Experimental culture of the Indian oyster, Crassostrea madrasensis (Preston) at Ashtamudi lake, Kerala

The edible oyster, Crassostrea Madrasensis, (P reston) occurs attached to hard substrates in the intertidal and subtidal regions of the coastal areas. Oyster meat is a highly esteemed seafood and aquaculture of oysters is widely prevalent and well established in many temperate countri

मानसून के दौरान बुकानीर ऐंचोवी का उपतट प्रवास

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Larval and juvenile rearing of black-lip pearl oyster, Pinctada margaritifera (Linnaeus)

The black-lip pearl oyster, Pinctada margaritifera (Linnaeus), has been cultured in the experimental shellfish hatchery at Tuticorin, India. The flagellates Isochrysis galbana and Pavlova lutheri were used independently as larval food at a concentration of 5 cells/μl up to day 5 and the ration was doubled thereafter until spat setting. The initial larval density was 1/ml. Straighthinge veliger stage (75×60 μm) was reached in 20 h, umbo stage (140×130 μm) on day 12, pediveliger (220×210 μm) on day 20 and plantigrade (260×240 μm) on day 23, and spat of 350×300 μm appeared on day 28. I. galbana promoted faster growth and early spat setting as compared to P. lutheri. The modal component of the larval population showed an average growth of 10.98 μm/day. A total of 6.3% of the initial larval population metamorphosed as spat. Juveniles cultured in the laboratory showed a growth rate of 0.09 mm/day. On transplantation to the culture raft in the farm, growth rate increased to 0.4 mm/day. The juveniles suffered heavy mortality after 4 months. It remains to be tested whether P. margaritifera juveniles would have a greater chance of survival in oceanic island conditions, as the natural distribution of the species in India is confined to the Andaman and Nicobar Islands

Spawning biology of Nemipterus delagoae (Smith) at Vizhinjam

Nemipierus delagoae Smith releases its eggs in batches and thus spawns twice in a year. Size at first maturity has been determined as 161-170 mm. This species has extended spawning season at Vizhinjam with peak spawning season from September to January. Males dominated over females during this investigations. Annual fecundity of the individual fish ranged from 86,184 to 497,230 eggs. Fecundity of the fish increases with the increase in the length and weight of the fish while ova per gram of fish body weight has no relationship with the length of the fish

A few observations on the taxonomy and biology of Nemipterus delagoae smith from Vizhinjam

Specimens of Nemipteriis delagoae Smith from Vizhinjam have a longer first pelvicfin ray, a slightly more body depth and a bigger snout than the specimens described by Smith (1939). There is no significant difference in the Regression coefficient between males and females and a common equation for lengthweight relationship is fitted. The species is a carnivore feeding mainly on crustaceans, fishes molluscs and annelids

Embryonic and early larval development of pearl oyster Pinctada fucata (Gould)

Hatchery production of seed is of great importance in aquaculture, particularly in situations where availability of natural seed is undependable. Besides, the system provides advantages of selective breeding keeping in view the genetic factors. Commercial hatcheries already sustain large-scale production of edible oysters in several countrie

Ranching of clams in the Ashtamudi lake

Ranching of clams in the Ashtamudi lak

Some observations on light fishing off Thiruvananthapuram coast

The artisanal fisheries of the Thiruvananthapuram coast axe of considerable importance in the fisheries of Kerala State due to their significant contributions to the catch of resources like tunas, anchovies, ribbonfish, caranglds, perches and cephalopods

Farming experiments and transfer of technology of bivalve culture along the southwest coast of India

The Central Marine Fisheries Research Institute (CMFRI) in India developed bivalve farming technologies in the 1970s. but these were not widely adopted at the time. In 1993, CMFRI undertook an action research program to encourage farming of edible oysters, mussels, clams and pearls along the southwest coast of India. Successful demonstration of the viability of bivalve farming led to the initiation of commercial farming of mussels and generated interest among farmers and entrepreneurs in developing production of pearls and farming of edible oysters. Given the high potential for mollusc aquacultu re, both for the local and export markets, issues such as demarcation and issuance of lease rights on aquaculture zones in public waterbodies by the government, organization of marketing systems and provisions for technical and fin ancial support to farmers need to be addressed

Comparative assessment of the impact of motorisation on the artisanal fisheries at Vizhinajam

The fishery statistics collected from Vizhinjam fish landing centre for seven years from 1986 to 1992 was utilised as the data for the motorisation period. The fishery data during the pre-motorisation period is taken from Luther et cd. (1982) for presenting the comparative assessment of the impact of motorisation. An Increase in the total fish catch as well as in the catch per unit effort is evident during themotorisation period. The fast accessibility to the distant fishing grounds by the motorlsed crafts, the increased number of fishing hands employed in the motorlsed units and the avEiilability of more time for actual fishing due to the time saved for rowing seem to be the major reasons for the higher catch and catch rate in the motorlsed units