Length-weight, length-length and a proposed empirical standard weight equations for the Italian endemic cyprinid species Sarmarutilus rubilio

Abstract. – Length and weight data of 21,040 specimens of the Italian endemic species Sarmarutilus rubilio (Bianco & Ketmayer, 2014) were collected throughout the area of distribution of the species and used to calculate total length-weight (TL-W), standard length-total length (SL-TL), fork length-total length (FL-TL), and standard weight (Ws) equations. The SL-TL equation was TL = 1.153 SL + 4.121; the FL-TL equation was TL = 1.037 FL + 0.288. The log-transformed TL-W equation was: log10W = –5.201 + 3.117 log10TL. The Ws equation was log10Ws = –4.043 + 1.919 log10TL + 0.315 (log10TL)2 (length-range 60-200 mm). The resulted Ws equation was not biased by length and its use is suggested as a way to calculate the relative weight (Wr) for the species throughout the area of distribution of the species. These equations represent the first reference for the species from its native distribution range and they will be useful tools to increase the basic knowledge on population ecology of this species.