The effects of temperature on growth and metabolism of flowing water cold-stenotherms [Translation from: Archiv fur Hydrobiologie 74(4) 479-495, 516-522, 1974]

A small stream in the French Alps was sampled at regular intervals to determine the size distribution of animals for growth studies. The temperature was also measured. The results obtained for Gammarus fossarum were compared with laboratory cultures and the laboratory animals were physiologically and chemically analysed. Chemical analysis was also carried out on field animals.

The effect of oxygen concentration in water on the growth and nitrogen metabolism in the fry of rainbow trout [Translation from: Rybnoe Khoziaistvo,V.33, 74-75, 1957]

To ascertain the effect of various concentrations of oxygen in water on the fry of rainbow trout experiments were made with aquaria at various concentrations of oxygen. The food supplied was chironomid larvae (Chironomus plumosus). A surplus of food was supplied to the fry. Indices are given of the reaction of the fry to different temperatures.

Feeding, metabolism and growth of brown trout

A short review of the work carried out by the FBA on feeding and growth of brown trout is presented in this article. Since the amount of work done on this subject is quite extensive, this review has to be very selective. The work has been previously described in 10 papers, 9 of which were written by the author (J.M.Elliott) and 1 written by the author and W.Davison- references for these, and the pioneer work of M.E.Brown and F.T.K.Pentelow, are supplied at the end of the article.

Community metabolism, P/R ratio and photosynthetic efficiency of a brackishwater farm

The productivity level of a brackishwater fish culture farm consisting of 25 ponds, with a water spread area of 2.5 ha, was studied. Gross community photosynthesis of the farm was found to be 46.32 Kcal/m2/day, which is equivalent to the release of 13.23 of O2/m2/day, or the fixing of 4.10 gC/m2/day. Respiratory demand of the farm was estimated to be 44.66 kcal/m2/day, which is equivalent to the uptake of 12.76 g O2/m2/day or the utilization of 3.95 gC/m2/day. Photosynthetic efficiency of the farm was high at 2.26%. The P/R ratio was 1.04, showing eutrophic nature.

Respiratory metabolism in Oreochromis mossambicus, Peters under different environmental conditions

Oxygen consumption in Oreochromis mossambicus, Peters (3-60g in weight) was measured under different stress conditions at a constant temperature of 20±1°C. The rate of oxygen consumption was significantly higher (0.170 ml gˉ¹hˉ¹)at a salinity of 30x10ˉ³ compared with that (0.132ml gˉ¹hˉ¹) in freshwater. The oxygen consumption was also found to be affected by changes in pH. Weight specific rate decreased significantly from 0.113 to 0.045 ml gˉ¹hˉ¹ with increasing body weight. A positive correlation was recorded between availability of dissolved oxygen and the rate of oxygen consumption by the fish. While copper sulphate and malachite green inhibited the respiratory metabolism, formaldehyde treatment raised it from 0.088 to 0.118ml gˉ¹hˉ¹.

Energetics of resting metabolism in an Indian major carp (Catla catla Ham.)

Resting metabolism in Indian major carp, Catla catla Ham. fingerlings were investigated. For this purpose a water recirculatory system in the laboratory was used. The metabolic energy losses were determined by the indirect method of oxygen consumption by the fish and were then multiplied by an oxycalorific coefficient (Q-ox). Five metabolism chambers in the experimental system were used where there were two same treatment runs in quadruplicate of mean total weight of fish fingerlings of 109.5, 110.4, 112.8 and 111.6g/chamber. The water temperature in the system was 28±0.5°C. The mean metabolic rate in the replicates showed no significant variation (p>0.05) and was found to be 151.66, 153.91, 150.25, 152.74 mgO-2/kg/h respectively. This showed an equivalent energy loss 5.40, 5.52, 5.51 and 5.56 KJ/chamber/day (35.60, 35.92, 36.67 and 36.40 KJ/kg/day) respectively. Energetics of resting metabolism in an Indian major carp (Catla catla Ham.)

Feeding metabolism in an Indian major carp (Catla catla Lin.) fed on different protein diets

Feeding metabolism in an Indian major carp, Catla catla fingerlings of 10.8+0.56g was investigated in a flow-through water recirculating system. The metabolic energy loss in resting metabolism and feeding metabolism were determined by the indirect method of oxygen consumption followed by multiplication by suitable oxycalorific coefficient. This was done in four metabolic chambers of a respirometer system. Ten fish fingerlings of mean total weight of 109.5, 110.4 and 112.8g/chambers respectively each in two experimental runs of three treatments a, b and c were used. The mean resting metabolic rate during unfed condition showed no significant variation in different treatments. The fish in three treatments a, b and c fed on diets containing 28, 33 and 38% crude protein had significantly different (p<0.05) post-fed SDA magnitude of 497.7, 638.7 and 735.5 mgO2/chamber/day having an equivalent energy loss of 12.68, 14.68 and 15.86 KJ respectively. The SDA co-efficient in three treatments a, b and c were 14.95, 19.00 and 22.36% respectively whereas, respiratory energy - 'R' as % of mean total ingested energy in three treatments were 26.93, 31.17 and 34.74% respectively showing a significant increase (p<0.05) with increase of protein. Feeding metabolism in an Indian major carp (Catla catla Lin.) fed on different protein diets.

