In northeast Thailand, fish seed production by private hatcheries is being encouranged by the Department of Fisheries. Dissemination of technical knowledge to hatcheries has considerably improved fish seed availability over the last decade, which has stimulated the adoption of fish culture.
The purpose of the project was to increase fish production, household nutrition, income and alternative employment opportunities of vulnerable Adivasi (tribal) people through promotion of small-scale aquaculture and enterprise related activities. The AFP is designed to bring the unused and/or underused seasonal ponds and rice fields into improved productive capacities with methods that are feasible, affordable and acceptable to poor Adivasi households.
The study has conducted the micro level analysis of hatchery operators, fishseed-rearing farmers and carp farmers with respect to their socio-economic characteristics, infrastructural development, husbandry practices and economics returns, based on the survey and on-farm trial data collected by the research partners in six Asian countries, viz. Bangaldesh, China, India, Indonesia, Thailand and Vietnam. The genetically-improved carp strain is economically viable and socially acceptable.
This document is part of a series of 5 technical manuals produced by the Challenge Program Project CP34 “Improved fisheries productivity and management in tropical reservoirs”. Inland capture fisheries in India have declined in recent years, leaving thousands of fishers to sink deeper into poverty. Freshwater aquaculture in small water bodies like ponds now contributes 80% of the country's inland fish production.
The success of induced spawning for the production of fish seed depends on many factors which affect hatchery conditions. This paper discusses the results of an investigation on the effects of six different levels of salinity on the fertilization and hatching of Heterobranchus bidorsalis eggs. The results indicate that spermatozoa of H. bidorsalis can survive under a wide range of saline concentrations, with survival increasing with an increase in salinity from 0 to 0.4% and then decreasing as the level of salinity increases. Survival was optimum of 0.4% saline concentration.
The major constraint to the development of aquaculture in Nigeria has been the non-availability of fingerlings in required numbers of cultivable species. A specifically designed trap to collect mullet (Liza falcipinnis; Liza grandisquamis) juveniles during high tides was successful in collecting juveniles year-round. The collectors was more successful during night spring tides than during neap tides or daytime collections.
Abu Al Abyad island is characterized by harsh environmental conditions. A preliminary trial conducted at the island to investigate the spawning and hatching performance of the blue finned sea bream Sparidentex hasta indicated that the fish can be successfully bred at high salinity levels exceeding 50 ppt.
The Southern Ocean Salmon project under study by ICLARM and under consideration by Chile has a major element a solmon hatchery tentatively located on the Salto Chico in southern Chile. This discussion, in the form of a progress paper, describe the physical concept on which this hatchery is based and develops a preliminary economic analysis for its operation. This analysis is , of course, very preliminary in nature although much of the cost information is taken frmo recent detailed studies of salmon enhancement in Washington State and Alaska.
The relationship between egg diameter ( Phi , mm), temperature (T, degree C) and egg development time to hatching (D, in days) was established for approximately spherical, pelagic marine fish eggs as log sub(10)D = 7.10 + 0.608 log sub(10) Phi - 4.09 log sub(10) (T + 26), which explains 82% of the variance of a data set of 140 cases, covering 84 species of teleost fishes, for temperatures from 2.8 to 29.5 degree C and eggs of 0.6 to 3.4 mm diameter.
Effects of presence/absence of a spawning substrate, and of temperature and water quality changes on seasonal fry production by Tilapia rendalli broodstock, were investigated from 29 December 1989 to 19 February 1991 (416 days) in tanks at the National Aquaculture Center, Domasi, Malawi. For each of the two treatments (with vs. without substrate), four 5-m super(3) tanks were stocked with T. rendalli broodstock of similar mean size (35.8-44.2 g). Fish produced batches of sticky eggs which adhered strongly to side and bottom walls of cement tanks.