Eastern-western Baltic cod: Improved management based on stock discrimination of eastern and western Baltic cod (Øst-Vesttorsk) (38989)

The aim of this project was to improve the management of western Baltic cod by incorporating stock identification routines in order to discriminate between eastern and western Baltic cod stocks. 
In recent years evidence from fishery patterns and otolith structures have indicated an increasing degree of mixing between the two cod stocks which up until 2013 were managed as two separate stocks. Changes in fishing pressure and patterns would therefore result in a risk for local depletion of the smaller western stock. 
Stock identification methods were based on established approaches using genetic discrimination and otolith shape analysis, and improved by linking these methods. This method provides a tool to estimate the degree of stock mixing using the existing otolith archives. This approach documented an increase of eastern Baltic cod from 30% to > 80% in the eastern part of the western Baltic Sea management area. As a consequence of this stock mixing, a new procedure incorporating stock mixing on an annual basis was set in place in, with the aim to improve stock exploitation and reduce the risk of local depletion.The knowledge gained also influenced recent management regulations, particularly a prolongation of spawning closer of the fishery in 2016.
The project was coordinated by Centre for Environment, Fisheries & Aquaculture Science, UK and funded by the Danish Minestry of Food, Agriculture and Fisheries and the European Fisheries Fund (EFF).
Research area: Marine Populations and Ecosystem DynamicsResearch area: Marine Living ResourcesResearch area: Population GeneticsResearch area: Fisheries Management