Length–weight relationships of five fish species from Carangidae family in waters of the northern Persian Gulf,Iran

This research describes and presents some biological aspects of five fish species from carangidae family including: Alepes djedaba, Ulua mentalis, Alectis indica, Carangoides coeruleopinnatus, and Carangoides bajad in the Iranian waters of the northern Persian Gulf (Hormozgan Province, Iran). Samples were collected from April to September 2016. The fishing gears were gill nets (80, 100, 120 and 145 mm stretched mesh size), bottom and midwater trawls (30, 40 and 75 mm stretched mesh size in cod‐end) of local and commercial fishery. The b values of length–weight relationships ranged from 2.512 (95% CL = 0.054) for U. mentalis to 2.953 (95% CL = 0.155) for C. coeruleopinnatus and the correlation coefficient values (r²) were high for all species.     

Length‐weight relationships of three fish species from the Jatinga River (Barak drainage) in Assam,India

The present study reports the Length‐Weight relationships of three freshwater fish species, Amblyceps laticeps (McClelland, 1842), Danio dangila (Hamilton, 1822) and Lepidocephalichthys berdmorei (Blyth, 1860), based on monthly collections between November 2016 and October 2017. Fishes were collected from selected sampling sites along the Jatinga River (a tributary of the Barak River drainage) using cast nets (2.5 m; mesh size: 1.0–1.5 cm) and electrofishing device (Safari Surveyor, 12 V 7 amp). Estimated b values were 2.78 for A. laticeps, 3.19 for D. dangila and 2.92 for L. berdmorei respectively.     

Length–weight and length–length relationships of five threatened fish species from the Jamuna (Brahmaputra River tributary) River,northern Bangladesh

The small indigenous species, namely Ailiichthys punctata (Day, 1871), Botia lohachata (Chaudhuri, 1912), Chanda nama (Hamilton, 1822), Laubuca laubuca (Hamilton, 1822) and Mystus cavasius (Hamilton, 1822), comprise an important component of riverine fisheries of Bangladesh. This study describes the length–weight relationships (LWRs) and length–length relationships (LLRs) of five threatened fishes from the Jamuna River, a distributary of the Brahmaputra River in northern Bangladesh. A total of 919 specimens from five species in five families used for this study were caught by traditional fishing gear, March 2010 through February 2011. The allometric coefficient (b) of the LWRs indicated negative allometric growth in A. punctata, B. lohachata, and C. nama (b < 3.00), but positive allometric growth in L. laubuca and M. cavasius (b > 3.00). Furthermore, the LLRs were highly correlated (r² > 0.978; P < 0.001). This study presents the first reference on LWRs and LLRs for these threatened species in Bangladesh. The results would be useful for sustainable management and conservation of the limited stocks in the Brahmaputra River ecosystem.     

Length–weight relationships of six fish species from the headstream region of the Dongjiang River,China

Dongjiang River, a main tributary of the Pearl River, is geographically situated in South China. The present study describes the length–weight relationships (LWRs) of six fish species (Acrossocheilus paradoxus, Barbodes semifasciolatus, Onychostoma elongatum, Microphysogobio fukiensis, Microphysogobio kiatingensis, Metzia lineata) from the headstream region of the river including five Chinese endemic species (A. paradoxus, B. semifasciolatu, O. elongatum, Mi. fukiensis, Mi. kiatingensis). Fish species of five genera of the same family were collected quarterly from April 2012 to October 2014 by using non‐selective fishing gears: drag nets (5 m, mesh‐size 3 cm), drift gillnets (30 × 15 m, mesh‐size 5 mm), fish cages (4 m, mouth opening 40 × 40 cm), scoop nets (mesh‐size 0.5‐1 cm), and electro‐fishing (12V, 200 Hz). The parameter a and b in the LWR equations (W = a L^b) ranged from 0.0014 to 0.0228, and 2.89 to 3.18, respectively. Compared with FishBase, this study provides the first LWR records for four cyprinids (A. paradoxus, B. semifasciolatu, O. elongatum, Me. lineata) and a new record of maximum body length for O. elongatum.     

