Regional influences on condition and reproductive outcome of female Atlantic cod (Gadus morhua) in Greenland waters

Greenland cod stocks were among the largest of the world but collapsed in the 1990s. In Greenland waters Atlantic cod lives in an environment that is influenced by arctic and subarctic climate, undergoing annual and decadal fluctuations, which is strongly impacted by climate change. Different current systems and water bodies from the cold polar region and the warmer North Atlantic encounter and mix in this region, providing habitats with different food sources and abundances. Differences in condition of cod can be seen along the east Greenland coast but the reasons for that are still not fully understood. Total lipid contents and fatty acid composition of livers and gonads of fish have shown significant correlations with its condition, spawning times, hatching success, larval survival and fecundity. Therefore, these parameters can be used as a complement to classic proxies used in fisheries biology to determine fish condition and reproductive output and to establish a connection between diet, condition and reproductive output. Thirty-two mature female individuals of 75-90 cm were sampled from three areas subject to different environmental conditions off the East and Southwest Greenland coasts Total lipid, fatty acid and stable isotope analysis were conducted. Additionally classical condition indices, liver macro-parasites and liver tissue degradation were measured. Two trophic regions were determined, where cod fed either majorly on benthic or on pelagic prey sources. Total lipid content of livers and gonads reflected the results of hepatosomatic indices and gonadosomatic indices. Fatty acid compositions of gonads were dependent of the sampling site. Mesopelagic fish and crustaceans as food sources promoted an enrichment in important polyunsaturated fatty acids and a better condition of female cod. Total lipid contents of liver and gonads, as well as fatty acid compositions of gonads indicated a difference in maturity stages of female cod between the sampling sites. According to large differences in condition and liver health of female cod and fatty acid amounts of gonads between sampling sites, it can be assumed that the habitat plays an important role for the reproductive outcome of Atlantic cod in Greenland waters.