the economic gain as attractive fishing grounds and seasons
might become restricted (Løkkeborg, 2003; Brothers et al., 1999) and the incentive to
comply with such regulations might be low (Boyce, 1996). However, as bycatch rates
are higher in breeding areas during the breeding season, this mitigation measure should
be considered, especially because northern fulmars are particularly vulnerable during
the breeding season. Mate-fidelity is strongly developed in northern fulmars. Both
partners share incubation and chick rearing (Mallory, 2006) and operate on the limit of
47
their capacities (Furness, 1987). When one of the partners is removed during the
breeding season the other partner is forced to temporarily leave the nest unattended in
order to find food or to abandon the nest to ensure its own survival, which in both cases
increases the chance of breeding failure (Chaurand and Weimerskirch, 1994). The
surviving partner may attempt to rear the chick solely which consequently has a
negative impact on its own condition. Also the chick can be in a less favourable
condition when fledging. Therefore the mortality of one mature northern fulmar can
impact the outcome of at least two other individuals during breeding season.
Night setting as a special type of temporal restrictions seems to be very efficient in the
Southern Ocean toothfish fisheries, however, on the Faroe, northern fulmars are the
major species attending longline vessels and these birds are known to also forage at
night (Furness & Todd, 1984). Most Faroese longline vessels are small and often only
go out for day trips, a change in the routine would impact the life and safety of
fishermen tremendously. Furthermore, in high latitudes this measure would affect
fishermen a lot during summer and again decrease fishing efficiency (Løkkeborg, 2011;
Bull, 2007).
48
49
6 Conclusions
This research was done in order to answer three questions. The first question was about
possible pitfalls of using the approach of stomach content analysis of bycaught seabirds
to estimate bait loss rates and whether this approach can be improved. The results and
the discussion show, that stomach content analysis can be a good addition to fishery
observer’s data, as the by-catch rate does not equal the number of bait that is lost to
seabirds. Therefore to calculate the economic loss, this data is crucial to collect, as
earlier research by Gandini and Frere (2012) also has emphasised.
The second research question addressed the economic loss that a fisherman on the
Faroe Islands might experience due to bait loss to seabirds. The data collected for this
research was not enough to calculate damage in detail, but did provide a simple model
to estimate the potential losses against which fishermen can balance costs of mitigating
measures.
The third research question focused on the suitability of mitigation measures to reduce
seabird bycatch and bait stealing and the economic loss. In this thesis a broad range of
possible scenarios shows the variability of economic impact the northern fulmars can
have on longline fisheries as costs can increase a lot (616 up to 88,000 DKK). However
this study also shows that there is a range of mitigation measures that are efficient and
affordable. Therefore the implementation of one or more of these measures can result in
a higher fishing efficiency with the higher economic benefit to the fisherman and at the
same time seabird populations could benefit as well.
This study highlights the lack of, and great need for on-board observations and at sea
trials of mitigating methods. Nevertheless, with the data provided a tool was
established that can easily be used by fishermen to calculate their own financial risk.
Even though exact numbers for costs of mitigation measures could not be revealed for
many of the mitigation measures presented, this thesis showed options that are low in
costs and are still capable in reducing bait loss and seabird mortality.
The Bird Scaring Lines seem to be the most convenient primary mitigation measure
that could be supported by other, secondary measures as strategic discard and weighted
50
lines. If these measures do not lead to the expected increase in fishing efficiency other
option should be considered as temporal and spatial closures. Those should be
implemented carefully to maximise seabird (and bait) protection but not compromise
the fishing options too much. In this case especially the breeding season and the space
around colonies should be considered for closures as research (including this one) has
shown higher numbers of bait stealing by seabirds during the breeding season. To
evaluate the success rates, again fisheries observers are an essential way to gather data
on:
a. the fishing efficiency with or without mitigation measures
b. factors contributing to different bycatch rates (weather, daytime,
seasons, etc.)
Together with such data, scientific-based improvements could be realized and tested. It
is important to bear in mind that implementation and compliance are easier, when
scientists, industry and government collaborate (Cox et al., 2007). A good stakeholder
involvement and the guidance throughout the process are crucial to make sure that
fishermen and nature both can benefit from mitigation measures to avoid bait loss. In
the Southern Ocean, the Commission for the Conservation of Antarctic Marine Living
Resources (CCAMLR) has been successful in implementing several mitigation
measures to reduce seabird bycatch. This shows that international cooperation, even on
a very large scale can improve the situation and should be motivating Faroese policy
makers to stimulate fishermen to use mitigation measures. Funding selected options of
mitigation with associated research on economic and ecological efficiency could prove
rewarding for the future Faroese fishing fleet.
51
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