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 four fish species from Visakhapatnam coast,India

Length‐weight relationships (LWRs) were determined for 4 deep water fish species from Visakhapatnam coast, India. Specimens were collected fortnightly between December 2013 and November 2015 from commercial trawls at Visakhapatnam fish landing centre (16.98°N–20.2°N, Long.82.19°–86.53°E). Individuals were captured between 100 and 300 m depth with shrimp trawl net (head rope length: 37–46 m and cod end mesh size: 30–40 mm). Total length (TL) (nearest to 0.1 cm) and body weights (nearest to 0.1 g) were taken each individual. All LWRs were significant with r² values ranged from 0.958 for Uranoscopus bicinctus Temminkc & Schlegel, 1843 to 0.983 for Uranoscopus chinensis Guichenot, 1882 and “b” values ranged from 2.832 for U. bicinctus to 3. 402 Synodus indicus (Day, 1873).This study provides a new maximum length data for three species (Uranoscopus bicinctus Temminkc & Schlegel, 1843; Uranoscopus chinensis Guichenot, 1882 and Uranoscopus marmoratus Cuvier, 1829).     

Length‐weight relationships of 10 coastal fish species from the Visakhapatnam coast,India

We analysed the length‐weight relations (LWRs) of 10 fish species inhabiting different habitats from Visakhapatnam, Coast of India. Samples were obtained between August 2013 and December 2016 from commercial trawlers at the local fish landing centre (16.98°N–20.20°N, Long.82.19°–86.53°E). Fishes were captured between 100 and 300 m depth with demersal trawl net (head rope length: 46 m and cod end mesh size: 40 mm with a 38 m high speed. Total length (TL; nearest to 0.1 cm) and body weights (nearest to 0.1 g) were taken from each individual. This study provides new maximum length data for two species (Archamia bleekeri (Günther, 1859) and Ostorhinchus fleurieu (Lacepède, 1802), and LWR estimates for rare deep reef associated fishes are provided for the first time. All LWRs were significant with r² values ranging from .908 for Sargocentron praslin (Lacepède, 1802) to .981 for Parapercis pulchella (Temminck & Schlegel, 1843) and “b” values ranged from 2.5216 for Parapercis pulchella (Temminck & Schlegel, 1843) to 3.4746 for Ostorhinchus fleurieu Lacepède, 1802.     

Length–weight relationships of three fish species from the Tibet reach of the Lancang River,China

Length‐weight relationships (LWRs) were determined for three fish species, Schizothorax lantsangensis (Tsao, 1964), Schizothorax lissolabiatus (Tsao, 1964) and Schizopygopsis anteroventris (Wu & Tsao, 1989), from the Tibet reach of the Lancang River, China (N 29°06′–31°30′, E 96°57′–98°38′). Specimens were collected in April and September 2017. The specimens were caught with drifting gillnets (mesh size 2.5 cm and 7.0 cm). The b values of these three fish species ranged from 2.974 to 3.075. The high r² values (all > .980) indicate that these relationships will be appropriate for use in fisheries management of these species.     

Length–weight relationships of three fish species from Bohai Sea,China

Length–weight relationships were determined for three fish species (Cynoglossus macrolepidotus (Bleeker, 1851), Liparis tanakae (Gilbert & Burke, 1912), Zoarces elongatus (Kner, 1868)) from Bohai Sea (38°38′–40°28′N; 119°42′–121°10′E), China. Fish specimens were sampled monthly between May 1982 to May 1983 using pair bottom trawlers (150.5 × 96.5 m, mesh size: 30–200 mm) with a cod end (mesh size: 30 mm), which were towed at a ship's speed of two knots for 1 hr at a maximum depth of about 80 m. Relationships between length and weight were fitted very well for all species (all R² > .90).     

