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.

Comparative studies on the canning properties of pomfrets and hilsa

Fresh silver pomfret, black pomfret and hilsa were canned at absolutely fresh and iced conditions and the qualities of the final products were studied comparatively in relation to the initial quality of the raw materials. Under identical conditions a maximum quantity of cook-drip and nitrogen contents were found to be lost in black pomfret and minimum in hilsa. Silver pomfret and black pomfret iced for 3 days gave fairly good products on canning while hilsa came out only as a satisfactory product on canning after the same ice storage period of the raw material.

Studies on smoking of eel fillets

A procedure has been worked out to (hot) smoke eel fillets. Some of the important factors such as size of the fillets, brining, pre-drying, source of smoke, smoking period, final drying have been studied. Best quality of smoked product is obtained on smoking eel fillets with a mixture of coconut-husk and sag saw-dust in 1:1 proportion for 15 hours. Optimum moisture level of the final product was fixed in the range of 30 to 35% and it had a storage life of about 8 months at room temperature.

Studies on fecundity, sex ratio and crossbreeding in different strains of Guppy

Studies on the fecundity, sex ratio and crossbreeding in different strains of the guppy Poecilia reticulata such as Butterfly I, Butterfly II and Cobra strains was carried out. The highest fecundity among Butterfly I strain was at the 5th breed while it was highest at the 6th and 8th breed among Butterfly II and Cobra strain respectively. The average male percentage was 39.88%, 43.39% and 45.02% among Butterfly I, Butterfly II and Cobra strains respectively. The crossbreeding of strains showed good results among crossbreeds of Butterfly II (♀) X Cobra (♂) and Butterfly I (♀) X Cobra (♂). The crossbreed among the Butterfly I (♀) X Cobra (♂) proved to be excellent from the point of view of more percentage, rapid growth, and brilliant body and finnage colouration.

Studies on the effect of compounded feeds on the growth of juvenile Banana prawn Penaeus merguiensis

Laboratory experiments were conducted to determine the effect of compounded feeds on growth of juveniles (3 to 4 cm) of the Banana prawn Penaeus merguiensis. In all, seven diets were prepared with different combinations of locally available ingredients. Diascure, a local tuber was used as source of carbohydrate and vitamin mineral mixture (1%) was used in all the diets. The results indicated that diets with groundnut cake (diet 2, 3, 5 and 7) produced better survival and growth. In diets 4 and 6 growth was good but survival was very poor. Amongst all the diets, diet 7 produced significantly better growth, survival and food conversion ratio.

Studies on paddy-cum-fish culture under different land situations

Paddy fields can be broadly classified on the basis of land situations viz. Upland - Shallow water (10-30 cm), Medium land-medium deepwater (30-100 cm) and Low land-deepwater (above 100 cm). Three major systems of paddy-cum-fish culture, viz. (A) high yielding paddy varieties (H.Y.V) and air-breathing fish under Upland, (B) H.Y.V./local paddy and Tilapia/common carp under Medium land and (C) deepwater paddy and major Indian carps under Low land situations have been successfully investigated in the farmers' fields and at the Research Stations (1982-92). Effects of low-cost artificial feeding on growth, yield and management practices of different types of fish showed a considerable increase of rice and fish yields and a decrease in insect-pest incidence. Under Upland situation, short duration H.Y.V. in combination with fast-growing air breathing fish was studied thrice a year (summer, winter & autumn seasons). Combined rice and fish culture produced highest yields in all the seasons than in the control.

Studies on the performance of Ovatide on breeding of Indian major carps

The paper deals with the experimental studies on breeding of Indian Major Carps - Catla catla (Valenciennes), Labeo rohita (Hamilton), Cirrhinus mrigala (Hamilton), & Labeo calbasu (Hamilton) with the help of 'Ovatide' which is being used as an alternative inducing agent for commercial seed production. This study has been conducted for six consecutive months (April - September, 2000) in a stone-pitched breeding channels of a farm located at Midnapore District, West Bengal. The doses of 'Ovatide' (0.5 ml/kg of fish weight) remained same for each female species during the entire study period and males were released without any dose. The physicochemical parameters of water during different months were estimated. The latency period and fertilization percentage varied in different months and species. The results confirmed that 'Ovatide' can be used successfully in a much more cost-effective way for induced breeding of carps, even in rural fish farms with morrum-pitched breeding channels.

Studies on length-weight relationship of Gerres filamentosus Cuvier from the estuaries of the southern Karnataka coast

Random samples of Gerres filamentosus Cuvier from the Netravathi-Gurpur, Mulky, Kallayanapura, Mabukala and Kundapura estuaries of the southern Karnataka Coast were collected in the years 2000, 2001 and 2002, and length-weight relationships for each estuary were derived using multiple linear regression technique with one dummy variable. Hence, combined or sex-wise length-weight relationships were obtained after testing for homogeneity and isometric growth condition of fishes for each estuary by t-test. The extent of closeness of length-weight relationships between sexes and among estuaries for different years is explained by a trend line graph. The whole process of multiple linear regression analysis with one dummy variable is a better substitute for the analysis of covariance technique.