Length–weight relationships of seven fish species from a fish landing port at Sungai Udang,Penang, Malaysia

The length–weight relationships (LWRs) are described for seven fish species from four families (Ariidae, Clupeidae, Leiognathidae and Sciaenidae) inhabiting Penang waters. A total of 471 specimens were sampled and measured from 19 to 20 January 2015, using a bottom trawl net with a 38 mm mesh size of cod‐end. No information regarding LWRs was reported previously in FishBase for Cryptarius truncatus, Escualosa thoracata, Johnius carouna, Nuchequula blochii, Plicofollis argyropleuron, Secutor hanedai or Secutor megalolepis, and the study also provides a new FishBase record of maximum total length for Escualosa thoracata (10.6 cm), Secutor hanedai (9.1 cm) and Secutor megalolepis (7.5 cm).     

Length–weight relationships for eight fish species from the Pearl River Delta,China

Length–weight relationships (LWRs) were estimated for eight native fish species collected in the lower reaches of the Pearl River, Guangdong Province, South China. Fish were sampled in March and September 2014 and January 2015, using gillnets with various mesh sizes (5–8 cm) and trawl nets with a 3 cm mesh size. A total of 568 specimens of the eight species were analyzed. The r² values for these species ranged from 0.951 to 0.991. The b values ranged from 3.00 for Takifugu ocellatus and Moolgarda cunnesius, to 3.57 for Clupanodon thrissa. New maximum total lengths are recorded for Takifugu ocellatus (17.6 cm) and Liza carinata (24.4 cm). For five species (Clupanodon thrissa, Megalobrama terminalis, Collichthys lucidus, Coilia grayii, Takifugu ocellatus), the LWRs are presented to fishbase for the first time.     

Length–weight relationships of three Gobiidae species from the Rupsha River in southwestern Bangladesh

This study reports the length–weight relationships (LWRs) of three Gobiidae fish species (Acentrogobius viridipunctatus, Apocryptes bato, and Odontamblyopus rubicundus) from the Rupsha River, southwestern Bangladesh. A total of 388 individuals were sampled using cast nets (mesh size ranges from 1.5 to 3.0 cm), gill nets (mesh size ranges from 2.0 to 3.0 cm) and square lift nets (mesh size ~1.5 cm) from December 2014 to November 2015. Allometric coefficient (b) values were 3.23 for A. viridipunctatus, 2.70 for A. bato, and 2.67 for O. rubicundus, respectively. The first LWRs records for these three Gobiidae species, they can be used online for FishBase as well as in future studies.     

Length–weight relationships of three fish species from the Arial Khan River,an outlet of the river Padma,Bangladesh

The present study narrated the length–weight relationships (LWRs) of three fish species Salmophasia sardinella (Valenciennes, 1844), Amblypharyngodon microlepis (Bleeker, 1853) and Macrognathus aral (Bloch & Scheider, 1801) from the Arial Khan River, a south‐eastward outlet of the river Padma, Bangladesh. Fish samples were collected monthly basis from fishermen who used cast nets (mesh size <0.5 cm) and set bag nets (mesh size 0.5 cm) for catching fish species from January to December, 2016. The growth coefficient b in LWRs were 3.004, 3.001 and 2.936 for M. aral, S. sardinella and A. microlepis, respectively.     

Length–weight and length‐length relationships of four endemic fish species caught from Payra River,Southern Bangladesh

The present study estimated the length–weight relationship (LWR) and length‐length relationships (LLR) of four fish species, Ompok pabo (Hamilton, 1822), Acentrogobius cyanomos (Bleeker, 1849), Acentrogobius caninus (Valenciennes, 1837) and Gagata cenia (Hamilton, 1822) collected from the Payra river over a period of 1 year between July 2015–June 2016 using set bag nets and cast nets with a mesh size of 0.5 cm and <0.5 cm, respectively. Altogether 593 individuals of O. pabo (59), A. cyanomos (221), A. caninus (240) and G. cenia (73) were sampled and studied. LWRs of O. pabo, A. cyanomos, and A. caninus are presented for the first time in Fishbase.     

