A Bayesian approach for estimating length‐weight relationships in fishes

A Bayesian hierarchical approach is presented for the estimation of length‐weight relationships (LWR) in fishes. In particular, estimates are provided for the LWR parameters a and b in general as well as by body shape. These priors and existing LWR studies were used to derive species‐specific LWR parameters. In the case of data‐poor species, the analysis includes LWR studies of closely related species with the same body shape. This approach yielded LWR parameter estimates with measures of uncertainty for practically all known 32 000 species of fishes. Provided is a large LWR data set extracted from www.fishbase.org , the source code of the respective analyses, and ready‐to‐use tools for practitioners. This is presented as an example of a self‐learning online database where the addition of new studies improves the species‐specific parameter estimates, and where these parameter estimates inform the analysis of new data.     

Length‐weight relationships of five fish species collected from Ranganadi River (Brahmaputra River tributary) in Assam,India

Length‐weight relationships (LWR) are presented for five fish species: Laubuka laubuca (Hamilton, 1822); Aspidoparia jaya (Hamilton, 1822); Channa gachua (Hamilton, 1822); Acanthocobitis botia (Hamilton, 1822) and Badis badis (Hamilton, 1822) collected from the Ranganadi River in the Lakhimpur district of Assam, India. There were no prior LWR data regarding three of these species.     

Length‐weight relationships of three cyprinid fishes from headwater of the Nujiang River,China

Length‐weight relationships (LWR) for three cyprinid fish species collected from the headwaters of the Nujiang River in Tibet, China, were determined. The values of parameter b in the LWR equations were estimated as 2.54 for Schizopygopsis thermalis, 3.3 for Ptychobarbus kaznakovi, and 2.74 for Schizothorax nukiangensis, respectively. These are the first LWR records for the three species.     

Species composition and length‐weight relationship of fishes in the Candaba wetland on Luzon Island,Philippines

The length‐weight relationships or LWR (W = aL^b) of 18 of the 21 fish species caught in 2007–2008 from the Candaba wetland in central Luzon, Philippines are reported. These species belong to 14 families and the LWR of six species are first documented in this paper. Cyprinids comprised the greatest number of species. The high significance of the LWR parameters indicate that fish weight may be predicted from length, at least within the range of the fish lengths recorded. This first reference to the LWR of fishes from the Candaba wetland provides baseline data for the conservation management of fish biota in this threatened ecological resource.     

Length-Weight Relationships for freshwater fishes from streams of the Atlantic Rainforest,State of Paraná, Brazil

This study reports the Length-Weight Relationships (LWR) for 10 freshwater fish species sampled in the Atlantic Rainforest, Southern Brazil. Sampling was conducted between 2016 and 2017, in nine streams, using electrofishing. Collected fishes were fixed in formalin, and thus some shrinking was unavoidable. The values of parameter b of the LWR (W = aL^b) ranged between 2.5 and 3.5. We report for the first time the LWR for seven species: Geophagus iporanguensis, Isbrueckerichthys duseni, Hypostomus interruptus, Kronichthys lacerta, Chasmocranu lopezi, Astyanax lacustris e Neoplecostomus ribeirensis. We highlight the importance of the LWR data in supporting further studies on fish stocks and environment in the Atlantic Rainforest, thereby contributing to the database needed to develop fisheries management and maintenance of ecosystem services.     

Length–weight relationship of nine fish species from Skadar Lake (Adriatic catchment area of Montenegro)

This study provides data on the length–weight relationships (LWR) of nine fish species sampled between 2010 and 2014 from Skadar Lake, Montenegro. Also provided are the first comprehensive data of LWRs for three freshwater fishes for which no LWR information was available in the FishBase data bank. The b parameter values ranged from 2.936 to 3.271, while values of the a parameter ranged from 0.002 to 0.014.     

Length–weight relationships for selected fish species of Rio Trombetas Biological Reserve: a reference study for the Amazonian basin

Length–weight relationships (LWR) are presented for 27 freshwater fish species representing 11 families captured in the Trombetas River, a clearwater left margin tributary of the Amazon River. The allometry coefficient (b) of the LWR (W = aTL^b) ranged from 2.51 to 3.49, with a median value of 3.00. This study represents the first reference on LWR for 23 species and new records of maximum lengths for 15 species.     

