Length–weight relationships and growth parameters of two endemic fish species (Floridichthys polyommus Hubbs, 1936 and Fundulus persimilis Miller, 1955) from the Yucatan Peninsula,Mexico

This study reports length‐weight relationships and growth parameters for Floridichthys polyommus Hubbs, 1936 and Fundulus persimilis Miller, 1955 from La Carbonera, a karstic tropical coastal lagoon on the northwestern coast of the Yucatan Peninsula, Mexico. Specimens were collected between April 2009 and March 2010. The resulting length‐weight relationship for F. polyommus was: W = 0.0180 Lt^3.37 and W = 0.0142 Lt^3.35 for F. persimilis. This study presents the first estimation for both species of the von Bertalanffy growth model parameters, the growth performance index, the L₅₀, and is the first report of the length‐weight relationship for F. persimilis.     

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 relationship of Pseudophoxinus alii Küçük,in Lake Yamansaz,a coastal freshwater lake in Antalya,Turkey

This study describes the length–weight relationship (LWR) of Pseudophoxinus alii from the Yamansaz Lake, a coastal freshwater lake in Antalya, Turkey. A total of 105 specimens were obtained using a variety of nets between April 2007 and March 2008. Total lengths ranged from 3.4 to 14.3 cm. The length–weight relationship showed a positive allometric growth (b = 3.012; R² = 0.988). The study presents the first reference on LWR for this threatened species. The results also indicate a new maximum total length not previously reported in the international literature.     

Length‐weight relationship and reproductive parameters of Botia dario (Hamilton, 1822) in Assam,India

The length‐weight relationships, spawning season, sex ratio, size at first maturity and fecundity of Botia dario (Hamilton, 1822), also known as the Bengal loach, were analyzed based on 556 specimens collected from the wetlands of Majuli Island, Assam between June 2012 and May 2013. The sex ratio (M : F) was 1 : 0.68, differing significantly (P < 0.05) from a 1 : 1 ratio. Size at first maturity (L_m50) was estimated as 6.8 cm for males and 7.4 cm for females. Analysis of monthly variations in the gonado‐somatic index (GSI), the monthly proportions of macroscopic gonadal maturity, and the ova diameter suggest a prolonged spawning season of B. dario from May to August, with a peak in July for both males and females (GSI = 15.0 in females; 7.0 in males). Absolute fecundity varied from 2523 to 51 377, with a mean of 18 367 ± 1254 oocytes per ovary. A positive correlation was recorded between total fecundity and body weight (r² = 0.678).     

Length–weight relationships and biological data on guayana pike‐conger Cynoponticus savanna (Bancroft, 1831)

This study presents the first references available for Cynoponticus savanna length–weight relationships (LWR) as well as other biological information, based on its unique population in the South Atlantic Ocean, specifically, Todos os Santos Bay, on the Brazilian central coast. A total of 464 individuals were obtained from artisanal fishing landings between July 2012 and June 2013. Total lengths ranged from 14.5 to 139.6 cm. The length‐weight relationship was BW = 0.716 TL^3.31. Length at first maturity (L_m) was 48.9 cm. Reproduction began gradually in May, reaching a peak around December, with most individuals completing reproduction by January. The gonadosomatic index (GSI) was highest in January (GSI = 0.21) and lowest in March (GSI = 0.024). The male index (GSI = 0.073) was lower than in females (GSI = 0.10) (P < 0.01). This study presents the first population data for C. savanna, which is under threat due to overfishing and habitat loss.     

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 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.     

Gonad maturation and spawning of cobia,Rachycentron canadum (Linnaeus, 1766) off the Dungun coast,Malaysia

The reproductive biology of cobia, Rachycentron canadum, from the coastal waters of Dungun, Malaysia was studied from June 2014 to May 2015. From commercial trawls, a total of 201 samples (combined sexes) were collected (fork lengths [FL] 37.5–124.0 cm; body weights 0.5–20.4 g). The overall sex ratio of females to males was 1:0.9, which was not significantly different (χ² = 2.12, df = 1; p < .05). Estimations of length at 50% maturity (L₅₀) showed that both sexes matured at approximately 75 cm FL; estimated spawning frequency was 6 days. Mean batch fecundity (BF) ranged from 0.55 to 4.32 million eggs. The average number of eggs per gram of ovary was from 2,100 to 5,400 eggs, and relative fecundity 147 eggs/g. There was a weak positive correlation (r² = .48) between BF and female FL as well as BF with an ovary‐free body weight (r² = .56), possibly due to females being in a continuous spawning condition and some possibly half‐spent, based on the histological examination of the female gonads. Despite cobia being asynchronous spawners, the gonadosomatic index in both males and females showed peaks in June, November, and particularly March. Based on histological examination, spawning‐capable males were encountered throughout the study period, whereas spawning‐capable females in the late developing subphase were found mostly in March and April. This is the first study on the reproductive aspects of cobia in Malaysian waters.     

