Population dynamics of pikeperch (Sander lucioperca) and its linkage to fishery driven and climatic influences in a southern Baltic lagoon of the Darss-Zingst Bodden Chain

Our study uniquely analyzes the population structure (stock sizes N in numbers, biomass B, recruitment R, spawning stock biomass SSB, yield-per-recruit Y/R, catch-to-biomass ratios Y/B) and the influence of natural (North Atlantic Oscillation NAO, regional environmental variables) and anthropogenic (fishing mortality F) forces on the population dynamics of a single isolated stock of the pikeperch, Sander lucioperca, in the north-eastern Baltic coast of Germany over a 25 years time period. N and F were estimated using the statistical virtual population analysis (VPA) approach while B, SSB, R, Y/R, Y/B were derived from these. Based on segmented regressions, the study of anthropogenic influences revealed a significant effect of F on R; an effect of F on Y/B was partly significant. In both cases a changepoint value of F = 0.56 was found. Based on cross-correlations and general linear regression models, the analysis of the influence of environmental factors detected significant lagged effects of the NAO and local temperatures and salinities on R while classical stock-recruitment models (Beverton/Holt, Ricker) and polynomials did not.