Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment...

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Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September 2005

Transcript of Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment...

Page 1: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Stock assessment, fishery management systems, and the FMSP Tools

-- Summary --

FMSP Stock Assessment Tools

Training Workshop

Bangladesh

19th - 25th September 2005

Page 2: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

The management context

The legal regime• Domestic laws• International agreements

Management approach to uncertainty

• Precautionary or adaptive management? Or both?

Management scope• Single or multi-species?• Ecosystem approach?

Property rights• Use rights?• Control rights?

Stakeholder roles in management

• State or community control?• Co-management?

Fishery scale• Industrial or artisanal?• Economically important?

Management capacity• Technical skills, staff, funds?

Sections 1.1 and 2.1 – 2.4

Fishery Policy

Define management intentions• Policy goals and operational objectives (biological,

ecological, economic, social, other sectors)Section 2.5.1

Stock assessment process

Data/Inputs

Intermediate parameters

Indicators Reference points

Management advice in terms of risk,

allowing for uncertainty

Chapters 3 and 4 and Parts 2 and 3

Management process

Fishery Management Plan

Define management standardsFor each operational objective:• Conceptual reference points

(target, limit, precautionary)• Indicators • Technical reference points

Set management measures• Decision control rules defined by

reference points and harvesting strategy• Management strategy, comprising

one or more control measures (inputs; outputs; technical, ecological etc)

Monitoring Control and Surveillance

Sections 2.5.2 – 2.5.5

Figure 1.1

A framework for fishery management (FTP 487)

Page 3: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

The new international legal regime

1992 Convention on Biological Diversity

Chapter 17 of UNCED’s Agenda 21

1995 UN ‘Fish Stocks Agreement’

1995 FAO Code of Conduct for Responsible Fisheries

2002 Johannesburg World Summit on Sustainable Development (WSSD)

Section 1.1

Page 4: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Examples of goals and op. objectives (3/3)

Section 2.3.1

Goals Operational Objectives

Biological To maintain the target species at or above the levels necessary to ensure their continued productivity

To maintain the stock at all times above 50% of its mean unexploited level

Ecological To minimise the impacts of fishing on the physical environment and on non-target (bycatch), associated and dependent species

To maintain all non-target, associated and dependent species above 50% of their mean biomass levels in the absence of fishing activities

Economic To maximise the net incomes of the participating fishers

To stabilise net income per fisher at a level above the national minimum desired income

Social To maximise employment opportunities for those dependent on the fishery for their livelihoods

To include as many of the existing participants in the fishery as is possible given the biological, ecological and economic objectives listed above

Page 5: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Indicators and reference points

Set indicators and reference points for each operational objective

An indicator is a specific state, or variable, which can be monitored in a system such as a fishery to give a measure of the state of the system at any given time (Cochrane, 2002)

A reference point is an estimated value derived from an agreed scientific procedure and/or an agreed model which corresponds to a state of the resource and/or of the fishery and can be used as a guide for fisheries management

Indicators and ‘RP’s should be used in combination to express the operational objectives in ways that can be measured in quantitative fisheries assessments.

Section 2.5.2

Page 6: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Catch

Fishing effort Stock size (biomass)

Catch

Fishing effort

Catch per unit effort (CPUE)

or

Stock size (biomass)

Long term (equilibrium) relationships

between Catch, Effort and Stock size Indicators

(not directly related!)

Page 7: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Risk of alternative reference points

Size ofCatch

Amount of Fishing

Maximum Catch - FMSY

Fcrash riskier

Point at which species

becomes extinct

Page 8: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Target or limit reference points?(defining the objectives and control rules)

Target RP - aim here, slightly above or below both OK

Indicator X

Limit RP - avoid danger zone below here

Indicator X

E.g. Catch rateE.g. Catch rate E.g. spawning stock size E.g. spawning stock size

Page 9: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

BMSY Stock size this year

FMSY

If Bnow < BMSY, no fishing allowed next year (danger zone)

Fishing mortality rate to be allowed next year

If Bnow > BMSY, fishing allowed at rate of FMSY next year

Decision control rules – a simple example

Section 2.3.3

Page 10: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Precautionary reference points

Such points were adopted in response to the UN Fish Stocks Agreement (see point 5 of Annex II), to help make sure that the LRPs are avoided.

Define the point at which managers should take action, to avoid the LRPs being reached.

The distance by which the precautionary point is removed from the LRP is usually set according to:• the uncertainty in the data • and the risk tolerance of the manager.

Section 2.3.4

Page 11: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

And ‘precautionary’ reference points...