Length-weight relationships of seven cyprinid fish species from the Kaptai Lake,Bangladesh

Length-weight relationships (LWRs) were estimated for seven small indigenous cyprinid fish species including Securicula gora, Osteobrama cotio, Esomus lineatus, Pethia gelius, Megarasbora elonga, Gonialosa manmina and Glossogobius aureus occurring in the Kaptai Lake, Bangladesh. Fish were collected monthly basis between March and October, 2018 from fishermen catches landed in the fish landing center, Rangamati. Fishermen operated lift net (mesh size < 0.5 cm), punti net (mesh size < 0.5 cm) and cast net (mesh size < 0.5 cm) for capturing these species. The value of exponent b ranged between 2.769 and 3.212 and regression parameter r² was between 0.926 and 0.992. New maximum total lengths were recorded for E. lineatus and G. manmina in this study.     

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.     

Length‐weight relationships for three endemic fish species from the upper reaches of the Yangtze River,southwestern China

Length‐weight relationships (LWRs) were evaluated for three endemic fish species (Sinibrama taeniatus Nichols, 1941; Ancherythroculter nigrocauda Yin & Wu, 1964; and Acrossocheilus monticola Günther, 1888) from the upper reaches of the Yangtze River, southwestern China. Samples were collected using gill nets (25 × 12 m, mesh‐size 2.0 cm) and fishing cages (0.5 × 0.5 × 10 m, mesh‐size 1.0 cm) as well as by electroshock (CWB‐2000 P, 12 V, 250 Hz), from July to September in 2013–2016. Prior to this study, the LWRs for these three species (S. taeniatus, A. nigrocauda and A. monticola) were unknown. In addition, new maximum size for A. nigrocauda and A. monticola were provided.     

FILTER-FEEDING DUCKS OF THE KAFUE FLATS, ZAMBIA, 1971–1973

The occurrence, chronology of breeding and wing-moult, and feeding habits of seven commonly occurring species of filter-feeding ducks on the Kafue Flats in Zambia are described, based on 20 aerial surveys over the central section of floodplain and intensive observations on the ground at Lochinvar National Park, between October 1970 and January 1974. At high flood levels ducks were almost restricted to areas heavily utilized by lechwe; this association persisted until the floodplain became dry, but during the dry season ducks were also found on vegetated lagoons. Five species—Dendrocygna bicolor, Dendrocygna viduata, Thalassornis leuconotus, Netta erythropthalma and Anas erythrorhyncha—were most abundant between June and September; a sixth—Anas punctata—was most abundant between December and March, while the seventh—Anas undulata—was probably resident. At times the numbers of D. bicolor, D. viduata and A. erythrorhyncha probably exceeded 25 000; those of N. erythropthalma reached 6500, but the numbers of T. leuconotus, A. punctata and A. undulata were much lower and at Lochinvar did not exceed 500. Small numbers of D. bicolor, N. erythropthalma, A. punctata and A. undulata nested on the floodplain in the vicinity of Lochinvar between March and July. All seven species completed their wing-moult between April and October in the area; large numbers, particularly of A. erythrorhyncha and D. bicolor, were involved. At Lochinvar, A. punctata fed mainly on aquatic invertebrates; the remaining species fed largely on shed fruits and seeds. The most important food plants were a terrestrial herb, Ambrosia maritima (January–April), two aquatic herbs, Nymphaea capensis and Nymphoides indica (May–August), and two aquatic grasses, Echinochloa stagnina and Vossia cuspidata (September–December). The herbs grew where grassland had been suppressed by lechwe; fruits of the aquatic grasses were found where lechwe had removed the overlying mat of stems. Despite similarities in diet the ducks differed from each other in feeding behaviour and/or preferred habitat. Five other species of filter-feeding ducks, Anas capensis, Anas smithii, Anas clypeata, Anas acuta and Anas querquedula, have been recorded from the Flats, but all are rare.     

