Condition factor,length–weight and length–length relationships of an endangered fish Ompok pabda (Hamilton 1822) (Siluriformes: Siluridae) from the River Gomti,a tributary of the River Ganga,India

The present study describes the condition factor, length‐weight and length‐length relationships for an endangered freshwater fish species Ompok pabda (Hamilton) of the family Siluridae from the River Gomti in Northern India. The values of regression parameter b ranged from 2.81 to 3.32 (r² > 0.90). During the pre‐monsoon, the allometric coefficient b of the LWR was close to isometric value (b = 3.08) allometric (b = 2.87), although it suggested negative allometric growth in monsoon periods while positive growth in post‐monsoon. The condition factor values ranged from 0.672 to 0.744. Results of the present study could be useful to help in conservation and sustainable fisheries management of this endangered species.     

Length–weight relationships for four fish species from lower stretch of River Ganga,India

Length‐weight relationships (LWRs) for four fish species from the River Ganga (India) is presented. Sampling was conducted in the lower stretch of the river (Buxar: 25°33′43.90″N and 83°56′3.10″E to Freserganj: 21°35′40.58″N and 88°15′28.92″E) on tri‐monthly basis from September 2016 to December 2017. Specimens were caught in gill nets (mesh, 18–68 mm), cast nets (mesh, 12–14 mm), seine nets (mesh, 12–14 mm) and various traditional traps those were put over night and lifted in early morning. Total length and wet body weight of fish were measured to the nearest 0.1 cm and 0.01 g by a digital caliper and electronic balance respectively. From LWRs, the estimated b values were found to be 2.88 (Pisodonophis boro) to 3.17 (Gagata sexualis) whereas a value ranged from 0.001 (Pisodonophis boro) to 0.009 (Botia lohachata). As per FishBase, the species Gagata sexualis and Botia lohachata had new TLmax reported for LWR estimation.     

Length–weight and length–length relationships for two gobiids from the Anzali Wetland,in the southern Caspian Sea basin

Length–weight (LWR) and length–length (LLR) relationships were estimated for specimens of two gobiid species collected from the Anzali Wetland and its related streams in the southern Caspian Sea basin, in August 2017. These represent the first reports of LWR and LLR data for Rhinogobius cf. similis Gill, 1859 (37°28′13″N, 49°20′33″E; 50 individuals) and Proterorhinus nasalis (De Filippi, 1863) (36°54′10.89″N, 53°48′48.33″E; 30 individuals) from the Wetland. A new maximum length is reported for P. nasalis. The length–weight parameter b for these species ranged a minimum of 2.99 for Rhinogobius cf. similis to a maximum of 3.04 for P. nasalis with regression coefficients (r²) ranging from .95 to .97. All LLRs were highly significant (r²>.96).     

Length‐weight relationship of three cichlid species in a stream in southwestern Amazon,Brazil

The paper investigates the length‐weight relationship of three cichlids species for the southwestern Amazon, Acre state. The individuals were collected at five sites during one year among august/2016 and june/2017 in Quinoá stream (10°06′03.33″S/67°40′11.50″W). The individuals were collected using: seine net, 6 m length, 2.25 high, and mesh size 5 mm, two dip nets, 5 mm mesh, 30 cm width, and 50 cm in length and two sieve with 5 mm mesh, 50 cm width, and 80 cm in length. The results show that one species presented positive allometric growth (Aequidens tetramerus) and the others negative allometric growth (Apistogramma acrensis and Crenicichla semicincta).     

Length–weight relationship of selected elasmobranch species from north‐eastern Arabian Sea,India

