MEPS prepress abstract  -  DOI: https://doi.org/10.3354/meps12325

Understanding the life cycle of North Sea brown shrimp (Crangon crangon): a simulation model approach

Axel Temming*, Claudia Günther, Chris Rückert, Marc Hufnagl

*Email: atemming@uni-hamburg.de

ABSTRACT: A simulation model of the life cycle of Crangon crangon was programmed in R tracking daily cohorts from the egg stage to the adult stage taking into account size specific seasonally varying natural mortality rates of all life stages, temperature dependent development rates of eggs and larvae, juvenile and adult growth rates as a function of temperature and size and sex, maturation, egg production and seasonally varying size specific fishing mortalities. The observed seasonal patterns of commercial catch and egg production could only be reproduced with fast growth rates linking winter egg production with the subsequent juvenile recruitment in May/June, the commercial catch peak in September and the peak in winter egg production. Likewise substantially lowered natural mortalities in winter are essential to generate seasonal patterns similar to the observed ones. The seasonal pattern of egg production can only be reproduced with a minimum spawning age. Cohorts from summer eggs are rapidly following the earlier winter egg cohorts forming an annual joint wave of growing shrimp. The summer egg cohort originate from summer eggs of the previous year and, depending on winter and spring mortality levels, also from large individuals of the preceding winter egg cohort. The developed model represents a new tool to investigate maximum yield per recruit in this species as a function of seasonal effort levels, mesh sizes and seasonal closures under different predation and temperature scenarios.