Length–weight relationships of three caught flatfish using shrimp trawler in Motaf fishing grounds,Bushehr province (Persian Gulf)

This study provides length–weight relationships (LWRs) for three flatfish species: Cynoglossus bilineatus (Lacepède, 1802), Solea elongata (Day, 1877), and Pseudorhombus elevatus (Ogilby, 1912) from Motaf fishing grounds (latitude 27°00′ to 28°03′N; longitude 51°41′ to 52°11′E), Bushehr province, Iran. A total of 103 fish specimens were collected using shrimp trawler with 40 mm (stretched mesh size) at depths of 10–30 m between August and September 2017. The LWRs for fish species were W = 0.0019L^3.353 for C. bilineatus: W = 0.0093L^3.174 for S. elongata, and W = 0.006L^3.181 for P. elevatus, respectively.     

Length‐weight and length‐length relationships of Oxynoemacheilus frenatus (Heckel, 1843) and Petroleuciscus esfahani Coad & Bogutskaya, 2010 from the Cheshmeh‐Langan river,Iran

The study presents length‐weight relationships (LWRs) and length‐lenght relationships (LLRs) for two freshwater fish species from the Cheshmeh‐Langan River (Iran; 32°50′N, 50°04′E), a part of the Tigris drainage basin. Fish were sampled by electrofishing (Samus 725M) in August and September 2017. The LWRs and LLRs obtained showed a high level of correlation (r² > .98).     

Length-weight relationship of three commercially important fish species from Mocka water,southern Red Sea,Yemen

Length-weight relationship was estimated for three fish species, including: Lethrinus microdon (Valenciennes, 1,830), Sphyraena jello (Cuvier, 1829) and Euthynnus affinis (Cantor, 1849). Specimens were sampled between May 2014 and June 2015 from the fish caught by the local artisanal fishery and landed in main fishing landing site of Mocka city. Values of b for fish ranged from 2.644 for S. jello to 2.706 for E. affinis and 3.187 for L. microdon. The determination coefficient (r²) between total length and total body weight ranged from .952 in E. affinis to 0.957 in S. jello and 0.960 in L. microdon.     

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.     

Length‐weight relationships of two cyprinid fishes from the Beijiang River,Guangdong, China

This study reports the length‐weight relationships (LWRs) of Acrossocheilus beijiangensis Wu & Lin, 1977 and Barbodes semifasciolatus (Günther, 1868) from the upper reaches of Beijiang River, Guangdong Province, China. Sample sizes for the two fish species were 335 for A. beijiangensis and 106 for B. semifasciolatus. Fishes were collected on a monthly basis between November 2013 and December 2014 using gill nets (30 m long × 1.2 m high, mesh‐size 1.5 cm) and fish cages (mesh‐size 0.5 cm). LWRs were established as W = 0.0052L^3.3249 (r² = .9696) for A. beijiangensis and W = 0.0088L^3.2405 (r² = .9469) for B. semifasciolatus. No previous information is available on LWRs for these two species in FishBase.     

Length–weight relationships of four small indigenous fish species from an inland artisanal fishery,Bangladesh

This study reports the length–weight relationships (LWRs) of four small indigenous species, Trichogaster lalius (Hamilton, 1822), Nandus meni (Hossain & Sarker, 2013), Lepidocephalichthys annandalei (Chaudhuri, 1912) and Botia dario (Hamilton, 1822) collected between July 2015 and August 2016 from fishermen's catches landed in an inland fish landing center, northeastern Bangladesh. In the study, a new maximum total length (TL) is given for L. annandalei and LWRs of three species T. lalius, N. meni and L. annandalei for the first time in FishBase. Estimated LWRs were W = .014 TL^3.17, (r² = .982) for T. lalius, W = .006 TL^3.38, (r² = .961) for N. meni, W = .004 TL^3.27, (r² = .965) for L. annandalei and W = .020 TL^2.87, (r² = .978) for B. dario.     

