Length-weight relationships of four fish species from the lower reaches of the Nujiang River and its tributaries in China

As one of the largest Southeast Asian rivers, flowing through China, Myanmar, and Thailand, the Nujiang (Salween) River contains a unique and rich diversity of fish species. In the present study, we investigated the length–weight relationships (LWRs) of four fish species (Pteronemacheilus meridionalis, Devario shanensis, Exostoma gaoligongense, and Glyptothorax granosus) collected from the lower reaches of the Nujiang River and its tributaries (24.175N~25.842N, 98.861E~98.903E), including the Mengboluo, Kungong, Luomingba and Laowo rivers in southwest China. Specimens were collected by using drift gill nets (100 m length × 1.5 m depth or 3 m depth, mesh-size: 1 cm-5 cm), cast nets (6.5 m, mouth opening: 35 × 45 cm², mesh-size: 4 mm) , and an electric shocker apparatus (12 V, 200 Hz) from different regions in the Nujiang River basin in September and October 2019 and June and September 2020. Before the collected fishes were placed in formalin, standard length (SL) and net weight (W) were measured respectively to the nearest 0.1 cm and 0.1g, respectively. Based on searches of the FishBase database and other relevant scientific literature, this study provides a new record of maximum size for P. meridionalis and LWRs for the four fish species.     

Length-weight relationships of six fish species from the Xiangjiang River in Guangxi region,China

This study aimed to estimate the parameters of length-weight relationships (LWRs) for six freshwater fish species that inhabit in the Xiangjiang River of Guangxi region, China. The specimens were sampled in April, July, and October 2014 and in January 2015 using electrofishing (CWB-2000P, China; 12 V import, 250 V export) and traps (mesh size 8.5 mm; length 200 m) at five sampling sites. For each sampling site, a trap was settled on one nearshore zone of the river for 24 hr, and the electrofishing was applied within 30 min from downstream to upstream with 200 m long. Standard length was measured (be accurate to 0.1 cm) and total weight determined (be accurate to 0.1 g) after preservation in formaldehyde (10%). The values for the parameter b of the length-weight relationships were estimated together with the coefficient of determination scores. In addition, this study provides a new tentative LWRs for the six species.     

Length–weight relationships of seven fish species in the Yangtze River Estuary and its adjacent waters,Eastern China

The length–weight relationships (LWRs) for seven fish species belonging to five families in the Yangtze River Estuary and its adjacent waters are presented. Cynoglossus gracilis, Cynoglossus macrolepidotus, Ctenotrypauchen chinensis, Collichthys niveatus, Ophichthus apicalis and Erisphex potti were collected monthly in 2009 using trammel nets (the size of smaller mesh net was 1.5 m × 15 m × 4 panels with mesh sizes of 2.5, 3.4, 4.3 and 5.8 cm; the size of larger-mesh net was 2.4 m × 30 m × 4 panels with mesh sizes of 5.0, 6.0, 7.0 and 8.0 cm; soaking overnight). Lophiogobius ocellicauda were collected December in 2020 using shrimp trawl nets (mesh size 2.0 cm). The precision of measurement for the fish specimens is 0.1 cm total length and 0.1 g total weight. The estimated ranges of the parameters a and b for the seven fish species were from 0.0001 to 0.0289 and 2.718 to 3.541, respectively. Two new maximum total length were recorded for Ctenotrypauchen chinensis and Ophichthus apicalis.     

New length-weight and length-length relationships of the fish fauna from the Xingu River,Amazon Basin,Brazil

This study provides new length‒weight (LWR) and length‒length relationships (LLR) for 25 indigenous fish species from Xingu River basin. Overall specimens were collected in different aquatic habitats in the Xingu River basin in quarterly collections between 2012 and 2018. The collections were carried out using distinct fishing gears, such as gill nets (20 to 180 mm mesh), seines (3 mm mesh), sieves (1 mm mesh), and casting nets (20 to 60 mm mesh). The present study shows the LWRs for 25 species, and the LLRs for 23 species. In addition, presents the new maximum total lengths for 20 species.     

Length-weight relationships of eight fish species from the Hailang river,China

The present study reports the length-weight relationships (LWRs) for eight fish species sampled in Hailang River, a left-bank tributary of the Mudan River in Northeast China. The fishes were collected from April to October bimonthly 2017 by electrofishing (fishing 2 kilometers along the river and within 5 meters from the bank) and netting (drift gillnet: mesh size 2 cm × 3 cm; 200 m net length). The specimens were weighed (nearest 0.1 g) and measured (nearest 0.1 cm) in the laboratory. This study provides an update in maximum lengths for five species.     

Length–weight relationships and length at first maturity for fish species in the upper Miranda River,southern Pantanal wetland,Brazil

Length–weight relationships (LWR) were estimated for 17 species and total length at first maturity (L50) for three species of freshwater fishes from the Miranda River, southern Pantanal, Brazil. The b values were compared for some species in the Paraguay River basin with the northern (Cuiabá River) part of the basin; differences in length–weight relationships were significantly different for Pseudoplatystoma corruscans, P. reticulatum (syn. P. fasciatum). First references on L50 and LWR are presented for two and eight fish species, respectively, as well as the new maximum total length for two species.     