Length–weight relationship (LWR) was estimated for 12 elasmobranch species; five shark species, four species of rays and three species of guitar fishes from north‐eastern Arabian Sea, India. Five major landing centres of Maharashtra were selected; Satpati (Lat. 19°43′15″N, Long. 72°42′00″E), Naigaon (Lat. 19°19′32″N, Long. 72°48′54″E), Versova (Lat. 19°08′33″N, Long. 72°48′11″E), New ferry Wharf (Lat. 18°57′29″N Long. 72°51′01″E) and Sassoon dock (Lat. 18°54′42″N, Long. 72°49′33″E). Samples were collected fortnightly during August 2016 to October 2017 from various gears; drift gill nets (Hung length 114–143 m and #100–270 mm) off Satpati coast at 35–50 m depth, dol nets (length 50–65 m and cod end # 30–69 mm) in Naigaon at 38–50 m depth and trawl (length 33–72 m and cod end # 17–32 mm) in Versova, New ferry Wharf and Sassoon dock operated at 20–50 m depth. Multiday fishing was carried out with 2–3 fishing trips in a month, each trip with duration of 7–13 days. Soaking time of gill net and dol net varied from 4 to 8 hr while each trawl haul lasted for 3–4 hr. Length–weight/Disc‐width‐weight relationship showed good fit with r² values varying from 0.818 to 0.999. In addition to information on LWR, new maximum size for three species of elasmobranchs is reported in this paper.     

Length–weight and length–length relationships of eight fish species from river Ganga,India

Present study provides length–weight relationships (LWRs) and length–length relationships (LLRs) of eight fish species from river Ganga, India. Specimens were sampled from gill nets (mesh, 22–120 mm), cast nets (mesh, 12–14 mm), and seine nets (mesh, 12 mm) on quarterly basis from September 2016 to September 2017 within the river stretch from Buxar (25°33′43.90″N and 83°56′3.10″E) to Freserganj (21°35′40.58″N and 88°15′28.92″E). The b value ranged from 2.86 (Otolithoides pama) to 3.08 (Polynemus paradiseus), whereas a value ranged from 0.004 (P. paradiseus) to 0.016 (Rita rita). Both relationships (LWRs and LLRs) were found to be highly correlated (p < .001). This study provides first report on LWR for Amblyceps mangois and Osteobrama cotio, whereas new maximum length recorded for Macrognathus pancalus. Furthermore, the estimate of R. rita should be considered as tentative because of the limited size range in the study.     

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 relationships of six fish species from São Marcos Bay,Northeastern Brazil

Length‐weight relationship parameters were calculated for six fish species from São Marcos Bay, in Northeast Brazil (the segment between 02°35′55″S and 44°20′58″W; 02°34′53″S and 44°21′48″W; 02º42′25″S and 44º26′46″W). The specimens were caught quarterly from April 2010 to February 2013, using monofilament gillnets (2, 4 and 6 cm between knots) from 100 m to 3,000 m long and 4 m to 6 m high. The present study covers a much wider size range for four species and adds new information for the maximum length of Notarius bonillai.     

Length–weight relationship and condition factor of Lepidocephalichthys goalparensis Pillai and Yazdani, 1976 in Assam,India

The present study describes the length–weight relationship (LWR), condition factor (K) and size at first maturity of a cobitid loach, Lepidocephalichthys goalparensis Pillai and Yazdani, 1976 of the family Cobitidae in Assam, India. A total of 716 specimens (males = 324, females = 392) ranging from 3.06 to 7.01 cm total length (TL) and 0.17–2.27 g body weight (BW) were analyzed. The overall value of the allometric coefficient b for the LWR indicated negative allometric growth (<3.00) for both males (2.774) and females (2.993). The size at first maturity (TL₅₀) for female L. goalparensis was estimated to be 5.6 cm TL. The condition factor values ranged from 0.56 to 1.35 in mature females. This is the first time that the biological parameters have been studied in this species.     

Length‐weight and length‐length relationships of thirteen fish species from the lower Jinsha River,southwest China

Length‐weight and length‐length relationships were investigated for 13 freshwater fish species from the lower Jinsha River, southwest China (from 101°32′49.63″E; 26°35′38.27″N to 104°37′48.14″E; 28°45′59.55″N). Fish were sampled from five sites during 2014 and 2016, using trap‐nets, gillnets (major mesh size: 2–6 cm), longline and electrofishing. Length‐weight relationships for six and length‐length relationships for 12 species are the first report to FishBase, respectively. Moreover, new maximum length for 11 species are also presented to FishBase in this study. All regressions were highly significant (p < .001), with the coefficient of determination r² > .950. These information will be helpful for management and conservation in local fishes and fisheries.     

