Intensive small scale cage, pen and enclosure fish production systems: towards 2010

A brief review of most of the publications by the author and other relevant workers on the three water-based fish culture systems was made. The present status of the culture systems in the National Food/Fish Programmes was highlighted. Strategies were advanced towards a successful implementation of the intensive water-based culture systems project as a contribution towards alleviating poverty, hunger and malnutrition under the concept of VISION 2010

Effect of fish meal in formulated diet on the growth of Heterotis niloticus in semi-intensive pond culture system

The aim of the investigation is to know the percentage of fish meal required to support the best growth of Heterotis niloticus in a semi intensive pond culture system. To achieve this, feed was formulated with equal percentages of blood meal, and corn meal and varying levels of fish meal. The experiment was in four treatments. Results showed that the mean weight gained was directly proportional to the quantity of fish meal made available to the fish fence 31.58g, 33.79g, 45.15g and 51.24g were recorded for treatments I, II, III and IV respectively. Result from this study when compared with previous works, shows that size of the water body to a greater extent affects the growth. The availability of fish meal in the feed made it more acceptable to the fish and hence a commensurate conversion in to flesh. The analysis of variance showed that there is significant difference in the growth performance in the treatments

Reducing feed costs in semi-intensive finfish culture: an update on mixed feeding schedules and an idea for enhancing endogenous food supply in ponds

Some interesting ideas on improving the cost-effectiveness of feeding in semi-intensive finfish aquaculture are presented.

Length-weight relationships of Penaeus monodon reared in semi-intensive culture systems of Kerala, India

The results of a study on length-weight relationships of Penaeus monodon, reared in fertilized ponds in Kerala, India, and fed three different supplementary feeds are presented.

Problems in culturing black tiger shrimp (Penaeus monodon) the semi-intensive way: an Indian experience

This paper details some of the problems encountered in culturing black tiger shrimp (Penaeus monodon) the semi-intensive way in India, which include aquatic macrophytes; invasions by molluscs, jellyfish and frogs; predators; fouling organisms; and others.

River Irk intensive survey

This is the River Irk intensive survey produced by the North West Water in 1986. This report focuses on the Intensive Survey carried out on the River Irk on 15 April 1986. The river Irk was one of the most polluted rivers in North West Water's area. In dry weather the bulk of the flow in the river originated from the 3 sewage works within the catchment (Castleton ETW, Royton ETW and Oldham ETW). The river Irk was badly affected by numerous unsatisfactory storm sewage overflows (SSOs) within the catchment. Several sewerage projects had been carried out within the Irk catchment especially in the Middleton area, where earlier major redevelopment of the old town centre took place between 1969 and 1976, at which time the main sewers were reconstructed. The survey was designed to investigate the changes in the water quality of the river Irk which take place during wet weather. Because of manpower and analytical restrictions the study on Wince Brook and the river Irk upstream of Wince Brook was limited to their bottom reaches.

Intensive biological survey of the Glaze Brook catchment May 1981

This is the Intensive biological survey of the Glaze Brook catchment May 1981 report produced by the North West Water Authority in 1981. The aim of this report is to identify those pollution problems not identified during the routine biological water quality surveys, and to check the suitability of the routine biological sampling point. This report looks at an intensive biological water quality survey of the Glaze Brook catchment which was carried out by Biol. (S) on 13th-15th May, 1981. Kick samples of invertebrates were taken at 5 sites and all invertebrates were identified and counted in the field. The most significant water quality observations in the report were from: Borsdane brook, Pennington brook, Glaze brook, Amberswood brook, Cunningham brook, Old Mill brook, Shakerley brook, Astley brook and Shaw brook.

