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.     

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 relationships of three estuarine fish species from Bangladesh

The length‐weight relationships (LWRs) of three fish species; Toxotes chatareus (Hamilton, 1822), Datnioides polota (Hamilton, 1822), and Chela cachius (Hamilton, 1822) collected between September 2016 and August 2017 from Tentulia estuary of Bangladesh were analyzed. Fish were caught seasonally using set bag net and cast net with mesh size of 0.5 cm and < 0.5 cm, respectively. LWRs of Toxotes chatareus, Datnioides polota and Chela cachius were calculated as W = 0.0154L^2.926 (r² = .962), W = 0.0149L^3.106 (r² = .992) and W = 0.0109L^2.968 (r² = .981), respectively. The study provides a new maximum total length for Chela cachius.     

Length to weight ratio of four fish species in estuary areas in the Northeast region of Brazil

The length to weight ratio (LWR) was used to estimate populations of four fish species sampled on the Amazon coast of the state of Maranhão, Brazil. The fishes were sampled in 2018 and 2019 by artisanal coastal fishing, using gillnets (0.20–0.60 mm). The parameters a and b of the equation W_T = a L_T^b were estimated. The obtained LWRs were W_T = 0.06LT^2.93, (r²) = .989 for Oligoplites saliens; W_T = 0.061L_T^2.57, (r²) = .982 for Peprilus crenulatus; W_T = 0.014L_T^2.80, (r²) = .985 for Bagre bagre; and W_T = 0.035L_T^3.21, (r²) = .981 for Nebris microps.     

Length–weight relationship of Hyporthodus haifensis and Mycteroperca rubra (Pisces; Serranidae) from the North‐Eastern Mediterranean Sea,Turkey

Length–weight relationships (LWRs) for Hyporthodus haifensis and Mycteroperca rubra were studied using longlines at depths of 5–150 m, in the Gulf of Antalya, northeastern Mediterranean Sea. Fishing operations were carried out daily with 15 fishing boats. A total of 170 individuals were sampled. The LWR relationships of Hyporthodus haifensis and Mycteroperca rubra were calculated as W = 0.009L^3.142 (r²) = 0.996 and W = 0.0081L^3.0652 (r²) = 0.989 P < 0.05, respectively.     

Length–weight relationships of two fish species from the middle reaches of the Jinsha River,China

This study provides the first report of length–weight relationships (LWRs) for Pseudogyrinocheilus prochilus (Sauvage & Dabry de Thiersant, 1874) and Jinshaia sinensis (Sauvage & Dabry de Thiersant, 1874) collected from the middle reaches of the Jinsha River, southwest China. Samples were obtained between June 2005 and November 2006. A total of 491 specimens belonging to two fish species were analyzed. LWRs were W = 0.0170L^2.970 (r² = 0.980) for P. prochilus and W = 0.0194L^2.849 (r² = 0.977) for J. sinensis. Prior to this study, the LWRs for P. prochilus were unknown. In addition, new maximum size for J. sinensis was provided.     

Length–weight relationships of three fish species from the upper reaches of the Beijiang River,Shaoguan, China

Fish assemblages were randomly collected in March 2015 from the upper reaches of the Beijiang River, Shaoguan, China. Fish were sampled on 10 occasions using gill nets (mesh size: 3 cm) and the length–weight relationships (LWRs; W = a × L^b) of three native species recorded: Xenocypris davidi, Xenocypris macrolepis and Culter recurviceps. The exponent b varied from 2.803 to 3.096 and r² values ranged 0.985–0.992. This is the first report on the LWRs of fish from this area, with valuable results for the research, management and conservation of fishery resources in the upper reaches of the Beijiang River.     

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 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 fish species from a coastal artisanal fishery,southern Bangladesh

This study presents the first report of length–weight relationships (LWRs) for Apocryptes bato (Hamilton, 1822), Salmophasia phulo (Hamilton, 1822), and Silonia silondia (Hamilton, 1822), excluding Anodontostoma chacunda (Hamilton, 1822), from fishermen's catches landed in a coastal artisanal fishery at Patuakhali, Southern Bangladesh. Specimens were sampled occasionally over a period of 1 year between August 2014 and September 2015. Fishes were collected from coastal fishermen using cast nets (mesh size <0.5 cm) for A. bato, set bag nets (mesh size 0.5 cm) for A. chacunda and S. silondia, and lift nets (mesh size <0.5 cm) for S. phulo. The LWRs obtained were W = 0.006L^2.99, (r²) = 0.976, W = 0.011L^3.04, (r²) = 0.971, W = 0.006L^3.00, (r²) = 0.945 and W = 0.007L^2.99, (r²) = 0.988 for A. bato, A. chacunda, S. phulo, and S. silondia, respectively.     

