The stomach contents of the Atlantic Horse Mackerel, Trachurus trachurus (Linnaeus, 1758), were analysed to investigate the food and feeding habits of this species with respect to fish size and season. A total of 60 different prey species was found belonging to five major systematic groups, i.e. Polychaeta, Crustacea, Mollusca, Chaetognatha and Osteichthyes. Crustaceans (especially Copepoda, Euphausiacea and Mysidacea) were the most important food category by percentage of relative importance index. Teleosts were the second most important food category, while Polychaeta and Chaetognatha were occasionally seen as food. Little seasonal variation in the diet of T. trachurus was observed: copepods and mysids were the dominant prey groups in all seasons, and teleosts except in spring were the most frequent prey. However, differences in size were highlighed, with fish larger than 16.9 cm feeding on teleost larvae. At least 45 Copepoda species were identified, with Acartia clausi and Oncea media being the most significant among them by the percentage of relative importance index groups in all seasons. Copepods, euphausiids and mysids were thus the most important prey to be consumed by Trachurus trachurus in all seasons as well as by the small size classes. Moreover, teleosts constituted the main food for larger specimens.

Data on feeding habits in aquatic ecosystems are of great importance in determining the role that a certain fish species plays in its habitat and in related ecosystems. In this study, the diet composition of Mediterranean horse mackerel, Trachurus mediterraneus was investigated for 728 specimens from the central Aegean Sea to compare our data with those from other regions of the Mediterranean Sea and throughout all four seasons. Catches from five major groups were identified. Crustaceans (particularly copepods) proved to be the most important food item considering the index of relative importance (IRI). At least 58 different copepod species were identified. Abundant copepod species that occur in every season were Corycaeus sp., Oncaea media, Oncaea spp., Isias clavipes, Euterpina acutifrons and Oithona nana. Isias clavipes occurred only in spring, with all of them appearing in the diet with a %IRI >10. Although found in a relatively smaller quantity, teleost larvae ranked as the second most important prey in the overall diet, with increasing quantities in fish larger than 18.0 cm.

This study aims to identify the spring diet composition and feeding strategy of the European sprat, Sprattus sprattus. Diet composition of European sprat was investigated for the first time in the central Black Sea coast of Turkey. Examined of the 115 specimens (6 - 9.1 cm total length) of stomach, 12 (10.4%) had emty. Diet analysis was described based on gravimetric percentages (W%), frequency of abundance (N%), frequency of occurrence (%F) and relative importance index (IRI%). Feeding strategy was analyzed and graphically (Costello) represented, considering the frequency of abundance (N%) and frequency of occurrence (%F) indexes and grouping prey into higher taxonomic categories. Twenty species were identified, belonging to four prey groups: Polychaeta, Crustacea, Mollusca and Chaetognatha. Finally copepods proved to be the most important food item considering the above-cited indexes. All other prey taxa were identified as accidental preys. At least seven copepod species were identified, where Calanus euxinus appeared all round with %IRI≥50. Also results of feeding strategy analyses revealed a trophic specialization toward a single prey.

This study examined the stomach contents of 230 individuals out of 439 samples obtained from commercial fishermen between January 2013 and March 2014 from a trawler using trawl bags with a full cod-end mesh size of 44 mm. It was found that 216 samples were full and the stomach fullness index was estimated at 93.9%. The varying diet composition of the species was determined by estimating the percentage numerical composition (N%), frequency of occurrence (F%), gravimetric composition (W%) and the index of relative importance (IRI%). Diversity (Shannon index), richness (Margalef index) and similarity (Bray-Curtis index) of the catches in different seasons were calculated using the Biodiversity Professional (Version 2) software. Three major groups were identified in the catches: Crustacea, Mollusca and Teleostei. At least 17 different prey groups were identified. With regard to the diversity of consumed prey, the winter (1.204), autumn (1.079) and spring (1.000) seasons were characterized by a medium level of diversity, summer (0.699) – by a low level of diversity. However, the richness of prey does not show seasonal differences. As indicated by the Bray-Curtis index, the highest similarity between the prey groups was observed between the autumn and winter seasons, at 81.61%.

Bu çalışma İzmir ili kıyı şeridinde (Çiğli, Karşıyaka, Konak, Göztepe, İnciraltı, Narlıdere, Güzelbahçe ve Urla) yapılan amatör balıkçılığın güncel durumunu belirlemek amacıyla gerçekleştirilmiştir. Araştırma sahasında Nisan 2015 - Ekim 2015 periyodunda amatör balıkçılık yapan 105 birey tesadüfi olarak seçilmiş ve gönüllülük esasıyla kırk soru içeren ankete katılımları sağlanarak orjinal veriler elde edilmiştir. Örneklem büyüklüğünün belirlenmesinde; ülkemizde nüfus içindeki amatör balıkçılık oranı ile ilgili herhangi bir kayıt olmaması nedeniyle coğrafik yakınlığı açısından Avrupa için belirlenen %4,8 değeri kullanılmıştır. Amatör olta balıkçıları ile yapılan anket çalışması sonucunda balıkçılık ile ilgili düzenlemeler hakkında bilgisi olup olmadığı değişkenlerin dağılımı ki-kare testi ile belirlenmiş ve yanılma olasılığı α = 0,05 seçilmiştir. Anket sonuçları SPSS ve EXCEL programları kullanılarak değerlendirilmiştir. Sonuç olarak yasal düzenlemeler hakkında bilgisi olan ve olmayanlar karşılaştırıldığında yaş grubu değişkeninde (χ 2 :14,305; p:0,008), meslek gruplarında (χ 2 :13,074; p: 0,004) ve ev sahibi olmaları değişkeninde (χ 2 :5,810; p:0,016) istatistiksel olarak farklılık gözlenirken diğer değişkenlerde gözlenmemiştir. Yasal düzenlemeler hakkında bilgisi olan ve olmayanları karşılaştırdığımızda ise balık tüketimi (kg/hafta) değişkeni (χ 2 :9.149; p:0,000), kaç yıldır amatör balıkçılık yapıldığı değişkeni (χ 2 :17,805; p:0,000), olta balıkçılığı belgesine sahip olma değişkeni (χ 2 :18,595; p:0,000), avlanmada geçirdikleri saat değişkeni (χ 2 :12,931; p:0,012), tehlikeli balık türleri hakkında bilgisi olup olmadığına ait değişkene (χ 2 :16,097; p:0,000) ve yasal düzenlemeler hakkında bilgisi olan ve olmayanların arasında (χ 2 :11,728; p:0,001) istatistiksel olarak farklılık saptanmış diğer değişkenlerde ise farklılık saptanmamıştır.