Limit

RP

Indicator X

Take action at the Precautionary RP to avoid the risk of getting to the Limit RP

Precautionary

RP

Page 12: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Setting reference points allowing for uncertainty and risk

Blim

(BMSY)

Bpa

(%ileBMSY)

Low risk Bpa at ~90th percentile of Blim distribution

Page 13: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Blim

(BMSY)

Bpa

(%ileBMSY)

Higher risk Bpa at ~75th percentile of Blim distribution

Setting reference points allowing for uncertainty and risk

Page 14: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Management measures

1. Input controls (fishing effort restrictions)2. Output controls (catch limits)3. Technical measures (size limits, closed seasons, closed

areas etc) 4. Ecological and integrated management

Input and output controls often vary between years, depending on harvesting strategy and state of stock

Technical measures usually fixed, or updated every few years based on long-term assessments

Sections 2.3.5 and 5.4

Page 15: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Phase I

Where are you now?

Phase II

Where do you want to be?

Phase III

How are you going to get there?

Time

Phase IV

How will you know you are there?

Plan

Do

ReviewNew plan

Do

ReviewNew plan

etc

Process for developing a management plan

See new guidebooks from FMSP project R8468

Page 16: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Summary of the management plan

Purpose Goals Objectives Management Standards

Management Measures

Indicator Reference Point

Management Measures

Decision Control Rules

Biological

Ecological

Social

Economic

How to quantify the goals and objectives

How to achieve the goals and objectives

Phase II

Where do you want to be?

Phase III

How are you going to get there?

Page 17: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Part 2 - The stock assessment process

Collecting fishery data

( Estimating intermediate parameters )

Estimating the current status of the fishery (performance indicators)

Estimating technical reference points

Providing management advice

Monitoring and feedback

Chapter 3

Page 18: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Stock assessment – collecting fishery data

1. Catch, effort and abundance (CPUE or survey-based or fishing experiments)

2. Catch compositions (length and/or age frequencies to estimate indicator F)

3. Other biological data (maturity, fecundity etc)

Section 3.2

Page 19: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Estimating intermediate parameters

Individual growth rates of fish (e.g. by LFDA)

Population growth rate and carrying capacity (e.g. CEDA)

Natural mortality rate (e.g. by Pauly equation)

Exploitation pattern / gear selectivity (from LF data)

Catchability (e.g. by CEDA)

Maturity and reproduction (from biological samples)

Stock and recruitment (usually from VPA)

• Not of direct value, but used as inputs to fishery assessments

• Not constants, may vary over time (e.g. q, K etc)

• Values will usually be uncertain, so use sensitivity tests

Section 3.3

Page 20: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Biomass dynamic or analytical?

Biomass dynamic models like Schaefer surplus production model used in CEDA and ParFish• relate fishery outputs (catch) directly to inputs (effort)• Useful where fish are hard to age – used to set quotas and effort

Analytical models used in ‘Yield’ and other ‘per recruit’ and dynamic pool approaches• include intermediary processes, both biological and fishery (e.g.

from LFDA)• may be length-based or age-based• Needed for management advice on size limits, seasons etc

Neither approach is more right or wrong than the other – they are just based on different models and assumptions

Section 3.1.3

Page 21: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

The analytical

stock assessment

approach using LFDA

and Yield

LFDA

Intermediate parameters

L∞, K, t0 (growth)

Z ( - M ) Fnow(Eq)

Biological data, management controls (size limits, closed seasons etc)

Compare to make management advice on F

e.g. if Fnow > FMSY, reduce F by management controls

if Fnow < FMSY, OK

Yield

Per recruit

Fmax F0.1 F%SPR

With SRR

FMSY Ftransient

Data / inputs

Assessment tools

Indicators

Reference points

Management advice

Length frequency data

Figure 4.1

Page 22: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

The CEDA stock

assessment approach

(DRP / biomass dynamic

model)

Figure 4.5 Section 4.5

CEDA

Intermediate parameters

r, K, q

Bnow

Current catch / effort data

Compare to make management advice on effort or catches

Data / inputs

Assessment tools

Indicators

Reference points

Management advice

Catch / effort time series

BMSY fMSY MSY

fnow Cnow

Page 23: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

The ParFish stock

assessment approach

Figure 4.10 Section 4.6

ParFish

Intermediate parameters

r, K, q

Current catch / effort data

Data / inputs

Assessment tools

Indicators

Reference points

Catch / effort time series

fnow Cnow

Stock assess’t interview data or other priors

Preference interview data

ParFish

flim Clim

Management advice on effort or catch controls, in terms of limit and target levels. Targets (fopt,Copt) incorporate the preferences of resource users. Limits are based on the risk that B will be reduced below a specified % of K.

fopt Copt

Management advice

Bnow

Page 24: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

What do the different FMSP stock assessment tools estimate? (Table 5 of new guide)

Parameters estimated Available FMSP tools Type Parameters

LF

DA

Yie

ld

CE

DA

Pa

rFis

h

Em

pir

ica

l m

eth

od

s

Be

ve

rto

n

an

d H

olt

in

va

ria

nts

r, K, q (production model) x x K, Linf, t0 (von Bertalanffy growth) x M (natural mortality rate 1) x x

