Coastal Aquaculture and Mariculture

Unit 8- Deep sea fisheries

8.1.1. Fisheries potential in deep sea
Sudarsan and others (1991) estimated a resource potential of 3.92 million tonnes from the Indian EEZ. Of this, the inshore water (0.50 m), 10 percent in area of the EEZ, possesses an estimated exploitable potential of 58 per cent (2.28 million tonnes). The rest, 1.64 million tonnes, are scattered over a very large area of (89 percent of EEZ) offshore waters (50-500 m). The 1.64 million tonnes of deep-sea resources comprise 45.25 percent of pelagic stock, 39.8 percent of demersal stock and 15 percent of oceanic species. The major fish groups are the threadfin breams, yellow fin tuna, pelagic sharks, cephalopods, carangids, and shrimps in the order of abundance. The new Deep Sea Fishing Policy (1991) seeks to facilitate the exploitation of these resources, but without considering the indigenous potential particularly that of the artisanal deep-sea-going fish workers and the likely adverse impact of welcoming foreign investment to exploit these resource.
The current yield of 2.7 million tonnes is mainly from 387,500 km² of inshore waters (within 100 m depth). The additional annual harvestable yield of 1.22 million tones is available in the extensive deep-sea and far sea (beyond 100 m depth) area of 1.63 million km² in the EEZ. While, harvestable potential is 7.0 tonnes/ km² in the inshore waters, it is only 0.7 tonnes/ km² deep-sea and far sea. Hence, scouting time, and manpower and fuel requirements will be very high to exploit deep-sea and far sea resources. Moreover, high cost of investment on larger vessels with several days of sea endurance makes operation expensive. Of the 1.22 million tonnes in the far sea, 0.97 million tonnes (15.7 tonnes/ km²) is available at depths of 100-200 m (area: 61,900 km²) and 0.25 million tonnes (0.16 tonnes/ km) beyond the continental shelf (200 m) in the EEZ. Thus, the under- exploited depth zone between 100 and 200 m has a high density of fish biomass. The partially exploited demersal resources offering scope for increasing exploitation in this depth zone are the threadfin breams, horse mackerel, scads, ribbon fishes and sciaenids, Some of the non-conventional varieties available in this depth zone are bullseye (Priacanthus spp.), black ruff (Centrolophus niger), green eye (Chlorophthalmus spp.) and Ariomma indica, Among crustaceans, deep- sea shrimps and lobsters are available in good concentration up to 500 m depth along the southwest coast, Wadge Bank (off Kanyakumari), the areas off Gulf of Mannar and Point Calimere. The spear lobster (Linuparus somniosus) along with other species of deep-sea lobsters occurring in 150-500 m depth in the Andaman waters can also be developed for a fishery. It has been identified that oceanic squids can also be a major fisheries resource in the deep sea.