In this study we addressed the estimation of annual exploitation rate (AER) in five angling clubs in Lower Saxony. 1,232 northern pike were captured and tagged. In total,156 tagged fish, including 59 high reward tag, were returned by the anglers, which gave us a reporting rate of 53± 9%. We encountered two major problems associated with the estimation of the AER relating to the mark and recapture method: (1) the uncertainty associated with the estimation of the reporting rate, tag loss and tagging mortality and, (2) the size dependent vulnerability. Instantaneous total mortality obtained from the annual exploitation rate was 0.44 for 2011, and 0.19 for 2012. The F safe should be 0.15, calculated as 0.75 M. Both years were unsustainable exploited and only two angling clubs exploited the fishery at a sustainable AER. We also estimated the selectivity curve with a binomial generalized linear model. As the curve never reaches one, it is suggested that this method was not appropriate to estimate size selectivity.
Size dependent angling exploitation rates in pike (Esox Lucius) in Northwest Germany
Díaz, Á. M. (2015). Size dependent angling exploitation rates in pike (Esox Lucius) in Northwest Germany. Student Project, Humboldt-Universiät zu Berlin / Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB) in Berlin
Erschienen in : Student Project, Humboldt-Universiät zu Berlin / Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB) in Berlin