Potential genetic impacts of hatchery-based resource enhancement

Abstract only.The global population according to the United States Census Bureau has reached 7 billion as of October 2013. The continuous growth in human population will continue to put tremendous pressure on food production. The demand for fish as source of good protein is no exception. In 2011 total capture fisheries supplied 90.4 million tons of food and total aquaculture provided 63.6 million tons. While aquaculture production has increased dramatically, more than 50% of fishery production still depends on capture fisheries. Overexploitation of wild fish stocks has become one of the biggest problems in global fisheries. Stock enhancement has become a potential viable strategy for marine fisheries in danger of collapse. With the tremendous progress made in the breeding and larval rearing techniques of marine species, hatchery-based stock enhancement is now operated in many stock enhancement programs. However, many questions are raised in the use of hatchery-reared fish in stock enhancement. This paper will discuss genetic considerations in stock enhancement in developing countries

Pagpapaanak o pagpaparami ng tilapya

Text in Filipino.The manual discusses spawning tilapia (Oreochromis spp) in concrete tank hatcheries, hapa hatcheries in ponds and in lakes in the Philippines. Also included in the manual are a list of agencies involved in tilapia research, a glossary of technical terms, and useful references.1st Ed

Genetic Research Initiatives for Sustainable Aquaculture Production in the Philippines

Oral Session

Pagpapalaki ng tilapya

Text in Filipino.The manual discusses tilapia culture methods in concrete tanks, netcages, and fishponds. It details the species of tilapia cultured in the Philippines, which include Oreochromis nilotucus, O. mossambicus, O. aureus. It covers the following: site selection; construction of netcages and its modules; fishpond construction and pond preparation; criteria for fry selection; stocking; netcage and pond management including water quality management; and harvest. The manual also lists the agencies involved in tilapia research and development in the Philippines; defines some technical terms in a glossary, and lists some useful references.1st Ed

Genetic Research Initiatives for Sustainable Aquaculture Production in the Philippines

Symposium mini revie

Tilapia, carp and catfish

Research activities on tilapia focused on Oreochromis niloticus and red tilapia. Experiments include developing new experimental and statistical procedures for strain evaluation, development of a stable reference strain, development of a high-yield red tilapia strain through introgressive hybridization, comparison of fish growth in different environments relevant to aquaculture, development of an index for routine monitoring of salinity tolerance of existing tilapia strains/experimental stocks, evaluation of nutritional requirements of red tilapia, and determination of heavy metal contents of tilapia in Laguna de Bay, Luzon, Philippines. Research on carp (Aristichthys nobilis) and catfish (Clarias macrocephalus) were focused on improvement of methods for induced spawning, development of seed production techniques, and nutritional requirement of bighead carp fry and broodstock. Research on carp (Aristichthys nobilis) and catfish (Clarias macrocephalus) were focused on improvement of methods for induced spawning, development of seed production techniques, and nutritional requirement of bighead carp fry and broodstock

Effects of initial stocking size on the growth of Nile tilapia fingerlings in cages without supplemental feed in Laguna Lake, Philippines

Oreochromis niloticus fingerlings were stocked at three different initial size ranges of 1-3, 7-12 and 20-30 g in fixed net cages in Laguna Lake, Philippines. These were reared without supplemental feed for 120 days. Fingerlings with the biggest initial size at stocking were the most efficient in terms of average weight gain, average final fish weight and total fish production

Test of size-specific mass selection for Nile tilapia, Oreochromis niloticus L., cage farming in the Philippines

One generation of mass selection based on the collimation procedure (early culling of large fry) was applied on Nile tilapia, Oreochromis niloticus L., in net cages set in Laguna de Bay, Philippines. The objective was to test the effectiveness of a low-cost, small-scale broodstock improvement procedure in this culture environment. Directional selection was performed in two steps after initial removal of large fry at 21 days. Selection of parents and testing of the offspring were also conducted in hapa net cages set up in Laguna de Bay. The selection resulted in a significant positive response of 3% relative to the control, which represents a projected 34% gain over 5 years in Laguna cage culture. The realized heritability is approximately 16%

An investigation of enzyme and other protein polymorphisms in Japanese stocks of the tilapias Oreochromis niloticus and Tilapia zillii

Contribution No. 138 of SEAFDEC Aquaculture Department.Samples of Oreochromis niloticus and Tilapia zillii were collected from the hatcheries of Osaka Prefecture Fisheries Experimental Station and Shiga Prefecture Fisheries Experimental Station, Japan, respectively. The samples were used for screening polymorphisms in 13 enzymes, skeletal muscle proteins and hemoglobins by horizontal starch gel electrophoresis. Among 35 loci examined, 12 loci for the 10 enzymes, sarcoplasmic protein and hemoglobins were polymorphic in O. niloticus and 2 loci for 2 enzymes were polymorphic in T. zillii. The observed numbers of phenotypes for respective loci agreed well with Hardy-Weinberg expectations. The genetic basis for each polymorphism is discussed. This investigation provides basis information on the status of these tilapias in Japan

Interaction between test and reference populations when tilapia strains are compared by the “internal control” technique

Several strains of Oreochromis niloticus, O. mossambicus and their hybrids occur in the Philippines, and others are likely to be introduced or developed locally in the near future. Our objective was to study biological interaction. The paper reports on an experimental design in which "reference" fish are included in each replicate to provide internal statistical control. Growth of 10 full-sib families from each of two domestic strains was compared. A third strain of red tilapia was mass spawned to provide reference fish. Thirty equal-sized fry from each family were matched with 30 red tilapia fry and reared for 8 weeks in laboratory aquaria. The fish were deliberately crowded to provide a "worst-case scenario" for the application of the reference-strain technique. The objective was to see whether behavioural interaction causes statistical or genotype × environment interactions that create problems in the analysis. The test strains interacted biologically with the reference strain in different ways: the growth (change in length) of strain 1 only was negatively correlated with reference growth. Statistical interaction did occur in this extreme situation. We speculate that the reference-fish technique will be more useful in experiments in ponds or cages, where variable environmental factors induce positive, rather than negative, correlations between reference and test strains