Weight‐length relationships and condition factor trends for thirty‐eight fish species in trawled and untrawled areas off the coast of northern Sicily (central Mediterranean Sea)

This paper reports the weight‐length relationship (WLR) for thirty‐eight fish species from the Gulf of Castellammare (NW Sicily, Mediterranean Sea). A total of 59 870 fish were collected and measured during four seasonal trawl surveys carried out in 2005 at 10 to 200 m depth. The b parameter of the WLRs ranged from 1.79 (Cepola macrophthalma) to 3.56 (Conger conger). Significant differences in both a and b values among seasons were detected for eight species. Moreover, the condition factors (as weight‐at‐length) of Merluccius merluccius and Mullus barbatus were compared in different area/year combinations characterized by the presence or absence of trawling impact. While M. barbatus showed a higher condition factor in trawled areas/years, possibly due to density‐dependent factors linked to the increased biomass in the no‐trawl area, no such link was detected in M. merluccius.     

Weight–length relationships of some fish species of the Iberian Peninsula

This study reports weight–length relationships (WLR) for Salmo trutta (Linnaeus, 1758), Phoxinus phoxinus (Linnaeus, 1758), Chondrostoma Chondrostoma miegii (Steindachner, 1866), Barbus graellsii (Steindachner, 1866), Barbatula barbatula (Linnaeus, 1758) and Gobio gobio (Linnaeus, 1758). Specimens were collected by electrofishing during summer between 1996 and 1998. The b values in the WLR W = aL^b varied between 2.97 and 3.42. To the best knowledge of the authors, this study presents the first reference on WLRs for four of the species in Spanish waters.     

Weight‐length relationships for five fish species from a temperate coastal lagoon of southern Europe

The weight‐length relationships (WLR) were estimated for five fish species of Ria Formosa, a coastal lagoon in southern Portugal. WLRs for Gobius couchi, Pomatoschistus microps and Parablennius pilicornis were determined for the first time ever and for Gobius cruentatus for the first time for the southern European Atlantic coast.     

Length‐weight relationships of 69 fish species in the Beibu Gulf,northern South China Sea

Sixty‐nine fish species belonging to 41 genera from 29 families and seven orders were collected during 2006–2007 by otter trawl in Beibu Gulf, northern South China Sea, for analysis of their length‐weight relationships (WLRs). The analysis included 19 species for which no previous WLR estimates were available in FISHBASE.     

Length‐weight and length‐length relationships of three indigenous fish species in Persian Gulf,Iran

In this study, length‐length relationships (LLRs) and weight‐length relationships (WLRs) were established for a Carangidae species: Uraspis helvola and tow Flatfishes: Pseudorhombus elevatus and Psettodes erumei that are substantial marine fish species to commercial fisheries in Persian Gulf that are indigenous marine fish species in the region. Samples were collected by non‐selective fish bottom trawler with stretch mesh size of 4 centimeters at the cod‐end area, which helped us to obtain such a broad range size that included small, medium and large size classes during June to August 2017. Hitherto, the length‐weight model presented in this study for Pseudorhombus elevatus and Uraspis helvola were not documented on Fishbase. Additionally, new records of maximum length are presented as 64.5 and 30 centimeters for P. erumei and P. elevatus respectively. A comprehensive size distribution and highly significant fitted model (r²>0.95) in this research provides useful insight for future studies on fish biology, fisheries assessment and ecological modeling.     

Reproductive biology of the lessepsian Reticulated leatherjacket Stephanolepis diaspros (Fraser - Brünner, 1940) in the Gulf of Gabes (Eastern Mediterranean Sea)

Fundamental information on the reproductive biology of the lessepsian fish Reticulated leatherjacket Stephanolepis diaspros from the Gulf of Gabes (Eastern Mediterranean Sea) was considered in this study. The study was carried out on a sample of 1,053 specimens of the Reticulated leatherjacket caught by trawlers and were monthly collected from May 2003 to December 2005. The length frequency distribution indicated that males are taller than females. The sex-ratio was 0.87:1 which significantly deviated from the hypothetical distribution of 1:1. The size and the season have an effect on this sex-ratio. Gonadosomatic Index (GSI%) values were highest in July for both sexes and this species accumulates energy reserves in the liver to be spent during the maturity of gonads and the spawning. First maturation occurred at 7.96 cm for females and 10.58 cm (L₅₀) for males. The fecundity of S. diaspros ranged from 28,250 to 218,000 with a mean of 100,778.76 ± 17,702.1. The relationships between absolute fecundity and total length, eviscerated weight and weight of gonads were will described and the correlation coefficients calculated between fecundity and each of these independent variables, are judged to be either significant (R² > 0.8) indication of a very good model for the fecundity study.     