Length–weight relationships of mesopelagic fishes from the equatorial and tropical Atlantic waters: influence of environment and body shape

Length–weight relationships (LWRs) were estimated for 36 mesopelagic fish species collected from the equatorial and tropical Atlantic encompassing several oceanographic regions: oligotrophic, equatorial, Cape Blanc, Cape Verde and the Canary Islands. The sample was composed of myctophids (25 species), gonostomatids (5), sternoptychids (3), stomiids (2) and phosichthyids (1). The species were clustered according to body shape: “short-deep” (sternoptychids), “elongate” (gonostomatids, stomiids and some phosichthyids) and “fusiform” (myctophids and some phosichthyids). Three types of weight and LWRs were considered: wet weight (WW), eviscerated wet weight (eWW) and eviscerated dry weight (eDW). The study demonstrated that most species present a positive allometric growth, independent of the weight used. However, the allometric value varied in 40–50% of species depending on the type of weight considered. Significant variations linked to fish morphology were found in the relationship between the slope and intercept of the LWR equation. Significant differences were also noted in the water content linked to fish body shape. Based on the distributions of several species we compare their fitness between oceanographic regions using the relative condition factor (K_rel). Except for Diaphus brachycephalus (oligotrophic vs. equatorial waters) and Lampanyctus alatus (equatorial, Cape Blanc, Cape Verde and the Canary Islands), no regional significant differences were observed in the species analysed.     

Length–weight and length–length relationships of 10 small fish species from the Ganges, Bangladesh

This study describes the length–weight (LWR) and length–length (LLR) relationships for ten small indigenous fish species from the lower part of the Ganges, Bangladesh, namely Ailia coila , Amblypharyngodon mola , Aspidoparia morar , Clupisoma atherinoides , Eutropiichthyes vacha , Glossogobius giuris , Gudusia chapra , Lepidocephalus guntea , Mystus vittatus , and Puntius ticto . A total of 2142 specimens, representing 10 species of 5 families used for this study were caught by traditional fishing gear from March 2006 to February 2007. Standard length (SL), total length (TL) and fork length (FL) for each specimen were measured by digital slide calipers and each body weight (BW) was taken by a digital balance. The allometric coefficient b of the LWR was close to the isometric value ( b  =   3.001) in G. giuris , although it suggested negative allometric growth in A. coila, A. morar, C. atherinoides, E. vacha, and P. ticto, whilst positive allometric growth in rest of the species. The results further indicated that the LLRs were highly correlated ( r ²  >   0.890; P < 0.01). To the best our knowledge, this study presented the first reference on LWR and LLR for most of the species in Bangladesh.     

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.     

Length–weight relationships for Eutropiichthys murius (Hamilton, 1822), Coilia reynaldi Valenciennes, 1848 and Johnius gangeticus Talwar, 1991 from lower stretch of the River Ganga,India

Length‐weight relationships (LWRs) for three fish species from the River Ganga (India) is presented. Sampling was conducted from the lower stretch of the River Ganga (Patna: 25°36′51.66″N & 85°12′7.02″E to Freserganj: 21°35′40.58″N & 88°15′28.92″E) during April, June and September and December of 2017. Specimens were caught using gill nets (18 nos.; mesh 18–32 mm), and bag nets (3 nos.; mesh 14–22 mm). The values a and b from LWRs ‐were found to be 0.007 and 2.977 for Eutropiichthys murius; 0.003 and 3.001 for Coilia reynaldi; 0.009 and 3.010 for Johnius gangeticus.     

Length-weight relationship of fish species from Central Amazon floodplain

Length-weight relationship (LWR) for 39 freshwater fish species captured in the Catalão Lake, a floodplain area at the confluence of the Amazonas and Negro rivers is presented. LWRs were calculated based on fish sampled over 18 years (1999–2017) using a set of ten gill nets with different mesh sizes, monthly immersed in water for 24-hr with 6-hr interval catches. Measurements were done for standard length (SL – 0.1 cm precision) and total weight (TW – 0.01 g precision). The LWRs were calculated by the linear regression of natural log-transformed SL and TW data: TW = a × SL^b. All statistical analyses were performed with R software. From all species considered, 32 are new LWR records for the international literature as well as for the Amazonian ichythyofauna; additional records expand the known size range for seven species.     

