No abstract

No abstract

This paper is the first reference of pumpkinseed (Lepomis gibbosus) in the lower Sakarya River basin (Turkey). The data were obtained from samplings carried out between April 2017 and July 2017. L. gibbosus is currently found in only two regions of Turkey, its introduced range is expanding rapidly, and for this reason it is important to monitor the impacts of this introduced species on natural ecosystems.

In this study, age and sex compositions, length distributions, growth parameters and length-weight relationships of common sole populations were determined in Güllük Bay, southern Aegean Sea, Turkey. Trammel nets and beach seines which have different full mesh sizes were used to obtain samples. Sex ratio (female:male) was found to be 1.14:1. Growth parameters of the common sole in Güllük Bay was described as; L ∞ =33.95, K=0.208 y -1 , t 0 =-0.032, L ∞ =31.98, K=0.236 y -1 , t 0 =-0.037 y and L ∞ =29.11, K=0.324 y -1 , t 0 =-0.030 y, for sexes combined, females and males, respectively. Lengthweight relationships for combined sexes, females and males were W=0.0079L 3.064 , W=0.0072L 3.101 and W=0.0088L 3.024 , respectively. Combined individuals and females showed positive allometric growth and males showed isometric growth. Ages ranged between 0-9 years. Study results could be useful for further common sole fishery management strategies.

Background. In the small-scale fisheries of the Gulf of Gökova (Turkish coast of the southern Aegean Sea) the marbled spinefoot, Siganus rivulatus Forsskål et Niebuhr, 1775, is a commercially important species. No sustainability study, however, has been carried out on the stock assessment and management of this species in the gulf. The aim of the presently reported study was to determine the mortality and biological reference points of Siganus rivulatus and suggest a proper fishery management plan for fishery regulations. Materials and methods. The sudy was conducted between July 2016 and June 2018. Fish samples were collected from the Gulf of Gökova small-scale fishery. The total mortality (Z), natural mortality (M), fishing mortality (F curr), and exploitation rate (E curr) were determined and compared with the biological reference points: the optimum fishing mortality (F opt), fishing mortality limit reference point (F lim), optimum exploitation rate (E opt). Results. Total mortality (Z), natural mortality (M), fishing mortality (F curr), and exploitation rate (E curr) were found to be 0.67, 0.32, 0.35, and 0.52, respectively. Furthermore, biological reference points (F opt , F lim , E opt) attained values of 0.16, 0.21, and 0.33 cm, respectively. Conclusion. The fishing pressure for Siganus rivulatus stocks the Gulf of Gökova should decrease for the sake of the sustainability of this resource.