Data on length-weight and length-length relationships, mean condition factor, and gonadosomatic index of Rutilus rutilus and Perca fluviatilis from the Ob River basin, Western Siberia

Raw data were obtained from 250 specimens of roach Rutilus rutilus and 274 specimens of perch Perca fluviatilis at 15 sampling sites located from North to South Taiga. Fish sampling was performed using gill-nets with 22 and 28 mm mesh. Total and eviscerated weights, total and standard lengths, fish sex, gonad weight and maturity stage were recorded. Linear regression analysis of log-transformed total weight and total length values was performed. Regression slope and intercept were used to obtain length-weight relationships and mean condition factor values. Length-length relationships were calculated by the linear regression between the total and standard lengths. Gonadosomatic index was determined using the gonad weight and the total weight of fish. The data are useful for establishing biomass, fish growth patterns, relative condition of individuals within a sample or across populations.


a b s t r a c t
Raw data were obtained from 250 specimens of roach Rutilus rutilus and 274 specimens of perch Perca fluviatilis at 15 sampling sites located from North to South Taiga. Fish sampling was performed using gill-nets with 22 and 28 mm mesh. Total and eviscerated weights, total and standard lengths, fish sex, gonad weight and maturity stage were recorded. Linear regression analysis of log-transformed total weight and total length values was performed. Regression slope and intercept were used to obtain length-weight relationships and mean condition factor values. Length-length relationships were calculated by the linear regression between the total and standard lengths. Gonadosomatic index was determined using the gonad weight and the total weight of fish. The data are useful for establishing biomass, fish growth patterns, Abbreviations: CF, condition factor; EW, eviscerated weight; GSI, gonadosomatic index; GW, gonads weight; LLR, length-length relationship; LWR, length-weight relationship; SL, standard length; TL, total length; TW, total weight. * Corresponding author.

Value of the Data
• The data contribute to the knowledge of given fish species biology and provide new cases for meta-analysis of length-weight, length-length, or weight-weight data. • Specialists involved in fish stock assessment can benefit from these data.
• Length-weight relationships are helpful in gaining data on fish growth and biomass.
• The data can be used to calculate the relative weight W rm [3] or other length-/ weight-related indices for comparing the condition of fish across populations. Fig. 1 and Fig. 2 present linear regression models for the log-transformed raw data on the total length (TL) and total weight (TW) of roach Rutilus rutilus and perch Perca fluviatilis . Descriptive statistics and estimated parameters of length-weight relationships are given in Table 1 . Fig. 3 and Fig. 4 show length-length relationships derived from the raw TL and standard length   Note: N -number of specimens used for the linear regression analysis; TL -total length; TW -total weight; CLconfidence limit; LWR -length-weight relationship; R 2 -coefficient of determination of the linear regression.

Experimental Design, Materials and Methods
Fish specimens were collected in 2011 and 2012 in the Ob River basin using gill-nets with 22 and 28 mm mesh sizes. Each individual, one after the other, was immobilized by a stunning blow to the head, quickly measured in TL and SL to the nearest 0.1 cm using a measuring board. Then, TW was determined, and a fish was subjected to cervical transection. Next, each specimen was dissected, and the sex and gonad maturity stage were determined visually. Gonads were excised and weighed (GW) to the nearest 0.1 g. After that, abdominal and pericardia cavities were cleared, and the eviscerated weight (EW) of a fish was measured. TW and EW were determined with an accuracy of 1 g using an Adam HCB 1002 digital balance.
In total, raw data on 250 specimens of Rutilus rutilus and 274 specimens of Perca fluviatilis were collected. Length-weight relationships were calculated by the linear regression of logtransformed total weight on total length [3] . Microsoft Office Excel was used for processing the data. Log 10 values of TL and TW were used to draw a scatter plot for each species. A trend line was added to each scatter plot to obtain a linear-regression equation (log TW = b log SL + log a ). Log a values were back-transformed to find a length-weight relationship (TW = a SL b ). Further, TL and SL were used to find a length-length relationship by linear regression. CF mean values were calculated according to the formula: CF mean = 100 a SL b -3 [3] . GSI values were obtained using the formula: GSI = 100 GW TW −1 .

Ethics Statement
Data collection complied with the ARRIVE guidelines and was carried out in accordance with the U.K. Animals (Scientific Procedures) Act, 1986 and associated guidelines, EU Directive 2010/63/EU for animal experiments.