Seasonal variation in the trawl codend selectivity of red mullet (Mullus barbatus)
Küçük Resim Yok
Tarih
2011
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu çalışmada Doğu Ege Denizi’nde 40 mm PE torba seçiciliğinin mevsimsel değişimi araştırılmıştır. Aynı torbanın seçiciliği, aynı gemi, av sahası, çekim hızı ve çekim süresi kullanılarak barbun için denenmiştir. İlkbahar (4-18 Nisan 2002), yaz (10-25 Temmuz 2002), sonbahar (26 Eylül-2 Ekim 2002) ve kış (22-23 Ocak 2003) mevsimlerinde 4 grup veri toplanmıştır. Veriler örtü torba tekniği kullanılarak elde edilmiş ve ‘En Yüksek Olabilirlik Yöntemi’ ile lojistik denklem kullanılarak analiz edilmiştir. Dört grup seçicilik eğrisi Fryer tarafından geliştirilen model kullanılarak karşılaştırılmıştır. Balığın kondüsyon faktöründeki mevsimsel değişimleri araştırmak amacıyla avdaki tüm boy aralığını kapsayacak şekilde alınan örneklerden boy ve ağırlık verisi toplanmıştır. Sonuçlar ilkbaharda hesaplanan L50’nin diğer mevsimlerdekinden belirgin derecede daha düşük olduğunu göstermektedir (P<0,05). En iyi ve en düşük $L _{50}$ değerleri arasında, sırasıyla yaz (11,1 cm) ve ilkbahar (10,1 cm), yaklaşık %10’luk bir fark vardır. Sonbahar (10,8cm) ve kışın (11,0 cm) $L _{50}$ değerleri bu iki değerin arasında kalmaktadır. Sonbaharda balıklar en iyi kondüsyon faktöründe ve su sıcaklığı yıllık döngüsünün en yüksek değerindedir.
Seasonal changes in the selectivity of 40 mm PE codend were investigated in the Eastern Aegean Sea. Selectivity of the same codend was tested for red mullet (Mullus barbatus), by using the same vessel, fishing ground, towing speed and duration. Four sets of data were collected in spring (4-18 April 2002), summer (10-25 July 2002), autumn (26 September-2 October 2002) and winter (22-23 January 2003). Data were obtained by using covered codend technique, and analysed by using logistic equation with the maximum likelihood method. Four sets of selection curves were analysed and compared using the model developed by Fryer. To investigate the seasonal changes in the condition of the fish, length and weight data were collected from samples taken to cover the whole length range in the catch. Results show that estimate of $L _{50}$ in spring is significantly lower than those for other seasons (P<0.05). There is about 10% difference between the mean L50 values of the best and the poorest seasons, summer (11.1 cm) and spring (10.1 cm), respectively. the $L _{50}$ values of autumn (10.8 cm) and winter (11.0 cm) lay between these two. Fish were in their best condition and the water temperature was at its highest point of the annual cycle in autumn.
Seasonal changes in the selectivity of 40 mm PE codend were investigated in the Eastern Aegean Sea. Selectivity of the same codend was tested for red mullet (Mullus barbatus), by using the same vessel, fishing ground, towing speed and duration. Four sets of data were collected in spring (4-18 April 2002), summer (10-25 July 2002), autumn (26 September-2 October 2002) and winter (22-23 January 2003). Data were obtained by using covered codend technique, and analysed by using logistic equation with the maximum likelihood method. Four sets of selection curves were analysed and compared using the model developed by Fryer. To investigate the seasonal changes in the condition of the fish, length and weight data were collected from samples taken to cover the whole length range in the catch. Results show that estimate of $L _{50}$ in spring is significantly lower than those for other seasons (P<0.05). There is about 10% difference between the mean L50 values of the best and the poorest seasons, summer (11.1 cm) and spring (10.1 cm), respectively. the $L _{50}$ values of autumn (10.8 cm) and winter (11.0 cm) lay between these two. Fish were in their best condition and the water temperature was at its highest point of the annual cycle in autumn.
Açıklama
Anahtar Kelimeler
Balıkçılık, Zooloji
Kaynak
Turkish Journal of Fisheries and Aquatic Sciences
WoS Q Değeri
Scopus Q Değeri
Cilt
11
Sayı
2
