Perch (Perca fluviatilis) growth, mortality and stock exploitation by 40–45 mm mesh-sized gillnet fishery in the Curonian Lagoon

Abstract

The aspects of the perch (Perca fluviatilis) population dynamics in the Curonian Lagoon were evaluated based on the age structure of the population, which was assessed using otoliths (N = 488) sampled in 2009. Estimations were done employing FAO FISAT II software. Analysis of length-at-age data showed the asymptotic length (L∞) of 49.99 cm and the growth curvature (K) of 0.13 yr⁻¹. The fishing mortality (F) caused by commercial 40–45 mm mesh-sized gillnet fishery was estimated to be 0.25, while natural mortality (M) was equal to 0.24. The relative yield per recruit model demonstrates that the current perch exploitation rate caused by commercially used 40–45 mm mesh-sized gillnets is equal to 0.51, which is above the optimum (E_0.5 = 0.36) and below the economic (E_0.1 = 0.6) and the maximum (E_MAX = 0.75) yield indices. The current assessment suggests that in order to get the optimum yield per recruit and biomass per recruit, the total exploitation rate of the perch population in the Curonian Lagoon should be set between 0.36 and 0.6 (E_0.5 and E_0.1).

Keywords:

• perch
• Curonian Lagoon
• stock exploitation
• 40–45 mm gillnet
• FISAT