Length–weight relationships of three fish species from Kerala waters,south‐west coast of India

Length–weight relationships (LWRs) of three fish species: Scomberomorus commerson, Alepes vari, and A. kleinii were estimated from Kerala waters, south‐west coast of India. Fish were captured between June 2016 and June 2017 by various gears such as ring seine (8–26 mm mesh size), trawl (30–40 mm cod end mesh size), hook and line (hook number VI–XII), smaller mesh sized drift gill net (26–90 mm) and larger one (120–170 mm) for bigger size fishes. Fish were collected on weekly basis from Cochin Fisheries Harbour (Lat. 09°56′327″N, Long. 76°15′764″E), Munambam Fisheries Harbour (Lat. 10°10′965″N, Long. 76°10′258″E), Kalamukku (Lat. 09°59′924″N, Long. 76°14′564″E) and Chellanam (Lat. 09°47′950″N, Long. 76°16′551″E). All LWRs were significant with r² values ranged from 0.944 to 0.996 and b values ranged from 2.722 to 3.021 (p < .001). In addition, this study provides the information on LWRs and new maximum size for Alepes vari and A. kleinii.     

Urbanization,sedimentation, and the homogenization of fish assemblages in the Etowah River Basin,USA

We tested the hypothesis that urbanization alters stream sediment regimes and homogenizes fish assemblages in 30 sub-basins of the Etowah River. Sediment variables included average particle size (mean phi) of the stream bed, percent fines (<2 mm) in riffles, and baseflow turbidity (NTU). Homogenization was quantified as ratios of endemic to cosmopolitan species richness (E_r:C_r) and abundance (E_a:C_a). High NTU and fine stream beds were associated with homogenized assemblages (i.e., lower E:C ratios). Mean phi and NTU were significantly correlated with E:C ratios (r = –0.74 to –0.76) and, when combined using multiple regression, accounted for 73% of the variance in ratios. Stream slope strongly covaried with mean phi (r = –0.92) and percent fines in riffles (r = –0.79), but multiple regression models showed that urbanized sites had finer beds and riffles than predicted by slope alone. Urban land cover was the primary predictor of NTU (r ² = 0.42) and, combined with slope in multiple regression, explained 51% of the variance in NTU. Our results indicate that stream slope is a background variable predicting particle size and E:C ratios in these streams. Urbanization disrupts these relationships by transforming clear streams with coarse beds into turbid streams with finer beds. These conditions favor cosmopolitan species, ultimately homogenizing fish assemblages. Bed texture was linked to urbanization; however, NTU was the best indicator of urban impacts because it was statistically independent from slope.     

Length-weight relationships of 6 fish species caught in a Mediterranean lake (Trichonis-NW Greece)

In the present study the length–weight relationships (LWRs) of 6 fish species which are endemic to Western Greece, caught in the natural Lake Trichonis by experimental gillnets and electrofishing were estimated. Benthic (mesh size 5–55 mm; height 1.5 m; length 30 m) and pelagic (mesh size 6.25–55 mm; height 6 m; length 27.5 m) Nordic type multimesh gillnets were used seasonally, between February 2019 and November 2019, at different depth zones (0-57m). Electrofishing (80 Hz) conducted in the littoral zone of the lake during four samplings (2018, 2019). All the estimated LWRs were highly significant (p < .05) with high correlation coefficient (r² ≥ 0.962). The estimated b values ranged from 3.058 to 3.344. For five of the studied species (Trichonis spined loach (Cobitis trichonica Stephanidis 1974), Trichonis blenny (Salaria economidisi Kottelat 2004), Trichonis rudd (Scardinius acarnanicus Economidis 1991), Acheloos roach (Leucos panosi (Bogutskaya & Iliadou 2006)) , Hellenic minnowroach (Tropidophoxinellus hellenicus (Stephanidis 1971)) new maximum total body lengths (TL) were recorded, while for two species (T. hellenicus and L. panosi) LWRs are presented for the first time.     

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.     

Length-weight relationships of seven cyprinid fish species from the Kaptai Lake,Bangladesh

Length-weight relationships (LWRs) were estimated for seven small indigenous cyprinid fish species including Securicula gora, Osteobrama cotio, Esomus lineatus, Pethia gelius, Megarasbora elonga, Gonialosa manmina and Glossogobius aureus occurring in the Kaptai Lake, Bangladesh. Fish were collected monthly basis between March and October, 2018 from fishermen catches landed in the fish landing center, Rangamati. Fishermen operated lift net (mesh size < 0.5 cm), punti net (mesh size < 0.5 cm) and cast net (mesh size < 0.5 cm) for capturing these species. The value of exponent b ranged between 2.769 and 3.212 and regression parameter r² was between 0.926 and 0.992. New maximum total lengths were recorded for E. lineatus and G. manmina in this study.     

