Özet:

The present study describes for the first time some biological aspects (size composition, sex ratio, length-weight relationship and condition factor) of Ponticola constructor (Caucasian goby) inhabiting Borçka Dam Lake and its tributaries from the lower Çoruh River Basin located in the northeastern Türkiye. Fish samples were caught from June 2017 to May 2018 by using trammel nets with various mesh sizes and by pulsed DC electrofishing device. A total of 145 Caucasian goby (78 females and 67 males) ranging from 6.8 cm to 13.4 cm TL were sampled during the study. The sex ratio of female to male was calculated as 1.16:1.00 which did not deviate from the expected ratio of 1:1 (χ² = 0.834, p˃0.05). The total length-weight relationships were determined as W= 0.016TL 2.896 (r 2=0.995, p˂0.05) for females, as W= 0.018TL 2.841 (r 2=0.993, p˂0.05) for males and as W= 0.017TL 2.856 (r 2=0.994, p˂0.05) for combined sex with the b-values were significantly different from isometric growth (b=3) indicating negative allometric growth of Caucasian goby for all sexes (Pauly’s t-test, p˂0.05). The regression analysis revealed that the coefficient of determination was r 2>0.99 showing a highly significant correlation between total length and weight. The differences in slopes ( b values) of the LWR were statistically significant for both sexes (ANCOVA, p<0.05). Fulton's condition factor (K) values ranged from 1.124 to 1.312 in females and from 1.076 to 1.426 in males indicating a good growth condition in this habitat. No significant difference was observed in mean K values between females and males (t-test, p>0.05). The present study will provide a baseline on some biological parameters of Ponticola constructor to provide a guideline for the fisheries management authority and fisheries scientists for further investigations as well as presents the first known reference on the LWRs of this species for the FishBase database. Furthermore, the reported results may contribute to the conservation and sustainability of this species in the area.

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