Anıl Gülşahin

This study aims to identify the non-indigenous fish species for which significant knowledge gaps persist by evaluating the existing scientific literature on their fundamental biology (age-growth and length-weight relationships). Data were synthesized descriptively following PRISMA 2020 guidelines. In the study, a list of 177 non-indigenous fish species recorded in the Mediterranean was compiled, and a systematic literature survey was conducted to identify scientific publications containing length-weight relationship (LWR) and age-growth (AG) parameters for these species. Studies outside the Mediterranean or on non-fish taxa were excluded. Databases were searched up to November 2025. Data were synthesized descriptively by species, country, and study type. Risk of bias was not formally assessed in this review. A total of 143 studies were identified. The analyses revealed an uneven geographical distribution of research, with Türkiye leading by a wide margin with 84 (58.86%) studies. Lagocephalus sceleratus with 25 studies for LWR, and Saurida lessepsianus with 11 studies for AG, stood out as the most researched species. However, it was determined that fundamental biological data are still unavailable for many non-indigenous species. These findings reveal critical knowledge gaps that need to be urgently addressed for the sustainable management of increasing non-indigenous fish populations and highlight the urgency of expanded scientific research on these species.

An occurrence of a red cornetfish Fistularia petimba here reported for the first time from the Aegean Sea. On 19 October 2019 four specimens from the Gökova Bay and on 17 November 2019 one specimen from the Güllük Bay, were collected using different fishing gears in the Aegean Sea. This finding shows that F. petimba is rapidly expanding northwards, from the Levantine Sea to the Aegean Sea.

The study aimed to determine the annual reproductive cycle of Siganus rivulatusfi females based on monthly variation of the gonadosomatic index (GSI) and histological changes in gonads. A total of 240 fish samples were collected monthly from small-scale (trammel nets) and recreational (angling and pot fishery) fishing from Gökova Bay, the southern Aegean Sea, between July 2017 and June 2018. The length and weight of female fish varied from 10.8 to 26.1 cm with a mean length of 18.7 ± 0.2 cm and from 14.98 to 293.42 g with a mean weight of 91.1 ± 2.93 g. GSI values began to increase in May, peaked in June and gradually decreased in July, indicating that the spawning season was early summer. A total of 240 gonads were histologically examined. Granular, pinkish structure of eggs was observed primarily between April and June, which was consistent with the increase in the gonadosomatic index. Post-spawning follicles were determined in July. Values of the gonadosomatic index gradually decreased after August and they were minimal between September and November. During this period, ovaries were surrounded by immature oocytes at the chromatin and peri-nucleolus stages. These results revealed thatSiganus rivulatusstarted vitellogenesis in April and the gonadosomatic index peaked in June.