Length–Weight Relationships and Condition Factors of Freshwater Fishes in the Sapanca Lake Basin (NW Türkiye)

This study analysed the length–weight relationships (LWR) and Fulton`s condition factors (K) of 20 fish species inhabiting the Sapanca Lake basin (North-West Anatolia, Türkiye). Fish specimens were collected from the lake and its streams in several times between May 2022 and December 2024 using gill nets and portable electro-shocker devices. LWR and K analyses were based on a total of 5993 specimens, ranging from five (Esox lucius) to 1674 (Rhodeus amarus). The allometric coefficient `b` estimated using a linear regression model of LWR ranged from 2.7684 (Clupeonella cultriventris) to 3.3555 (Neogobius melanostomus) and most species (12) showed positive allometric growth. The coefficient of determination (R2) values of the LWRs ranged from 0.8953 (C. cultriventris) to 0.9991 (Alosa maeotica). K values were minimum for Atherina boyeri (0.422) and maximum for Petroleuciscus borysthenicus (2.608). This study provides the first contribution to the LWR and K parameters of six species (A. boyeri, C. cultriventris, Leucaspius delineatus, N. fluviatilis, R. amarus, Squalius pursakensis) in the Sapanca Lake Basin. The findings of this study can serve as a resource for assessing the impact of ecosystem health on fish growth in the lake basin.