Dimethylacetamide - an alternative to glycerol as cryoprotectant of Malabari buck semen

The key role of a cryoprotectant is to minimize the chemical and physical stress which occurs during cooling, freezing and thawing of semen. The difference between the cryoprotectant (CPA) occurs in their permeability coefficient and the structural model of the cryogenic agent. The beneficial effect of dimethylacetamide (DMA) as a cryoprotectant especially for sperms had been observed in several studies. The aim of the study was to study the cryoprotective effect of DMA in freezing the Malabari buck semen compared to glycerol. Ten ejaculates were taken from fourMalabaribucks . After preliminary evaluation sample split technique was followed with Tris based extender containing glycerol (6.7 per cent) as cryoprotectant (control) and Trisextender containing DMA (3 per cent) as cryoprotectant (treatment group). The semen straws (0.25mL) after filling were subjected for equilibration and manual freezing. Sperm kinetics was studied using computer-aided sperm analyzer. Pre-freeze and post-thaw evaluation included sperm viability, sperm abnormality, hypo osmotic test, acrosome integrity test and DNA fragmentation. Results indicated that inclusion of 6.7 per cent glycerol had significantly higher (p<0.05) post-thaw values than DMA. From our study we conclude that 6.7 per cent glycerol was better than 3 per cent DMA in cryopreservation of Malabari buck semen

Reproductive biology, diet and feeding pattern of longtail tuna Thunnus tonggol (Bleeker, 1851) in the north-eastern Arabian Sea off Gujarat, India

Longtail tuna Thunnus tonggol (Bleeker, 1851) is the major tuna resource in the neritic realms of the northern Arabian Sea and forms considerable fishery in the coastal nations in the region. Gujarat, on the north-west coast is the major province landing longtail tuna in India. The paper attempts to add to the hitherto sparse knowledge base on biology of the longtail tuna fished along the north-west coast of India, through a study spanning from 2011 to 2015. Reproductive biology, spawning, food and feeding dynamisms of the species were investigated. Sex ratio of the species was estimated as 1:2.1 and depicted an increase in male preponderance as the size increased. The fish attains maturity at 607 mm and it spawns during summer months starting from May. The fish is typically a non-selective feeder and over 22 taxa comprising of fishes, cephalopods and crustaceans formed the diet at varying rates over the year. Variation in feeding intensity at different reproductive stages is discussed besides the constraint posed by the large presence of unidentifiable, partially digested gut content

Case study on dol net fishing operation and its economic analysis off Gujarat, north-west coast of India

Dol net is traditionally used for fishing along the north-west coast of India. In this study, the operational as well as economic aspects of dol net operation off Navabandar, Gujarat was studied. Dol nets operations from mechanised boats locally called as Van along Navabandar coast were considered for the present study. The overall length (OAL) of the mechanised vessels were in the range, 10-12.8 m with 2.4-3.6 m breadth and 1-1.8 m height. The total capacity of vessels was in the range 15-20 t and average fish holding capacity was 2.5 t. The fishing vessels had six cylinder engines of 87 to 105 hp. Fishermen themselves fabricated the nets for the dol net, which had seven different parts with various lengths. Kaba-sus system using steel pipes was the method of dol net fishing off Navabandar. They were locally known as Bochi, Patiya, Aor, Trijo, Bangu, Chothi and Jalo. The study indicated that the profit of a dolnetter at Navabandar in a year was `2,88,122

Ecological impacts of tuna fisheries of Lakshadweep, the archipelagic territory of India situated in the Central Indian Ocean

Lakshadweep islands are an archipelagic territory of India situated some 200 nautical miles away in the eastern Arabian Sea off the South-West coast of India on the northern part of the Chagos Ridge. Oceanic situation of these atolls make them a haven for the oceanic resources like tunas and tuna like fishes. Similar to the Maldives, the adjacent island nation, tuna fishing have been the mainstay of the economy of this island group with a population of less than one lakh against land area of 32 sq.km. This is the only territory under India where pole and line fishing for skipjack tuna is in existence for a long time

