Differences in life history features of long rough dab Hippoglossoides platessoides within Scottish waters

Abstract

Recent studies have shown differences in life history features of long rough dab Hippoglossoides platessoides among populations of the North Atlantic. Here, length frequency distributions from commercial catches and age information from otolith readings are used to compare long rough dab from the North Sea and the West of Scotland. Catch data from the Scottish demersal fisheries show differences in the length distribution of long rough dab between the 2 areas, with large fish (>20 cm) more prevalent in the North Sea. The maximum length of long rough dab observed in commercial catches is 8 cm greater in the North Sea, where otolith readings indicate that the species has a greater longevity. Growth models suggest that long rough dab of age 3+ are significantly smaller in the West of Scotland. Potential explanations for the observed contrasts in hie history features include spatial differences in temperature-related metabolic costs, food availability, sex ratios (males tend to be smaller), or age-specific loss rates (emigration or mortality). Of these, we conclude that the hypothesis involving temperature-dependent metabolic costs is the least likely explanation.