Length–weight and length–length relationships of five Mystus species from the Ganges and Rupsha rivers,Bangladesh

This study focused on the length–weight and length–length relationships of five Mystus species from Bangladesh. A sum of 398 individuals (Mystus bleekeri = 47, Mystus cavasius = 171, Mystus gulio = 59, Mystus tengra = 65, and Mystus vittatus = 56) was collected from the Ganges and Rupsha rivers, Bangladesh. Fishes were caught by gill net (mesh sizes: 2.0–4.0 cm) and cast net (mesh sizes: 1.5–3.0 cm) from July 2014 to June 2015. Total length (TL), fork length (FL) and standard length (SL) were measured to 0.1 cm, while whole body weight (W) was taken to the nearest 0.1 g for each individual. The TL ranged from 6.0–13.5 cm for M. bleekeri, 5.0–15.0 cm for M. cavasius, 7.4–17.2 cm for M. gulio, 4.6–11.6 cm for M. tengra and 5.5–12.3 cm for M. vittatus. The W varied from 3.0–18.2 g for M. bleekeri, 1.3–30.4 g for M. cavasius, 6.1–62.2 g for M. gulio, 1.7–15.1 g for M. tengra and 2.7–19.2 g for M. vittatus. All LWRs were highly significant (p < .001), with all r² values ≥.950. The LLRs were also highly significant (p < .001), with all r² ≥.980. This study provides information on LWRs and LLRs for M. gulio and M. tengra for the first time. The results of this study can be very effective for stock assessment of Mystus species in the Ganges and Rupsha rivers as well as in the surrounding ecosystems.     

Reproductive biology of the endemic cyprinid fish Hypselobarbus thomassi (Day, 1874) from Kallada River in the Western Ghats,India

The study provides new information on the reproductive biology of Hypselobarbus thomassi (Day, 1874) an endemic cyprinid fish in the Western Ghats–a biodiversity hotspot of India. A total of 384 specimens (males = 244 and females = 140) were collected monthly from April 2009 to March 2011 from Kallada River of Southern part of Western Ghats, India. Monthly sex ratio indicated that males predominated in the fishery, and an overall sex ratio was significantly different from the expected value of 1:1 (male:female = 1:0.57, x² = 28.17, p < .01). Based on the monthly analysis of gonadosomatic index (GSI) and the proportion of mature individuals, the spawning season of H. thomassi occurred between May to October with a peak in June to August. The length at first maturity (L₅₀) recorded was 290 mm TL in males and 330 mm TL in females. The absolute fecundity ranged between 305 (234 mm TL) to 1,089 (414 mm TL) and relative fecundity oscillated between 77.3–220.69 oocytes/g of fish. The fecundity established a linear relationship with total length, body weight and ovary weight. The findings of this study would be very effective to impose sustainable conservation plan for this threatened species in Kallada River and other Western Ghats river systems.     

Length‐weight relationships,condition factor,gonadosomatic index‐based size at first sexual maturity,spawning season and fecundity of Aspidoparia morar (Cyprinidae) in the Jamuna River (Brahmaputra River distributary), northern Bangladesh

The present study describes the length‐weight relationships (LWRs), length‐length relationships (LLRs), Fulton's condition factor (K_F), size at first sexual maturity, spawning season, sex ratio and fecundity of the Morari Aspidoparia morar (Hamilton, 1822) (Cyprinidae). Sampling was done using traditional fishing gear jhaki jal (cast net) from July 2010 to June 2011. Total length (TL), fork length (FL) and standard length (SL) were measured with digital slide calipers. Individual body weight (BW) and gonad weight (GW) were determined to an accuracy of 0.01 g for all specimens. The gonadosomatic index (GSI) was calculated and size at first maturity for males and females estimated using GSI and TL as indicators. Female ≥ size at first maturity was used to determine fecundity. A total of 1200 specimens (males = 552, females = 648) ranging from 4.06–12.84 cm TL and 0.53–16.75 g BW were analyzed. The overall coefficient b for the LWR indicated positive allometric growth (>3.00) in males and isometric growth in females (~ 3.00). ancova (analysis of covariance) revealed significant differences between males and females (P < 0.001). All LLRs were highly correlated (r² > 0.973, P < 0.001). Sizes at first sexual maturity for males and females were 6.0 and 7.0 cm TL, respectively. K_F changed little throughout the year and GSI peaked in November to April, indicating the spawning season (GSImax = 15.0 in females, 2.0 in males). Mature females were dominant during the entire spawning season except in April. Mean total fecundity was 6700 ± 3500, ranging from 1860 to 19680. In addition, relative fecundity ranged from 190 to 1200 (mean 560 ± 235) in the Jamuna River. To ensure sustainable management of this species, the protection of mature individuals during the peak spawning season is highly recommended.     

