A case study of the disappearance of Arius tenuispinis (marine catfish) in the vicinity of Visakhapatnam due to mechanised fishing

Visakhapatnam is on the eastern sea board of India (17 degree 40' N and 83 degree 15' E) having a continental shelf of 45 km width which is provided with a polychaete rich, silty clay sea floor to a distance of 15 km and beyond, from the shore. Repeated trawling by a large number of trawlers over an area of 900 sq.km (30 x 30) resulted in the hardening of the substratum to the extent of making it uninhabitable to the polychaetes and polychaete feeding fish. The shoaling and strictly demersal marine catfish, Arius tenuispinis, which is a prolific polychaete feeder on the fishing grounds off Visakhapatnam, has been on the decline since 1979. The catch rate of fish dropped from 9.7 kg/boat per day in 1979 to 2.6 kg by 1985-86. In the bottomset gillnets, the catch per net dwindled from 4.4 kg in 1973 to 0.04 kg by 1985-86. The species has virtually disappeared from the fishing grounds off Visakhapatnam and further north, as a results of the cumulative effect of overfishing with trawlnets and bottomset gillnets. It is further aggravated by the hardening of the sea floor on these grounds due to repeated trawling over a narrow zone.

Biodeterioration of wooden boats: a major problem facing marine fisheries

In India, the fishing industry alone incurs an annual loss of over 120 million rupees on account of biodeterioration of wooden fishing craft. None of the timber species, currently in demand for boat-building, possesses an natural bioresistance and will be completely destroyed within 6 to 12 months. Preventive measures against biodeterioration range from application of several indigenous formulations to metallic sheathings and pressure impregnation of wood with preservative chemicals. These methods do not provide lasting protection, as each has its own short-comings and inadequacies. The need for long-term research in the field of marine biodeterioration for improving the efficiency of currently known control measures, with emphasis on application of non-polluting biological methods, is stressed.

Marine pollution and zooplankton: some recent trends in marine pollution studies

The presence of even very minute quantities of pollutants may become harmful either due to their direct effect on zooplankton or indirectly due to the transfer of the pollutants to other trophic levels through zooplankton. The recent trend in marine pollution studies is therefore to find out the effects of very minute quantities of these pollutants on marine zooplankton and the methods of their accumulation and transfer to the organisms of higher trophic level including man. A review of laboratory and field studies concerning the effects of pollutants such as hydrocarbons, crude oil, heavy metals, pesticides and heated waste water on the survival, breeding, movement, faecal pellet production, growth and development on marine zooplankton is presented.

Hermaphroditism in some marine animals

Hermaphroditism, a phenomenon in which one and the same individual produces sperms, the male gamate the ovum, the female gamate, is generally common in plants and lower animals and hence is considered as a primitive character. However, it is rare in higher invertebrates such as insects, spiders, prawns and also in the lower vertebrates to which fishes belong. Prawns and fishes have highly evolved reproductive systems and occur as separate individuals of males and females. Both these groups do have some species which are regurarly hermaphrodites and others which are teratologically hermaphrodites.

Marine pollution in the Indian Ocean: problems, prospects and perspectives

Following a brief outline of the physiography of the Indian Ocean, an examination is made of the current situation regarding contamination of the environment. Prominent marine pollutants and the consequences of the marine disposal are discussed, considering in particular oil pollution, heavy metal pollution, agricultural wastes and domestic wastes. Research activities conducted in the area investigating the levels of marine pollution are detailed, and an evaluation made of future prospects concerning the monitoring and control of pollution.

Environmental characteristics of the marine and estuarine habitats of Karwar: an overview

A review is made of the environmental features of Karwar coastal waters, describing the currents, waves, inshore water hydrology and bottom features of the bay. The intertidal and the estuarine environment are described, considering various environmental stress factors. Future prospects regarding man's effects on the environment, such as development projects, are discussed briefly.

