Assessment of quality of fish landed at the Cochin fisheries harbour

Assessment of quality of fish and shrimps landed at the fish harbour, Cochin, was made over the period January, 1980 to December, 1982. A total of 201 samples were analysed. Nearly 75% of the samples scored between 6-10 in a 10 point hedonic scale and the percentage unacceptability based on sensory assessment was 5. 5%. In 10.1% of the samples, total volatile nitrogen was >30 mg% and in 8.3% of the samples trimethylamine- nitrogen was >10 mg%. Both, the gr Torrymeter and Intellectron Fish Tester VI readings marked significant correlation with sensory scores and chemical indices; but failed to bear any significant correlation with bacterial counts. Of the 5-1 total samples 66.7% had total plate count (TPC) ≥10 super(5) g super(-1) and 8.5% were considered unacceptable based on TPC >5x10 super(5) g super(-1); 63.2% of the samples were free from Escherichia coli; 26.4% had >20 E. coli g super(-1) and 20.4% of the samples contained faecal streptococci >10 super(3) g super(-1). Seven percent of the samples showed coagulase positive staphylococci >100 g super(-1). Salmonella could not be detected in any of the samples examined. Crushed ice samples and the platform of the harbour had high bacterial loads.

Towards optimisation of bridle lengths in bottom trawls

Apart from increasing the swept area of the trawls, the importance of bridles as a herding device based on fish behaviour is discussed. The results of 10, 20 and 30m bridles when rigged with a 15m bulged belly trawl in combination with 114x57cm flat rectangular otter boards are presented. The net with 20m bridle landed better catches.

Chitosan for removal of mercury from water

Chitosan from prawn waste was used for the removal of mercury from solutions. Mercuric chloride solutions containing 250, 500, 1000, 10000 and 100000 ng of Hg super(+2)/ml were treated with chitosan samples of different particle size for different periods. The effect of initial concentration of mercury in the solution, particle size of chitosan and time of treatment on the adsorption of Hg super(+2) was studied. The residual mercury content after treatment for ten min. with chitosan of 40 mesh size from a solution of initial concentration 10000 ng/ml was 10 ng/ml whereas it was 50 ng/ml for chitosan of larger particle size (10-20 mesh). From solutions of lower concentrations complete removal of mercury was possible by chitosan treatment. Though the particle size and time of treatment have significant effect, the concentration of mercury in solution is more influential on the removal of mercury from solution.

On the comparative efficiency of "V" shaped and rectangular flat otter boards for trawling off Veraval, north west coast of India

V shaped all steel boards, with their inherent stability to tide over obstacles and mud, interchangeability of starboard and portside boards are found to be superior to conventional flat rectangular boards for bottom trawling. These are cheaper in construction, offer less resistance and give longer service. Comparative trials with the two types of boards showed significant difference in tension between the boards but not in catch or horizontal opening.

Vertical distribution of marine wood boring and fouling organisms from the estuarine areas of the south west coast of India

Vertical distribution of marine wood boring and fouling organisms from three different estuarine areas namely, the Ernakulam channel in the Cochin backwaters, Ayiramthengu in the Kayamkulam Lake and Neendakara in the Asthamudi Lake during the post-monsoon, the pre-monsoon and the monsoon periods is presented. The boring organisms noticed during the present study were Martesia striata, Teredo furcifera, Nausitora hedleyi and Sphaeroma terebrans. The dominant fouling organisms were Balanus amphitrite amphitrite, calcareous worms and Modiolus sp. Algae and diatoms were very common on the sub-tidal panels during the monsoon. The incidence of Teredo, Nausitora and calcareous tube worms were significantly high on the bottom panels. Sphaeroma, Balanus and Modiolus occurred in greater numbers on the intertidal panels.

