Maternal influences on offspring size variation and viability in wild European lobster Homarus gammarus
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In many marine species, large females tend to produce more robust offspring than small females. However, knowledge on maternal influences in decapod crustaceans is limited. This is unfortunate since many decapod populations are being intensively harvested and show signs of ‘juvenescence’, i.e. the loss of large (and presumably old) individuals. In this study, we quantified maternal influences in European lobster Homarus gammarus from Skagerrak, southern Norway. Historical lobster catches in Skagerrak were substantial but the stock has suffered a major decline over the past 30 to 40 yr and is currently red listed as near threatened according to the IUCN (International Union for Conservation of Nature) criteria. We studied eggs and larvae from wild-caught ovigerous females ranging in carapace length from 79 to 152 mm (n = 45). Mean egg size increased while sibling size variation decreased significantly with increasing maternal size. Mean larval size at hatching was closely linked to both maternal size and mean egg size. A laboratory experiment showed a weak but significant nonlinear increase in pelagic larval survival with increasing mean egg size in the absence of food. These findings suggest that maternal influences on offspring quality could be a significant source of variation in lobster recruitment. Consequently, maternal influences could be an important source of error in fisheries science and management if they are assumed to be absent or unimportant.