MSC certification of the plaice fishery in area IIIa – basic investigations and development of a management model (39025)


A management plan isan important requirement for MSC certification of specific fisheries. However,prior to this project, reliable stock assessments, which are necessary for amanagement plan for plaice (Pleuronectesplatessa) in area IIIa (Kattegat/Skagerrak), had not been available. Theseproblems most likely originated from insufficient knowledge about thegeographical distribution of populations as well as the interactions betweenpopulations in Kattegat/Skagerrak and neighbouring areas. Through a mapping ofthe distribution and dynamics of populations, this project aimed at providingthe missing data that would ultimately allow for the development of amanagement plan for the plaice fishery in area IIIa. The work includedinformation from genetics, tagging, otolith based growth estimation,oceanographic modelling and analyses of survey and fisheries data. 
Results from theproject showed evidence of both local population components in theKattegat/Skagerrak as well as substantial mixing between North Sea populationand these local components, and consequences of lumping or splitting thepopulations for stock assessment and management were discussed. 
The outcomes of thework directly influenced the policy decisions since 2015. Decision was finally madeto proceed with the lumping option, thus allowing a quantitative analyticalassessment and management advice for the area. However, because of thedifferences in size between the two populations, there is a risk of depletionof the local Skagerrak population if the fisheries on it increase as aconsequence of the increase in the North Sea stock. In terms of management,some mechanisms already exist for reducing the fishing pressure in theSkagerrak if deemed necessary, as plaice in the North Sea and in the Skagerrakare managed by two different Total Allowable Catches (TACs). It has thereforebeen suggested that routine monitoring of the survey and fisheries patternswould allow detecting any departures from the current situation, i.e. adecoupling of trends in the different areas and the different seasons thatcould indicate a reduced productivity of the local stock. 
In the longer-term,the current progresses on the biological knowledge of the stock in Skagerrakshould be sustained. Additional genetic allocation of individual fish to the differentpopulations should be performed to obtain a better quantification of the mixingin different areas and seasons, and the survey coverage should be improved inthe Skagerrak.
The project was coordinated by DTU Aqua.
The prject was funded by the Danish Minestry of Food, Agricutulture and Fisheries and the European Fisheries Fund (EFF).
Effective start/end date01/07/201231/12/2014


  • Research area: Population Genetics --- Research area: Fisheries Management --- Research area: Marine Living Resources