Coastal Aquaculture and Mariculture

Unit 7- Molluscan resources

7.3. Cephalopods
Cephalopods that include squids, cuttlefishes and octopuses belong to the phylum Mollusca. At present, there are about 700 described species of living cephalopods worldwide. In India, the species diversity of cephalopods is very poor. The order Nautiloidea has no representation in Indian coast as its distribution is restricted around Australia and south East Asian countries. As far as squids are concerned, the order Sepioidea is represented only by three families namely, Sepidae (True cuttle fishes), Sepiadaridae (Bottle tail squid) and Sepiolidae (Bobtail squid). The rest of the families namely, Idiosepidae and Spirulidae have no representation in Indian waters. Therefore under Sepioids, true cuttlefishes of the family Sepiidae is the dominant variety in Indian waters with the representation of two genera namely, Sepia and Sepiella. So far 13 species have been reported under the genus Sepia and one species namely, Sepiella inermis under the genus Sepiella.
As far as squids are concerned, the neritic squids come under the suborder, Myopsida are represented by the members of the family Loliginidae. The family, Pickfordiateuthidae is completely absent in Indian waters. The family Loliginidae is represented by four genera namely, Loligo, Doryteruthis, sepioteuthis and Loliolus. Of the 28 families of deep sea squids (suboreder Oegopsida) only three families viz Onychoteuthidae (Onychoteuthis banksii), Thysanoteuthidae (Thysanoteuthis rhombus), Ommastephidae (Ommastrepheus bactrami & Symplectoteuthis ovalaniensis) are represented in the deep seas of Indian waters. .
In the case of Octopus, an intresting group of Octopods namely Cirrate, Octopods are completely absent in Indian waters. Further, out of the eight families of Incirrate Octopods, only two families namely, Octopodidae and Argonautidae. The family Octopodiae is represented by four genera namely, Octopus, Cistopus, Hapalochlaena and Berrya. The family, Argonuta is represented by the single genus, Argonauts.
Cephalopods are commercially exploited all along the Indian coast. The catches of cuttlefish and squid are almost equal along the Indian coast. The contribution of octopus to the cephalod landings is negligible, but showing an increasing trend nowadays. Cephalopods were thrown overboard as discards until mid 70's. Export demand in the mid 70's induced the fishermen to improve the catches of cephalopods. Since then, the production has been rapidly increasing and the present annual production is about 100,000 tonnes. The cephalopods contribute to about 4% of total marine landings. They account for about 10% by value of the total marine products exported. There are about 80 species recorded from Indian waters but only a dozen are of commercial importance.

The production of cephalopods increased from 94 t in 1961 to 1,11, 534 t in 2000 along the Indian coast. The rapid increase in the catch during 1961-76 could be attributed to the combined effect of finding virgin trawling grounds for cephalopods in the inshore waters after the introduction of commercial trawlers in the early 1960s, as well as export demand. The extension of fishing grounds to areas beyond 50 m depth (up to 100 m depth), by introduction of larger trawlers (OAL 13-18 m) and high opening bottom trawls along the Indian coast. The cephalopods have been fully exploited up to 100 m depth contour along the Indian coast during the last five years.