Length-weight relationship and condition factor of the glasshead grenadier Hymenocephalus italicus (Gadiformes: Macrouridae) from Gökçeada Island (Northern Aegean Sea, Türkiye)
DOI:
https://doi.org/10.61326/jofbs.v6i1.03Keywords:
LWR, Trawl, Discard, Condition factor, Macrourid species, Deep-sea fishAbstract
This study investigated the length-weight relationship (LWR) and condition factors of the glasshead grenadier Hymenocephalus italicus (Giglioli, 1884) from the deep waters surrounding Gökçeada Island in the northern Aegean Sea (Türkiye). Fish specimens were collected between March 2015 and April 2017 during commercial bottom trawl operations at depths ranging from 109.7 to 332.8 m. A total of 245 individuals were analyzed. Total length (TL) ranged from 4.10 to 14.10 cm (mean: 11.20±0.10 cm), while total weight (W) ranged from 0.41 to 5.45 g (mean: 2.62±0.05 g). The LWR was described by the equation W = 0.0577·TL1.5667, corresponding to the logarithmic form log(W)=-1.2388+1.5667·log(TL). The regression model was statistically significant (p<0.001) and explained a moderate proportion of the variance (R2=0.545). The estimated growth coefficient (b=1.5667; 95% CI: 1.386-1.748) was significantly lower than the theoretical isometric value of 3, indicating negative allometric growth. Mean Fulton’s condition factor (K) and relative condition factor (Kn) were 0.194±0.005 and 0.171±0.005, respectively. This investigation provides foundational biological data for H. italicus in the northern Aegean Sea. It underscores the importance of standardized morphometric protocols, particularly the use of pre-anal length (PAL), in future studies of deep demersal ichthyofauna.
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