Marine Fisheries Policy Series No.12; Lakshadweep Livebait Fisheries Management Plan

Lakshadweep islands being atolls situated in the midst of oceanic waters is unique with respect to the marine biodiversity and fish wealth. The waters are replete with high value oceanic resources like the tuna and tuna like fishes. Historically, the islanders have been tapping these resources using traditional fishing methods. The island group boasts of being the only territory in the country where pole and line, a one-by-one fishing method is practiced. Low impacts on the stock and high selectivity make the pole and line method a highly sustainable one. Local ownership and shorter duration of fishing are few other uniqueness of the fishery in Lakshadweep. Though, over the years, there has been progresses in fishing sector with respect to mechanisation; craft size and amenities on-board, marketing strategies etc., the fishery is still rooted to the sustainability principles. Hence, the islands possess immense potential for developing the fisheries sector on the strengths of its sustainability quotient to provide enhanced income to the fishers and quality job to its youth. Livebait is an essential part of pole and line fishing for tunas. Since, the livebaits are collected from the reef system; the harvest of these species should also be guided by the sustainability principles; ensuring low impact on the stock and continuity of other ecosystem services by these fishes. Hence, close monitoring of the livebait fisheries is essential and the fishery need to be managed based on scientific acumen. The CMFRI have been providing guidelines and policy briefs to the maritime states for development of fishery management plans. These briefs are made based on scientific data generated by the Institute over the years through close observation of the fisheries in each state. The Institute have accumulated information on the fisheries of Lakshadweep through the Minicoy Research Centre and other projects over the years. A fisheries management plan project for Lakshadweep has been in place since 2017 for continued monitoring of the fishery, data generation and preparation of management guidance in due course. The Lakshadweep Livebait Fisheries Management Plan (LLFMP) is one of the outputs of the project and intends to rationalise the bait fisheries of the islands based on the scientific information available. The Plan lists actionable points with the responsible entity and time frame to achieve the set goals under each overarching objective. It also provides administrative, legal and institutional requirements for the successful rolling out of the Plan. The Plan has been reviewed through focus meetings at the institute and consultations with the Administration and the public. The Plan, when formalised and enforced by the Administration will increase the sustainability quotient of the Lakshadweep tuna fisheries, benefiting the ecosystem and the fishery in a large way

Fishery for the Large Pelagic resources in Gujarat

Large pelagic fishery resources contributed about 4% of total marine fish landing in Gujarat. Tunas dominated among LP resources, followed by seerfishes, queenfish and dolphinfish. They are targeted by mechanized gillnetters and the multiday trawlers with region between Veraval and Porbander as the major fishing zones. Mainly limited to the shelf areas within 200 m depth, the operations extended to oceanic areas beyond 200m during summer months. Poor handling and onboard storage effect the quality of the fishes and market value realised by the fishers. Mainly dried products of LP are traded within the country as well as abroad like Sri Lanka, Tunisia and Thailand

Dead Bryde's whale washed ashore at Veraval, Gujarat

Bryde’s Whale (Balaenoptera edeni Anderson, 1879) measuring 10.4 m in length and weighing about 7 tons was found washed ashore on the beach of Veraval on 4th august 2017. Locally called as “Machchh” it was found in dead condition with small injuries in the caudal peduncle and genital region. With the intervention and supervision of forest officials, it was towed ashore and a veterinary officer conducted post-mortem after which it was buried on the shore. Occurrenc