Length–weight relationships of two sympatric species (Knipowitschia byblisia Ahnelt, 2011 and K. caunosi Ahnelt, 2011) in Köycegiz Lake,Turkey

This study provides basic information on length–weight relationships for Knipowitschia byblisia Ahnelt, 2011 and Knipowitschia caunosi Ahnelt, 2011, two endemic species of Köycegiz Lake Basin (Southern‐West of Turkey). Samplings were carried out seasonally from 2014 to 2015 by means of beach seine nets with mesh sizes from 10 to 35 mm. A total of 343 individuals from the two fish species were examined, with more specimens belonging to K. byblisa (90.4%). The total length–weight relationships were calculated as: W = 0.0054 TL^3.384for K. byblisia and W = 0.0058 TL^3.417for K. caunosi, respectively.     

Length–weight relationship of 12 fish species from the Lhasa River and surrounding area in Tibet,China

Presented are the relationship between standard length (SL) and weight (W) for 12 fish species in Tibet, China, representing three families and six genera from the Lhasa River. All fish samples were collected by either electro‐shocker (12 V, 200 Hz), fish cages (mouth opening: 40 × 40 cm², 5 m), or drift gillnets (3 × 1.5 m; mesh‐size: 3 cm to 8 cm) from different areas in the Lhasa River Basin, August and September 2015. Parameter b ranged from 2.88 to 3.29, and all correlation coefficient (r²) values were higher than 0.95. Length–weight relationships (LWRs) for three of the species as well as one maximum length are first reports for FishBase.     

Reproductive biology of a Gobiid fish Oxyurichthys tentacularis (Valenciennes, 1837) inhabiting Ashtamudi Lake,S. India

Reproductive traits of Oxyurichthys tentacularis, a most demanded fish in Ashtamudi Lake, S. India were studied from samples collected using gill net, cast net and dip net during 2013–2015. Sexes were separated by observing the urogenital papilla in males and the gonads. Five maturity stages were identified by examining the gonads. Though advanced maturity stages were encountered throughout the year, higher preponderance of ripe gonads was discernible during August to November and February to April. Gonadosomatic indices indicated same trend in both sexes. The length at first maturity was 86.67 mm in males and 80.17 mm in females. The absolute fecundity ranged from 5,112 (102 mm TL) to 52,431(175 mm TL). Fecundity established linear relationships with total length, body weight and ovary weight. Ova diameter studies revealed that spawning takes place in batches at regular intervals and the species is a multiple spawner. The ratio of males to females was found to be 1:0.7 (χ² = 10.8; p < 0.05). The pooled average for the whole period showed a perceptible dominance of male population in all of the months except in January (χ² = 2.3; p > 0.05) could be observed.     

Length–weight relationships for two marine fish species from the Gulf of Oman: Uranoscopus guttatus Cuvier, 1829 and Lagocephalus inermis (Temminck & Schlegel, 1850)

This study presents the first report of length–weight relationships (LWRs) for Uranoscopus guttatus and Lagocephalus inermis from the Iranian coast on the Gulf of Oman. A wide range of body lengths and weights were obtained using samples from non‐selective trawling surveys. The LWRs obtained were W = 41.408L^3.519 and W = 16.525L^2.847 for U. guttatus and L. inermis, respectively.     

Age,growth and reproduction of the white seabream Diplodus sargus sargus (Linneaus, 1758) off the eastern coast of Algeria

The objective of this study was to determine the basic population‐specific parameters necessary for fish stock assessment in the area and to compare these with data from other Mediterranean regions. White seabream Diplodus sargus sargus (n = 449) were caught along the Algerian coast between December 2005 and December 2006. Total length ranged from 12.2 to 34.6 cm, representing age classes between 0 and 10 years. Validity of the otolith readings for estimating age and growth was supported using the back‐calculation method. The von Bertalanffy growth parameters for all fish were calculated as: TL = 36.3 cm, k = 0.154 year⁻¹, t₀ = −0.488 year. The growth performance index (φ) showed a relatively slow growth of the local population. The length‐weight relationship showed an isometric growth (b = 2.98; r = 0.98). Subspecies Diplodus sargus sargus was characterized as being a proterandric hermaphrodite. Overall ratio of males to females was 1 : 1.4, with males predominant in the smaller size intervals and females in the larger ones. The reproductive season extended from January to May, with a March–April peak in spawning activity. Fifty per cent maturity of the tested cohort was reached at a total length of 20.2 cm for males and 20.0 cm for females.     

