Length–weight relationships for five fishes in the Nmai Hka River,Myanmar

Length–weight relationships (LWRs) were investigated for five fish species occurring in the Nmai Hka River. Fish were collected monthly from five sites between January and May 2009, using five gill nets in the main river and electrofishing in tributaries. The results of LWRs for Bangana devdevi (Hora, 1936), Garra qiaojiensis Wu & Yao, 1977, Amblypharyngodon atkinsonii (Blyth, 1860), Schizothorax meridionalis (Tsao, 1964) and Mystus pulcher (Chaudhuri, 1911) provide basic data useful in fisheries science. All values of parameter b ranging from 2.89 for Bangana devdevi (Hora, 1936) and 3.47 for Garra qiaojiensis Wu & Yao, 1977(in all cases r² > .951).A new total length has been recorded for Garra qiaojiensis Wu & Yao, 1977 when comparing with records given in the international electronic databank FishBase (Froese & Pauly, 2017).     

Length‐weight relationships for three fishes in the Mali Hka River and Nmai Hka River,Myanmar

Length‐weight relationships (LWRs) were investigated for three fish species occurring in the Mali Hka River and Nmai Hka River. Fish were collected monthly from five sites between January and May 2009, using gill nets in the main river and electrofishing in tributaries (gill nets of three types: (a) = 10 m long, 0.5 m depth, 0.5 cm mesh size); (b) = 15 m long, 1 m depth, 2.0 cm mesh size; and (c) = 20 m long, 1.5 m depth, 6.0 cm mesh size. Soaking time for all was 24 hr). The LWRs for Botia histrionica Blyth, 1860, Crossocheilus burmanicus Hora, 1936 and Schizothorax grahami (Regan, 1904) are given in Table 1 along with the appropriate statistics for the parameters a and b of the equation as well as the confidence intervals and the correlation coefficient. All values of parameter b ranging from 2.57 for Botia histrionica Blyth, 1860 and 3.19 for Crossocheilus burmanicus Hora, 1936 (in all cases r² > 0.96). A new total length has been recorded for Schizothorax grahami (Regan, 1904) when comparing with records given in the international electronic databank FishBase (Froese & Pauly, 2018).     

Length–weight and length–length relationships for six commercial fishes from southern Korean waters

Presented are the relationships between total length and weight, and between total length and standard length for six commercial fishes collected twice a month from local fish markets in southern Korea between 2005–2006 for Acanthopagrus schlegelii (Bleeker, 1854), Hexagrammos agrammus (Temminck & Schlegel, 1843) and Hexagrammos otakii (Jordan & Starks, 1895), and monthly in 2004 for Dentex tumifrons (Temminck & Schlegel, 1843), Doederleinia berycoides (Hilgendorf, 1879) and Scomberomorus niphonius (Cuvier, 1832). The LWR for D. tumifrons is estimated for the first time, and a new maximum length was recorded for S. niphonius. All total length and weight relationships were significant (all r² > .953). The values of exponent b, estimated using simple linear least squares of log‐transformed weight and length data, ranged from 2.945 to 3.317.     

The relationships between fish size and otolith dimensions in the common sole (Solea solea (Linnaeus, 1758)) captured in the Northeastern Mediterranean

Fish specimens were captured by a commercial bottom trawler at a depth of 50–80 m from Iskenderun Bay (Hatay, Turkey) between December 2017 and May 2018. The bottom trawl gear used was equipped with a 44 mm stretched mesh size net at the cod-end. Blind side and eyed side otolith lengths (OL), otolith breadths (OB) and otolith weights (OW) were measured from each specimen to the nearest 0.001 mm and 0.0001g respectively. A total of 110 fish (43 females and 67 males) were collected. Total length ranged from 20.8 to 28.2 cm and 68.0 to 166.1 g (males) and 21.1 to −28.5 cm and 74.5 to 201.4 g (females). The coefficients of determination between fish weight and otolith weight, and total length and otolith weight (sexes combined) were found as R² = .7694 (0.77) and R² = .6274 (0.63), respectively. A moderate positive relationship between the total length-otolith dimensions, and fish weight-otolith dimensions, was also demonstrated.     

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 and length–length relationships for seven fish species from the Zohreh River,Iran

Length–weight and length–length parameters were calculated for seven fish species belonging to five families in the Zohreh River, Iran. The weight–length relationships were estimated using the equation W = aL^b. The b values varied between 2.72 and 3.33, with a mean ± SD of 2.88 ± 0.28. The b values parameter in the length–weight relationship equations were calculated as 3.15 for Alburnus mossulensis Heckel, 1843; 3.78 for Barilius mesopotamicus Berg, 1932; 2.86 for Cyprinion macrostomum Heckel, 1843; 2.89 for Nuchequula gerreoides (Bleeker, 1851); 2.80 for Mastacembelus mastacembelus (Banks & Solander, 1794); 2.72 for Liza abu (Heckel, 1843); and 3.19 for Paraschistura nielseni (Nalbant and Bianco, 1998). This study presents the first LWR and LLR references for these species in the Zohreh River.     