Fishery and stock status of billfishes exploited from the Eastern Arabian Sea

Billfishes are a group of highly predatory fishes distributed extensively along the world oceans. In India, the billfish fishery is supported by four genera and following five species: Istiophorus platypterus, Istiompax indica, Makaira nigricans, Xiphias gladius, Tetrapturus audax and T. angustirostis. Mechanised gillnetters contributed major share of their landings. I. platypteurs was the dominant species in the fishery and T.angustirostis was sporadically landed. Billfishes along the Indian coast were mainly exploited by mechanised gillnetters followed by other mechanised crafts operating pelagic longlines. The west coast of India recorded 60% of annual billfish landings. The maturity and length range of I. platypterus, I. indica, M. nigricans and X. gladius, the major species in the fishery, were monitored during 2019 and the length at which 50% of the population matured (Lm50) and stock parameters of these four species of billfishes were estimated based on samples collected from major landing centres along the eastern Arabian Sea. Fishery biological observations of billfish species indicated that the stocks in general are healthy, with fairly high spawning stock biomass and are being fished at sustainable levels

Correlation of phytoplankton density with certain hydrological parameters along the coastal waters of Veraval, Gujarat

The present study was conducted to study the biological diversity of phytoplankton and the impact of abiotic factors on them along coastal waters at two locations viz., Location-1 (Jaleshwar) and Location-2 (Sagareshwar Mandir), Veraval from May 2012 to April 2013. Six classes of marine phytoplankton were identified from these locations. Out of the total 162 species of marine phytoplankton collected, nine could not be identified. Diatoms were the dominant group (133 spp.) followed by dianoflagellates (12 spp.), blue-green algae, brown or orange chromatophores and green algae. The correlation between the density of phytoplankton with the environmental variables viz., Dissolved Oxygen and pH were significantly positive, whereas it was inversely correlated with temperature and salinity. The density of phytoplankton, ranged from 4,90,495 to 8,57,160 cells L-1 and 3,87,495 to 8,65,665 cells L-1 at Location-1 and Location-2 respectively. Phytoplankton cell count was the highest and lowest in January and March respectively and the diversity was higher in winter than other seasons. The diversity of marine phytoplankton was very high along the coastal waters of Veraval (at both the locations of study) which confirms that the Veraval coastline is very productive and supportive for fish production and also for other marine biodiversity

Diet composition and feeding behavior of largehead hairtail Trichiurus lepturus Linnaeus 1758 along the Eastern Arabian Sea and Western Bay of Bengal

Information on diet composition and feeding habits of species is very much essential for the scientific planning to develop sustainable management plans. The feeding biology of Trichiurus lepturus was studied during 2014 to 2018 from 6167 and 3346 specimens collected on a weekly basis along Eastern Arabian Sea (EAS) and Western Bay of Bengal (WBB), respectively. Crustaceans mainly represented Acetes spp. (98.6 %) and were categorized as dominant and preferred (%QI = 51.35; %IRI = 53.31) food item; teleosts were categorized as dominant and secondary (%QI = 47.46; %IRI = 45.71) food items and molluscs as accidental and accessory food items of T. lepturrus based on the values of dietary coefficient and Index of Relative Importance along the Eastern Arabian Sea (EAS) while, teleosts were completely dominant (%QI = 99.61; %IRI = 99.27) with both molluscs (%QI = 0.34; %IRI = 0.56) and crustaceans (%QI = 0.01; %IRI = 0.17) forming accessory and accidental food items along the Western Bay of Bengal (WBB). The teleostean prey items belonging to 23 genera were encountered in the guts of T. lepturus from EAS with Stolephorus spp. (17.09 %), Sardinella longiceps (6.65 %), Decapterus spp. (5.75 %), Rastrelliger kanagurta (1.36 %), and Megalaspis cordyla (0.89 %) as major component; whereas, in WBB, 16 genera of teleosts representing Sardinella longiceps (50 %), Stolephorus spp. (31.52 %), Decapterus spp. (4.57 %), and Rastrelliger kanagurta (2.26 %) formed the major portion of diet by %IRI. Crustaceans were dominated by Acetes spp. (52.61% IRI) in EAS, while other crustaceans’ contribution as prey item was negligible. However, along WBB, the crustaceans’ contribution as food components was very minimal. Molluscs did not contribute much as dietary constituents of T. lepturus in both EAS and WBB. About 50.15 % and 56.83 % of the stomachs had food content in various proportions in EAS and WBB, respectively and rest of the stomachs were empty