Intermediate

Z (total mortality rate) x YPR / BPR (yield / biomass per recruit) x Yield / biomass (absolute, equilibrium 3) x Bt (biomass in year t) x 2 x x Nt (numbers in year t) x 2 x Feq (fishing mortality rate, Z-M) x

Indicators

CPUA (catch per unit area) x MSY, fMSY, BMSY, FMSY x x x Fmax, F0.1, F0.x, F%SPR (per recruit) FMSY, F%SSB, Fcrash (absolute 3) Ftransient (risk-based)

x x x

flim, Clim (risk-based, biological limits) fopt, Copt (adjusted for ‘preferences’)

x x

Reference points

Fmax (max yield per recruit) FMSY (max absolute yield 3)

x x

Page 25: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Which tools can be used to provide advice for different management measures

(Table 6 of new guide)

Management measures

Bio

log

ical

st

ud

ies

Yie

ld

CE

DA

Par

Fis

h

Em

pir

ical

m

eth

od

s

Bev

ert

on

an

d H

olt

in

vari

ants

Fishing effort (‘input’) controls, e.g. limited vessel licensing x1 x x x2 x1 Catch (‘output’) controls, e.g. quotas or ‘TACs’ x3 x x x2 x3 Closed seasons x x x Changing size at first capture (e.g. with minimum legal mesh size or fish size regulations)

x x x

Closed areas x x x 1 In combination with LFDA or some other method of estimating current fishing mortality rate. 2 Per unit area. 3 If biomass also known.

See also Section 2.5.5 in FTP 487

Page 26: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Data collection training

Why collect data?

Useful references on data collection

------------------------------------------------------------------------------------

Data commonly used in stock assessments (e.g. using FMSP tools)

Data needs of the different SA approaches and FMSP tools

------------------------------------------------------------------------------------

Data collection methods (C/E, LF, biological, ParFish)

System design

Sampling design

Data forms

Database systems

Page 27: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Data needs of the different approaches / tools

Analytical approach (LFDA / Yield) (See FTP 487, Tables 4.1 & 4.3)

• Catch composition data (either from length frequency data – LF, or ageing studies)

• Biological data (e.g. size at maturity)

• Management advice can be produced from just one seasons’ sampling (e.g. from a short time-series sample of LF and biological data)

• But note some reference points also need long-term Stock-Recruit relationship

Biomass dynamic approach and depletion modelling (CEDA)• Multi-year time series of catch and effort data, or catch data with a

secondary index of abundance (e.g. from a survey)

• Short-term time series of C & E for depletion modelling of N0 and q

ParFish approach• Uses C/E and/or abundance data as with the other biomass dynamic

models

• Due to Bayesian formulation, can also add other sources of information to improve the analysis, e.g. where few or no C/E data are available, and to ‘tune’ the outputs to local users preferences

Page 28: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

Data collection - Discussion questions

• What data do you have already that could be used for stock assessment? In FRSS or in local management units?

• How are catch and effort estimated? How reliable are the data?• What effort measures are used for different gear types? Would they

provide useful, unbiased indicators of abundance?• Do you have any routine survey data that could provide abundance

estimates (time series)• Do you collect length frequency or age frequency data? How often?

For what species, what sample sizes?• Do you have biological data needed for analytical methods?• How could national (e.g. FRSS) and local management data

collection systems be integrated, especially in inland fisheries? Are any data collected in both?

• What other data should be collected, besides C/E, LF, biological?

Page 29: Stock assessment, fishery management systems, and the FMSP Tools -- Summary -- FMSP Stock Assessment Tools Training Workshop Bangladesh 19th - 25th September.

The management context

The legal regime• Domestic laws• International agreements

Management approach to uncertainty

• Precautionary or adaptive management? Or both?

Management scope• Single or multi-species?• Ecosystem approach?

Property rights• Use rights?• Control rights?

Stakeholder roles in management

• State or community control?• Co-management?

Fishery scale• Industrial or artisanal?• Economically important?

Management capacity• Technical skills, staff, funds?

Sections 1.1 and 2.1 – 2.4

Fishery Policy

Define management intentions• Policy goals and operational objectives (biological,

ecological, economic, social, other sectors)Section 2.5.1

Stock assessment process

Data/Inputs

Intermediate parameters

Indicators Reference points

Management advice in terms of risk,

allowing for uncertainty

Chapters 3 and 4 and Parts 2 and 3

Management process

Fishery Management Plan

Define management standardsFor each operational objective:• Conceptual reference points

(target, limit, precautionary)• Indicators • Technical reference points

Set management measures• Decision control rules defined by

reference points and harvesting strategy• Management strategy, comprising

one or more control measures (inputs; outputs; technical, ecological etc)

Monitoring Control and Surveillance

Sections 2.5.2 – 2.5.5

Figure 1.1

A framework for fishery management (FTP 487)