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.

Postmortem changes in hilsa fish. Pt. 1. Studies on rigor-mortis, typical yields and protein composition of dark and white muscle of hilsa fish (Tenualosa ilisha Ham.)

Hilsa (Hilsa ilisha) caught by gill net were immediately killed by cranial spiking. Three fish were kept in ice (0°C) and three other at room temperature (33°C) to follow development of rigor mortis and changes in muscle pH. The rest were frozen stored at -20°C. Rigor started 15 minutes after death in all fish and reached full rigor (100%) state in 2 and 4 hours respectively in fish kept at 33° and 0°C. The fish at 33°C deteriorated 16 hours after while in full rigor but those at 0°C lasted 26 hours of death without deterioration. Freshly caught hilsa had a muscle pH around 7 which decreased with time rapidly at 33°C and slowly at 0°C. The relative proportion of protein fraction in white and dark muscle of fish stored at 0°C and -20°C were also studied. The proportion of dark muscle was 30.34% of the white muscle. White muscle in fish at 0°C was found to contain 32.0% sarcoplasmic, 57.6% myofibrilla, 9.4% alkali-soluble and 1.1% stroma protein whereas these proteins in dark muscle were 29.9%, 58.4%, 9.8% and 1.9% respectively. The protein fractions of white muscle in frozen-fish were found 27.6% sarcoplasmic, 64.7% myofibrilla, 6.0% alkali-soluble and 1.7% of stroma protein whereas they were 30.6%, 58.6%, 8.9 and 1.9% for dark muscle. Some changes occurred in protein composition during frozen storage. The relative amounts of sarcoplasmic, alkali soluble and stroma protein fractions decreased while myofibrilla fraction increased in frozen condition. This may be attributed to drip loss of soluble protein during thawing.

Study on fishing gears, species selectivity toward gears and catch composition of BSKB beel, Khulna, Bangladesh

An investigation on the types of fishing gear used and their species selectivity and effects on fishes of BSKB beel in Khulna was conducted from June '95 to January '96. Fishermen were found to follow 6 fishing techniques viz., netting, trapping, angling, spearing, dewatering and hand picking. Among them 23 types of the fishing gear was recorded to be used by the fishermen of which 7, 8, 4 and 4 are nets, traps, hooks and lines, and hand harpoon respectively. A total of 47 species of fish were identified in the catches of different gears used by the fishermen in BSKB beel. Particulars, mode of operation, fishing season and catch composition of different fishing gears were determined. Seine, cast and lift net, traps (charo, arinda and ghuni), and hooks and lines (dhawn and nol broshi) were recorded as nonselective gear considering the fish species caught. However, gill nets (punti, koi and fash jal), clasp nets (bhuti jal), some traps (khadom, tubo), hooks and lines (chip borshi, chasra) and all spears were used as more or less selective gear. With respect to species and its size fash jal, bhuti jal, trap (khadom, ramani), and koach, juti and jhupi among spears were regarded to be more or less large-species-gear. But punti jal, koi jal, trap (koi dughair, charo, tubo, arinda and ghuni), nol borshi and spear (ful-kuchi) were small-species-gear. Among all gears seine net, cast net, lift net, koi dughair and ramani were recorded deleterious for carps especially for stocked fingerlings. For relatively small sized wild fishes koi jal, punti jal and ghuni traps were identified as detrimental gear.

Nutritional value of some small indigenous fish species (SIS) of Bangladesh

Twenty three small indigenous fish species (SIS) in the size range of 3-18 cm were analyzed for proximate composition and minerals (Ca and P) content to evaluate their nutritive value. The moisture content of different species ranged between 71.00 and 81.94%. In general, small sized fishes showed higher moisture content. The muscle protein content among the species varied widely (16.16-22.28%). In general, the muscle protein content of fishes showed higher value than the whole carcass protein content. The carcass lipid content varied between 1.87 and 9.55% and showed an inverse relationship with the moisture content. The gross energy content ranged from 19.51-27.30 KJ/g on dry matter basis. In the present study, the calcium and phosphorus contents ranged between 0.85-3.20% and 1.01-3.29% respectively. The calcium and phosphorus ratio (Ca/P) varied between 0.44 and 2.00. From the nutritional point of view, it shows that the SIS are good source of protein and minerals especially calcium and phosphorus

Studies on the post-mortem changes in shrimp and prawn during ice storage. Pt. 2. Biochemical aspects of quality changes

