Güney-Doğu Karadenız’de (Ordu-Samsun) Mezgit Balığı (Merlangius Merlangus (Lınnaeus, 1758))’nın Yıllık Beslenme Periyodunda Kanibalıst Davranış Özelliklerinin Araştırılması

Abstract

Bu araştırma; mezgit balığının, Merlangius merlangus yıllık beslenme beslenme rejimini ve kanibalist davranış özelliklerini araştırmak için Eylül 2016-Ağustos 2017 tarihleri arasında Güney-doğu Karadeniz’in Ordu ve Samsun kıyılarında yürütülmüştür. Araştırmanın mezgit balığı örnekleri aylık olarak ticari avcılıktan elde edilmiştir. Araştırma süresince incelenen 762 mezgit balığı midesinden %75.7’sinin boş olduğu tespit edilmiştir. Mezgit balıklarının midelerinde 5 balık (istavrit, hamsi, çaça mezgit ve kayabalığı) ve bir Gastropod türüne rastlanmıştır. Balık türlerinden istavrit, mezgit balıklarının hem Ordu hem de Samsun kıyılarında en önemli besin kaynağını oluşturduğu tespit edilmiştir. Bu balık türünü hem Ordu hem de Samsun kıyılarında sırasıyla hamsi ve mezgit izlemiştir. Ancak, Samsun kıyılarında yaşayan mezgit balıkları için besin kaynağı olarak kendi türünün önemi Ordu kıyılarında yaşayan mezgit balıklarına göre çok daha düşük bulunmuştur. Başka bir ifadeyle, Samsun kıyılarında kanibalizm oranı Ordu kıyılarına göre çok daha düşük bulunmuştur. Güney-doğu Karadeniz’de mezgit balıkları arasında kanibalizm oranı %12 IRI ve %14 PRIV olarak tespit edilmiştir. İlkbahar ve sonbahar mevsimindeki kanibalizm oranı yaz ve kış dönemlerine göre daha düşük bulunmuştur. Mezgit balıklarının ilkbahar ve yaz mevsimlerindeki en önemli besin kaynağını istavrit balığı iken, sonbahar ve kış mevsimlerinde hamsi olduğu saptanmıştır. Bu balık türlerini ilkbahar ve yaz mevsimlerinde mezgit, sonbahar mevsiminde mezgit ve istavrit, kış mevsiminde ise istavrit ve mezgit balığı izlemiştir. Bu sonuçlar, mezgit balığının besin kaynaklarındaki azalmaya bağlı olarak ilkbahar ve yaz aylarında kanibalizme yöneldiğini göstermektedir. Mezgit balıklarının, boylarının Ordu kıyılarında %37.6’sı, Samsun kıyılarında %24.3’ü kadar büyüklükteki kendi türünün bireylerini tükettikleri saptanmıştır. Mezgit balıklarının ağırlıklarının, Ordu kıyılarında %11.2’si, Samsun kıyılarında ise %8’i kadar olan kendi türünün bireylerini tükettikleri belirlenmiştir.,The study was conducted in the coasts of Ordu and Samsun of the south-eastern Black Sea between September 2016 and August 2017, to investigate the cannibalistic behavioral characteristics of the whiting.Whiting samples were obtained monthly from commercial fishing. During the study, 75.7% of 762 haddock stomachs were found to be empty.In the stomach of whiting, five fish species (horse mackerel, anchovy, sprat haddock and goby) and a Gastropod species were determined. It is determined that horse mackerel was the most important food source both in Ordu and Samsun coasts. This food source was followed by the anchovy and the whiting in the both sampling areas, respectively.However, the importance of its own species as a food source for whiting on the Samsun coasts was found to be much lower than the whiting on the Ordu coasts.In other words, the rate of canibalism was found to be much lower on the Samsun coasts than the Ordu coasts.In the south-eastern Black Sea, the rate of cannibalism among whiting fish was found to be 12% IRI and 14% PRIV. The rate of canibalism in spring and autumn was lower than in summer and winter.The rate of canibalism in spring and autumn was lower than in summer and winter. While the most important food source of the whiting in spring and summer was the mackerel fish, the anchovy in the autumn and winter seasons.These fish species was followed by haddock in spring and summer, whiting and horse mackerel in autumn and horse mackerel and haddock in winter.These results show that the whiting tends to cannibalism in spring and summer due to the decrease in food sources.It was determined that whiting fish consumed individuals belonging to their own species as large as 37.6% of their lengths in the Ordu coasts, 24.3% in the Samsun coasts.The whiting consumed individuals of their own species which were up to 11.2% of their weight in the Ordu coasts and 8% in the Samsun coasts.

The study was conducted in the coasts of Ordu and Samsun of the south-eastern Black Sea between September 2016 and August 2017, to investigate the cannibalistic behavioral characteristics of the whiting.Whiting samples were obtained monthly from commercial fishing. During the study, 75.7% of 762 haddock stomachs were found to be empty.In the stomach of whiting, five fish species (horse mackerel, anchovy, sprat haddock and goby) and a Gastropod species were determined. It is determined that horse mackerel was the most important food source both in Ordu and Samsun coasts. This food source was followed by the anchovy and the whiting in the both sampling areas, respectively.However, the importance of its own species as a food source for whiting on the Samsun coasts was found to be much lower than the whiting on the Ordu coasts.In other words, the rate of canibalism was found to be much lower on the Samsun coasts than the Ordu coasts.In the south-eastern Black Sea, the rate of cannibalism among whiting fish was found to be 12% IRI and 14% PRIV. The rate of canibalism in spring and autumn was lower than in summer and winter.The rate of canibalism in spring and autumn was lower than in summer and winter. While the most important food source of the whiting in spring and summer was the mackerel fish, the anchovy in the autumn and winter seasons.These fish species was followed by haddock in spring and summer, whiting and horse mackerel in autumn and horse mackerel and haddock in winter.These results show that the whiting tends to cannibalism in spring and summer due to the decrease in food sources.It was determined that whiting fish consumed individuals belonging to their own species as large as 37.6% of their lengths in the Ordu coasts, 24.3% in the Samsun coasts.The whiting consumed individuals of their own species which were up to 11.2% of their weight in the Ordu coasts and 8% in the Samsun coasts.