Water loss in desert ants: caste variation and the effect of cuticle abrasion

Water loss rates (WLRs) varied across castes (workers > alate males > alate females) for desert ants in the genera Aphaenogaster, Messor and Pogonomyrmex. Exposure to soil caused increased WLRs in workers and foundresses (mated, dealate females), apparently because of cuticular abrasion caused by nest excavation. Moreover, field‐collected workers and foundresses from incipient nests (those exposed to soil) had similar WLRs, as did unabraded workers and alate females (those unexposed to soil). These data call into question previous adaptive scenarios for differences in WLRs across ant species and castes. For live alate females, WLRs increased over two stages. The first increase occurred immediately after mating, and the second occurred for foundresses collected 2 days later from incipient nests. By contrast, WLRs of HCN‐killed females were unaffected by mating, but increased significantly for foundresses collected from 2‐day‐old nests.     

Weight–length relationships for 20 fish species collected in the mangroves of Guadeloupe (Lesser Antilles)

Weight–length relationships (WLR) are reported for 20 fish species from the mangroves of Guadeloupe (Lesser Antilles). The fishes were collected using fishing hoop nets. In the present study, the regressions were calculated after separating juveniles and adults. The b coefficient in the WLR varied between 2.37 and 3.85, with a mean of 3.15 ± 0.15.     

Weight–length relationships for 50 fish species collected in seagrass beds of the Lesser Antilles

Weight–length relationships (WLR) are presented for 50 fish species from the seagrass beds of Guadeloupe and Martinique. Samples were taken in shallow waters (<2 m) with different types of fishing gear: seine net, hoop net and gill net. The b coefficient in the WLR varied between 2.63 and 3.61 and showed a mean value of 3.07 (SE = ± 0.06).     

Length–weight relationships of three endemic fish species from the upper Yellow River,China

Length–weight relationships (LWRs) of three Chinese endemic fish species (Gymnocypris eckloni eckloni Herzenstein, 1891, Platypharodon extremus Herzenstein, 1891 and Triplophysa pseudoscleroptera (Zhu & Wu, 1981)) were analyzed, collecting from the upper Yellow River (Xunhua and Guide Counties, Qinghai Province). Totally 347 specimens monthly collected by gill nets with 40 mm mesh size and traps with 5 m length from August to October 2014, were used to estimate the relationship parameters. The allometric factor b values ranged from 2.96 in T. pseudoscleroptera to 3.33 in G. eckloni eckloni. The condition factor a values varies between 0.0063 and 0.0175 in three species. Three WLRs of fishes distributed in the upper Yellow River were firstly reported and will fill in some of the empty spaces on endemic species in the Fishbase.     

Condition status of the endangered desert pupfish,Cyprinodon macularius Baird and Girard, 1853, in the Lower Colorado River Basin (Mexico)

The length‐weight relationship (LWR) was used to test differences in the fish somatic condition factor among four populations of the endangered desert pupfish, Cyprinodon macularius, from the Lower Colorado River Basin, Mexico. Bimonthly fish sampling and habitat assessments were carried out from September 1996 to August 1997 for four sites in Baja California and Sonora. Slope b of the WLR varied from 3.238 (Cerro Prieto population) to 3.613 (Welton‐Mohawk population), showing in all populations a positive allometric growth. Male b values were higher than those of females for Cerro Prieto (3.303 vs 3.071), Welton‐Mohawk (3.866 vs 3.579), and Flor del Desierto (3.357 vs 3.169) populations. The Cerro Prieto population showed the highest somatic condition (y‐intercept, a = ?11.759). Water depth and salinity were the ecological variables that better accounted for most of the variation in the somatic condition of this pupfish, with a negative and a positive effect, respectively.     

Length–length and length–weight relationships of oilfish (Ruvettus pretiosus), escolar (Lepidocybium flavobrunneum), snake mackerel (Gempylus serpens), and longnose lancetfish (Alepisaurus ferox) from the Gulf of Mexico and the western North Atlantic Ocean

Oilfish, escolar, snake mackerel (order Aulopiformes, family Gempylidae), and longnose lancetfish (order Perciformes, family Alepisauridae) sampled from the western North Atlantic and the Gulf of Mexico were analyzed for length–weight and length–length relationships. These species are encountered as occasional bycatch of pelagic longline fisheries. The fish (161 specimens, 19.0–149.1 cm TL) were collected over a 3‐year period (January 2007–January 2010) from pelagic longline gear targeting swordfish and tuna. For each species, 95% confidence limits (CI) of parameters b and log a and regression coefficients (r²) were calculated for log‐transformed length–weight relationships. The length–weight parameter b for all species ranged from 2.881 to 3.358, with regression coefficients (r²) ranging from 0.75 to 0.98. Linear relationships between fork lengths, standard lengths, and total lengths were also calculated.     

Length‐weight relationships of four fish species from the continental shelf of Yucatán (SW Gulf of México)

This paper presents length‐weight relationships (LWR) for four fish species from the continental shelf of Yucatán, at the Sonda de Campeche (southwestern Gulf of México). Samples were taken using shrimp trawl nets (5.71 cm squared mesh size in the cod‐end) in the mid‐summer of 2016. All LWRs were significant with r² values ranged from .946 to .994 and the values of exponent b, estimated using simple linear least squares of log‐transformed weight and length data, ranged from 2.54 to 3.10 (p < .001).     

