Operational fish larval drift modelling

Bjørn Ådlandsvik og Frode VikebøInstitute of Marine Research

Opnet meeting, Geilo, 14-15 May 2008

Why larval drift modelling

Study recruitment processes in fish stocks Prediction Effects of climate variability

Basis for biological Individual Based Models Larval behaviour in the vertical Growth Survival

Why operational

Fish eggs and larvae are vulnerable to oil spill accidents A year class of a major fish stock is worth GNOKs

Useful information for fish larval surveys Useful information for sea bird research ...

How?

Particle tracking Lagrangian Advection and Diffusion model, LADIM

Start from knowledge of typical spawning areas Include simple Individual Based Model

Vertical movement Temperature dependent growth

Operational requirement

Consistency requirement for oil spill overlap analysis:

Fish larvae and oil transport must be forced from the same regional ocean circulation model Otherwise exposure will be controlled by different

current patterns

Difference from oil drift models

Oil drift: Usually know initial condition

time and location of oil spill Larval drift:

Knowledge of typical spawning areas and times Longer simulation time Can be reinitialized if more information becomes

available

Practical implementation

Daily download operational ocean model forecast (Nordic4km) from met.no to IMR

Append to a current and hydrographic archive Rerun the offline larval drift simulation from

spawning/hatching Make plots and put the results on a web site

Presently: http://www.imr.no/~bjorn/oplarve

Cod from Møre

Cod from Moskenesgrunnen

Cod from Malangsgrunnen

Total cod larvae distribution

Total herring larvae distribution

Vertical behaviour for herring larvae Day: 5-20 m, Night:

20-40 m Vertical swimming

speed up to 1/6 bodylength per second

Combination of a deterministic and a random component

To do

Improve the design of the web site Now home made, get help from info dep.

Give the web site a more prominent (and permanent) URL at www.imr.no

Implement larval drift into operational model suite at met.no 24/7 operational organization More frequent updates of current forcing