Mariculture of Kappaphycus alvarezii in the coastal waters of Palk Bay: crisis due to climate change or carrying capacity?

Gradual expansion in the cultivation of carrageenan yielding red alga, Kappaphycus alvarezii in the Palk Bay from the year 1996 reached its peak in 2012. Large scale introduction of numerous rafts bearing propagules of this marine alga within the bay area registered tremendous decline in the production due to decay of thallus and poor growth since August 2013. At present more than 50% of the rafts were abandoned in the shore due to drastic reduction in yield and for want of sufficient seed material required for subsequent crop. Analysis of data on SST and nutrient profile of seawater from Palk Bay area demands need for urgent carrying capacity studies for optimum biomass production. It is advisable to restrict the number of rafts (3 x 3 m size) to 225 and seed quantity of 5.4 to 6.0 tonnes per hectare

Seagrass Meadows and Conservation

Seagrasses are submerged monocotyleodnous flowering plants adapted to complete their life cycle below the sea surface. They harbour rich diversity of marine flora and fauna of commercial imprtance; and help prevent beach erosioan and siltation. Seagrass meadows are facing numerous challenges and threats in the present context and need urgent conservation strategies for increasing fish wealth and sea health

Experimental fishing in Hirakud Reservoir, Orissa (1965-67)

The comparative efficiencies of simple gill net, vertical line net and framed net in exploiting the fishery of Hirakud Reservoir in Orissa were studied. Though comparatively costlier to fabricate, the framed net gave better results than the other two

Preliminary observations on the lunar and tidal influences on the catches of seer by gill nets

The paper deals with the lunar and tidal influences on the catches of seer by gill nets. The landings during full moon and new moon nights, during low and high tides and during different quarters of the lunar month for three fishing seasons are discussed

Standardisation of specification for different trolling lures

Fishing experiments were conducted with buffalo horn, wooden and galvanised iron jigs of different lengths and weights rigged in troll lines. It was observed that jigs with 12 cm length and 60 g weight were superior to others in luring seer fish. Fish head jigs of 60 g weight showed a higher efficiency index than those of 50 and 70 g tried in these studies

Mesh selectivity for spotted seer, Scomberomorus guttatus (Bloch & Schneider)

An attempt has been made to evolve a suitable mesh size for the commercially significant size group of S. guttatus. To obtain maximum sustainable yield taking biological factors also into consideration, 52 mm mesh bar nets are suggested for exploiting the fishery on both the East coasts of India

Recurrent dinoflagellate blooms in the South-eastern Arabian Sea - A preliminary assessment with focus on Ornithocercus magnificus blooms along the nearshore waters off Dakshina Kannada, South-west coast of India

Frequent bloom incidences of the dinoflagellate Ornithocercus magnificus Stein, 1883 along the surface waters off Southeastern Arabian Seas (SEAS) have been reported since 2015 and specifically during the years 2015, 2019 and 2020. All these blooming incidences coincided with the strong El Nino phases in the Indian Ocean. The present study addressed the bloom (1.65 x 106 cells l-1) of this species in the nearshore waters (7 m depth) off Dakshina Kannada (Surathkal and Chitrapur) on 11.02.2016 which occurred during pre-monsoon period and corresponding to the super El Nino year 2015/2016. A detailed evaluation of the physico-chemical characteristics and phytoplankton abundance as well as community structure was made, concurrent to the three phases viz., pre-bloom, bloom and post-bloom periods in this region. The study revealed that the bloom occurred in high saline (35.0±0.91 PSU), well oxygenated (7.414±0.823 mg l-1) and nitrogen limited waters (oligotrophic conditions) and had a positive correlation with oceanic nino index (ONI; rs= 0.790, p<0.001). Some of the O. magnificus (3%) harboured ectosymbionts probably cyanobacteria in their cingulum in response to the beginning of a stratified oligotrophic condition in this region. The water quality was fair during the bloom period with no conspicuous discolouration of the surface waters. The present study also attempted to evaluate the influence of the increasing frequency of the O. magnificus blooms on the oilsardine fishery along the SEAS

Phytoremediation potential of selected plants in Netravati and Gurupura estuary of Karnataka

Unsustainable land use due to increasing human population, economic development and emerging global markets have resulted in contamination of soil, soil erosion and eutrophication in coastal regions. Freshwater needs of people are met almost entirely by precipitation on land, with a small though increasing amount by desalination. Hence, appropriate technologies need to be adopted to conserve and protect both soil and water. Use of plants to reduce environmental pollutants is considered as a non invasive technology. Mangrove ecosystem in the estuarine waters of Netravati and Gurupura rivers acts as a shield to absorb the heavy metals before it reaches the Arabian sea. The heavy metal Cu absorbed by Acanthus ilicifolius (AI) was 9.24±2.87 ppm, while Cd, Cr and Hg absorbed in the sedge plantCyperus malaccensis (CM) was 0.40±0.47 ppm, 1.09±0.32 ppm, and 0.21±0.05 ppm, respectively. Out of the 7 different plants selected from the estuarine area near the bar mouth of Mangaluru, Acanthus ilicifolius and Cyperus malaccensis was observed to have greater potential to adsorb heavy metals. Treated, semi treated and untreated wastewater discharged from urban area into the Arabian sea through the estuary is rich in nutrients leading to eutrophication. Preliminary treatment studies were carried out to assess the removal of nutrient load from this effluent water in laboratory conditions using aquatic weeds. This revealed that Hydrilla verticillata reduced 42.8% ammonia in the effluent water while Eicchornia crassipes and Pistia stratiotes reduced 61.7% phosphate and 68.2% nitrite, respectively. The study reveals that aquatic weeds could be used to remove nutrients from wastewater before it enters the marine ecosystem and locally available mangrove and sedge plants aid in reduction of contaminants in the coastal ecosyste

Wealth from waste-utilisation of fish waste for production of biogas

A biogas unit was installed in the premises of Mangalore Research Centre of CMFRI during November, 2016 in order to utilize the fish waste generated from the biological analysis done in the lab. This biogas unit installed is first of its kind in the state to utilize fish waste. A unit was installed gainfully utilizing the fish waste generated after the biological analysis of fish. Disposal of the fish waste generated periodically at the Research Centre during sampling made for biological studies was becoming difficult. However, with the installation of the biogas unit- designed and supplied by private manufacturer in Kerala, solved the disposal problem of fish waste

Samarasya-National workshop on Harmonizing Coastal Industrialization with Marine Ecosystem Health

Sāmarasya, the Souvenir released on the occasion of National Workshop, HCIMEH, 2017 at Mangaluru, commemorating the Platinum Jubilee of ICAR- Central Marine Fisheries Research Institute (National workshop on Harmonizing Coastal Industrialization with Marine Ecosystem Health