Length-Weight Relationships of Four Fish Species from the Dongting Lake Basin, Central South China

,


Introduction
Dongting Lake, situated on the southern bank of the Jingjiang section in the middle reaches of the Yangtze River, ranks as China's second-largest freshwater lake.Te lake receives infow from four major tributaries, Yuanjiang, Xiangjiang, Zishui, and Lishui Rivers, as well as three inlet channels, specifcally Songzi, Hudu, and Ouchi Rivers.It drains into the Yangtze River via a single outlet, Chenglingji.Te Dongting Lake basin is recognized as one of the world's 200 priority ecoregions for global conservation [1].Covering an approximate area of 2.67 × 10 5 km 2 , the basin constitutes around 12% of the Yangtze River's total foodplain area.Te basin serves as a biodiversity hotspot, which is home to a diverse array of 217 fsh species [2].Moreover, the basin stands as one of the Yangtze River's most productive regions, ofering a range of ecosystem services including biodiversity conservation, wetland maintenance, water and soil retention, as well as carbon sequestration [3,4].
Length-weight relationships (LWRs) play a crucial role in both fsh biology and fsheries research, serving various analytical purposes [5,6].Specifcally, LWRs are instrumental in assessing fsh biomass, evaluating the body condition of individual species, and comparing speciesspecifc growth across diferent habitats and localities.However, the comparability of these studies hinges on the use of standardized sampling methods and protocols to mitigate the impact of gear selectivity [7].To examine the correlation between total length and body weight, data were collected for four fsh species in the Dongting Lake basin from May 2021 to July 2023.Subsequent analyses were  Te LWR was assessed by applying the following allometric equation [10,11]:

Materials and Methods
where W i is the body weight (g), L i is the total length (cm), and a (intercept) and b (slope) are the estimated parameters applying the linear regression model with the logtransformed data according to the following equation: log 10 W i  � log 10 (a) + blog 10 L i  + log 10 ξ i . ( Te corrected back-transformed predicted value of the response variable was calculated by multiplying the backtransformed predicted value by the correction factor (cf ), where RSE is the residual standard error and log e (10) is used to adjust for the base of the logarithm used [12,13].
Te 95% confdence limits (95% CL) for parameters a and b were calculated [14].All statistical analyses were performed by using R software (version: 4.2.3), with a � 0.05 as the signifcance level.

Results
Descriptive statistics for the four fsh species, all belonging to the Cyprinidae, are summarized in Table 1.Table 1 includes sample size, length and weight ranges, and estimated parameters a and b of the length-weight relationships (LWRs), along with their 95% confdence limits and determination coefcients (r 2 ).All LWR values for the four species were statistically signifcant (p < 0.001).Te b values in the regression models for LWR varied from 2.9709 in Acrossocheilus jishouensis to 3.4373 in Onychostoma barbata.Te coefcients of determination (r 2 ) ranged from 0.984 in Sinilabeo tungting and O. barbata to 0.999 in Onychostoma rara.

Discussion
Te length-weight relationships (LWRs) for all four fsh species were statistically highly signifcant, with p < 0.001.Te coefcient of determination (r 2 ) exceeded 0.98, indicating robust positive correlations between length and weight for each species.Tese fndings align with previous research [15,16] and suggest that the models possess strong explanatory power for estimating LWR variations.Tey serve as a reliable resource for FishBase in the context of the Dongting Lake basin [9].Furthermore, the estimated b values in the regression models for all species ranged from 2.9709 to 3.4373, falling within the expected range of 2.5 to 3.5 [14].Our study also provides the frst empirical records for S. tungting, A. jishouensis, O. rara, and O. barbata in the Dongting Lake basin, expanding upon previous FishBase reports.
In this study, A. jishouensis and S. tungting are endemic to the Yangtze River Basin.Te populations of S. tungting, O. rara, and O. barbata are in signifcant decline due to various anthropogenic stressors, such as hydropower dam construction.Consequently, sample collection poses a challenge.While the LWR reported here are initial estimates for these four species, caution is advised in their interpretation due to limited sample sizes (N < 30) and restricted size ranges.
Te estimated LWR values may be infuenced by various technical factors, including sampling methodology, equipment, and fsh grid size [17].In addition, the sample size, size range, gender, and seasonal variations at the time of sampling could also afect the LWR estimates [14,18].Terefore, future research should investigate the growth heterogeneity of these species.
In conclusion, this study ofers length-weight relationships (LWRs) for four freshwater fsh species in the Dongting Lake tributaries.Tese fndings contribute valuable data to FishBase, serving as a critical resource for further fsheries research, conservation eforts, and efective management of the Dongting Lake ecosystem.

Table 1 :
Descriptive statistics and estimated parameters of length-weight relationship for four fsh species sampled between May 2021 and July 2023 from the tributaries of the Dongting Lake, Central South China.