Length–weight relationships of 11 deep‐sea fishes from the western Bay of Bengal and Andaman waters,India

Length–weight relationships (LWRs) are presented for 11 deep‐sea fishes caught in the western Bay of Bengal and Andaman waters during August 2010 using a 38 m high speed demersal trawl II (HSDT II, crustacean version, codend mesh size 40 mm) and a 45.6 m Expo model demersal trawl (codend mesh size 30 mm). The b values ranged from 2.34 to 3.3 and the coefficient of variation (r²) ranged from .82 to .98. LWR estimates of eight deep‐sea fishes are provided for the first time. The estimated LWR values were compared with the Bayesian LWR estimates available in FishBase, based on models developed to improve the accuracy and predictability of species‐specific growth parameters of data‐poor species.     

Length–weight and length–length relationships for nine species of the genus Paracobitis (Nemacheiliidae) in Iran

Length–weight (LWR) and length–length (LLR) relationships were estimated for 330 specimens from nine Paracobitis species in 11 localities throughout Iran. All fish were collected upon occasion by electrofishing throughout Iran from July 2010 to October 2016. These represent the first reports of LWR data for eight species including: Paracobitis atrakensis, P. hircanica, P. longicauda, P. molavii, P. persa, P. rhadinaeus, P. smithi and P. vignai and first LLR data for all species. A new maximum length is reported for P. malapterura. Four of these species are endemic and five species are native to Iran. The length–weight parameter b ranged from a minimum of 2.74 for P. atrakensis to a maximum of 3.01 for P. longicauda, with regression coefficients (r²) ranging from 0.96 to 0.99. All LLRs were highly significant (r² > .96).     

Length–weight relationships of 20 fish species from Bahía de Matanchen,in the southeast Gulf of California,Mexico

Length–weight relationship (LWR) parameters were determined for 20 fish species belonging to 14 genera and seven families. The fishes were collected monthly (May 2013 to February 2014) by soft‐bottom trawls in Bahía de Matanchén, southeast of the Gulf of California. Sizes ranged between 5.5 and 36.0 cm total length (TL) and weighed between 1 and 901 g. The allometric coefficient (b) of the LWR varied from 2.638 for Chloroscombrus orqueta to 3.668 for Neopisthopterus tropicus. This is the first report of LWR estimations for 15 of the species.     

Length–weight relationship of six notothenioid species from sub‐Antarctic waters (Beagle Channel,Argentina)

This study presents length‐weight relationships (LWR) for six species of fishes of the Suborder Notothenioidei that inhabit the sub‐Antarctic waters of the Beagle Channel (Argentina). These species represent five of the nine families of this Suborder. The specimens belong to historical fish collections in the area (from 1987 to 1990) using gill and trammel nets. All species but Eleginops maclovinus had no previous LWR estimates. The coefficient of determination (r²) ranged from 0.91 to 0.99 and b values ranged from 2.74 to 3.2. Harpagifer bispinis was the only species with a b value lower than three. This information is useful to predict the weight from the length data and to provide insights into the ecology of sub‐Antarctic nototheniod fish.     

Length–weight relationships for fishes caught by shrimp trawl in Santa Catarina coast,south Atlantic,Brazil

Length–weight relationships (TW = a TL^b) were estimated for fish species caught by bottom shrimp trawl north of Santa Catarina Island (Brazil) from October 2003 to September 2004. For three of the species this is the first LWR data in Brazil.     

Length-weight relationships of eight reservoir fish species in Puerto Rico

Length-weight relationships (LWR) of eight fish species, Lepomis auritus (Linnaeus, 1758), Amphilophus labiatus (Günther, 1864), Oreochromis mossambicus (Peters, 1852), Cichla ocellaris Bloch & Schneider, 1801, Parachromis managuensis (Günther, 1867), Vieja melanura (Günther, 1862), Pterygoplichthys pardalis (Castelnau, 1855), and Gobiomorus dormitor Lacepède, 1800, collected by electrofishing and gillnetting from ten reservoirs in Puerto Rico were determined using 3,557 individual fish records collected between 1998 and 2014. All LWRs were significant with r² values ranged from 0.900 for A. labiatus (Günther, 1864) to 0.996 for C. ocellaris Bloch & Schneider, 1801. The LWR parameter b ranged from 2.807 for P. pardalis (Castelnau, 1855) to 3.180 for C. ocellaris Bloch & Schneider, 1801. Data presented herein expand the knowledge base for these species as they have limited or no LWR data available. Also, our samples provide a new maximum length data for P. pardalis (Castelnau, 1855).     