Intensive biological survey of the Glaze Brook catchment. Supplementary report on the water quality as indicated by macrophytes. August 1981

This is the Intensive biological survey of the Glaze Brook catchment: Supplementary report on the water quality as indicated by macrophytes produced by the North West Water Authority in 1981. This report describes the results of the macrophyte survey including data on their distribution and the prevailing water quality (nutrient status and toxic metal contamination) It supplements the initial report,TS-BS-81-3, which described the macroinvertebrate survey. The aim of this project is to describe the distribution of macrophytes within the river, paying attention to areas where weed growth may directly affect water quality or amenity usage, and describe the distribution of toxic metals. In the survey 16 sites of 500 m lengths of river were analysed, noting the relative abundance and percentage cover of the macrophytes present, plant score and Community Description Class (C.D.C.) were computed.

The effect of intensive line fishing on the virgin biomass of a tropical deepwater snapper, the crimson jobfish (Pristipomoides filamentosus)

An intensive commercial hook-and-line fishing operation targeted the demersal fisheries resources at Saya de Malha Bank in the Southwest Indian Ocean. Fishing was conducted with 12 dories that were equipped with echo sounders and electric fishing reels and supported by a refrigerated mothership. Over a 13-day period in the 55–130 m depth range, a total of 74.3 metric tons (t) of fish were caught, of which the crimson jobfish (Pristipomoides filamentosus) represented 80%. Catch rates decreased with time and could not be attributed to changes in location, climatic conditions, fishing depth, fishing method, or bait type. The initial virgin biomass of P. filamentosus available to a line fishery at the North Western promontory of Saya de Malha Bank was estimated at 72.6 t through application of the Leslie model to daily catch and effort data. Biomass densities of 2364 kg/km2 and 1206 kg/km were obtained by applying the initial biomass estimates to the surface area and to the length of the dropoff that was fished. The potential sustainable yield prior to exploitation was estimated at 567 kg/km2 per year. The quantity of P. filamentosus caught by the mother-ship-dory fishing operation represented 82% of the initial biomass available to a hook-and-line fishery, equivalent to more that three times the estimated maximum sustainable yield. The results of the study are important to fisheries managers because they demonstrate that intensive line fishing operations have the potential to rapidly deplete demersal fisheries resources.

Food preference and intake pattern of Penaeus monodon (Fab.) in semi-intensive culture system

P. monodon juveniles prefer natural food than artificial feed in their initial stage of rearing. However, the percentage preference towards artificial feed increases as the days of culture/average body weight increases. Consumption of artificial feed was high during evening meal (1700h) and low during night meal (2200h). The index of intestine fullness was high (8.4±0.7) during initial stage of rearing, compared to that of final stage of rearing (4.9±0.4), probably due to low nutritional value of intake material and low water depth at initial stage. At all stage of rearing omnivorous feeding habit was established and no evidence of diet periodicity in feeding activity was observed.

Semi-intensive shrimp farming system of Kerala, India: a production function analysis

An analysis of the factor-product relationship in the semi-intensive shrimp farming system of Kerala, farm basis and hectare basis, we are attempted and the results reported in this paper. The Cobb-Douglas model, in which the physical relationship between input and output is estimated, and the marginal analysis then employed to evaluate the producer behaviour, was used for the analysis. The study was based on empirical data collected during November 1994 to May 1996, covering three seasons, from 21 farms spread over Alappuzha, Ernakulam and Kasaragod districts of the state. The sample covered a total area of 61.06 ha. Of the 11 explanatory variables considered in the model, the size of the farm, casual labour and chemical fertilizers were found statistically significant. It was also observed that the factors such as age of pond, experience of the farmer, feed, miscellaneous costs, number of seed stocked and skilled labour contributed positively to the output. The estimated industry production function exhibited unitary economies of scale. The estimated mean output was 3937 kg/ha. The test of multi-co-linearity showed that there is no problem of dominant variable. On the basis of the marginal product and the given input-output prices, the optimum amounts of seed, feed and casual labour were estimated. They were about 97139 seed, 959 kg of feed and 585 man-days of casual labour per farm. This indicated the need for reducing the stocking density and amount of feed from the present levels, in order to maximise profit. Based on the finding of the study, suggestions for improving the industry production function are proposed.