Photosynthetic bacteria in the marine environment at Porto-Novo

Sediment and water samples were collected from mangrove and estuarine biotopes at fortnightly intervals. The physico-chemical characters of the overlying water were studied. In the mangrove biotope maximum temperature (31.5°C) and in the estuarine biotope maximum salinity (35.6‰) were recorded during the summer season, whereas in post-monsoon period the sulphate content was increased to 516 p.p.m. and the pH was reduced to 7.4. Invariably both in the enriched sediment and water samples four major peaks (at wavelengths 460, 705, 772 and 850 nm) and two minor peaks (at wavelengths 580 and 663 nm) of absorption spectra were noticed. A pure culture of Chromatium sp., isolated from mangroves sediment, showed three peaks of absorption spectra at wavelengths, 500, 580 and 850 nm. The effect of sodium chloride on the growth of Chromatium sp., was also studied and it was observed that maximum growth occurred in the range 1-3% sodium chloride concentration. This isolate was also capable of utilizing various sulphur and carbon compounds. Glycerol and glucose did not show any specific effect whereas pyruvate, malate and acetate increased the growth.

A study on the piscifauna of the Idukki Reservoir and catchment area

From the area under report 17 species, 15 endemic and 2 exotic, of freshwater fish have been identified. Of these, 8 species are commonly found in the catches and are of fishery significance. The fact that small fish species which have no fishery importance also support life in other trophic levels of this ecosystem is well exemplified by the interaction of the birds and mammals with these species. A scientific management and monitoring of the reservoir waters as well as the remaining segments of forests are recommended to salvage the wild life and vegetation from a possible rapid deterioration within years.

The Gjerstad kiln: a combined hot and cold smoking kiln

A combined hot and cold smoking kiln has been constructed for use at Lake Turkana, Kenya. Used for cold smoking, the kiln's main advantages over the traditional kilns used in this area are its greater smoking capacity and lower firewood consumption. Having the option of using the same smoke house for cold and hot smoking reduces the total construction costs for an operator producing both types of smoke cured product. The hot smoking process was found to require markedly less firewood than cold smoking, a fact of considerable importance in desert or semi-desert areas with sparse vegetation.

Sampling plans for pre-packed fish and fish products

An outline is given of a sampling plan for prepacked fish products based on the net weight of the container, which may be used to make the inspection of fish and fish products easier and more effective.

Preparation of lime from mussel shelf waste

A process is described for the utilisation of mussel shell wastes by their conversion into lime, which may be used for white washing and plastering.

Towards a mathematical system for extension education

A system of equations describing the relationship of change agent in extension education and client (e.g. a leader of a local community) is presented. The main task of the former is to ensure that he is able to transfer information to the latter, also learning difficulties involved and passing them into institutions of higher learning.

Analysis of dimensions involved in the option of improved fish curing practices

A statistical analysis was made of the dimensions involved in the adoption of improved fish curing practices.

Correlation of cell numbers with catalase activities of pure strains of bacteria

An attempt was made to correlate the catalase production with the actual number of aerobic bacterial cells generating the enzyme: bacteria were obtained from the surface of marine fish. A linear correlation was found between the log of catalase activity and log of bacterial count in single culture.

A brief account on the 'Gunja Net' fishing of the Kutch Backwaters (Gujarat)

A survey was made of the fishing gear (Gunja net) and methods used in the prawn fishery of the coastal waters of the Gulf of Kutch.

Selective release of fatty acids during lipid hydrolysis in frozen-stored milk fish (Chanos chanos)

Lipid hydrolysis and the nature of fatty acids lost as a result of lipid hydrolysis in milk fish (Chanos chanos) during frozen storage at -20°C is discussed in this paper. There was a preferential loss of saturated acids during the first three weeks of storage. This was followed by loss of polyunsaturated acids during the next seven weeks. Sharp decrease in the levels of monounsaturated acids was observed from the 10th week of frozen storage. These observations are due to the preferential hydrolysis of phospholipids with relatively high proportion of saturated acids during the first three weeks, followed by the hydrolysis of phospholipids with high proportions of polyunsaturated fatty acids from the 3rd to the 10th week, and finally, predominant hydrolysis of neutral lipids from the 10th week onwards. Storage of fish in the ice prior to freezing was found to accelerate lipid hydrolysis, especially that of neutral lipids, during frozen storage.