Sterol composition of marine algae from Karachi coast of Arabian Sea

During the course of chemical investigation of marine algae collected from Karachi coast of Arabian Sea, five sterols named as sarangosterol(1), 23-methyl cholesta-5, 25-dien-3ß-ol(2) from Endarachne binghamiae (brown alga), sargasterol(3) from Dictyota indica (brown alga), cholesterol(4) from Laurencia obtusa (red alga) and clerosterol(5) from Codium iyengarii (green alga) have been isolated. Their structures were elucidated with the help of spectroscopic means.

Some observations on the problem of marine timber destroying organisms of Indian coasts

In India the chief marine timber boring organisms are 2 species of Martesia, 28 species of shipworms, 4 species and a variety of Sphaeroma and 9 species of Limnoria besides bacteria and fungi. The occurrence, abundance and activity of the various species of borers show remarkable variations and fluctuations in the different harbours of India, each harbour or area having its own dominant set of species and an assemblage of less important forms. These species have their own characteristic preferences, life history and seasons of attachment and a scheme evolved for one locality may prove ineffective for another. Through a delicate and complex ecological adjustment the borers occurring in a locality have reached an interrelationship reducing interspecific and intraspecific competition. The seasons of settlement of the dominant borers in the different harbours of India are indicated. The need for a detailed biological enquiry is stressed.

A note on the production trend of marine shrimps in India

The paper reviews the production statistics of marine shrimps in the different maritime states of India from 1950 to 1962. It is pointed out that for a correct appraisal of the status of any fishery, it is necessary to have data on effort E and catch per unit effort in addition to the conventional data on catch C. A relationship between U and E has been developed and the status of the fishery of Metapenaeus dobsoni has been discussed in this connection with reference to the data on catch and effort obtained from trawler operations off Cochin.

On the naturalness of change in marine populations

Based on a talk given before a meeting of the Society of Fisheries Technologists, India.

Bacterial flora of marine fish doma (Sciaenoids) (Small spp.) from Bombay coast

Marine fish doma (Sciaenoids) (Small spp.) from Bombay coast was studied for total bacterial counts on the surface and gut. Large number of Micrococcus species (77.4%) was found whereas few species from Achromobacter, Bacillus, Bacterium, Flavobacter, Pseudomonas and Sarcina were noted.

Contribution to the study of the marine algae of Ceylon

Description of Ceylon marine algae are scattered through a range of scientific publications which are not readily available to students and research workers in Ceylon. There are few detailed studies in Algal taxonomy and the general distribution of algae in Ceylon has not been studied thoroughly. Some work has been done by foreign phycologist each of whom was in the island for a few months only and experienced difficulty collecting specimens from different parts of Ceylon.

Some marine algae from Ceylon - 1

Since his last publication "Contribution to the Study of the Marine Algae of Ceylon"(1961), the author has made several collections which contain interesting material which he has not hitherto described. This and any other material which he come across in future surveys will be described in a series of papers of which this is the first. The present paper includes the description of fourteen species of which three are new to science. These are deposited in the Herbarium of the Royal Botanical Gardens, Peradeniya, Ceylon.

Sinum haliotoideum (Linnaeus, 1758), a gastropod mollusc new to the marine waters of Pakistan (northern Arabian Sea)

Sinum haliotoideum (Linnaeus, 1758) was collected on only two occasions. However, it was given attention when the recently collected specimen netted on 24 August, 1993 was brought live to the laboratory where its movement towards the source of light was noticed, leading to a careful examination and illustration. The specimen survived for 4 days. Illustrations and shell from the earlier collected specimen (August, 1991) were sent to Dr. Alan R. Kabat, division of Mollusck, National Museum of Natural History, Smithsonian Institution, USA, who confirmed that the specimen was Sinum haliotoideum (Linnaeus, 1758). He further informed that this is a moderately common Indo-Pacific species. The material has been deposited in the collections of the Marine Reference Collection and Resource Centre. (MRC) The species being new to the region is briefly described.

Embankment damaging marine organisms and their control measures using calcium carbide

Five species of crabs and three species of fishes were the main marine organisms found damaging embankments owing to their burrowing nature. Among crabs, Scylla serrata was in the highest percentage, while among fishes, Boleopthalamus dussumieri was recorded in maximum percentage calcium carbide 10-15 per burrow was effective in eradicating the crabs.