Coastal Aquaculture and Mariculture

Unit 5- Major groups of Fisheries in India

5.3.3. Sciaenids
Sciaenids commonly known as croakers, grunters, drummers and jewfishes belong to the family, Sciaenidae. They are small to moderately sized demersal fishes. They inhabit muddy bottom in coastal waters. About 30 species have been recorded in the Indian and adjacent waters. Of these 12-17 species form the commercial fishery. Two larger species of sciaenids, Otolithoides biauritu and Protonibea diacanthus form substantial component of the sciaenid fishery in the northwest region.
Distribution
Global
They are distributed in Southeast Africa, Kenya, Madagascar, Persian Gulf, India, Sri Lanka, Indonesia, Australia etc.
India
They are distributed in both east and west coasts o0f India. However, they are abundant in the Northwest coast.
Production trend
The annual average landing of sciaenids for the 1961-2000 period was 95, 319 t. Sciaenids sustain one of the major demersal marine fisheries of India and contributed to 6.5% (1,71,687 t) of the total marine fish production during 2000. The landing of sciaenids registered an increasing trend over the decades in all the regions with the northwestern region contributing to more than 50% to the total catch of this resource. The west coast recorded substantial landing of 67,485 t (71%) during 1961-2000. Gujarat ranks always first in sciaenid catch, followed by Maharashtra.

Species composition
The sciaenid fishery is supported by about 20 species. Otolithes cuvieri is the most abundant sciaenid in the Indian waters.
Common species
Centre viz Species

The contribution of juveniles, i.e., immature fish to the fishery is more during the monsoon and post monsoon months at Veraval, Mumbai and Kakinada.
Mode of exploitation
Juveniles are caught mainly by trawl nets, dol nets and seine nets. Trawl nets contributed about 75% of the total sciaenid catch, followed by drift gill nets and shore seine.
Food and feeding
Sciaenids are carnivores and active predators; young ones feed on crustaceans, especially prawns and adults feed on fishes (piscivorous). They also feed on molluscs, echinoderms, annelids etc. to certain extent.
Size at first maturity
The smaller sciaenids attain maturity in the second year and breed in shallow coastal waters. The bigger sciaenids in general attain maturity late in their life. Pseudosciaena diacanthus which reaches a size of 150-180 cm in length, becomes mature when it is 3 -4 years old and 850 mm is length.
Spawning season
The spawning season for the majority of sciaenid species is during the monsoon and post-monsoon months. During the protracted spawning period, i.e., spawning over six months, the individual fish spawns twice.
Fecundity
Fecundity of sciaenids varies from species to species. It is 5000 - 12,250 in P. diacanthus, 32,174 - 60,840 in Johnius dussumieri and 49, 216 - 1, 91, 932 in Otolithus ruber.
Age and Growth
The majority of the sciaenid species have short life span of 2 -3 years except the larger sciaenids such as P. diacanthus and O. biaurilus. The average size of a 13-year old O. biauritus is 1520 mm. P. diacanthus attain a length of 1270 mm at the end of 7 years.
Utilization
The swim bladders of larger species like ghol and koth are dried and exported to far eastern countries for the manufacture of isinglass used in the wine industry as a clarifying agent. The larger sciaenids are filleted and processed for local and export markets. The smaller species are sold in fresh condition or salted and sundried. The catches of very small juveniles are used for fishmeal production.
Conservation and management
The fishes below the size at first maturity are not exploited so as to give them a chance to grow and breed for contributing to the recruitment process. It is proposed that the present cod end mesh size of 25-30 mm can be retained or increased by 10% without increasing the fishing effort in all the regions.