Length–weight relationships (LWRs) of 12 Indian freshwater fish species from an un‐impacted tropical river of Central India (River Ken)

The length–weight relationships (LWRs) were studied of 441 fish individuals covering six families, eight genera and 12 freshwater species (L. dyochilus, L. calbasu, L. gonius, L. fimbriatus, P. sarana, L. boggut, C. mrigala, W. attu, B. bagarius, E. vacha, N. notopterus and S. aor) captured in the River Ken (tributary of the Yamuna River) from December 2007 to January 2009. The b value ranged from 3.52 for Cirrihinus mrigala, to 2.11 for Labeo gonius, with a mean of 3.03 at p < 0.001 for all species. The present observations are significant for conservation and management because the Ken River has been approved under India’s first interlinking plan with the River Betwa. The objective was to evaluate the LWRs of the freshwater fish species of an unimpacted and understudied river, which serves as a baseline for comparison to other relatively altered tropical Indian rivers.     

Length–weight and length–length relationships of 26 fish species from the Yiluo River,a tributary of the Yellow River,China

From February to October 2016, a total of 9,754 fish specimens were collected from the Yiluo River, a tributary of the Yellow River, China's second longest river. Based on these samples, length–weight relationships (LWRs) and length–length relationships (LLRs) were estimated for 26 species. Among these data, LWRs for 1 species, LLRs for 11 species, and maximum total lengths for six species were not previously recorded in FishBase. The a values of the LWRs varied between 0.0019 and 0.0116, and b values from 2.805 to 3.883. All regressions for LWRs and LLRs were highly significant (p < .001). These results will be useful for sustainable management and conservation of the fish resources in the Yiluo River and the Yellow River ecosystem.     

Reproductive biology of Prochilodus argenteus Agassiz, 1829 (Pisces: Prochilodontidae) in São Francisco River,Brazil

Knowledge of the main reproductive parameters of a species is fundamental for comprehension of the reproductive behavior of a species within its habitat. To evaluate the reproductive biology of curimbatá, Prochilodus argenteus, an important species for commercial fisheries of the São Francisco River basin, Brazil, 153 females and 174 males were captured during 1999–2000 in the São Francisco River. The females (maximum total length 71.2 cm and maximum weight 7.8 kg) were larger than the males (65.0 cm and 4.3 kg). The weight–length ratio indicated isometric growth for females (b = 3.15) and for males (b = 3.04). Prochilodus argenteus presented total spawning from October to January. Increase in rainfall was the main triggering factor for reproduction, showing a positive correlation with the gonadosomatic index (r = 0.84 females; r = 0.95 males). Size at gonadal maturation of females and males was 31.0 and 25.5 cm, respectively. This study provides information to aid in future implementation of captive breeding and management practices that intend to reduce the ongoing depletion of natural stocks.     

Length and weight relationships of five different fish species from northern areas of Pakistan

In present study five different species were studied from three different rivers from northern Pakistan. Specimens were collected in the period of January to December 2017 using cast nets (10–12 mm mesh size) for Barilius, Glyptothorax and Schistura species while cast nets (mesh size 1.25 × 1.25 cm) used for Schizothorax species. Total length (TL) and fork length (FL) to the nearest 0.1 cm and body weight (BW) to the nearest 0.1 g were recorded for each individual.     

Length‐weight relationships of nine fish species from the Qingjiang River,Yangtze River basin,China

This study presents the first report of length‐weight relationships (LWRs) for five fish species (Parabotia fasciata, Megalobrama mantschuricus, Plagiognathops microlepis, Rhodeus sinensis, Rhodeus fangi) and maximum total lengths for four species from the Qingjiang River, Yangtze River basin, China. Specimens were sampled in six sections along the Qingjiang River over a period of 1 year between April 2016 and March 2017 with gill nets (150 × 10 m; mesh size: 1–14 cm), benthic fyke nets (mouth opening: 12 × 12 cm; 10 m; mesh size: 1 cm) and stationary lift nets (10 × 10 m; mesh size: 0.8 cm).     

Length–weight relationships in seven ornamental freshwater species of Characiformes from the Unini River basin (Brazilian Amazon)

The aim of the current study was to address length‐weight relationships (LWRs) in seven ornamental fish species from the Unini River basin—the main tributary of lower Negro River (Brazilian Amazon). Specimens were seasonally sampled by using hand nets and beach seines (mesh size < 1 mm) in five different occasions (August 2009—December 2010). Preserved specimens (initially kept in 10% formalin and transferred to 70% ethanol 10 days later) were measured and weighted in laboratory. The LWR was calculated based on a log‐transformed linear regression. The maximum standard length of each species was different from the ones previously reported at Fishbase. In addition, b values were different from the ones reported for the four species whose data were available in the literature.     

