Title:
Bycatch of juvenile cod in the Barents Sea shrimp fishery.
Abstract:
In the Barents Sea and adjacent water, fishing grounds are closed for
shrimp fishing if the Norwegian Directorate of Fisheries Monitoring and
Surveillance Service (MSS) believes the expected number of juvenile cod
caught exceeds a certain limit per kilogram shrimp. In this work we have
constructed a Bayesian hierarchical spatio-temporal model for shrimp
catch and bycatch of juvenile cod in the Barents Sea shrimp fishery that
can help the MSS to predict the bycatch rate. We have done this by
assuming that the occurrence of shrimp and juvenile cod can be modeled
by a linear combination of covariates and Gaussian fields. Integrated
Nested Laplace Approximations (INLA) is used for fast calculation of the
posterior distributions. By using these models we can predict (with
uncertainty) the bycatch rates in commercial shrimp catches, and thereby
be able to help the MSS in deciding when and where it is allowed to
trawl for shrimps. Further by using the model for bycatch with the data
from fishermen logbooks, we can estimate the total bycatch in the
commercial fishery (with uncertainty) and thereby give a better
understanding on how big the bycatch problem is.