Use of environmental models to simulate the spatio-temporal dynamics of tuna in New Caledonia EEZ

Transcription

1 Use of environmental models to simulate the spatio-temporal dynamics of tuna in New Caledonia EEZ Karine BRIAND, Xavier COUVELARD, Vincent FAURE Secretariat of the Pacific Community Institut de Recherche pour le Developpement PFRP PI workshop, Nov , Hawaii

2 ZoNéCo project 2007 Objectives To understand the parameters that influence the horizontal and vertical distribution of tunas at a regional scale, and use them for fishing and management purposes in New Caledonia EEZ Fine analysis of the 3D spatio-temporal variability of the ecosystem using regional models ROMS (Regional Ocean modeling system) and PISCES (Pelagic Interaction Scheme for Carbon and Ecosystem Studies)

3 Coupled models : Methodology Forcing data Winds Buoyancy Waves Tides ROMS Physical model PISCES U,V,T 1/3 SEAPODYM Tuna Ecosystemic Model ALB tuna Biogeochemical model PP, O 2 Forcing data Dust (Fe) Irradiance (Light)

4 Study Zone : The South-Western Pacific From Couvelard et al,in press

5 Simulation strategy Domain 143 E 190 E 30 S 8 S Resolution 1/3 degree ROMS-PISCES Climatological forcing fluxes (COADS) Interannual wind forcing (NCEP2) Climatological boundaries conditions (ORCA05) 10 year spin-up (Ecosystem stable after 6 years) Computation time : around 15 min/month on 20 processors

6 Mean Current : Comparisons with Drifters Data ROMS Drifters

7 Seasonal variability of Chla Surface Chl.a, µmol.l -1 PISCES Model Seawifs Summer Winter

8 Seasonal variability of Chla Surface Chl.a, µmol.l-1

9 Spatial Ecosystem And Population Dynamic Model ROMS-PISCES forcing variables (1/3 ) Bio-physical environment Mid-trophic sub-model Fishing data Primary Production, Euphotic depth Predictions 3-layer data: Temperature, currents, Oxygen Six forage components: epi-pelagic Migrant and non-migrant meso-pelagic Migrant, non-migrant and highly-migrant bathypelagic Pole-and-line: tropical and sub-tropical gears Purse seine: associated and unassociated fleets TADR tuna model Eqns for 0-3 month old juveniles: spawning, foraging, passive transport, survival, mortality, cannibalism Eqns for 1-X quarter old adults: recruitment, foraging, migrations, ageing, natural and fishing mortality Predictions Tuna spatial distributions, catch and length frequencies time series Longline: Shallow, deep, ALB C, E, LF Optimization: Preliminary sensitivity analysis Constructing cost function according to data distribution minimization, parameter estimation and errors. Estimates of model parameters Reference: Senina, I., Sibert, J., Lehodey, P. (in press). Parameter estimation for basin-scale ecosystem-linked population models of large pelagic predators: Application to skipjack tuna.

10 Methods Low resolution global data (ORCA2-PISCES) SEAPODYM stretch grid (ZEE Zoom) High resolution regional data (ROMS-PISCES)

11 Methods We focus on the South Albacore stock & Stretched grid is not yet available we saved computational cost reducing the zone the South Pacific 1 step: 2 deg optimized South Pacific Simulation Biologic parameters estimates Fisheries selectivity and catchability estimates 2 step: Blending of low resolution South Pacific ORCA2-PISCES output With high resolution Southwest Pacific ROMS-PISCES output. Focus on New-Caledonia EEZ

12 Blending of Models: ROMS>ORCA2 ROMS vs ORCA2 forcings ORCA2 T, UV ORCA2 PP ORCA2 O2 ROMS T, UV ROMS PP ROMS 02

13 Blending of Models: ROMS>ORCA2 To evaluate ROMS mesoscale activity impact on forage 2 forage runs were realized: One reference run with ORCA2 data interpolated on a 1/3 seapodym grid One run with MIXED ORCA2 & ROMS data interpolated on a 1/3 seapodym grid

14 Blending of Models: ROMS>ORCA2 : Impact on EEZ forage On the 3 Layers Forage difference between ORCA2 and ROMS (ROMS ORCA2) (kg/km2) Epi(0-100m) Meso( m) Bathy( m) Qtr1 Qtr2 Qtr3 Qtr4

15 Blending of Models: ROMS>ORCA2 : Impact on EEZ forage On the migrant compartment Forage difference between ORCA2 and ROMS (ROMS ORCA2) (kg/km2) m-meso m-bathy hm-bathy Qtr1 Qtr2 Qtr3 Qtr4

16 Conclusions First interannual 1/3 simulation is available. Interpolating tools are ready A first 1/3 ORCA-ROMS-PISCES Run had been realized. Showing a strong Island effect on tuna forage; i.e. increase of biomass in Island wake (except for epi & hmbathy compartment ) Work to come: Evaluate mesoscale activity impact in tuna biomass and catch Continue optimization work on the coarse grid apply the new parameter to the 1/3 run Use higher resolution catch data to optimized at 1/3. And evaluate resolution impact on optimization