Effects of gamma radiation on nutritional and microbial quality of Pampus chinensis (Euphrasen 1788)

To evaluate the efficiency of gamma radiation in combination with low temperature Chinese pomfret, Pampus chinensis were preserved by the treatment of different doses of gamma radiation (3, 5 and 8 KGy) at freezing temperature (-20°C) during 90 days of storage period. Quality assessments for fish were carried out at an interval of 15 days during the storage period. Quality assessments were done by organoleptic, chemical (Total Volatile Nitrogen, TVN and Trimethylamine, TMA) and microbiological (Total Bacterial Count, TBC and Total Mould Count, TMC) evaluation. From the analysis of all parameters, maximum shelf-life was observed for irradiated (8 KGy) sample. It remained acceptable up to 75 days and that was the highest duration among 4 types of samples.

Preservation of Bombay duck (Harpodon nehereus) and Rohu (Labeo rohita) by gamma irradiation

The gamma irradiation procedures for preservation of Bombay duck and rohu were studied in collaboration with Bhabha Atomic Research Centre, Bombay. Irradiation at 0.1 M rad extended the storage life of Bombay duck to 20-22 days at 0-2°C due to partial destruction of spoilage organisms as against rapid deterioration of un-irradiated samples within 5-6 days. In the case of the fresh water fish, rohu, the storage life was enhanced by about 7-10 days by the same dose of irradiation over the control under identical storage condition. In all the cases, empirical relations were worked out between organoleptic rating and total volatile nitrogen.

Diversification in utilisation of trash fish by gamma irradiation

Radiation pasteurisation enhances the shelf stability of trash fish varieties and enables the grading of fish depending upon the freshness quality. As against the ice-chilled fish which spoils within 8-10 days, exposure to 100 Krad and storage at ice temperature helps in maintaining the quality in Grade I, II or III up to 10, 20 or 25 days respectively. The improvement in quality thus provides scope for greater utilisation of trash fish for various secondary products.

Effects of gamma radiation and -20°C temperatures on the shelf life of Hilsa, Tenualosa ilisha (ham.-Buch. 1822)

The combined effect of radiation and refrigeration on the shelf life of hilsa, Tanualosa ilisha was studied by monitoring the microbiological, chemical and sensory changes of unirradiated and irradiated fish samples using low dose irradiation, doses of 300 krad, 600 krad and 900 krad. Irradiation (900 krad) dramatically reduced population of bacteria, namely total viable counts 48.850cfu per gm for unirradiated, 31.850cfu per gm and 19.600cfu per gm of 300 krad and 600 krad, respectively. The effect was more pronounced at the higher dose (900 krad), total viable count were 14.100cfu per gm. Another microbial indicator total mould counts (TMC) was 8.750cfu per gm, 6.350cfu per gm, and 19.600cfu per gm for 300 krad and 600 krad, respectively. The effect was more pronounced at the higher dose (900 krad) where total viable counts were 14,100cfu per gm. Total volatile nitrogen values increased slowly attaining a value of 101.02mgN per 100gm for unirradiated T. ilisha during refrigerated storage, whereas for irradiated fish, lower values of 71.13, 59.33 and 47.03mgN per 100gm muscle were recorded. Sensory evaluation showed a good correlation with bacterial populations on the basis of overall acceptability scores.

Effects of gamma radiation and freezing on the chemical and sensory changes in shrimp Penaeus monodon (Fabricius, 1978)

Gamma radiation (3, 6 and 9 kGy) in combination with low temperature (-20°C) were applied to retain the quality and shelf-life of shrimp, Penaeus monodon for a longer period. The quality was assessed by monitoring the chemical (TVN, TMA) and sensory changes in irradiated and non-irradiated (control) samples. Among chemical indicators of spoilage, total volatile nitrogen (TVN) values for irradiated shrimps were found to be 2.26, 2.18 and 1.57 mg N/100g of sample at 3, 6 and 9 kGy respectively after 90 days whereas for non-irradiated samples it was found 2.45mg N/100 g of sample. Trimethylamine (TMA) value for non-irradiated samples after 90 days were found 2.30mg N/100 g sample whereas that for irradiated shrimps at 3, 6 and 9 kGy were found to be 2.10, 2.08 and 1.98 mg N/100 g sample respectively. The sensory scores of control sample were gradually decreased with the progress of storage period. From this study, it was clear that gamma radiation in combination with low temperature showed shelf-life extension (90 days) in each dose of radiation used but during the use of 9 kGy radiation, P. monodon showed best quality.

Effect of gamma radiation in combination with freezing on the microbiological changes in frozen shrimp Penaeus monodon

In this study gamma radiation (3, 6 and 9 kGy) in combination with low temperature (-20°C) were applied to retain the quality and shelf-life of shrimp, Penaeus monodon for a longer period. The quality was assessed by monitoring microbiological changes (TBC, TMC, TYC, TCC and Salmonella count) in irradiated and non-irradiated (control) samples. Among microbiological indicators of spoilage, total bacterial count (TBC) values for irradiated shrimps were found to be 1875, 1625 and 1525 cfugˉ¹ of sample at 3, 6 and 9 kGy respectively after 90 days whereas for non-irradiated samples it was found 2475 cfugˉ¹ of sample. Total moulds count (TMC) value for non-irradiated samples after 90 days were found 425 cfugˉ¹ sample whereas that for irradiated shrimps at 3, 6 and 9 kGy were found to be 275, 250 and 200 cfugˉ¹ sample respectively. Total yeast count (TYC) value for non-irradiated samples after 90 days were found 4125 cfugˉ¹ sample whereas that for irradiated shrimps at 3, 6 and 9 kGy were found to be 2850, 2150 and 1725 cfugˉ¹ sample respectively. Total coliform count and Salmonella count showed that those were absent during 90 days storage period. From this study, it was clear that gamma radiation in combination with low temperature showed shelf-life extension (90 days) in each dose of radiation used but during the use of 9 kGy radiation, Penaeus monodon showed best quality.