Further studies on dehydration of prawns in rotary drum dryer

The paper deals with studies made to modify the process of drying of prawns in rotary drum dryer reported by the authors earlier. Prawns belonging to any species except M. monoceros can be satisfactorily dried. With M. monoceros invariably considerable adherence of shell occurs. Prawns of any size group can be dried provided in the case of medium and big size prawns they are beheaded prior to drying. In all size groups, beheading prior to drying results in better appearance of the end product in addition to the output of the dryer per charge being increased.

Studies on the preparation of fish protein concentrate

The paper deals with the method of preparation of an edible fish protein concentrate from cheap miscellaneous fish. The method consists in cooking the fish with 0.5% glacial acetic acid, and extracting batch—wise, using ethyl alcohol followed by an azeotropic mixture of hexane and alcohol (B. Pt. 58-68°C). The product is finally vacuum dried during which the residual solvent is also removed. The concentrate prepared by this method contains 85% protein of which 96% is pepsin digestible. The product is practically odorless and almost white in color.

Ni-resist iron for propellers

Ni-Resist is the name applied to a group of alloy irons to which a sufficient amount of alloying element (mainly nickel) has been added to produce an austenitic matrix. Because of the alloy content and the austenitic matrix, Ni-Resist irons exhibit much better corrosion resistance and toughness than do ordinary cast irons.

Comparative fishing ability and economic efficiency of mechanised trawlers operating along the Kerala coast

This study was undertaken with a view to finding out the comparative fishing ability and economic performance of different fishing vessel sizes 9.15m (30'), 9.76m (32') and 10.97m (36') designed by the Central Institute of Fisheries Technology and operating along the Kerala coast. Data were collected from selected vessels of these sizes for four consecutive fishing seasons from 1964-65 to 1967-68. The catch/unit effort and total effort per year for the 10.97m (36') vessels were much better than those for the 9.76m (32') vessels. The yearly landings and the crew remuneration for the former were about twice those of the 9.76m (32') vessels. The economic efficiency of the 10.97m (36') vessels was also much better. The decline in landings per year in both size groups was more due to the reduction in the effort per year than the decline in catch/unit effort.

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.

Stray current corrosion of copper sheathing and keel cooling pipe of a 36' trawler

The results of investigations into the cause of an accelerated corrosion of copper sheathing and keel cooling pipe of a 36' wooden trawler are reported. The corrosion is attributed to the stray electric currents originating from the electrical wiring system. The sources of stray currents and the remedial measures have been suggested.

Preliminary trials on the toxicity of "Algistat" to fish and algae

Preliminary toxicity trials conducted with "Algistat" (an algicide) indicated that a dose of 0,66ppm of the compound was highly toxic to fish and 0.8ppm was the general lethal level for Spirogyra sp. The blue green algae, Oscillatoria sp., Mycrocystis sp. and Anabaena sp. were adversely affected by dosages higher than 0.5 ppm Euglena sp. was not affected even at 1.0 ppm.

Phosphate treatment of frozen prawns. Pt. 1. Screening of various phosphates for prevention of drip loss

Various phosphates and their mixtures were screened for their efficiency of preventing drip loss in frozen prawns. The effectiveness of the phosphates decreased in the following order: Sodium tripolyphosphate — Sodium pyrophosphate — Sodium hexametaphosphate Sodium metaphosphate — Sodium dihydrogen phosphate; the last two being ineffective. Even though thaw drip loss was reduced by the above treatments the organoleptic quality of the thawed as well as cooked products was unsatisfactory, discoloration being the major defect. A solution of a mixture of 12% sodium tripolyphosphate and 8.6% sodium dihydrogen phosphate or 2% citric acid in water when used as dip prevented thaw drip loss, improved cooked yield and organoleptic quality without adversely affecting the biochemical characteristics. Commercial scale trials showed that the results are highly reproducible.

Seasonal variation in the chemical composition of pomfrets. Pt. 1. Black pomfret (Parastromateus niger)

Seasonal variations in proximate composition of the different parts such as head, middle, tail and skin of black pomfret (Parastromateus niger) are reported over three years on monthly basis. The lean and fatty conditions of fish are discussed on the basis of spawning period, food and feeding activity, size group appearance and the gonadal maturity of the pomfret.

General principles of the design of trawl net

The classification and the principles of design and construction of trawls in general are described. The method of calculating the length of rope required at each part for mounting the net and the requirements of floats and sinkers are given. The cutting rates to tailor machine made webbing are also indicated.

The narcotising impulse threshold values of certain fresh water fishes

The effect of impulse current on the fish at a particular impulse rate and voltage depends on the size and kind of the fish. It is directly proportional to the temperature and inversely proportional to the conductivity of the medium.

Indigenous substitutes for "Lignum vitae" for making stern bearings for fishing boats

Difficulties are very often encountered in selecting proper material for making stern bearings for fishing boats. Conventional materials such as white metal, bronze etc. wear out too fast also causing considerable wear to the propeller shaft. Lignum-vitae, a natural wood commonly used for this purpose, is not available on a commercial scale in our country. Results of trials carried out to find out suitable substitutes for lignum-vitae from among indigenous timbers are presented in this paper.

A mechanical device for eradication of submerged aquatic weeds

This paper embodies details and method of operation of a mechanical device developed for eradication of submerged aquatic weeds. The economics of operation is also discussed.

On the troll line investigations off Cochin during five fishing seasons. Pt. 1. Investigations during 1960-61 and 1961-62 seasons

There is apparently great scope for improvement of the design and operational aspects of the gear particularly for the effective exploitation of seasonal fisheries like that of seer, tuna, barracuda etc. In order to evolve improved, yet cheap trolling gear regular investigations were undertaken by the Craft & Gear Wing of the Central Institute of Fisheries Technology, off Cochin for five fishing seasons and the results of these studies are incorporated in this paper.

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.