Length–weight relationships of four freshwater cyprinid species from a tributary of Ganga River Basin in North India

This paper provides length‐weight relationships (LWRs) for four freshwater cyprinid fish species, namely Barilius bendelisis (Hamilton, 1807), Bangana dero (Hamilton, 1807), Chagunius chagunio (Hamilton, 1807) and Labeo dyocheilus (McClelland, 1839) from the Kosi River, a tributary of the River Ganga in northern India. Altogether 848 specimens were caught bimonthly (for B. bendelisis) and quarterly for the other three species between March 2013 and December 2014 using cast nets (9 m length, 9 m width and 1/2 cm mesh size). LWRs for two of the four species (B. dero and C. chagunio) are recorded for the first time. The present study results will be useful for fishery researchers, management and conservation in this least‐explored tributary of the Ganga River Basin.     

Length–weight and length–length relationships for four fish species of Upper Paranaíba river basin,Brazil

Here the length–weight and length–length relationships of four species are provided. Fishes were collected bimonthly from December 2015 to November 2016 with sieves and trawl net, with mesh size of 0.3 cm, in eight sites from the upper Paranaíba River basin, Southeastern Brazil. Fishes were measured (cm) and weighted (0.1 g) still in the field. First record of LWR and LLR are presented for three and four species, respectively.     

Length–weight and length–length relationships of 20 fish species from the upper Yangtze River,southwest China

Length–weight (LWR) and length–length (LLR) relationships were estimated for 20 species of fish from the upper Yangtze River, southwest China. Samples were collected using multiple types of gear (2–6 cm mesh trammel nets, 2 cm mesh trap nets, and baited hooks) in Jiangjin and Yibin sections from 2007 to 2009. New maximum lengths for 16 species were recorded for FishBase. LWRs were significant for all species. Standard length–total length equations for converting size measurements for these 20 species are also presented. The results provide primary data for future fish research and conservation.     

Length–weight relationship of 12 fish species from the Lhasa River and surrounding area in Tibet,China

Presented are the relationship between standard length (SL) and weight (W) for 12 fish species in Tibet, China, representing three families and six genera from the Lhasa River. All fish samples were collected by either electro‐shocker (12 V, 200 Hz), fish cages (mouth opening: 40 × 40 cm², 5 m), or drift gillnets (3 × 1.5 m; mesh‐size: 3 cm to 8 cm) from different areas in the Lhasa River Basin, August and September 2015. Parameter b ranged from 2.88 to 3.29, and all correlation coefficient (r²) values were higher than 0.95. Length–weight relationships (LWRs) for three of the species as well as one maximum length are first reports for FishBase.     

北京市河流滨岸带植被调查

采用样地样方调查法,通过Margalef指数、Shannon-weiner指数和Pielou指数综合分析了北京市3条主要河流(潮白河、拒马河、清水河)的滨岸带植被物种丰富度、多样性及均匀度。结果表明:在11个样地中共记录植物74科248种,其中蕨类植物3科7种,双子叶植物56科166种,单子叶植物15科75种。清水河滨岸带的植物Mar-galef指数、Shannon-weiner指数和Pielou指数均高于潮白河与拒马河,植被状况保持较好。     

Length‐weight and length–length relationships of three algae‐scraping cyprinid species from Iran

The study presents length–weight relationships (LWRs) and length–length relationships (LLRs) for three algae‐scraper species; Capoeta coadi from the Kouhrang River (Iran; 32°23′N, 50°08′E) a part of the Tigris drainage basin, Capoeta pyragyi from Cheshmeh Langan River (32°55′N, 50°10′E) a part of Zayanderud River basin and Capoeta umbla from Chooman River (35°57′N, 45°47′E). Fish were sampled by electro fishing (Samus1000; Power Out: 200 watts) in August, September and October 2017. Sampling was carried out each months in sites covering an area of about 100 m² including runs, riffles and pools at a water depth of 10–60 cm. The obtained LWRs and LLRs showed a high level of correlation (r² > 0.99).     

Length–weight relationship and condition factor of the Characidae matrinxã, Brycon falcatus (Müller & Troschel, 1844), in the Teles Pires River,southern Amazon

The aim of this study was to verify whether the in situ supply of soybean as a fish attractant bears any influence on the length–weight relationship and condition factor of the omnivorous fish species, Brycon falcatus. In addition, estimated was the length–weight relationship, standard and total length, condition factor, and size of B. falcatus in the spawning period in the Teles Pires River Basin. In the experimental design, rivers of the Teles Pires Basin containing soybean attractant (Verde River, Celeste River, Teles Pires River and the Tapaiuna River) were mapped. Fish were also collected from the Cristalino River, which contained no soybean attractant (treatment control). Samples were collected from August 2012 to July 2013. Length–weight relationship of B. falcatus in the Teles Pires River Basin can be obtained by the expression: Wt = 0.0091*SL^3.376, r² = .97, n = 102, and length‐length relationship: TL = 1.128*SL + 3.978, r² = .96. The condition factor of all specimens collected in the Teles Pires Basin was k = 1.055. Size at capable phase (L50) of spawning was estimated at 23 cm standard length. Results showed no significant difference in the length–weight relationship or condition factor of B. falcatus collected from rivers with or without soybean attractant. Concluded is that the in situ supply of soybean as a fish attractant does not interfere with the wellbeing of B. Falcatus in the Teles Pires River Basin.