Journal of Fisheries (University of Rajshahi)
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New record of spot-tail sleeper ray Narke dipterygia (Bloch and Schneider, 1801) (Elasmobranchii, Torpediniformes, Narkidae) from the coast of Gujarat, India
Get PDFNarke dipterygia (Bloch and Schneider, 1801), commonly known as numb ray, is a widely distributed species in the Arabian Sea and South-East Asian countries. It has been recorded from Oman, Pakistan, Sri Lanka, Malaysia, Singapore, Indonesia, Thailand, Viet Nam, China, Taiwan Province of China and Japan. In India, majority of the findings of the species is from east and west coasts of India, only two records were reported namely Bombay of Maharashtra and Kerala. The present paper confirms the presence of N. dipterygia for the first time from Gujarat coast located on the west coast of India. The diagnostic characteristics and remarks on the taxonomy and distribution of N. dipterygia have been described in this paper
Living conditions and coping strategy of coastal communities contribute to the environmental integrity at the world heritage site of Dungonab Bay Mukkawar Island Marine National Park at the Sudanese Red Sea coast
Get PDFWorld natural heritage sites (WNH) are those areas recognised for their unique natural resources and/or processes. The main objective of this study was to investigate the living conditions and diversity of livelihoods of coastal communities of the world natural heritage site of the Dungonab Bay-Mukkawar Island Marine National Park (DMNP-WNH). The fishing communities at Dungonab and Mohamed Gol villages were found to be deprived in water, electricity, education, health care, sanitation, flooring, cooking fuel and other livelihood assets. The expenditure of 82.9% of Dungonab and 91.2% of Mohamed Gol households exceeded their income. Accordingly, DMNP-WNH fishers were not able to invest in their livelihood assets and they used hook and line as the sole fishing gear. These conditions have restricted the access of respondents to fishing grounds. About 95% of Dungonab and 93.7% of Mohamed Gol respondents were experiencing extreme poverty. The quality of life at study sites was discouraging for human settlement, therefore, limiting the population growth and consequently the consumption of natural resources at DMNP-WNH. This has positively contributed to the environmental integrity. Access to clean water, electricity and diversification of fishermen livelihoods are of key importance to stimulate blue economy and sustain the environment of the DMNP-WNH
On the investigation of electroanaesthesia in Labeo rohita under DC and PDC electric field
Get PDFThis study investigates electroanaesthesia under Direct Current (DC) and three low frequency Pulsed Direct current (PDC) of 1 Hz, 3 Hz and 6 Hz in Labeo rohita. All the current types in this study were effective in anaesthetizing L. rohita with fast induction and rapid recovery period in all fishes. The threshold value of voltage gradient (V cm–1) for inducing anaesthesia was higher in DC than PDCs. Opercular movements were significantly lower during anaesthesia, significantly higher one minute after recovery in all current types and reduced significantly in DC, PDC 1 Hz and PDC 3 Hz after 10 min of recovery from anaesthesia. Blood glucose level returned to the near control values after 8 hours of exposure in all current types in this study. DC sharp rise and PDC 3Hz may be preferred for inducing anaesthesia considering the recommended criteria of anaesthetic induction and recovery time. Result of this study indicates that electroanaesthesia technique with fast induction and rapid recovery may proffer a cost effective, safe and ecofriendly alternative for aquaculture activities in L. rohita
Evaluation of the reproductive cycle and gonadal development in the climbing perch, Anabas testudineus (Bloch, 1792) in captivity
Get PDFThe climbing perch Anabas testudineus, the most demanded indigenous fish species of India, were used for the evaluation of reproductive strategy and gonadal development at first maturation under the controlled laboratory condition. In both sexes, four distinct gonadal developmental stages namely preparatory, pre-spawning, spawning, and post-spawning were identified based on the gonadosomatic index (GSI), hepatosomatic index (HSI), gonadal morphology, and the levels of serum sex hormones. The spawning stage was identified from July and August and the fecundity ranged from 6500–11000 eggs. The GSI exhibited a significant increase from preparatory to pre-spawning and spawning stages, and maintained high until August. The HSI was maintained the same during preparatory, pre-spawning, and spawning stages while increased in post-spawning stage in both sexes. Serum estrogen and testosterone levels increased significantly during pre-spawning, and spawning stages in both sexes. Fecundity showed a positive correlation with the length, weight, and ovary weight. Histological sections showed that male A. testudineus were group-synchronous spawners. Both sexes showed discrete reproductive cycles characterized by distinct changes in gonadal size, sex hormones and gonadal indices. This study will bridge the gap of insufficient knowledge to support the best practices suitable for the A. testudineus culture and survival under captivity
Range extension and re-recording of Redigobius bikolanus (Herre, 1927) from Great Nicobar, India
Get PDFRedigobius is a genus of goby fish belonging to order Gobiiformes. Redigobius is currently represented by 15 species worldwide of which Redigobius bikolanus is a widespread species. This species was recorded previously from Middle Andaman Island in 2002. There was not a single evidence of the species after that time, from Indian region. Recently, during a faunal survey in great Nicobar Island resulted in collection of a R. bikolanus for the first time and proving evidence for range extension of the same from Nicobar group of Islands. The species was collected from one of the estuarine creeks of Great Nicobar island. Details of the morphological data, live colouration and wild habitat are provided for the new record
Using the hydroacoustic and mini trawl data for estimating fish density in the eastern part of Banyuasin coastal waters, South Sumatra of Indonesia