Length‐weight relationship and relative condition factor of five indigenous fish species from Torsa River,West Bengal,India

Length‐weight relationships (LWRs) for five indigenous fish species under five genera and two families, namely Cyprinion semiplotum (McClelland, 1839), Barilius barna (Hamilton, 1822), Barilius barila (Hamilton, 1822), Gagata sexualis Tilak, 1970 and Pseudolaguvia shawi (Hora, 1921) were studied from Torsa River in West Bengal, India. Sampling was done at quarterly intervals from November, 2015 to December, 2016 and a total of 701 fish specimens were collected using cast nets (mesh size of 15–20 mm), gill nets (mesh size 20–35 mm) and bamboo traps. In the present study, b value ranges from 2.686 to 3.268. LWRs for these fish species (except P. shawi) have not been reported in FishBase. A new maximum length has been recorded for P. Shawi and G. sexualis. The relative condition factor (Kn) values was found to range from 1.004 to 1.028.     

Length-Weight Relationship analysis of four freshwater fish Species from Doyang reservoir at Nagaland,India

The LWRs (length–weight relationships) of four freshwater fish species from medium categorized Doyang reservoir at Wokha District, Nagaland were studied, namely as Garra naganensis Hora, 1921; Devario naganensis Chaudhuri, 1912; Chagunius nicholsi Myers, 1924 and Schistura manipurensis Chaudhuri, 1912. Fish sample were collected in every 15 days interval by cast-nets (1.0 × 1.0 cm mesh size covering the 4.5 m² areas), gill-nets (0.4–5.0 cm mesh size), scoop-nets (mesh size with 0.3 × 0.3 cm to 0.6 × 0.6 cm) and also from the local fishermen in between July 2017 to January 2019. The regression value of slope (b) is fallen into 2.860–3.115 range with significant correlation values (r² ≥ .960).     

Length–weight relationship and condition factor of the Characidae matrinxã, Brycon falcatus (Müller & Troschel, 1844), in the Teles Pires River,southern Amazon

The aim of this study was to verify whether the in situ supply of soybean as a fish attractant bears any influence on the length–weight relationship and condition factor of the omnivorous fish species, Brycon falcatus. In addition, estimated was the length–weight relationship, standard and total length, condition factor, and size of B. falcatus in the spawning period in the Teles Pires River Basin. In the experimental design, rivers of the Teles Pires Basin containing soybean attractant (Verde River, Celeste River, Teles Pires River and the Tapaiuna River) were mapped. Fish were also collected from the Cristalino River, which contained no soybean attractant (treatment control). Samples were collected from August 2012 to July 2013. Length–weight relationship of B. falcatus in the Teles Pires River Basin can be obtained by the expression: Wt = 0.0091*SL^3.376, r² = .97, n = 102, and length‐length relationship: TL = 1.128*SL + 3.978, r² = .96. The condition factor of all specimens collected in the Teles Pires Basin was k = 1.055. Size at capable phase (L50) of spawning was estimated at 23 cm standard length. Results showed no significant difference in the length–weight relationship or condition factor of B. falcatus collected from rivers with or without soybean attractant. Concluded is that the in situ supply of soybean as a fish attractant does not interfere with the wellbeing of B. Falcatus in the Teles Pires River Basin.     

Relationships between fish size and otolith size of four bathydemersal fish species from the south eastern Arabian Sea,India

The objective of this study was to estimate a prey body size from the hard parts (e.g. otoliths) of a fish species frequently found in the guts of predators. Length–weight relationships between otolith size (length, height, weight and aspect ratio) and fish size (total length and weight) were determined for four fish species captured in the Arabian Sea by bottom trawl (2015 survey on‐board FORV Sagar Sampada, 200–300 m depth), off the west coast of India: Psenopsis cyanea, Pterygotrigla hemisticta, Bembrops caudimacula and Hoplostethus rubellopterus. No significant differences were noted between the size of the left and right otoliths (t test) in any of the four species. The length–weight relationship of the otolith in all four species showed a negative allometric growth pattern (t test, p < .05). The data fitted well to the regression model for otolith length (OL), otolith height (OH) and otolith weight (OW) to total length (TL) and total weight (TW). Results showed that these relationships are a helpful tool in predicting fish size from the otoliths and in calculating the biomass of these less‐studied fish species during feeding studies and palaentology.     

Length‐weight relationships of four fish species from mangrove of Zhanjiang,China

Length‐weight relationships were determined for four fish species [Acentrogobius viridipunctatus (Valenciennes, 1837); Acentrogobius caninus (Valenciennes, 1837); Glossogobius olivaceus (Temminck & Schlegel, 1845); and Lutjanus ophuysenii (Bleeker, 1860)] belonging to two families. Samples were collected from 2002 to 2010 by cage net (50 × 15 × 15 cm, mesh size 0.5 cm) from Zhanjiang mangrove in China (20°36′N; 110°54′E). The total length ranged is between 2.3 and 18.1 cm and weighted between 0.3 and 90.2 g. The allometric coefficient (b) of length‐weight relationship varied from 2.72 for Zenarchopterus buffonis to 3.48 for Acentrogobius viridipunctatus. Length‐weight relationships for these four fish species were determined for the first time.     

