Stock status and management for the exploited whiting (Merlangius merlangus Linnaeus, 1758) in the Eastern Black Sea

Abstract

This study used data from commercial fisheries along Turkey's southeastern Black Sea coast. A total of 3,394 samples of Merlangius merlangus were collected. The von Bertalanffy growth parameters, asymptotic length (L_∞), growth constant (K) and to, were determined to be 40.89 cm, 0.10 cm and − 1.1411 cm, respectively. The first capture length (Lc₅₀) was determined to be 11.82 cm, while total natural and fishing mortality was estimated to be 0.85, 0.29 and 0.56, respectively. In the recruitment pattern, three periods were found: March, August, and November. The estimated fixed biomass based on VPA data was 569.620.7 tonnes. Maximum sustainable yield (MSY) for whiting could be achieved at an exploitation rate of 0.66. For an exploitation rate of E_0.1, the marginal increase in relative yield per recruit by 10% was 0.507, and for an exploitation rate of E_0.5, it was 0.311. The current level of exploitation (approximately 449.70 tonnes) was determined using the Thompson and Bell method with an F-factor of 0.56. The F-factor of 1.0 corresponds to a maximum sustainable yield (MSY) of 498.180 tonnes. At the current fishing level (F = 0.56), biomass was reduced reduced by 25% (168.026 tonnes) of unfished biomass (666.206 metric tonnes).