Length–weight relationships of two endemic species of Alburnoides nicolausi (Bogutskaya & Coad, 2009) and Alburnus zagrosensis (Coad, 2009) in Houzian River,Lorestan Province,Iran

This investigation prepares the length–weight relationships (LWRs) of two fish species, including Alburnoides nicolausi (Bogutskaya & Coad, 2009) and Alburnus zagrosensis (Coad, 2009) from Houzian River (latitude 33°22′15.20″ to 33°21′31.57″N; longitude 49°44′39.66″ to 49°44′17.67″E), Lorestan province, Iran. Fish specimens were collected monthly using seine net with 5 mm (Stretched) mesh size between April to September 2017. The LWRs for fish species were W = 0.0059L^3.405 (male) and W = 0.0053L^3.494 (female) for A. nicolausi, W = 0.0035L^3.341 (male) and W = 0.003L^3.387 (female) for A. zagrosensis, respectively. The highest value of r² was .931 for male of A. zagrosensis and lowest value was .964 for male of A. nicolausi.     

Pelagic fish distribution and ontogenetic vertical migration in common mesopelagic species off Lützow-Holm Bay (Indian Ocean sector,Southern Ocean) during austral summer

The horizontal and vertical distributions of fish were examined off Lützow-Holm Bay in the Indian Ocean sector of the Southern Ocean during midnight sun in January 2005. Fish were sampled from six discrete depth layers (0–2,000 m). The most abundant fish in layers from the surface to 200 m were larval stages of Electrona antarctica and Notolepis coatsi. In layers from 200 to 2,000 m, fish assemblages were relatively uniform among all stations and were dominated by E. antarctica (juvenile–subadult), Cyclothone microdon, and Bathylagus antarcticus. Cluster analysis revealed three epipelagic communities related to water temperature and salinity. An ontogenetic habitat shift to deeper layers was apparent for E. antarctica, N. coatsi, and B. antarcticus. Preferences for warm waters were observed in E. antarctica (larvae) and N. coatsi (preflexion to flexion larvae), although they were distributed across a broad range of temperature and salinity in epipelagic zones.     

Length-weight relationships of eight fish from seagrass meadows in Wenchang,China

The length-weight relationships (LWRs) were studied for eight seagrass fish from Wenchang, China, using gill nets (150*1 m, mesh size 0.5 cm), including Gerres oblongus, Ambassis kopsii, Halichoeres nigrescens, Sillago aeolus, Yongeichthys criniger, Oxyurichthys tentacularis, Lethrinus haematopterus and Hypoatherina tsurugae, in November 2017, March and August 2018. Results suggest that mean LWR parameters b for these eight seagrass fish varied from 2.801 for L. haematopterus to 3.640 for A. kopsii, and r² valued from .950 for L. haematopterus to 0.993 for H. nigrescens. This study will help us to better understand the ecological parameters these seagrass fish.     

Length–weight and length–length relationships of three ecologically important fishes caught from a wetland,northeastern Bangladesh

Length–weight relationships (LWRs) and length–length relationships (LLRs) of three ecologically important fishes (Aplocheilus panchax, Danio rerio and Esomus danrica) were reported from a wetland, northeastern Bangladesh (23 58 N, 89 38 E). Samples were collected monthly using traditional fishing gear including fine meshed (2.0 mm) push net and fine meshed (3.0–4.0 mm) surrounding net during January to December 2014. For each individual, total length (TL), fork length (FL) and standard length (SL) was measured to 0.1 cm, while body weight (BW) was measured to 0.01 g accuracy. Allometric coefficient (b) values were 3.10 for A. panchax, 3.38 for D. rerio and 3.52 for E. danrica. In addition, the LLRs were also highly significant with r² ≥ 0.954.