Trends of white grouper landings in the Northeastern Mediterranean: reliability and potential use for monitoring


Mavruk S.

MEDITERRANEAN MARINE SCIENCE, cilt.21, ss.183-190, 2020 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 21 Konu: 1
  • Basım Tarihi: 2020
  • Doi Numarası: 10.12681/mms.18986
  • Dergi Adı: MEDITERRANEAN MARINE SCIENCE
  • Sayfa Sayıları: ss.183-190

Özet

As a consequence of national fishery statistics showing a sharp decline in the landings of white groupers (WG) - Epinephelus aeneus (Geoffroy Saint-Hilaire, 1817) - after 2010, the decision to ban any further fishing of the species was taken by the Turkish management authority in 2016. Stakeholders have since strongly objected to this decision claiming that the trends of landing statistics are unreliable. Here, this assertion is questioned using multiple sources of data comprising the catch per unit effort (CPUE) from the fishery independent bottom trawl survey (2004-2018), officially reported landing statistics (2002-2017) and the microdata set of landings (2012-2016) gathered by the Turkish Statistical Institute (TUIK). Based on the results of this study, there were clear correlations among the datasets. Landing records and the CPUE time series revealed unimodal non-linear patterns over time (p<0.001). Landings increased until 2010 and decreased thereafter, whereas CPUE values started to decrease after 2009. In the segmented time series, there were no statistically significant differences between the direction and magnitude of slopes calculated from landings and fishery independent data. Cross-correlations between landings and CPUE were statistically significant with one and two-year time lags. This was because the earlier age groups were sampled with coastal bottom trawl operations. Combined with further efforts, these findings may help to develop a monitoring program for the status of white grouper populations in the northeastern Mediterranean and contribute to a better management strategy.