Preliminary observations on changes in nucleotides in oil sardine and certain Penaeid prawns during chill storage

Preliminary study has been made of the changes in common 5' nucleotides in oil sardine (Sardinella longiceps) and two Penaeid prawns of Indian waters during chill storage. The course of nucleotide degradation has been followed in the fresh fish and shell fish during ice storage. The level of inosine monophosphate (IMP) in prawns showed significant but steady decrease during ice storage and this appears to serve as useful indication of length of storage. Comparison has been made on the pattern of nucleotide changes in block frozen fish and individually quick frozen fish stored at -23°C.

Preliminary studies on the effect of irradiation as a means of preservation of fish and shellfish

Preliminary investigations on the effect of irradiation on commercially important fish and shell fish like silver pomfret, Bombay duck and prawns were conducted. Irradiated samples had an extended storage life compared to their respective controls even though yellowish or brownish discoloration occurred earlier in irradiated fish. Irradiation enhanced the rate of drip formation. Brine treatment prior to irradiation retarded this rate. Pre-blanching was found to further extend the storage life of irradiated fish.

On the results of preliminary fishing trials with shark long lines in Veraval waters

Experimental fishing operations with shark long lines were conducted in the sea off Veraval with a view to studying their efficiency and gathering information on the available resources of sharks to be used for planning the future gear investigations. The trials were undertaken in 1967, employing departmental fishing vessel "Fishtech No. IV" (10.9 m O.L. and 48 H.P. engine). A total of 5525 hooks were employed and 242 sharks weighing 8629 kg were landed. Data on composition of catch, weight of fishes landed, effectiveness of various baits in capture of different species of sharks and effectiveness of gear including its catch efficiency in this area were compiled. Bait preference was also observed in certain species of sharks caught. Chirocentrus dorab proved to be the cheapest and most effective bait in capture of all the three varieties of sharks landed.

Results of preliminary fishing trials with 15.8m six-seam otter trawl

The paper deals with the results of trawling operations conducted along the Saurashtra Coast of Gujarat State with 15.8 m six-seam otter trawl. Fishing operations carried out from Fishtech No. 8 with this new net were the first of their kind in the country and the results proved to be encouraging. The design in question is passed on to private agencies for commercial operations.

Preliminary observations on the effect of electrical seine on fish catch

Forty-six experiments were done with the electric seine in 24 tanks with a.c. and interrupted a.c. The source of electrical energy was a 3 Kw a.c. generator of water-cooled diesel engine. A control seining without applying electricity was conducted for every experiment with electric "seine" to have a comparison for the efficiency of electric "seine" over control ones. Electric seine was found to have an increased catch over control seining both in numbers and in weight. Electric seine with two electrodes was found to have better effect over three electrodes. Benthic fishes like Cirrhina mrigala, Notopterus notopterus, Cyprinus carpio, Glassogobius giuris, Ophicephalus sp. and Mystus sp. were found to be more sensitive in electric "seine". Increased catch of small fishes like C. mrigala, N, notopterus and Ophicephalus sp. has been observed in electrical "seine" in addition to larger ones.

Preliminary observations on the morphometric characteristics, length weight relationship, food and fedding habits and fecundity of Saurida tumbil (Bloch) off Bombay coast

Fifteen morphometric and four meristic characters of Saurida tumbil were studied and their relationships with total length and head length were established. The length weight relationship worked out to be W= -5.6055 L(super)3.291. The fish is a carnivore, feeding mainly on small fishes, molluscs and crustaceans. Larger fishes are selective feeders on fish. It is a long protracted spawner. Fecundity varied from 6008 to 17384 eggs in specimens of size group 212-420 mm. Fecundity-total length, fecundity-total weight of fish and fecundity - total weight of ovary relationships were worked out to be F=0.9414 L(super)1.6626, F=180.7069 W(super)0.7531 and F=3153.0375 W(super)0.8278 respectively.

Oyster mushroom waste as manure in fish culture: a preliminary study

In an attempt to recycle the waste substrates of the oyster-mushroom crop, tanks were stocked with seed of Indian major carp Cirrhinus mrigala at the rate of 600,000/ha and waste substrate was applied at weekly interval at 0, 50, 100, 150, 200 and 250 g/tank. Oyster mushroom waste not only provided highly nutritive colonised detritus to the fish as direct feed, but also produced rich plankton in the tank. In waste treated tanks, production was better than in the control in 150, 200 and 250 g/tank treatment suggesting the possibility of fish-oyster mushroom integration.

A preliminary study on Dodecaceria pacifica (Fewkes)

In various areas along the coast in the vicinity of Monterey there are many colonies of the Polychaete worm Dodecaceria pacifica. An attempt has been made to find out something of the distribution, size, structure and the flora and fauna associated with these colonies.