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 and length–length relationships of two goby species,Neogobius caspius (Eichwald, 1831) and Proterorhinus nasalis (De Filippi, 1863) from the southern Caspian Sea

The present study provides the length–weight (LW) and length–length (LL) relationships for two goby species, Neogobius caspius and Proterorhinus nasalis, which were captured in the southern Caspian Sea. Total length (TL) and standard length (SL) were determined as well as weight. Specimens were collected monthly from September 2014 to August 2015 by beach seine (mesh size 10 mm). The LW parameter b for these species was 3.17 and 2.99, respectively, with a high coefficient of determination (r² > .95). All LLRs were highly correlated (r² > .97). Both species had no previous LWR and LLR estimates in FishBase.     

Length‐weight relationships of 10 coastal fish species from the Visakhapatnam coast,India

We analysed the length‐weight relations (LWRs) of 10 fish species inhabiting different habitats from Visakhapatnam, Coast of India. Samples were obtained between August 2013 and December 2016 from commercial trawlers at the local fish landing centre (16.98°N–20.20°N, Long.82.19°–86.53°E). Fishes were captured between 100 and 300 m depth with demersal trawl net (head rope length: 46 m and cod end mesh size: 40 mm with a 38 m high speed. Total length (TL; nearest to 0.1 cm) and body weights (nearest to 0.1 g) were taken from each individual. This study provides new maximum length data for two species (Archamia bleekeri (Günther, 1859) and Ostorhinchus fleurieu (Lacepède, 1802), and LWR estimates for rare deep reef associated fishes are provided for the first time. All LWRs were significant with r² values ranging from .908 for Sargocentron praslin (Lacepède, 1802) to .981 for Parapercis pulchella (Temminck & Schlegel, 1843) and “b” values ranged from 2.5216 for Parapercis pulchella (Temminck & Schlegel, 1843) to 3.4746 for Ostorhinchus fleurieu Lacepède, 1802.     

Population structure,growth and production of the yellow clam <Emphasis Type="Italic">Mesodesma mactroides</Emphasis> (Bivalvia: Mesodesmatidae) from a high-energy,temperate beach in northern Argentina

The yellow clam Mesodesma mactroides (Bivalvia: Mesodesmatidae) was once the most abundant intertidal species on the Atlantic coast of northern Argentina and an important commercial resource in South America. This study of a population inhabiting the intertidal zone of the sheltered-dissipative sandy beach Santa Teresita documents the species’ population biology, including demographic structure, growth and production during December 2004 and December 2006, and adumbrates the critical state of M. mactroides at present. A total of 3,015 M. mactroides were collected and measured, whereas individuals were found with an anterior–posterior shell length between 2 and 64 mm. A von Bertalanffy growth function with an asymptotic length (L _∞) of 85 mm and a growth constant (K) of 0.47 year⁻¹ was established from length–frequency distributions. The longevity of the species is estimated at approximately 6 years, and instantaneous mortality rate was about three times higher than 40 years ago. Besides, this study confirmed that the overall growth performance index (OGP) is habitat-specific and can be used to group M. mactroides and M. donacium from different areas into temperate and upwelling species. Furthermore, OGP is inversely correlated with the latitudinal distribution of Mesodesma populations. The intertidal biomass ranged between 0.06 and 0.07 g AFDM m⁻² year⁻¹. Individual production was observed to be highest at 47 mm length (0.35 g AFDM m⁻² year⁻¹), and annual production ranged between 0.12 and 0.19 g AFDM m⁻² year⁻¹, resulting in productivity values (P/B) between 1.84 and 2.93. The comparison of the results of the present study with those of growth studies conducted on M. mactroides 40 years ago revealed the following considerable differences in the population structure of M. mactroides, indicating the conservation status of this intertidal bivalve as endangered: (1) present growth rates are faster, but that the maximum length attained has decreased, (2) the numbers of individuals per square metre were many times higher in the past than in the present, (3) bivalves from the present work never reached the ‘commercial size’ of 60 mm and (4) 40 years ago, the population of M. mactroides was composed of up to three cohorts, whereas in this study, there was only one single cohort visible.