Results of ichthyoplankton surveys along the southwest coast of India with special reference to pelagic fish resources

A well planned and systematic Ichthyoplankton survey programme was carried out by the UNDP/ FAO Pelagic Fishery Project, Cochin (1971-79) along the southwest coast of India. These surveys were part of the Project's programmes for assessment of the Pelagic fish resources of the Project area extending from Ratnagiri to Tuticorin. Major part of the field work was conducted from 1971 to 1975 over the shelf and adjacent waters. The survey results indicated that all the dominant pelagic species spawned over the shelf in the entire range of their distribution in most months of the year. The peak of spawning in almost all cases was aligned to the Southwest Monsoon period with a secondary peak in the Northeast Monsoon in some species ; including the mackerel. The larval distribution showed a southward drift and concentration in areas south of 12° N, spreading over oceanic waters in this sector. No consistent and positive relationship between the abundance of larvae of a particular species with the magnitude of its fishery in the area was evident. However in cases like the whitebaits the larval abundance gave corroborative evidence supporting the findings of simultaneous acoustic surveys on the very high potential of these fishes. On the other hand the predominance of the larvae of frigate mackerels, compared to those of Indian mackerel is not supported by commensurate fishery for the former species or potential in the surveyed area. The paper critically reviews the findings of the surveys on the spawning, distribution and abundance of the larvae of the major pelagic fishes and their resources along the southwest coast of India