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Growth pattern, mortality and reproductive biology of common sole, Solea solea (Linneaus, 1758), in the Sea of Marmara, Turkey

Kahraman Abdullah Ekrem, Yıldız Taner, Uzer Uğur, Çanak Özgür

Oceanological and Hydrobiological Studies

2021

Vol. 50, No. 4

398--410

The study deals with the growth pattern, mortality, and reproduction of common sole, Solea solea (Linneaus, 1758), from the Sea of Marmara (Turkey). A total of 580 fish specimens were sampled monthly from October 2017 to September 2018. The total length of all sampled individuals ranged from 11.1 to 29.5 cm, corresponding to ages from 1 to 3 years. The length–weight relationship was expressed as W = 0.022 TL2.6838, where the slope indicated negative allometric growth. Growth parameters were L∞ = 33.7 cm, k = 0.48, and t0 = −0.18 for all samples. A seasonally oscillating growth model, indicating the amplitude of oscillations, revealed an important seasonal growth pattern. Total, natural, and fishing mortality rates were calculated as 1.42, 0.47, and 1.01, respectively. The exploitation ratio (E = 0.68) indicates that the fishing pressure on the common sole in the Sea of Marmara was high. The sex ratio (♀/♂) was 1.18. The gonadosomatic index (GSI) for females showed that two main spawning seasons were observed: one in spring (May) and one in autumn (September–October). Sizes at the onset of sexual maturity were estimated for both females and males at 21.6 and 18.6 cm, respectively.

Reproductive Biology of the Mediterranean Green Crab Carcinus aestuarii Nardo, 1847 (Crustacea, Brachyura, Portunidae) in Homa Lagoon, Aegean Sea, Turkey

Özbek M., Koçak C., Acarli D.

Oceanological and Hydrobiological Studies

2012

Vol. 41, No. 4

77-80

The Mediterranean green crab Carcinus aestuarii Nardo, 1847 (Crustacea, Brachyura, Portunidae) is a common inhabitant of the shallow waters of Homa Lagoon in Izmir Bay, Turkey, in the eastern Mediterranean. Monthly samples were collected in Homa Lagoon from June 2006 to May 2007 using trammel nets, fyke nets, beach seines and fence traps. In total, 608 males and 559 females of C. aestuarii were collected. The highest sex ratio (81-86% females) was recorded between October and December, and in August (58% females). Ovigerous females were obtained only from November to February with the highest ratio of ovigerous females (55%) observed in January 2007. The maturation curve presenting the carapace width showed that 50% of female crabs with the carapace width of 26.84 š1.58 mm (r= 0.72) were physiologically mature. Regression analyses indicated that the number of eggs was positively correlated with carapace width and wet weight (P < 0.05, in both cases).