Bergen September2006

Slide1: 

Long-term yield of cod in the Barents Sea – a joint Russian-Norwegian ecosystem approach Sigurd Tjelmeland, IMR Anatoly Filin, PINRO

Improving management of fisheries by: 

Improving management of fisheries by Including species interactions and environmental impacts into fish stock assessments Evaluating harvesting control rules, also on a multispecies basis Mike Sinclair: 1: Effects on ecosystem 2: Effects from ecosystem 3: Manipulation This project: 2 (adjust expectations) It’s about knowledge production and integrating knowledge

Basic model EcoCod: Background: 

Basic model EcoCod: Background

Basic model EcoCod: Background: 

Basic model EcoCod: Background 1-2 years 3-6 years 7 years and older

The role of the Russian-Norwegian Fishery Commission: 

The role of the Russian-Norwegian Fishery Commission Negotiating quotas Cod: Adopted HCR based on Precautionary Approach considerations Is this good in the long term? REQUEST: What are the perspectives for long term yield taking into account species interactions and influence from the environment? Existing science Later to comprise other species (order of priority) Capelin Herring Harp seal Minke whale Shrimp Haddock Etc.

Implementing the Ecosystem Approach: Relating to fish, relating to decision makers: 

Implementing the Ecosystem Approach: Relating to fish, relating to decision makers Biologists Modellers Managers Assessment Quota setting ”Ecosystem Models”

Starting point: 

Starting point A HCR for cod has been tested by the model CodSim (in PROST), which is implemented in the line ICES WG -> Commission. The HCR is adopted and now in use F = 0.40 (Blim considerations) F decreased when SSB < Bpa Stability, only 10% change from previous year when SSB > Bpa Destroyed by illegal fishery Technical solution (practical and implementational considerations) PROST is kept as it is Density dependent weight and maturation Cannibalism on age 3 and older Augmented little by little using a separate model EcoCod

Modelling: 

Modelling The crux: Spawning stock – recruitment relationship

The modelling cycle: 

The modelling cycle

Starting point: Recruitment relation matters: 

Starting point: Recruitment relation matters

Organisation of project: 

Organisation of project Jointness in all parts, essential for successful implementation First stage: 2005-2007 – Cod i focus Second stage: 2008 – 2014 – Multispecies modelling STOCOBAR Bifrost SystMod Further elaboration of EcoCod

How does a changing environment change cod population dynamics?: 

How does a changing environment change cod population dynamics? Environment: Temperature and capelin Growth Increases with temperature Increases with food abundance Fecundity Increases with food abundance Malformation of eggs Decreases with age (Env. Effect not linked to model temperature yet) Mortality Decreases with food abundance (Cannibalism) Increases with marine mammals Recruitment Increases with temperature Increases with food abundance (SSB) Decreases with food abundance (Cannibalism)

Non-modellable entities: Scenarios: 

Non-modellable entities: Scenarios Temperature Marine mammals Problematic: Harp seals Technical problem: Marine mammals influence M on cod in the assessment (age 3 and older)

Regressions: 

Regressions Growth of cod Capelin has an effect of cod younger than 7 years Temperature has an effect on cod younger than 8 years Cod has an effect for all age groups, most pronounced for the oldest Fecundity Dependent on length and condition Malformation of eggs Dependent on age (environmental effect?) Skipped spawning Fish with condition less than 0.7 skips second-time spawning Distribution (normal) of condition from August surveys Mean condition from model Pre-recruit cannibalism Dependent on capelin

The cod-capelin-plankton-herring model: 

The cod-capelin-plankton-herring model

The cod-capelin-plankton-herring model(estimated parameters in red): 

The cod-capelin-plankton-herring model (estimated parameters in red) Biomass age-structured capelin model Capelin recruits as 2 years Mature capelin: > 14 cm in autumn Capelin model: Plankton model: planktonBiomass = planktonBiomass + planktonCapelin (planktonCapelinSetpoint – capelinBiomass) + inflow

The cod-capelin-plankton-herring model: 

The cod-capelin-plankton-herring model No update capelin – good fit to plankton Update capelin – good fit to capelin

Simulations: 

Simulations Constant cod length distribution Constant capelin maturation ogive Constant temperature Constant herring abundance Temperature affects (as yet) only growth of cod younger than 7 year (not recruitment) Uncertainty: Only estimation uncertainty in cod recruitment 150 years, 10 replicates

Modification of MSY: 

Modification of MSY F Range: 0.06 20% MSY: Range 1 million tonnes Must explore the spawning stock – recruitment relation Large variation in MSY, small variation in FMSY

It’s all in the recruitment relation: 

It’s all in the recruitment relation PROST model Including ecosystem effects (only recent points)

Next steps: 

Next steps Stochastic herring scenarios from herring assessment model Improvement of recruitment relation Temperature Model uncertainty Plankton as food for cod Marine mammals Uncertainty Here: Only estimation uncertainty in recruitment model Uncertainty in other sources Model uncertainty Recruitment Beverton-Holt Segmented regression Other Implementation IMR/PINRO Commission (“Basic Document”) ICES (Arctic Fisheries WG) Stakeholders?