Studies were conducted on biochemical changes in P. monodon and M. rosenbergii during ice storage. At the end of 10 days of ice storage, moisture and protein content of freshwater prawn slightly decreased from 78.34 to '77.35% and 18.46 to 17.10, respectively, while lipid and ash content slightly increased. The moisture, crude protein, lipid and ash content of one day ice stored tiger shrimp samples were 78.07, 18.06, 1.3 and 1.29% respectively. The protein composition of freshwater prawn immediately after killed were 36.51% sarcoplasmic, 44.63% myofibrillar, 8.12% stroma and 6.44% alkali soluble protein. At the end of 10 days of ice storage, sarcoplasmic and stroma protein slightly decreased while there was little or no changes observed in myofibrillar and alkali soluble protein. In case of one day ice stored tiger shrimp, the composition of protein were 35.32% sarcoplasmic, 46.29% myofibrillar, 7.86% stroma protein and 7.08% alkali soluble protein. At the end of 10 days in ice, sarcoplasmic protein decreased from 35.32% to 32.16% while there was slight change in other protein fractions. The TVB-N value of 1 day ice stored shrimp was 10.5 mg/100g of sample. It increased gradually with the lapse of storage period and at the end of 10 days storage in ice, the value increased up to 60 mg/100g sample. The tiger head on shrimp in ice storage were found organoleptic acceptable condition for 8 days and at that time the TVB-N values were 32.2 mg/100g which is slightly above the recommended limit for TVB-N for export.

A study on the lipid distribution pattern in muscles of two teleosts, Arius dussumieri and Ophiocephalus striatus

The muscles of the various regions and zones of the body of the two teleosts, A. dussumieri and O. striatus have been analyzed for lipid contents. There is a significant dorsum-ventral gradient in lipid concentration exhibited by both the fishes with higher lipid values in the ventral aspect of the body, especially the belly flaps. As regards the vertical series, both the fishes exhibit comparatively higher lipid contents at the dorsal aspects of the caudal region and at anterior portion of the dorsal fin area with lower lipid values at cephalic and middle portions of the body. The red muscle of Arius exhibits higher lipid content than the white muscle.

Species composition and abundance of different Macrobrachium species in a natural habitat of Kalu River near Titvala, Maharashtra State

Juveniles of freshwater prawns caught by the traditional cylindrical bamboo traps operated by the local fishermen in a natural habitat of Kalu River near Titvala were sampled every week during September to December 1991 and 1992, to study the composition and relative abundance of different species and their relationship with hydrobiological parameters. The juvenile catch comprised Macrobrachium rosenbergii, M. idella, M. scabriculum and M. bombayensis. Among these M. rosenbergii was more abundant followed by M. idella. It is also observed that high tide catches are more productive than those of low tides.

Nutritional characteristics of the two fermented fish products: Hentak and Ngari of Manipur

Proximate composition and nutritional characteristics of the two fermented fish products Hentak and Ngari of Manipur (India) were evaluated. Percentage of moisture, protein, lipid and ash contents in Hentak and Ngari were respectively: 36.30 versus 36.03; 33.33 versus 38.38; 13.60 versus 13.34 and 11.43 versus 5.49. Digestibility values in feeding trials in laboratory rats for 28 days were 82.37% for Hentak 89.46% for Ngari and that of Casein was 92.69%. The biological value, food conversion ratio and protein efficiency ratio (PER) of Hentak were 96.94, 4.83 and 1.8 respectively and that of Ngari were 97.83, 3.17 and 1.8 respectively. The α amino nitrogen of Hentak and Ngari in Pepsin + Trypsin phase were 28.40 and 28.92 respectively. The TBA number, peroxide value and TVBN were within the acceptable limits.

Ecophysiological response of Nerita oryzarum (Recluz), a gastropod, to variations in temperature, pH and salinity

During ecophysiological investigations on an intertidal gastropod, Nerita oryzarum (Recluz), of Mumbai shore, various biochemical changes could be recorded. Glycogen and lipid contents of N. oryzarum were found to decrease, whereas, water content increased with decreasing salinity. The rate of oxygen consumption declined with the decrease in salinity and also in highly acidic (pH 2) as well as highly alkaline (pH 10) sea water. The observed variations in the rate of oxygen consumption and changes in biochemical composition in the animal with changes in salinity, pH and temperature are probably the process of physiological and biochemical adjustments to the fluctuating environmental conditions in the intertidal region.

Wadge Bank trawl fishery studies. Pt. 3. Nature and composition of the resident population

The demersal stock of the Wadge Bank is known to be made up of two major groups, namely the resident and migrant stocks (Sivalingam 1966b). It is necessary to analyse the two groups separately in order to correctly interpret the changes in relative abundance of the demersal fish stocks of the Bank. The object of this paper is to present the nature of the resident stock and discuss its changes in composition from 1945 to 1960. That of the migrant population will be presented later. The significance of this analysis has been discussed earlier (Sivalingam 1966a).