A Preliminary study of the defensive spines of some Malayan freshwater fishes

The defensive spines of fifteen Malayan freshwater fishes have been studied morphologically. The classification of spines has been slightly modified from the previous work of Fernando and Fernando (1960). They are divided into simple, denticle-bearing and venom-carrying. The simple spines are further sub-divided into single and multiple and the denticle-bearing into Bagriid and Clariid types. The latter agree morphologically with the venom-carrying spines of previously studied forms and may be a degenerate condition. Simple spines occur singly in the Cyprinidae where they are found at the anterior end of the dorsal fin. A spine of similar structure occurs in the catfish Glyptothorax. In the families Anabantidae, Cichlidae and Mastacenbelidae simple spines occur as a series. Denticle-bearing spines occur in the catfishes (Order-Nematognathi). Those having denticles on one face occur in the Bagridae, Siluridae, Sisoridae, and Akysidae. They are referred to as Bagriid type. In the other type denticles occur on the anterior and posterior faces of the spine. They are referred to as Clariid type. None of the Malayan species studied had venom-carrying spines and they are unlikely to be found in the freshwater species. The functioning of the defensive mechanism whose morphological bases are spines is discussed and the relation between the size and habitat on the effectiveness of the spines is mentioned. The evolution of defensive spines is discussed briefly.

A Preliminary survey of 21 Ceylon lakes. 1. Fisheries of two lakes, Parakrama Samudra and Minneriya Wewa

Fourteen species of indigenous fish and three species of introduced fish commonly used for food are present in Parakrama Samudra and Minneriya Wewa. Commercial fishing is done throughout the year in these two lakes by gill nets, shore-seines ("Ma-del" nets) and cast nets. From records of fish landings maintained from 1957 it is seen that the production of fish at Parakrama Samudra has increased from 41 pounds per acre per annum in 1957 to 117 pounds per acre per annum in 1962 and at Minneriya Wewa from 11 pounds per acre per annum in 1957 to 118 pounds per acre per annum in 1962. Tilapia mossambica formed the chief constituent of the catch at both these lakes and it was due to this fish that the commercial fisheries at both these places were successful. It is recommended that fishing effort be further increased in both these lakes and records be kept to note any tendency towards over-exploitation.

A Preliminary survey of 21 Ceylon lakes. 2. Limnology and fish production potential

Some morphometric, physical and chemical conditions of 21 lakes in Ceylon are described. The values for the organic matter in the plankton and for the dry weight of bottom fauna in the lakes have been calculated. These values have been utilised to evaluate the potential fish production figures for the lakes. Fishing trials were made in each lake. Suggestions regarding mesh sizes and time of fishing are put forward.

A Preliminary survey of 21 Ceylon lakes. 3. Parasites and predators, food of fish, and marginal fauna

Three nematodes, two acanthocephalans and three cestodes were collected by dissecting 15 species of fish. Of these parasites only Hedruris sp. a larval nematode is responsible directly for the death of fish, since it is found in predatory species a reduction of these might prove of considerable consequence to fish, production. Bothriocephalus gowleonensis, a cestode probably introduced from China with Chinese carp, was recorded in an indigenous carp Puntius sarana. This parasite causes heavy mortality in grass carp in China and is a potential danger to local species. A single crustacean parasite was recorded. It is likely that they are widespread. No protozoa were recorded but there can be little doubt that they occur in local freshwater species and may be of considerable importance in fisheries. Several predators (insects, fish and other vertebrates) were recorded and are doubtless of considerable importance. However, the role of parasites and of predators (especially fishes) in relation to the productivity of fisheries can hardly be assessed at present and needs further study. A study of the fauna found at the shallow edges of 21 irrigation reservoirs showed an abundance of fauna in the low-country reservoirs whilst the up-country reservoirs had a poor fauna. The fauna showed insects, crustacea and mollusca in this order of abundance. The presence of insect and molluscs feeding fish in our fauna shows that these rich sources of food are being utilised.

A preliminary study of two village tanks (reservoirs) in the Polonnaruwa area with biological notes on these reservoirs in Ceylon

The present study was initiated in conjunction with a project to utilize some of these small tanks as fishponds by introducing desirable species like Tilapia mossambica Peters and harvesting them at the end of a single season which may vary from 4-8 months depending on the reservoir. Two reservoirs Timbirigaswewa and Dalukanawewa were chosen for this study. Both of these are in the Polonnaruwa area (Fig. 1). Timbirigaswewa (Fig 4) is as all rain fed tank of about 30 acres while Dalukanawewa (Fig. 2) is stream fed with an acreage of just over 100.

A preliminary report on Chanos fry surveys carried out in the brackish water areas of Mannar, Puttalam and Negombo

This paper records the results of the Chanos fry surveys carried out in Mannar, Puttalam and Negombo lagoon areas since 1967, and gives a summary of the earlier surveys. The maximum amount of Chanos fry was obtained from Mannar area during April and May. All three areas have their main commercial fry season in April and May with a second commercially negligible season in October–November. The quantity of fry collected has been utilized to evaluate the potential fry production figures. Mannar 400,000,000 fry/annum. Puttalam 200,000,000 fry/annum. It would be extremely difficult to estimate the number of eggs laid, the larvae hatched and the fry available each year along the coastal areas of Ceylon. It is necessary to obtain biological, meteorological and oceanographical data so as to provide a basis for the prediction and estimation of fry populations in the coastal waters of Ceylon. The suggested ideal season for commercial catches of Chanos fry is April–May with operations to be carried out simultaneously all along the west coast.

Some preliminary observations on the biology of Strongylocentrotus lividus (Lamarck)

The present study of Strongylocentrotus lividus is an attempt to add to the knowledge in this field with particular reference to a tropical species of whose biology little is known. The aim of the study was to examine the growth of the animals in relation to the development of their gonads, to elucidate the food preferences of the sea urchins and to study their associations with other animals.