Aspects of growth of the lessepsian goldband goatfish [Upeneus moluccensis (Bleeker, 1855)] population living in İskenderun Bay, Türkiye

Abstract

Background and purpose: Upeneus moluccensis has become one of the most abundant lessepsian species which penetrated into the eastern Mediterranean since 1950’s. It is considered one of the important species of commercial trawl fisheries, in abundance (approximately 60% of the catch per unit effort) from İskenderun Bay. Despite its economically importance in this region, there is a lack of biological information available for this species since 2005 and its growth and stock managament studies are limited. The present study deals with growth patterns of U. moluccensis.

Materials and methods: A total of 663, approximately 70 specimens per month were caught by trawl surveys during a 1 years’ period from İskenderun Bay between 2017 and 2018. Age determination was based on indirect ageing through length –frequency data using the Bhattacharya method. Length-weight relationships, and von Bertalanffy equation were used to estimate the growth. Sexes were determined by macroscopic observation of gonads. Spawning period of this species was determined according to gonado-somatic index (%).

Results: Total length was measured between 7.0-17.9 cm and 7.0-18.9 cm in female and male, respectively. There was no significant difference in number of females and males from the expected 1:1 ratio (p>0.05). The population reached a maximum age groups of III. The von Bertalanffy growth equation (in length) was found as Lt=20.75 [1−e−0.33(t+0.56)], for all individuals. b values were estimated as 3.36 and 3.37 in female and male, respectively (b>3.0). Mortality and exploitation rates were derived as Z=0.94, M=0.33, F=0.63 and E=0.67, respectively

Conclusions: The calculated exploitation rate (≈0.67) of the goldband goatfish stock in eastern Mediterranean Sea is above the optimum value, indicating a high fishing pressure on the population. This confirms the need to enforce some regulations on commercial fisheries for U. moluccensis.