Diet Composition of Bluefish Pomatomus saltatrix (Linnaeus, 1766) in the Sea of Marmara

Abstract

In this study, diet composition of bluefish Pomatomus saltatrix (Linnaeus, 1766) was investigated. A total of 512 bluefish samples were monthly collected from commercial fishing boats operating in the Sea of Marmara between January and December 2014. It was determined that the total length distribution of the samples varied between 12.3-47.3 cm. 367 of them (71.67%) were found to be the full of the stomach. The nutritional composition of stomach contents only two main prey groups (teleostei and crustacean) were identified. In evaluation, relative importance indexes (IRI) food groups were calculated. According to the relative importance index (IRI=91.8%) anchovy (Engraulis encrasicolus) has been found to be the most preferred food group. The number of individuals whose stomachs were found to be full was low in the winter months; it started to rise with spring and reached the highest level in the autumn months. It was determined that the increase in the total number of stomachs occurred between August and October in relation to the reproductive period. It was found that stomach fullness rates significantly relationship between sex and seasons (p<0.01).

Variation in the stable isotope trophic position of the bluefish Pomatomus saltatrix (Linnaeus, 1766) from two Mediterranean sites: insights from a global meta-analysis

“…The global database collated here confirmed this tenet: the differences in TP values among locations was paralleled by a considerable variability observed for the same location when different baseline species were used (Table 2). Anchovies belonging to the genus Engraulis are a dominant item in the diet of bluefish worldwide (Juanes et al, 1996;Lucena et al, 2000;Schilling et al, 2017;Bal et al, 2020); therefore, we are confident regarding the robustness of estimations for the Strait of Otranto. For the Gulf of Taranto the demersal Lithognathus mormyrus was used as the baseline species.…”

“…S2). For the Strait of Otranto, E. encrasicolus was chosen as it is a highly preferred prey for pelagic P. saltatrix populations (e.g., Georgieva & Daskalov, 2019;Bal et al, 2020); indeed, large schools of bluefish are frequently observed in the fall chasing forage fish shoals moving along the Adriatic coast of the Salento Peninsula (Mancini, personal observation).…”

“…Immature juveniles prey mainly on crustaceans, cephalopods, and small fish, while sexually mature adults become opportunistic generalists preying on pelagic and demersal fish depending on local conditions and prey availability (Juanes & Conover, 1994;Buckel et al, 1999a;Lucena et al, 2000;Potts et al, 2016;Schilling et al, 2017). Noticeably, for the Mediterranean Sea dietary studies have been carried out mainly in the south-eastern sectors (Dhieb et al, 2001;Karachle & Stergiou, 2008;Bal et al, 2020; see also Georgieva & Daskalov, 2019 for the Black Sea); in contrast, beside the pan-Mediterranean preliminary assessment by Sanchez-Jerez et al (2008), only Iveša et al (2021) have focused on bluefish populations in recently colonized areas.…”