Depletion of European hake stock in the Sea of Marmara

Demirel N.

52nd European Marine Biology Symposium, Piran, Slovenia, 25 - 29 September 2017, pp.70

  • Publication Type: Conference Paper / Summary Text
  • City: Piran
  • Country: Slovenia
  • Page Numbers: pp.70
  • Istanbul University Affiliated: Yes


The aim of ecosystem-approach to fisheries management is to provide the sustainability level of target stock via indicators with the minimum impact on other ecosystem components. Fishing activity must consider as a chain activity rather than evaluating it as a single activity between target organism and the fishermen, which affected all components related to target organism as well as the fishing conditions on related stocks. The main challenge of the approach is that in Turkey, stock assessments cannot be done properly. This is mainly because of the insufficient fish market data as well as the discontinuity of already few stock assessment projects. Based on this motivation, this study focuses on stock status and temporal changes of European hake in the Sea of Marmara with processing the several fisheries data which had been taken by monitoring studies between the years 1990-2016 by Istanbul University, Institute of Marine Sciences and Management. Certainly, one of the most important demersal fish species in the Sea of Marmara is the European hake. Its production occupied around 50% of demersal fishery in mid-90s. Decreasing started in mid-2000s and drastically deteriorated below 10% percent in 2015. According to national catch statistics, only 81 tonnes European hake were caught in the Sea of Marmara last year. The results of this study indicates clear decline with estimated biomass ratio in catch composition of European hake 53% in 1995, 60% in 1996, 36% in 2009, 16% in 2010, 23% in 2011 and less than 1% in 2016. According to stock assessment results performed by CMSY analysis, the European hake stock in the Sea of Marmara is outside of safe biological limits between the years 2000 and 2015. Current biomass estimation over maximum sustainable biomass is below the threshold level of 1 in whole period and after 2003 the values are estimated below the critical point of 0.5. Fishing pressure estimation is over 1.5 between the years 2000 and 2012 which implies the overfishing. After 2012, fishing pressure was below 0.5, however it is considered that the stock is severely depleted in the Sea of Marmara.