Latest Research Findings
Seasonal and interannual variations of oceanographic conditions off Mangalore coast (Karnataka, India) and their influences on the pelagic fishery
Mangalore coast is well known for its multi-species and multi-gear fisheries and the fishery and oceanographic features of this region is a true representation of the Malabar upwelling system. Ten years of study (1995-2004) of oceanographic parameters has been carried out from the inshore waters off Mangalore to understand their seasonal and interannual variations and influences on the pelagic fishery of the region. Attempt has been also made to understand the influence of local and global environmental conditions on the alternating patterns of abundance between the Indian mackerel and oil sardine from the area. Field and satellite-derived oceanographic data have shown that coastal upwelling occurs during July-September with a peak in August resulting in high nutrient concentrations and biological productivity along the coast. Nearly 70% of the pelagic fish catch, dominated by oil sardine and mackerel, was obtained during September-December, during or immediately after the upwelling season. Catches of scombroid fishes were significantly related to cold Sea Surface Temperature, while such relationships were not observed for sardines and anchovies. Significant positive correlations were observed between the ENSO events (MEI) and seawater temperature from the study area. The extreme oceanographic events associated with the cold La Nina, which preceded the exceptional 1997-98 El Nino event, were responsible for the collapse of the pelagic fishery, especially the mackerel fishery along the southwest coast of India (Malabar upwelling system). Coinciding with the collapse of the mackerel fishery, oil sardine populations revived during 1999-2000 all along the southwest coast of India. Tolerance of oil sardine to El Nino / La Nina events and the low predatory pressure experienced by their eggs and larvae due to the collapse of mackerel population might have resulted in its population revival.

(P. K. KRISHNAKUMAR and G. S. BHAT, Fisheries Oceanography 17:1, 45-60, 2008)

Impact of Climate Change on Indian Marine Fisheries
Climate change is projected to cause massive changes in the environment which are on a scale unprecedented in the last 1,000 years. The causative factors of climate change are the greenhouse gases, viz., carbon dioxide, methane, ozone and nitrous oxide. The most confident projections on the fall-out of climate change are for the amount of warming and changes in precipitation. The 20th century is the warmest century in 1,000 years, the 1990s the warmest decade, and 1998 and 2004 the warmest years. The relatively steady warming in the 20th century increased the mean temperature by 0.6o C. However, the projections from global warming models indicate that we may see nearly continuous warming of about 0.5o C per decade for every decade of this century. Thus each coming decade may successively add nearly as much warming as the entire 20th century.

Considering the enormity of the problem and the need to address the issues connected with climate change and marine fisheries including sea food security and livelihood, the CMFRI has taken up a major ICAR Network Project entitled “Vulnerability of Indian Marine Fisheries to Climate Change”. Preliminary results from this project indicate that the distribution of fish species with more rapid turnover of generations may show the most rapid demographic responses to temperature changes. The distribution of the oil sardine Sardinella longiceps, for instance, has responded markedly to increase in sea temperature. With the northern latitudes becoming warmer, the oil sardine, which is essentially a tropical species, is able to establish itself in the new territories and contribute to the fisheries along the northwest and northeast coasts of India.

The strategies adopted by other fish groups are also becoming evident. Some pelagic species such as the Indian mackerel Rastrelliger kanagurta show shift in the depth of distribution and are now caught by bottom trawlers. Demersal species such as threadfin bream Nemipterus japonicus appear to shift the month of peak spawning toward colder months off Chennai. There are also indications, which show that copepod abundance is shifting toward colder months off Mangalore. These findings indicate that the adaptable species may be able to adjust to the immediate challenge of rise in temperature for a shorter or longer duration. On the other hand, the vulnerable groups such as the corals are in peril. It is found that extensive coral bleaching occurred in Gulf of Mannar and Andaman and Lakshadweep Seas when the SST was 31oC or more in 1998 and 2002. The intensity of bleaching was directly related to the number of days the higher temperature prevailed.

These initial results emphasize the need for finding answers to several questions. What will be the influence of rising seawater temperature on the Bombay duck, whose northern boundary is landlocked? The distribution and migration of oceanic tunas, which are influenced by thermocline, may be strongly influenced. The sex of sea turtles is critically determined by the soil temperature at which the embryo develops. Temperature above 28o C produces only females. How the turtles would adopt to this crisis? Will there be species succession of phytoplankton with the domination of temperature tolerant species? Is the massive intrusion of pufferfish and medusae into the Indian coastal waters in recent years a fall out of climate change?

It is much more difficult to project how populations will behave under radically different conditions. Under these conditions, fisheries stock assessment, already difficult, may prove impossible. Fisheries management will likely become far more contentious because the abundance of fish populations and the composition of communities will change in unexpected ways.



(Extract of article by E. Vivekanandan in CMFRI Newsletter 112: Oct-Dec 2006; http://203.200.148.2/cdhome/Newsletter/Number_112_2006 )

Production of Designer Mabe Pearls in the Black-lipped Pearl Oyster, Pinctada margaritifera, and the Winged Pearl Oyster, Pteria penguin, from Andaman and Nicobar Islands

Production of designer mabe pearls (value added pearls) of images of various shapes in the black-lipped pearl oyster, Pinctada margaritifera, and the black winged pearl oyster, Pteria penguin, from the Andaman and Nicobar Islands is described. The production protocol is elucidated including the dosage of anesthetic to be used for each species, the position on the shell for fixing the image, the grow-out containers, and the culture period. The images were introduced into the oysters by two methods viz., mantle cavity insertion (MCI) into the anterior-dorsal region or by pasting them on the ventral regions of the inner nacreous surface of the valves using a commercial cyanoacrylate based commercial glue. Large P. margaritifera with dorso-ventral measurement (DVM) of 101.0 ± 10.3 mm can be fully relaxed by 375 ppm menthol within 120 min and small oysters of 72.1 ± 5.8 mm by 250 ppm within 95 min. P. penguin of DVM 96.5 ± 17.9 mm can be completely anesthetized by 145 ppm of menthol within 75 min to facilitate base image implantation. Good quality
mabe pearls were obtained in 60 days. Gluing was found to be more effective than MCI with potential for multiple mabe production.

(V. Kripa, K.J. Abraham, C.L. Libini, T.S. Velayudhan, P. Radhakrishnan, K.S. Mohamed and M.J. Modayil, Journal of the World Aquaculture Society, March 2008)