Length–weight relationships of six fish species from the Zengqu River and the Ouqu River,southwest China

This study provides the first report of length–weight relationships (LWRs) for six endemic fish species collected from the Zengqu River and the Ouqu River, two of the tributaries to the upper reaches of the Jinsha River, southwest China. Samples were obtained in May 2013 and September 2013 using various types of fishing gear. A total of 413 specimens belonging to six fish species were analyzed; their LWRs were W = 0.0069L^3.086 (r² = 0.987) for Schizothorax wangchiachii (Fang, 1936), W = 0.0076L^3.029 (r² = 0.980) for Schizothorax dolichonema (Herzenstein, 1889), W = 0.0029L^3.315 (r² = 0.961) for Schizopygopsis malacanthus (Herzenstein, 1891), W = 0.0082L ^2.970 (r² = 0.950) for Ptychobarbus kaznakovi (Nikolsky, 1903), W = 0.0017L^3.464 (r² = 0.957) for Triplophysa stolioczkae (Steindachner, 1866), and W = 0.0037L ^3.190 (r² = 0.956) for Triplophysa orientalis (Herzenstein, 1888). Prior to this study, the LWRs for S. dolichonema, P. kaznakovi and T. orientalis were unknown. In addition, new maximum sizes for four of the species are provided.     

Length–weight relationship and condition factor of wild,grow‐out and ‘loose‐shell affected’ giant tiger shrimp,Penaeus monodon (Fabricius, 1798) (Decapoda: Penaeidae)

Length–weight relationships and condition factors of wild, cultured, and cultured loose‐shell affected Penaeus monodon (2,609 specimens total) were studied from March to August 2007. The regression equation for healthy cultured shrimps was log W = ?1.811 + 2.721 log L (r² = 0.71); log W = ?1.444 + 2.485 log L (r² = 0.91) for wild shrimps; and log W = ?1.112 + 2.237 log L (r² = 0.92) for loose‐shell affected shrimps. All shrimps showed negative allometric growth, although ancova indicated significant differences (P < 0.05) among them. This study presents the first known reference dealing with LWRs and condition factors of cultured, wild and loose‐shell affected P. monodon.     

Biological parameters and current status of European eel (Anguilla anguilla Linnaeus, 1758) from Asi River,Northeastern Mediterranean region,Turkey

The biological characteristics of eels from the Asi River, Turkey, were assessed between December 2017 and November 2018. Eels were sampled monthly using fyke nets (operated by professional fishermen), yielding a total of 509 specimens. Total length and weight were measured, sex, age and maturity stages (silver or yellow eel) were determined. Catch Per Unit Effort (CPUE) was calculated for both biomass per unit effort and numbers caught on a monthly and annual basis. The length-weight relationships (LWRs) of silver and yellow eel was W = 0.009*TL^3.22 (n = 262) and W = 0.0106*L^3.09 (n = 247), respectively. The age of the sampled fish ranged from year class II to VI. Von Bertalanffy growth parameters were estimated as L_∞=69.25 cm, K = 0.43 1/year, t₀= −0.41 and phi prime index ( ǿ )= 3.31 for all samples. The overall eel fishing mortality rate (F) was 0.31 year^-1, and the exploitation and survival rates of silver stage eels were estimated with 30% and 39%, respectively.     

Length–weight relationship of Rastrelliger brachysoma (Bleeker, 1851) and Rastrelliger faughni Matsui, 1967 from the Andaman Islands,India

This study reports the length–weight relationships (LWRs) of Rastrelliger brachysoma (Bleeker, 1851) and Rastrelliger faughni Matsui, 1967 from Andaman Islands, India. Sample sizes for the two fish species were 78 for R. brachysoma and 57 for R. faughni. Fish collected monthly from Junglighat fish landing center. Fish were captured by commercial ring seine units (mesh size ranging from 2 to 4 cm) between February 2016 and March 2017. LWRs were established as TW = 0.0042TL^3.332 (r² = .989) for R. brachysoma and TW = 0.0096TL^3.022 (r² = .980) for R. faughni.     

Length‐weight relationships of nine fish species from the Tetulia River,southern Bangladesh

The present study describes the length‐weight relationships (LWRs) for nine fish species from the Tetulia River, southern Bangladesh, namely Anabas testudineus, Coilia dussumieri, Otolithoides biauritus, Otolithoides pama, Pethia conchonius, Polynemus paradiseus, Puntius lateristriga, Setipinna taty and Sillaginopsis panijus. A total of 1380 specimens were caught using traditional fishing gear from March 2012 to February 2013. Individual total length (TL) and body weight (BW) were measured by digital slide calipers and digital balance, respectively. The LWR was calculated as W= a L^b, where the W is the BW in g and L the TL in cm, a and b are regression parameters. This study presents the very first references on LWRs for seven of the species. The results are valuable for the application of sustainable management and conservation of these fishes in the Tetulia River and surrounding ecosystems.     

