ആഴക്കടൽ ജൈവവൈവിദ്ധ്യം

ആഴക്കടൽ ജൈവവൈവിദ്ധ്യ

भारत के गहरा सागर पख मछली प्राणिजात

गहरा सागर, पृथ्वी पर समुद्र का 53% क्षेत्र सहित सबसे बड़ा आवास है। उथले क्षेत्र की तुलना में यह दूरस्थ क्षेत्र अधि क दबाव के कारण मुख्य रूप से ठंठ, सूर्य प्रकाश की कमी और कम उत्पादकता से युक्त है। इस क्षेत्र में बसने वाले प्राणि जातों ने वि परीत पर्यावरण परिस्थिति यों का सामना करने के लिए अतिविश िष्ट अनुकूलन वि कसि त कि या है। गहरे समुद्र की मछलियाँ 200 मी. से अधि क गहराई में रहने वाली प्रजाति यां हैं और गहराई के आधार पर इन्हें मि सोपेलाजि क, बाति पेलाजि क एवं बेंतोपेलाजि क श्रेणि यों में वर्गी कृत कि या जा सकता है। धीमी वृद्धि, देरी से यौन परिपक्वता, लंबा जीवनकाल एवं कम संतति यों का उत्पादन गहरे समुद्र मछली प्रजाति यों की विश ेषताएं हैं

Length-weight relation and relative condition factor of six deep-sea fishes from the south-eastern Arabian Sea

The present study estimates the length-weight relationships of six deep-sea finfishes belonging to six families and four different orders. Of the six species studied, first-time information is provided for three species: Polyipnus indicus, Antigonia indica and Champsodon vorax. The samples were collected from the south-eastern Arabian Sea by deep-sea trawlers landing at Sakthikulangara Fisheries Harbour, Kollam, Kerala, India. The b value ranged from 2.14 to 3.46, and r2 values ranged from 0.903 to 0.968. Four species (Bathyclupea hoskynii, Synagrops japonicus, C. vorax and P. indicus) exhibited negative allometric growth, and two species (Eridacnis radcliffei and A. indica) exhibited positive allometric growth. The b values obtained from the present study were compared with the Bayesian model in Fish Base. Relative condition factor estimates showed lower ranges for E. radcliffe and S. japonicus, indicating that some individuals had a suboptimal status of K>1

New deep-water species of snake eel, Xyrias anjaalai sp. nov. (Anguilliformes: Ophichthidae), from the Western Indian Ocean

A new species of snake eel Xyrias anjaalai sp. nov. (Anguilliformes: Ophichthidae) is described from morphological analysis of 12 specimens and molecular analysis of four specimens, caught off Kollam, Kerala, southwestern India, by deep-sea trawling. X. anjaalai is distinguished from its congeners by having a large eye diameter, a short snout, a different dentition pattern as in the 3rd row of maxillary teeth beginning at the level of the 4th vomerine tooth between the two existing rows in the inner series of maxillary teeth, an irregular tooth patch for approximately 1/10th of the lateral side of the dental arch in the distal portion and a vertebral count of predorsal vertebrae 18–21, preanal vertebrae 73–76 and total vertebrae 147–149. Phylogenetic relationships of X. anjaalai with other species in Ophichthidae were examined using partial nucleotide sequences of the COI gene (617 bp). The genetic analyses suggest that the new species is closest to X. revulsus followed by Apterichtus klazingai with Kimura 2 parameter (K2P) values of 0.6 and 2.8% respectively. In the phylogenetic reconstruction, sequences of X. anjaalai formed a distinct clade demonstrating their uniqueness as a separate species

New species of six-gilled hagfish (Myxinidae: Eptatretus) from the Lakshadweep Sea

A new species of hagfish, Eptatretus wadgensis sp. nov., is described from the Wadge Bank, Lakshadweep Sea, India, obtained from a depth of ~250–300 m through deep-sea trawling. It is diagnosed by having six pairs of gill pouches and gill apertures, 3/3 multicusp teeth, total slime pores 67–69, six branchial slime pores, and ventral aorta bifurcating at the 4th or between 4th and 5th gill pouch. The new species has significant morphological differences in total dental cusps, total slime pores, body proportions and the absence of the nasal-sinus papilla when compared to congeners and formed a distinct clade in phylogenetic reconstruction and a genetic distance of 3.41–4.00% when comparing K2P parameters with the nearest species. A key to the Eptatretus species of the Indian Ocean is provided

Reconnoitring Annual Landings and Biochemical Profiling of Deep-Sea Driftfishes (Cubiceps: Nomeidae): A Promising Food Source

The deep-sea ecosystem is the largest habitat on the earth’s surface and is a major reservoir of global biodiversity. ▪ The deep-sea fishery is majorly focuses on edible and commercially important deep-sea shrimp resources. ▪ Only a few of the deep-sea fin fishes are presently commercially important and are mostly used for producing fish meal and manure. The rising demand and declining conventional fishery practices have brought deep-sea finfish into focus as a promising new protein source. Cubiceps whiteleggii (Waite, 1894) and Cubiceps baxteri McCulloch, 1923 included under the family Nomidae (Driftfishes) is gaining recent importance in the commercial markets

Emergent fishery of the catostylid jellyfish Crambionella orsini along the southern coast of India

Sporadic and seasonal landings of jellyfishes along the southern coast of India have been under investigation since 2018. The catostylid jellyfish Crambionella orsini is the only species that contributes to a fishery in this region. In the October to January months, a seasonal fishery exists along the Kanyakumari, Thiruvananthapuram and Neendakara coast, with catches being made variously by gillnetters, single day trawlers, multi-day trawlers and shore seines. An unprecedented 44 day fishery on the Neendakara coast from December 2020 to January 2021 was investigated in depth, with estimated landings of 453.16 metric tonnes landed at Sakthikulangara and Neendakara Fisheries Harbours in Kollam District, Kerala. Economic efficiency of the fishery from Sakthikulangara Fisheries Harbour was estimated as 44.76 gross value added as percentage of gross revenue and net operating income of `1313 per fishing trip with average earning to a crew member being `510 per trip. The oral arms of C. orsini is the only part of the jellyfish that are traded and exported, mainly to China and South east Asian countries after salt curing. Emergence of this augmentative fishery has come as a boon to fishers combating the regressive environment of the Covid-19 period. Promotion of this fishery with increased processing and export facilities and investigations into value added products from the resource is recommended