Length–weight relationships of seven myctophid fishes (Myctophiformes: myctophidae) in the South China Sea

The study included 546 specimens of seven myctophid fish species from the South China Sea (captured during June 2015 by bottom and mid‐water trawls). Length‐weight relationships (LWRs), W = aL^b, were estimated using standard length. The species belong to four genera. The values for the parameter a ranged from 0.006 to 0.022, while the b values ranged from 2.710 to 3.476 (Range of r² values: .938 to .971). According to FishBase, this study presents the first LWRs for these species, including two maximum standard lengths for Diaphus chrysorhynchus and Notoscopelus resplendens.     

Length–weight and length–length relationships and seasonal condition factors for two mudskippers,Periophthalmus modestus (Cantor, 1842) and P. magnuspinnatus (Lee,Choi & Ryu, 1995) (Gobiidae), on tidal flats of Korea

Presented are the length–weight and length–length relationships and condition factors for two mudskippers, Periophthalmus modestus and Periophthalmus magnuspinnatus, on the tidal flats of Korea. Values of the exponent b, estimated by nonlinear least squares from weight and length data, were 3.031 for P. modestus and 3.044 for P. magnuspinnatus. All relationships between total and standard length were linear (r² > 0.974). The condition factors were significantly higher during the post‐spawning season than at other times for both species.     

Length‐weight and length‐length relationships of three small indigenous fishes from the Payra River,southern Bangladesh

Length‐weight relationships (LWRs) and length‐length relationships (LLRs) for three small indigenous fishes (Esomus danrica, Pachypterus atherinoides and Salmostoma bacaila) were reported from the Payra River, southern Bangladesh. Samples were collected using traditional fishing gear including cast net (mesh size ranges from 1.0 to 2.0 cm), seine net (mesh size ranges from 1.5 to 2.5 cm) and square lift net (mesh size ~ 1.0 cm) in August to September 2017. Allometric coefficient (b) values were 2.66 for E. danrica, 3.08 for P. atherinoides and 3.06 for S. bacaila. The LLRs were also highly significant with r² ≥ .956.     

Length–weight and length–length relationships for three species of Squalius (Cyprinidae; Leuciscinae) from the Caspian Sea,Namak and Tigris basins of Iran

Length‐weight and length‐length relationships were estimated for three species of the genus Squalius. These fish were sampled from the Caspian Sea as well as the Namak and Tigris basins of Iran. Sampling took place between July 2009 and August 2010 using a seine net (15 m long, 2 m width and 5 mm mesh size). The values of the b parameter in the length‐weight relationship equations were determined as 3.37 for S. turcicus, 3.25 for S. namak and 3.14 for S. berak (b > 3).     

Length–weight and length–length relationships of three fish species from the Heihe River,northwest China

Length‐weight (LWRs) and length–length (LLRs) relationships are reported for three fish species belonging to two families and two genera from the Heihe River, northwest China. Fish samples were collected using trap nets (mesh size 1 cm) in May and December of 2016, and April and October 2017. Standard length (SL) and total length (TL) for each individual were measured to the nearest 0.1 cm by digital slide caliper and each body weight (BW) was measured to an accuracy of 0.1 g using digital balance. The b‐values for LWRs varied from 2.580 to 3.164 (r² > .956). The results further indicated that the LLRs were highly correlated (r² > .991; p < .01). This study presents the first references on LWRs for Gymnocypris chilianensis and Triplophysa hsutschouensis, and LLRs for G. chilianensis, Triplophysa leptosoma and T. hsutschouensis. This biometric data and their relationships are relevant to the management and conservation of local fishes and fisheries.     

Length‐weight relationships of three freshwater fish species from the Nandu River and Changhua River in Hainan Island,China

Length‐weight relationships (LRWs) were determined for three fish species from the Hainan Island, China. Fish specimens were sampled across the Nandu River and Changhua River from May 2017 to June 2018 with benthic fyke‐nets (stretched mesh size: 0.4 cm), multi‐mesh gillnets (stretched mesh size ranging from 1.0 to 12.5 cm) and electrofishing. Relationships between length and weight were fitted very well for all species (all R²>0.95). The b values of the LRW equations ranging from 2.938 for Liniparhomaloptera qiongzhongensis to 3.259 for Toxabramis houdemeri.     

Length–weight and length–length relationships of four fish species from the middle reaches of the Minjiang River,southwest China

Length–weight (LWR) and length–length (LLR) relationships are reported for Glyptothorax fokiensis (Rendahl, 1925), Microphysogobio kachekensis (Oshima, 1926), Pseudobagrus brevicaudatus (Wu, 1930), and Sinibrama taeniatus (Nichols, 1941) from the middle reaches of the Minjiang River and its tributaries, Sichuan Province, in southwest China. A total of 675 specimens were obtained between 2013 and 2016 using various types of fishing gear and electroshock fishing techniques. Standard length and total length for each individual were measured by digital slide caliper and each body weight was taken by digital balance. The b‐values for LWRs varied from 2.617 to 3.249 (r² > .954), and the LLRs were highly correlated (r² > .983; p < .01).