Length‐weight relationships of Acanthopagrus longispinnis (Valenciennes, 1830), Raconda russeliana (Gray, 1831) and Coilia neglecta (Whitehead, 1967) from the Bay of Bengal coast,Bangladesh

Current study reports the length‐weight relationships (LWRs) of three marine fish species collected from the fishermen catches covering three seasons i.e., rainy, autumn and winter between June, 2016 and February, 2017. Fishermen caught the species using beach seine net (3.5 cm mesh size) and set bag net (0.5 cm mesh size) up to 200 m far away from the shoreline. The LWRs for fish species were W = 0.0180TL^3.192 for A. longispinnis, W = 0.0109TL^2.971 for R. russeliana and W = 0.0098TL^2.942 for C. neglecta with their r² values of 0.971, 0.962 and 0.997, respectively.     

Growth characteristics of Uranoscopus scaber Linnaeus 1758, inhabiting the Iskenderun Bay (Northeastern Mediterranean)

This study aimed to determine the age and some growth characteristics of Atlantic stargazer (Uranoscopus scaber) from Iskenderun Bay (Northeastern Mediterranean). For this purpose, a total of 150 Atlantic stargazer ranging in size from 9.1 to 28.0 cm in total length (weight: 11.7–345.7 g) were collected as by-catch from a commercial trawl fishing boat at a depth of 80–100 m between May 2015 and January 2016. The bottom trawl gear used was equipped with a 44 mm stretched mesh size net at the cod-end. The percentage of females and males were 46.7% and 53.3% respectively. The total length–weight relationships equation with coefficient of determination (R²) were found as W = 0.011*TL^3.131, R² = .9728, for all individuals, W = 0.015*TL^3.021, R² = .9512 for females and W = 0.0102*TL^3.136, R² = .9553 for males. By using the von Bertalanffy equation, the growth parameters of Atlantic stargazer were estimated to be L_∞ = 42.35 cm, k = 0.098, t₀ = −1.8474 for all individuals; L_∞ = 36.92 cm, k = 0.138, t₀ = −1.2693 for females and L_∞ = 38.77 cm, k = 0.1, t₀ = −2.334 for males. In this study, age reading was done by two independent readers and index of average percentage error (IAPE) was calculated as 6.1%. The highest condition factor value calculated as 1.81 in the age group 6 and the lowest condition factor value was calculated as 1.48 in the age group 1.     

Length‐weight relationships of Notopterus notopterus and introduced Oreochromis niloticus from the Indus River,southern Punjab,Pakistan

This study describes the length–weight relationships (LWRs) for Oreochromis niloticus and Notopterus notopterus, collected in 2006 and 2009 respectively from the Indus River, southern Punjab, Pakistan, with W = 0.0393 L^2.72 for O. niloticus and W = 0.0121 L^2.87 for N. notopterus. Negative allometric growth is indicated for both species.     

Age and growth of the blackchin guitarfish Glaucostegus cemiculus (Geoffroy Saint-Hilaire, 1817) from Iskenderun Bay (Northeastern Mediterranean)

Between September 2010 and June 2012, a total 291 (166 females and 125 males) blackchin guitarfish Glaucostegus cemiculus were captured by a commercial bottom trawler (F/V Coşkun Reis) in Iskenderun Bay, Turkey (northeastern Mediterranean Sea). The total length (L) and total weight (W) of the female and male guitarfish ranged between 32.0–165.0 cm and 88 g–16.68 kg, and 34.3–128.3 cm and 112 g–6.00 kg, respectively. Vertebral age estimates ranged from 0 to 8 years for females and 0 to 5 years for males. The growth models of von Bertanlanffy and Gompertz were fitted to the length at age data using the nonlinear regression method. Model selection was based on the values of the residual standard error and the Akaike's information criterion corrected for small sample size (AIC_C) associated with each fit. The von Bertalanffy growth model provided the best fitting growth curves for each sex with parameters reaching L_∞ = 187.17 cm, K = 0.195 year^-1, t₀ = −1.38 year for females, and L_∞ = 144.85 cm, K = 0.321 year^-1, t₀ = −1.13 year^-1 for males. The W–L relationship parameters did not differ significantly between sexes, the estimated values of a and b were 0.0018 and 3.11, respectively. By using these values of a and b, and also respective estimates of L_∞, the values of W_∞ were obtained as 20.53 kg for females and 9.25 kg for males. The overall percentage ratios of females and males in the samples were 57% and 43% respectively.     

Length–weight relationships for three fish species from Yalong River in China

This study provides the first report of length–weight relationships (LWRs) for three fish species collected from the Yalong River, one of the tributaries to the upper reaches of the Yangtze River, China. The LWRs of these fish species were BW = 0.0070TL^3.0539 (r² = 0.9662) for Schizothorax wangchiachii, BW=0.0134TL^2.8523 (r² = 0.9676) for Schizopygopsis malacanthus, and BW=0.0143TL^2.9253 (r² = 0.8538) for Euchiloglanis kishinouyei, respectively. Also investigated were the spawning season, absolute fecundity and main food items of the three fish species in the natural environment. In addition, new maximum sizes for the three species are provided.