Description: Sie sind total lecker, sagen die Angler. Sie sind total wichtig für unsere Flüsse und Bäche, sagen die Naturschützer. Aber: Man weiß nicht genau, wie sich ihre Population entwickelt hat und entwickeln wird. Deshalb haben sie heute mit Elektrokäschern Stichproben gesammelt an einem Nebenfluss der Schlei. Denn eins ist sicher: Meerforellen sind ein wichtiger Indikator für die Sauberkeit der Gewässer. Was ist zu tun, damit Angler einen leckeren Fisch auf dem Teller haben und auch die Naturschützer zufrieden. Das Schleswig-Holstein Magazin war bei einem Fischzug dabei

Description: Abgefischte Gebiete werden nicht durch andere Fische der gleichen Art neu besiedelt. Die Tiere bleiben lieber in ihren alten Territorien. Das ist für die Fischer eine wichtige Neuigkeit.

Description: Atlantic cod (Gadus morhua) is a species of great ecological and economical importance in the Baltic Sea. Here, two genetically differentiated stocks, the western and the eastern Baltic cod, display substantial mechanical mixing, hampering our understanding of cod ecology and impeding stock assessments and management. Based on whole-genome re-sequencing data from reference samples obtained from the study area, we designed two different panels of Single Nucleotide Polymorphisms markers (SNPs), which take into account the exceptional genome architecture of cod. A minimum panel of 20 diagnostic SNPs and an extended panel (20 diagnostic and 18 biologically informative SNPs, 38 in total) were developed and validated to distinguish unambiguously between the western and the eastern Baltic cod stocks and to enable studies of local adaptation to the specific environment in the Baltic Sea, respectively. We tested both panels on cod sampled from the southern Baltic Sea (n = 603) caught in 2015 and 2016. Genotyping results showed that catches from the mixing zone in the Arkona Sea, were composed of similar proportions of individuals of the western and the eastern stock. Catches from adjacent areas to the east, the Bornholm Basin and Gdańsk Deep, were exclusively composed of eastern Baltic cod, whereas catches from adjacent western areas (Belt Sea and Öresund) were composed of western Baltic cod. Interestingly, the two Baltic cod stocks showed strong genetic differences at loci associated with life-history trait candidate genes, highlighting the species’ potential for ecological adaptation even at small geographical scales. The minimum and the extended panel of SNP markers presented in this study provide powerful tools for future applications in research and fisheries management to further illuminate the mixing dynamics of cod in the Baltic Sea and to better understand Baltic cod ecology.