“Length weight relationship of four non commercial fish species from the Southwest coast of India”

Length weight relationships (LWRs) were estimated for four species of low value fishes that belongs to four families from the southwest coast of India. The specimens of, Callionymus margaretae, Dactyloptena peterseni, Rogadius serratus and Minous inermis were collected for a period of 1 year from the fishing trawlers of Cochin Fisheries Harbour (Lat. 09° 56′ 327″ N, Long. 76° 15′ 764″ E). The estimated allometric coefficient b values ranged from 2.5020 (Rogadius serratus) to 3.2438 (Dactyloptena peterseni) and r² values ranged from 0.9492 (Rogadius serratus) to 0.9869 (Dactyloptena peterseni). All the LWRs were highly significant, with p < .001.This study provides the first estimate of LWRs for these low value by catch fish species.     

Length‐weight relationships of five needlefish species from Kerala waters,south‐west coast of India

Length‐weight relationships (LWRs) were estimated for five needlefish species such as Ablennes hians (Valenciennes, 1846), Tylosurus crocodilus (Péron & Lesueur, 1821), Tylosurus acus melanotus (Bleeker, 1850), Strongylura leiura (Bleeker, 1850), and Strongylura strongylura (van Hasselt, 1823). Specimens were collected on weekly basis from Cochin Fisheries Harbour (Lat. 09056′327″N, Long. 76015′764″E), Munambam Fisheries Harbour (Lat. 10010′965″N, Long. 76010′258″E), Kalamukku (Lat. 09059′924″N, Long. 76014′564″E) and Chellanam (Lat. 09047′950″N, Long. 76016′551″E), between October 2015 to August 2017. Fish were captured by traditional long liner (hook no. IX‐XIV) and ring seiner (mesh size 8–24 mm). The estimated allometric co‐efficient b values ranged from 3.063 (Tylosurus acus melanotus) to 3.962 (Strongylura leiura) and r² values ranged from 0.850 (Tylosurus acus melanotus) to 0.992 (Tylosurus crocodilus). All the LWRs were highly significant, with p < .001. In addition, the study provides the first estimate of LWR for Tylosurus acus melanotus and new estimate for other four species of needlefish.     

Length‐weight relationships of seven fish species from Amazonian Equatorial coast,Brazil

Parameters of the length‐weight relationship (LWR) were estimated for seven fish species from Amazonian Equatorial coast of Maranhão, Brazil. Samplings were carried out in three sample points of the lower stretch of the Itapecuru River (2°57'6.2"S and 44°14'26.5"W; 3°0'33.0"S and 44°15'54.7"W; 3°3'42.9"S and 44°15'1"W). The specimens were caught quarterly from June 2012 to August 2014 using monofilament gillnets (10, 20, 30, 40, 50, 60, 70 and 80 mm between knots) from 10 m to 30 m long and 4 m to 6 m high. This study provides the LWR parameters for Schizodon dissimilis, Curimata macrops, Prochilodus lacustris, Geophagus surinamensis, Hassar affinis, Platydoras brachylecis and Hypostomus plecostomus.     

Length‐weight relationships of seven fish species from Jequitinhonha River basin,southeastern Brazil

The present study established the length‐weight relationships (LWR) for seven fish species from Jequitinhonha River basin, a Brazilian coastal drainage, collected with gillnets (3 to 16 cm) between 2011 and 2016. For the LWR, standard length and total weight were used. The allometric coefficient b varied from 2.66 to 3.26. These results provide biological data for a region of extreme biogeographical importance that is suffering serious environmental disturbances.     

Length–weight relationships for seven fish species from Marajó Bay,Amazon estuary,northern Brazil

Length–weight relationships (LWR) were estimated for seven fish species inhabiting the intertidal mudflats in the Marajó Bay, northern Brazil. A total of 514 specimens were collected quarterly between November 1994 and December 1995 using a beach seine (5 mm mesh size between opposite knots). Slope b of the LWR varied between 2.93 and 3.11, with a mean of 3.02. This study represents the first reference on LWRs for seven species and a new maximum length record for one of these species.