Fluctuations in species composition of Penaeid prawns in estuaries

During a study of the distribution of penaeid prawns in Sri Lanka waters a difference was noticed in the species composition from one estuary to another. Moreover, a marked monthly fluctuation in the relative abundance of the different penaied species was also observed. This indicated migratory behaviour. In order to study this phenomenon in the different species of prawns, regular samples of prawns were collected from two estuaries on the south-west coast of Sri Lanka, namely at Moratuwa/Panadura and at Negombo. The investigation was spread over a period of three years from 1957-1959.

The freshwater zooplankton of Sri Lanka, with a discussion of tropical freshwater zooplankton composition

Based on the study of over 500 zooplankton samples collected in Sri Lanka during 1965-1974, the species composition from different habitats is analysed. The zooplankton assemblage is typically tropical with relatively few species of Cladocera and Copepoda. The Rotifera include a large number of species of the genus Brachionus. The limnetic zooplankton resembles the pond zooplankton closely in that all the eurytopic species found in the different types of habitats, including ponds; also occur in the limnetic zooplankton. The large Cladocera belonging to the genus Daphnia are very rare. In general, large zooplankters are absent. The size composition of the zooplankton has a smaller range than in temperate regions. This is due to the absence of large-sized zooplankton species. The reasons for the differences in species variety and size composition between zooplankton of temperate and tropical regions is perhaps due to a number of factors. These include the effects of high and uniform temperatures, food availability and predation by fish and invertebrates.

A comparative study of the morphometrics and the proximate composition of two edible molluscs Crassostrea cuculata (Born) and Perna perna (L.)

The morphometrics and the bio-chemical characteristics of Crassostrea cuculata and Perna perna were studied. In the oyster, the length was found to be positively correlated with breadth and total body weight. There was also a positive relationship between the total body weight and the total muscle weight. In the mytilid the total body weight was positively correlated with length and total muscle weight. The muscle weight was also found to be highly correlated with the length. In both animals the relationship between the length and the total body weight was curvilinear. In the oyster, the protein content was found to increase with the total body weight and the total muscle weight. In the mytilid the protein content increased not only with the total body weight but also with the length. In both animals, the relative content of protein is higher than that of carbohydrates, lipids and ash.

Nutritional evaluation of some small coastal fish in Sri Lanka

Small pelagic fish play a very important role in human nutrition and health. Lipids of these fish differ remarkably from plant and other animal lipids. The aim of the study was to describe the proximate composition of thirty-three small pelagic fish species commonly available in Sri Lanka. Fish species were collected from Negombo and Chillaw fish landing sites and subjected to analysis for moisture, ash, protein and total lipid content. Tiger tooth croaker (Otolithus ruber) was found to have the highest moisture percentage (80.0%) followed by Clarias sp. (78.9%), Indian anchovy (Steloporus indicus) and Comerson's anchovy (Stelophorus commersonii), (78%). The lowest percentage of moisture, 69.4%, was recorded in white sardinella (Sardinella albella). Indian ilisha (Ilisha melastoma) was found to have the highest amount of ash (10.1%) followed by Otolithus sp. (8%) and big-eye barracuda contained the least amount (2.5%). Carassius Carassius, pick handle barracuda (Sphyraena jello) and Indian mackerel (Rastrelliger kanagurta) contained higher amounts of protein, 24.3, 20.6 and 19.2% respectively. The lowest protein content (10.1%) was found in Indian scad (Decapterus russelli). The protein content of the fish was in the range of 13-15%. The results revealed that the small fish are moderate protein sources. The total lipid content varied between 0.6-8%. White sardinella recorded the highest percentage of lipid (8%) where tiger tooth croaker contained the lowest percentage (0.6 %). The study showed high fatty species to contain low amount of moisture and vice versa establishing an inverse relation between fat and moisture quantitatively.

Effect of lykamin on growth and biochemical composition of long whiskered catfish, Mystus gulio (Hamilton) fingerlings under laboratory conditions

A growth trial was conducted to test the effect of Lykamin (dietary supplement) on growth, survival and feed conversion in Mystus gulio. Four isoproteic diets were formulated by incorporating the growth promoter, Lykamin at the levels of 0, 0.25, 0.50 and 0.75% diet. The crude protein content was 30% in each diet. The diets were fed to triplicate groups of catfish fingerlings twice daily at a level of 5% of the total body weight for 120 days. Regular fortnightly sampling was done to evaluate the growth performance of the experimental animals. Water quality parameters during the experimental period were maintained within the range suitable for catfish. The results showed better specific growth rate, weight gain, protein efficiency ratio and feed conversion ratio in the group which was given 0.75% Lykamin diet.