Length‐weight relationships of six native and one introduced species in small perennial watercourses of the Chocó region of Ecuador

This study estimated the length‐weight relationship (LWR) of seven species (six native species and one introduced species) in two small perennial watercourses of the Chocó region of Ecuador. Specimens were collected bimonthly with two different fishing methods between August 2016 and July 2017 (Seine net: 46 × 21.20 m, 3 mm mesh size and casting net: 2.10 m radius, 10 mm mesh size). This is the first report of the LWR and a new report on maximum length for two endemic species (Eretmobrycon ecuadorensis and Andinoacara blombergi). The intercept (a) of the LWR ranged from 0.0124 to 0.0316 and the slope (b) ranged from 3.03 and 3.16. The LWRs are useful and, in connection with the collection of other key data on fish biology and the environment they can contribute to management and conservation of the local inland fisheries.     

Length–weight and length–length relationships and length at first maturity for freshwater fish species of the Salto Santiago Reservoir,Iguaçu River Basin,Brazil

Length‐weight (LWR) and length‐length (LLR) relationships were estimated for 20 species and lengths at first maturity (L₅₀) for six species of freshwater fishes caught in the Salto Santiago Reservoir, Iguaçu River Basin, Brazil. In nine species significant differences were found in the LWR between sexes. Average b‐value for species with no differences between sexes in LWR was 3.12 (SE = ±0.05). Average b‐value in LLR was 0.823. First references on LWRs and L₅₀ are presented for 13 and four fish species, respectively, as well as the new maximum total lengths for eight species.     

Length‐weight relationships for six freshwater fish species from the Seyhan Reservoir (south‐eastern Anatolia,Turkey)

Length–weight relationships (LWRs) were evaluated for six freshwater species from the Seyhan Reservoir (south‐eastern Anatolia, Turkey): Alburnus orontis, Capoeta angorae, Capoeta erhani, Garra rufa, Luciobarbus pectoralis and Salaria fluviatilis. A total of 525 specimens were captured from five locations using gill nets, scoop nets, and trammel nets of various mesh sizes in November 2012, March 2013 and September 2013. Regressions of all species were found to be significant. These are the first LWR reports for these species from the Seyhan River basin, and the first LWR reports for three of these species (Alburnus orontis, Garra rufa, Luciobarbus pectoralis) from inland waters of Turkey.     

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 and length–length relationships for 11 species of the genus Alburnoides Jeitteles, 1861 (Cyprinidae) from Iran

Length–weight (LWR) and length–length (LLR) relationships were estimated for 11 Alburnoides species from 15 localities throughout Iran. These represent the first reports of LWR and LLRs data for 10 species, including: Alburnoides coadi (40 specimens), A. damghani (30), A. eichwaldii (110), A. holciki (30), A. idigensis (113), A. namaki (30), A. nicolausi (30), A. parhami (30), A. qanati (30) and A. tabarestanensis (30) and first LLR data for A. samiii. Nine of these species are endemic and two are native to Iran. The length–weight parameter b for these species ranged from a minimum of 2.94 for Alburnoides nicolausi to a maximum of 3.37 for Alburnoides parhami, with regression coefficients (r²) ranging from 0.91 to 0.99. All LLRs were highly significant (r² > 0.96).     

Length–weight relationships of two cyprinid fish species,Crossocheilus latius (Hamilton, 1822) and Garra gotyla gotyla (Gray, 1830) from the Ganga River Basin,India

This study provides length–weight relationship (LWR) information for two fish species (family Cyprinidae), Crossocheilus latius (Hamilton, 1822) and Garra gotyla gotyla (Gray, 1830), from a tributary of the Ganga River Basin, India. Both species had no previous LWR estimates as per Fishbase 2014.     

Length–weight relationship of six freshwater fish species in upper‐middle Tocantins River basin (Brazil)

Length–weight relationships (LWRs) were analyzed for six abundant fish species in the upper‐middle Tocantins River, northeastern Brazil. Analyses included data from 486 specimens sampled in five expeditions between August 2013 and May 2015 by gillnets. New maximum values of total lengths for the literature and FishBase were presented for six species, as well as first time estimates of LWR for Galeocharax gulo, Curimata acutirostris and Aphanotorulus emarginatus.