Spatio-Temporal Variability of Harbor Porpoise Life History Parameters in the North-East Atlantic

摘要: Harbour porpoises exhibit early maturation, relatively short gestation/lactation periods and a faster rate of reproduction as compared to other cetacean species. Intrinsic extrinsic factors can influence both population vital rates structure, which ultimately cause changes in dynamics within between populations. Here, we undertook retrospective analysis mortality data collected over 24-year period for assessing life history traits the North-east Atlantic harbour porpoise population. We use time-period specific models key relationships that considered death individuals (as proxy health status), sex management unit (MU). Sexual variation asymptotic length, age, average length at 50% maturity (L50) age (A50) were observed, with females attaining larger L50, delaying attainment sexual physical maturity, males. While are constrained their minimum body size due giving birth proportionally offspring, males exhibited more plasticity enabling re-allocation available energy resources towards reproduction. Data then used compare biological parameters among two MUs UK waters, current study reduced reproductive geographic regions. In MUs, significantly increased A50 declined L50. An increase was also observed sexes, along significant decline Gompertz growth parameter apparent female data. availability suitable prey may be limiting factor, combination cannot ruled out. Porpoises Celtic Irish Seas MU maximum L50 North Sea throughout period, suggesting limited gene flow these MUs. These results justify maintenance or assessment units, separate range population, indicator assessments under EU’s Marine Strategy Framework Directive.