Data from: Marine protected areas rescue a sexually selected trait in European lobster

Marine protected areas (MPAs) are increasingly implemented worldwide to
maintain and restore depleted populations. However, despite our knowledge
on the myriad of positive responses to protection, there are few empirical
studies on the ability to conserve species’ mating patterns and secondary
sexual traits. In male European lobsters (Homarus gammarus), the size of
claws relative to body size correlates positively with male mating success
and is presumably under sexual selection. At the same time, an intensive
trap fishery exerts selection against large claws in males. MPAs could
therefore be expected to resolve these conflicting selective pressures and
preserve males with large claws. We explored this hypothesis by
contrasting claw size of males and females in three pairs of MPAs and
nearby fished areas in Southern Norway. By finding that male lobsters have
up to 8 % larger claws inside MPAs compared to similarly sized males in
fished areas, our study provides evidence that MPAs rescue a secondary
sexual trait. Recovery from harvest selection acting on claws is the most
likely explanation, however, the higher abundance of lobster inside MPAs
does not rule out a plastic response on claw size due to increased
competition. Regardless of the underlying cause, our study demonstrates
(1) the value of protected areas as a management tool for mitigating
fishery-induced evolution, and (2) that MPAs help maintaining the scope
for sexual selection in populations with vulnerable life-histories and
complex mating system.