Geographic and environmental drivers of fecundity in the European lobster (Homarus gammarus)

Fecundity in the European lobster (Homarus gammarus) has been shown to exhibit extensive spatial variation across northern Europe. Previously, this has been attributed to a lack of methodological standardization among samples. Instead, we show significant correlations between fecundity and both geographical and environmental drivers. Weuse linear mixed-effect models to assess the contribution of latitude, longitude, and measures of sea surface temperatures on the size-fecundity relationships of 1058 ovigerous females from 11 locations in the UK, Ireland, and Norway. We include new data for 52 lobsters from Falmouth, UK, the southwest limit of existing samples. Fecundity at mean female size correlated positively with eastings and greater annual ranges in sea surface temperature, but not with mean temperature or latitude. This contradicts the established latitudinal and mean temperature dependence reported for the closely related H. americanus. We postulate that proximity to stable Atlantic currents is the most likely driver of the relationship between fecundity and longitude. Mechanisms are discussed by which egg production or retention may be influenced by temperature range rather than by mean temperature. With further validation, we propose that temperature-correlated fecundity predictions will provide a valuable tool in ensuring that management thresholds are appropriate for the reproductive characteristics of lobster populations.