AquaPark Panabo Stakeholders meeting interim results AquaPark – Norad funded project Planning and...

AquaPark Panabo Stakeholders meeting interim results

AquaPark – Norad funded projectPlanning and management of

aquaculture parks for sustainable development of cage farms in the

Philippines


TROPOMOD modelling of aquaculture zones

Chris CromeyMap and Marine Ltd

Out put from AquaPark

Aquapark Project Partners–Bureau of Fisheries and Aquatic Resources–Akvaplan-niva AS–Map and Marine Ltd



Model assumptions


Simulation

TROPOMOD modelling approach

3 important aspects:

1.How severe is the impact – what is the maximum impact underneath cages?

2.How far to the boundary of the impact? (Allowable Zone of Effect)

3.How can husbandry practices be optimised to use the zone most productively?

Objectives

Predict if impact is SEVERE underneath cages

as shown by this deposition footprint

Zone colour

Predict distance to boundary of MODERATE impact

Zone colour Edge of Park

Maintain enough spacing between cage rows so that remediation of sediments can take place – impact should be LOW between rows in each zone

Maintain enough space between cage rows to prevent reduction of currents by high aggregation of cages

Zone colour

TROPOMOD modelling Approach

Encourage careful feeding, so that there is less waste feed and less wastage of money

Encourage better quality feed: Feed digestibility is increased Less feed is needed Better quality feed also breaks up less, so more goes to growth

Distance between parks

Prevent overlap of impact by predicting the extent of the zones – e.g. 600 m between zones for this site

0 200 400 600 800Scale (m )

TROPOMOD modelling Approach


Panabo sediment trap model validation studies

Objective – to measure flux (deposition) of waste feed and faeces under cages and compare with model predictions – this helps us to verify the model predictions and test different scenarios

Sediment traps were deployed in Spring 2010 survey:

One transect for Milkfish (0 metres from cage, 10 m and reference)

One for Grouper (0 metres from cage, 10 m and reference)

Chris Cromey – EMMA2 project modeller using data from Akvaplan and BFAR survey teams


Sediment trap model validation study – method for deploying sediment traps

75 cm

H:D = 5:1 ratio

Sea bed

1. Deploy traps

2. Retrieve, filter, dry solids

3. Calculate observed flux

(total waste feed and faeces in traps = grams per m2 bed per day)

4. Compare with TROPOMOD model

Cage

Current


TROPOMOD model – method• Cage positions were obtained from recent

Google Earth image

• Feed ration for cages obtained from AquaPark production survey

• Production survey results summarised to include modelling of different stages of Milkfish monoculture (starter, grower and finisher), as well as other species (Milkfish-Siganid polyculture, Grouper, etc.)


TROPOMOD model – method• Settling velocity of feed obtained from EMMA2

project pellet break up experiments and PHILMINAQ project experiments

• Settling velocity of Milkfish faeces from PHILMINQ project

• Depth obtained from BFAR surveys

• Uneaten feed (27%), digestibiity (49%) and water content (9%) – data from PHILMINAQ project


TROPOMOD model – method• Current meter data from BFAR surveys used

• TROPOMOD set up with information and used to predict flux of waste feed and faeces (grams per m2 bed per day) for Panabo Aquaculture park


TROPOMOD predicted flux (deposition) of waste feed and faeces for Panabo

The colours show different amounts of flux

Sediment trap transects:

Grouper (traps are in 6 m depth)

Milkfish transect (traps are in 27 m depth)Reference traps

Model predictions

Higher flux and predicted impact in the inshore areas


Milkfish sediment trap transect

Problem – cage locations taken from recent Google Earth image and trap locations taken from survey do not match as station M0m should be at cage edge, and M10m should be 10 m from cage

Solution – make minor adjustments to cage/station positions in model so they match

Two stations (three traps at each)

Feed ration = 50 kg per cage per day


Grouper sediment trap transect

These cages are in shallower water and feed ration is 10 kg per cage per day, which is less than for Milkfish monoculture

Two stations (three traps at each)


Milkfish – comparison of observed flux and predicted

For both the 0 m and 10 m stations, the model slightly over-predicted flux

Note the variation between traps at the same station

Traps are adjusted for background sedimentation


Grouper – comparison of observed flux and predicted

Model predictions of flux were satisfactory for Grouper

Note the variation between traps at the same station

Traps are adjusted for background sedimentation


All sediment trap data collected by Cromey et al. at SAMS

Panabo measurements were less than 20 g m-2 d-1, which is at the low end of measurements taken


Conclusions and next steps

TROPOMOD predicted flux satisfactorily for Grouper, but over-predicted for Milkfish – we will look at this more carefully after refinements

Modelling of the whole park showed higher impact in the inshore areas, where the depth is shallower and dispersion is lower

Modelling the whole park requires care, as cage locations and feed inputs vary widely across the park depending on the source of data – for management scenarios, some randomness can be introduced to account for this


Conclusions and next steps

Next steps are to model the park by organising species into zones

Identify areas for oysters and seaweed

Further refinements of the modelling are needed, incorporating as much information from the Spring 2010 surveys as possible

AquaPark Panabo Stakeholders meeting interim results AquaPark – Norad funded project Planning and...

Documents

Transcript of AquaPark Panabo Stakeholders meeting interim results AquaPark – Norad funded project Planning and...