Length–weight relationships of three fish species from Wujiang River,China

Length–weight relationships were determined for three fish species (Pseudogyrinocheilus prochilus Sauvage & Dabry de Thiersant, 1874; Folifer brevifilis Peters, 1881; and Garra imberba Garman, 1912). Samples were collected from the Wujiang River in China, from May to July in 2009–2011 using gillnets (25 × 12 m, mesh size 0.5 cm) and fish cages (0.5 × 0.5 × 10 m, mesh size 0.5 cm mesh). Length–weight relationships for these three fish species were determined for the first time.     

Length-weight relationships of eight fish from seagrass meadows in Wenchang,China

The length-weight relationships (LWRs) were studied for eight seagrass fish from Wenchang, China, using gill nets (150*1 m, mesh size 0.5 cm), including Gerres oblongus, Ambassis kopsii, Halichoeres nigrescens, Sillago aeolus, Yongeichthys criniger, Oxyurichthys tentacularis, Lethrinus haematopterus and Hypoatherina tsurugae, in November 2017, March and August 2018. Results suggest that mean LWR parameters b for these eight seagrass fish varied from 2.801 for L. haematopterus to 3.640 for A. kopsii, and r² valued from .950 for L. haematopterus to 0.993 for H. nigrescens. This study will help us to better understand the ecological parameters these seagrass fish.     

Length‐weight relationships of three indigenous fish species from National Nature Reserve for Rare and Endemic Fishes of the upper Yangtze River,China

Length‐weight relationships (LWRs) were estimated for three small indigenous fish species, (Sinogastromyzon szechuanensis, Sinogastromyzon sichangensis and Sinocrossocheilus labiatus) in the upper Yangtze River, China. Samples were collected using three types of local traditional fishing gears, including gill nets (mesh size: 1 cm), fish cages (mesh size: 0.5 cm), and electrofishing techniques (CWB‐2000 P, 12V, 250 Hz), in April, July and October 2013 and 2014, and April and October 2016. The sample size for each species were gathered separately, with 100 for S. szechuanensis, 381 for S. sichangensis and 49 for S. labiatus from National Nature Reserve for rare and endemic fishes of the upper Yangtze River, China. The length‐weight relationship parameter values of b were calculated as 2.986 for S. szechuanensis (b: 2.854–3.118), and 3.284 for S. sichangensis (b: 3.209–3.359) and 3.119 for S. labiatus (b: 2.911–3.326). The primary data will be meaningful for further research about sustainable development and scientific management of fishery resources of the upper Yangtze River.     

Biology of the kingsoldier bream (Argyrops spinifer, Forsskål 1775; Sparidae), from the Arabian Sea, Oman

It is recognized by the FAO that management of fish resources in the western Indian Ocean is complicated by the lack of data on the basic biology and landing statistics for exploited fish species. In this paper data are presented on the population biology of kingsoldier bream, Argyrops spinifer (Forsskål 1775), in the Arabian Sea with a view to contributing towards the development of management plans for its sustainable exploitation. Samples were obtained from the Omani artisanal hand‐line fishery catch, January 2001–December 2002. Total length (L_T) of fish sampled ranged from 20 to 68 cm (males) and 25 to 70 cm (females). The male : female ratio was similar up to 55 cm L_T but the larger size‐classes were composed predominately of male fish. L_T/carcass weight (W_C) relations for male and female fish were similar and the combined data produced an equation W_C = 0.00005 × L_T^2.67. Marginal increment analysis indicated an annual cycle of opaque and translucent ring formation in otoliths that was related to the change in surface water temperature during the annual monsoon period. The opaque zone was completed in May and the translucent zone began to form in June. Female and male fish age ranged between 2 and 25 years. Both males and females exhibited similar asymptotic growth patterns; the combined von Bertalanffy growth function was L_t = 64.6(1 ? e^{[?0.142(t + 0.489)]}). Gonadosomatic indices and gonad condition of male and female fish indicated that the spawning season occurred between September and January. Size (L₅₀) and age at first maturity (A₅₀) were estimated to be 36.5 cm L_T and 5.0 years for males and 37.2 cm L_T and 5.6 years females, respectively. The results of this study provide fundamental information on the biology and population dynamics of A. spinifer in the Arabian Sea that can be used in management models for the continued sustainable exploitation of this species in the Omani demersal coastal fisheries.     