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).     

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 three fish species from the Qiantang River,China

Length–weight relationships (LWRs) of the three fish species, Pseudobagrus albomarginatus(Rendahl, 1928), Pseudobagrus crassilabris (Günther, 1864), and Rhinogobius davidi(Sauvage & Dabry de Thiersant, 1874), were determined respectively. Samples were collected from Qiantang River, China during March 2016–December 2017. The bvalues ranged from 2.525 to 2.917, the coefficient of determination (r²) ranged from 0.96 to 0.97. Prior to this study, the length–weight relationship for P. albomarginatus and R. davidi were unknown to FishBase and the new maximum total lengths for three species were not recorded in FishBase. These results are useful for the fishery research and management in Qiantang River.     

Length–weight relationships of nine fish species from the Tongjiang section of the Songhua River,China

Length–weight relationships were evaluated for nine fish species from the Tongjiang section of the Songhua River in China. A total of 675 fish specimens were collected from 4 May to 29 October 2014. Length–weight relationships for six fish species (Romanogobio tenuicorpus, Leuciscus waleckii, Opsariichthys bidens, Microphysogobio amurensis, Pelteobagrus ussuriensis and Misgurnus mohoity) were new to FishBase in 2015, but the length–weight relationships of P. ussuriensis was studied by Ma in 2015. New data on M. mohoity is offered, and this study also shows new maximum total lengths for three fish species. The r² values ranged from .95 to .99. Values of b varied from 2.504 to 3.471.     

Length–weight and length–length relationships of seven freshwater fish species from the Daning River,a tributary of the Yangtze River,southwest China

This study determined the length–weight relationships (LWRs) and length–length relationships (LLRs) of seven freshwater fish from the Daning River, a tributary of the Yangtze River, southwest China. Specimens were collected between July 2016 and July 2017 using drift gill nets (mesh size 1, 2 and 3 cm), cage net (0.5 cm mesh size) and electroshock fishing techniques quaterly. Parameter b values of LWRs ranged from 2.647 to 3.276 (r² > .963) and b values of LLRs ranged from 1.091 to 1.213(r² > .985). Six new LLRs and seven new maximum length data are presented. The biometric data and their relationships are relevant to Fishers science to supplement other data sets needed for fisheries management.     

Length-weight relationship of six small fish species from the Negro River basin in the Brazilian Amazon

The main objective of the study was to estimate the parameters of the length-weight relationship for six small fish species of lower Negro River basin. The fish were sampled using monofilament gillnets (20 × 2 m, mesh size 5 mm between knots), and landing net for 2 days of each month in September and December 2017 and February, March and April 2018. The gillnets were placed in the river twice a day, in the morning (9–11 a.m.) and the afternoon (3–5 p.m.). Total length and total weight were measured to a precision of 0.1 cm and 0.01 g, respectively. The parameters a and b of the equation WT = a.LT^b were estimated.     

Length‐weight relationships of three gobiid species (Perciformes: Gobiidae) along the Iranian intertidal coast of the Persian Gulf and Makran Sea

Length weight relationships (LWRs) were estimated for three gobiid species, Bathygobius meggitti(Hora & Mukerji, 1936), Acentrogobius dayi Koumans, 1941 and Cryptocentroides arabicus(Gmelin, 1789) (Perciformes: Gobiidae) collected from 13 localities of the Iranian intertidal coast of the Persian Gulf and Makran Sea in seven times from November 2015 to September 2017 using a hand net with mesh size 1.30 mm. The b values showed significant differences between males and females of all species except the C. arabicus. Bailey's t test revealed that b value significantly deviated from the expected cube value of 3 in three species.     

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.     

Utility of fish scales from stock assessment surveys in stable isotope analysis for initial assessments of trophic relationships in riverine fish communities

The utility of using fish scales collected during stock assessment exercises to assess the trophic relationships of riverine fishes using their stable isotopes of d¹³C and d¹⁵N was tested using three riverine fish communities in England (Rivers Great Ouse, Ivel and Goyt). In each river, European barbel Barbus barbus was an important species, with other cyprinid species, including chub Squalius cephalus, present. Stable isotope analyses was completed using relatively small sample sizes per species (<11) from fish samples collected in 2001, 2005 and 2006 when up to 5 scales were collected from each fish. The calculation of standard ellipse areas (as a measure of trophic niche size) revealed that relative to other fishes, B. barbus occupied high trophic positions with minimal overlap in their trophic niche with other species, especially S. cephalus. As the analysed fish samples comprised species of various length ranges and as length has strong ontogenetic consequences for fish diet composition, generalized linear models were developed in which length was the covariate; model outputs included length‐adjusted mean δ¹³C and δ¹⁵N for each species. In each fish community, significant differences in δ¹³C and δ¹⁵N were apparent between B. barbus and S. cephalus, but were less apparent between B. barbus and other fishes. Thus, whilst the utility of using fish scales from stock assessments in stable isotope analyses are limited due to the differing length ranges of the sampled fishes, they can be useful in identifying trophic differences between species when methods such as stomach content analyses are unavailable.