Crangon

Development, Parameterization and Application of a Specific Y/R Model of North Sea Brown Shrimp (Crangon crangon L.) for the Assessment of the Fishing Situation

Funding: German Federal Ministry of Food, Agriculture and Consumer Protection

Funding Period: 2005-2008

Contact: Marc Hufnagl, Chris Rückert

Description

In May 2005 the Institute of Hydrobiology and Fishery Science started a project which is funded by the German Federal Ministry of Food, Agriculture and Consumer Protection for a further development of the Y/R model presented on the WGCRAN meeting 2002 in Oostende.

Until April 2008 two Ph.D. candidates (Marc Hufnagl and Chris Rückert) will deal with the following issues:

The growth rates used in the model are based on the work published by Kuipers and Dapper. In their work, males are not separated from females; hence new trials were conducted on Helgoland to determine growth rates in dependency of length, gender and temperature.
At the end of these tests the condition index, the RNA, DNA, protein and calorific content of these individuals and of monthly taken field-samples (Büsum and Meldorf) will be determined to allow a parameterisation of growth rates in the field. Further animals were gained from a cooperating project from Wilhelmshaven for the same purpose. As a result of these activities, future model versions will parameterise and simulate both, male and female cohorts.
Additional tank experiments concerning C. crangon´s behaviour relative to tidal streams were and will be conducted.
A complexity reduced version of the model will be combined with a hydrodynamic model to analyse the life-cycle with regard to differing temperature-regimes on the drift paths.
Length dependent mortalities will be introduced to take into account effects of sieving, discard and industrial fishery.
A closed life-cycle will be implemented; the model shall generate the seasonal recruitment patterns.
The model program will come with more advanced output-routines and user-friendly modification interfaces.
Additionally, tests of the robustness of model outputs in relation to assumptions and parameter variability as well as scenario-runs simulating different fishing and temperature conditions will be conducted.