Get PDFThe hydroacoustic and mini trawl sampling was conducted to estimate a distribution pattern of fish density in the eastern part of Banyuasin coastal waters, South Sumatra, Indonesia. These surveys were carried out in September 2017 using a SIMRAD EK15 single‐beam echo sounder with a 200 kHz operating frequency. Catch data obtained from the mini bottom trawl were used to examine a dominant species for refining the TS value concerning the fish density estimation along the hydroacoustic track. The ponyfishes (Eubleekeria jonesi) from the Leiognathidae family were found at each station with the highest relative abundance (50.98%). Hence this species was used to refine target strength values for estimating the acoustic volume density. These volume densities of 206 ESDU ranged from 0 to 9048 fish 1000m–3, with an average of 930 fish 1000m–3. The results also described a distribution pattern of fish densities hence this information could be valuable to the fishery manager for improving sustainable management approaches
Exotic fish and decreasing habitats vis-à-vis conservation of freshwater fish biodiversity of Bangladesh
Get PDFMultiple stressors including biological invasion have long been recognised in conservation of freshwater fish biodiversity. Works in this line have, however, been still scanty in Asia and South America – the continents known for rich biodiversity. In this study, the first of its type in Bangladesh, impacts of exotic fish and declining habitats on native fishes have been investigated. Regression and correlation analyses of 16 years production data of ponds, practically the only habitat where exotic fish are cultured commonly with indigenous ones, reveals that a maximum of 25% of the abundance decrease of native fish could be due to the effects of five commonly cultured exotic fish. Rest of the decline might largely be due to shrinkage, degradation, and destruction of habitats. Inland habitats other than ponds shrink, commonly, by about 80 % during the dry season, and most rivers are heavily polluted except for the brief mid rainy season. Decline in native fish populations may result in reduced genetic diversity. Another potential danger is the probable genetic introgression from the less fit hatchery-originated fish with the wild ones. The study concludes that the native freshwater fishes are endangered by declining habitats, exotic fishes, genetic consequences of hatchery supplementatio
Use of aluminium sulphate as flocculant for spirulina (Arthrospira platensis) with notes on the use of antioxidants for preservation under refrigerated conditions
Get PDFOne of the bottlenecks in microalgae harvesting is the lack of an efficient method for separating the microalgae from its culture medium. Moreover, the lack of viable and simple preservation techniques for microalgae starters hinders the immediate recovery of cultures after experiencing collapse. Hence, the present study was conducted to evaluate the use of aluminium sulphate as a flocculant for harvesting spirulina (Arthrospira platensis) and compare it with other flocculation techniques (electrolytic flocculation and autoflocculation). Moreover, the use of antioxidants to lengthen the storage of viable spirulina cells in refrigerated conditions was explored. The results of the study showed that the optimum dosage of aluminium sulphate for flocculation of spirulina is 200 ppm with 94.82 ± 0.59% efficiency in 15 – 45 minutes post-administration. Moreover, the combination of ascorbic acid and alpha-tocopherol at 0.01% v/v resulted in the highest viable cells at 57.76 ± 2.48% until the 3-week refrigeration period. This may help in maintaining viable starters. However, further investigations are needed to ascertain residuals of aluminium in harvested biomass and explore low-cost options for its reduction or removal and optimize the use of antioxidants in spirulina preservation in refrigerated conditions
Diversity and conservation status of fish in the Nijhum Dweep National Park, Bangladesh
Get PDFNijhum Dweep National Park lacks a detailed inventory of aquatic fauna including fish. This study reported the diversity and abundance of fish along with their conservation status from the surrounding waters of the national park to fill the knowledge gap. Fish samples were collected randomly from 16 spots of surrounding water of the park between October 2017 and March 2018. There were 47 fish species recorded belonging to 10 orders, 27 families and 44 genera. Odontamblyopus rubicundus was the dominant fish species that comprised 20.24% of the total catch, followed by Rhinomugil corsula (15.54%), Mystus gulio (12.03%) and Eleutheronema tetradactylum (9.92%). One nationally Endangered fish species (Clupisoma garua) and three Vulnerable fish species (Gudusia chapra, Sicamugil cascasia and Wallago attu) were recorded. Fish diversity of the park was rich but exceeding extraction rate, huge disposal of by catch, and presence of exotic omnivorous fish species was disconcerting that require monitoring and further studies
Species suitability for small indigenous species (SIS) of fish farming in carp polyculture ponds under drought prone area
Get PDFReduced culture period with lack of guidelines in selecting appropriate species are major constraints for promotion of small indigenous species (SIS) based carp polyculture in ponds under drought prone area. In order to address this issue, an experiment was conducted to determine the suitable species for farming of SIS fishes in carp polyculture ponds in Rajshahi district, Bangladesh. Three different species of SIS fishes were tested under three treatments (T1, Heteropneustes fossilis; T2, Clarias batrachus; T3, Mystus cavasius). Carp species were Hypophthalmichthys molitrix, Gibelion catla and Labeo rohita. Stocking density of SIS fishes (37050 individuals ha–1) and carps (H. molitrix, 500; G. catla, 250 and L. rohita 250 individuals ha–1) were same for all the treatments. Fishes were fed 35% protein containing supplementary feed twice a day at the rate of 6% of biomass. Common water quality parameters were monitored monthly and found within the suitable range for fish culture. Treatment T2 was significantly higher than others in terms of fish yield and cost benefit ratio. Further research is also recommended to optimize the stocking density of C. batrachus based carp polyculture