Length-weight relationships of four fish species from the lower reaches of the Nujiang River and its tributaries in China

As one of the largest Southeast Asian rivers, flowing through China, Myanmar, and Thailand, the Nujiang (Salween) River contains a unique and rich diversity of fish species. In the present study, we investigated the length–weight relationships (LWRs) of four fish species (Pteronemacheilus meridionalis, Devario shanensis, Exostoma gaoligongense, and Glyptothorax granosus) collected from the lower reaches of the Nujiang River and its tributaries (24.175N~25.842N, 98.861E~98.903E), including the Mengboluo, Kungong, Luomingba and Laowo rivers in southwest China. Specimens were collected by using drift gill nets (100 m length × 1.5 m depth or 3 m depth, mesh-size: 1 cm-5 cm), cast nets (6.5 m, mouth opening: 35 × 45 cm², mesh-size: 4 mm) , and an electric shocker apparatus (12 V, 200 Hz) from different regions in the Nujiang River basin in September and October 2019 and June and September 2020. Before the collected fishes were placed in formalin, standard length (SL) and net weight (W) were measured respectively to the nearest 0.1 cm and 0.1g, respectively. Based on searches of the FishBase database and other relevant scientific literature, this study provides a new record of maximum size for P. meridionalis and LWRs for the four fish species.     

Length-weight relationship of 16 fish species from the Negro River basin (Amazonas state,Brazil)

This study aimed to estimate the parameters of length-weight relationship for 16 freshwater fish species that inhabit the Aracá and Demeni Rivers, which are two tributaries of the Negro River (Amazonas state, Brazil). The fishes were sampled using gillnets (15 × 2 m, mesh size 30–120 mm between opposite knots), during 6 days each year, in April 2016, November 2018 and April 2019. The gillnets were placed in the river twice each day; in the morning (5–9 a.m.) and in the evening (5–9 p.m.), with a standardized time of 4 hr. Measurements were taken for standard length (SL – 0.1 cm precision) and total weight (TW – 0.01 g precision). The parameters a and b of the equation W_T = a.L_T^b were estimated. This study also provides new data on of maximum lengths for six species, namely, Argonectes longiceps, Hemiodus atranalis, Chalceus erythrurus, Astrodoras asterifrons, Trachydoras steindachneri and Acarichthys heckelii.     

Length–weight and length–length relationships of three fish species from the Yarlung Zangbo River in Tibet,China

Length–weight relationships and length–length were evaluated for three fish species (Schizopygopsis younghusbandi Regan, 1905; Ptychobarbus dipogon Regan, 1905 and Oxygymnocypris stewartii Lloyd, 1908) from the Yarlung Zangbo River in Tibet. Specimens were captured monthly using floating gillnets (mesh size 7.5 cm), bottom gillnets (mesh size 6.5 cm), and trap nets (mesh size 1.5 mm) from August 2008 to August 2009, March to August 2012, and March to April 2013. Regression coefficient (b) values of length–weight relationships (LWRs) ranged from 3.045 for P. dipogon to 3.193 for O. stewartii, whereas the a values ranged from 0.0040 to 0.0168 for O. stewartii and P. dipogon, respectively.