Studies on the seasonal cycle of sea surface temperatures, salinities and phytoplankton in Puttalam Lagoon, Dutch Bay and Portugal Bay along the west coast of Ceylon.

The monthly average temperatures at Puttalam Lagoon, Dutch Bay, Portugal Bay towards Kovilmunai and Portugal Bay towards Pallugaturai showed a distinct annual cycle. The peak was in April and values gradually fell till September. There was a further gradual fall in temperature from October to January. The highest temperatures in all four stations were in April. The highest salinities in all the stations were from May to October i.e., during the south-west monsoon. The salinities at Dutch Bay and Portugal Bay were high in March and April corresponding to the highest temperatures reached during these months. Two maxima have been observed in phytoplankton production. A primary maximum in May-June and a secondary maximum in October. The primary and secondary maxima are due to the influx of nutrient laden waters from the rivers Kal Aru and Pomparippu Aru. The phytoplankton producing blooms were Rhizosolenia alata. Rhizosolenia imbricata, Chaetoceros lascinosus, Chaetoceros pervianus, Ch,aetoceros diversus, Coscinodiscus gigas, Thallasionema nitzschioides, Thalassiosira subtilis, Thallassiothrix frauenfeldii, Asterionella japonica, Sceletonema costatum, Bacteriastrum varians and Biddulphia sinensis. Sudden outbursts of a single species were common. These diatoms were species of Chaetoceros and Rhizosolenia, and Thallassiothrix frauenfeldii. Wide fluctuations have been observed in the distribution of phytoplankton but no definite conclusions can be drawn as the period of observation was only one year.

Further studies on the water bugs of the genus Anisops (Hemiptera:Notonectidae) in Ceylon

In the present paper a short account is given of the biology of Anisops in Ceylon, their distribution and descriptions of Anisops ali and A. occipitalis. All the other Ceylonese species are described by Leong and Fernando (1962 . Brooks (1951) has given detailed descriptions of all the Ceylonese species except Anisops ali. A revised key to the Ceylonese Anisops is given and includes for the first time A. ali whose male has so far not been described and therefore omitted from the keys of Brooks (1951) and Leong and Fernando (1962).

Studies on the phytoplankton of inshore and offshore waters off Colombo and some data on the hydrological conditions of these waters

The present paper gives a comparative account of the hydrological conditions and phytoplankton within the Continental Shelf and beyond the Continental Shelf. 54 water samples were taken for hydrological analysis and 18 surface tows for plankton.

Studies on the seasonal cycle of sea surface temperatures, salinities, oxygen and phytoplankton in Koddiyar Bay, Trincomalee in relation to the shore seine fishery

In Sri Lanka waters, Durairatnam (1963, 1969) had reported on the seasonal variation of plankton at Puttalam lagoon, Dutch Bay, Portugal Bay and in the inshore and off shore waters off Colombo. Similar investigations were carried out at Koddiyar Bay especially in the estuarine waters where the three tributaries of the river Mahaveli empty their waters into the bay. The estuary is perennial. The fishes constituting the estuarine fisheries are mostly shallow water marine species which can tolerate considerable variations of salinities. Prawns and crabs also constitute a very valuable fishery in estuarine waters.

Results of the Austrian-Ceylonese hydrobiological mission 1970 of the 1st Zoological Institute of the University of Vienna (Austria) and the Department of Zoology of the Vidyalankara University of Ceylon, Kelaniya. Pt. 2. Hydrochemical studies on mountain rivers in Ceylon

The morphology, climate, geology and geochemistry of Sri Lanka is briefly described. The separation into a wet zone (the south-west and greater part of the central highland) and a dry zone with two very dry parts in the south-east and in the north-west, is obvious and has great influence on the hydrochemistry of the island. Geology is very homogenous (Precambrian crystalline series) and some Jurassic and Miocene limestones (only in the north).

Rotifera from Sri Lanka (Ceylon) 2. Further studies on the Eurotatoria including new records

In the first paper of this series, Chengalath and Fernando (1973) dealt with the genus Lecane from Sri Lanka. In all, twenty five species were recorded, of which seventeen species were new records. Two new species were also described. On the present paper the authors deal with the rest of the Eurotatoria. Again they have found many new records. In all 79 species are described in the present paper of which 47 are new records. The present study is based on the examination of over 300 samples from 135 localities including large and small tanks, ponds of various sizes, rice fields, streams and marshes. The collections cover the whole area of Sri Lanka and were taken during different seasons of the year mainly from 1968-1972.

Studies on the fish ponds at Pitipana, Negombo 1: seasonal and diurnal variation of some hydrobiological factors

The present paper is a part of a detailed investigation on the biology of grey mullet, Mugli cephalus L., and the feasibility of its culture in the brackish waters of Sri Lanka. The authors present the results of investigation on the water quality of five experimental ponds at the Pitipana Brackishwater Fisheries Station, Negombo, carried out over a period of one year, December 1976 to November 1977, together with studies on the primary productivity are presented.