The STRAINS Table
This table allows the documentation of the ancestry of cultivated strains of fish. It was developed primarily to serve as the Tilapia Strain Registry recommended by The Second International Symposium on Tilapia in Aquaculture (ISTA II) in 1987, in Bangkok, Thailand (Pullin 1988). The information was subsequently extended to cover other species utilized in aquaculture, as recommended in Articles 7 and 10 of the Convention on Biological Diversity (UNEP 1992). The genetic data, including histories of founding population, broodstock management, status of the strain and descriptions of the distinguishing characters of the strains will assist in the utilization and conservation of intraspecific genetic variation in aquaculture. Nomenclature standardization continues to be a problem and there is presently no universally accepted system for naming strains within a species.
As domestication of aquatic species progresses, one can expect more genetically distinct strains will emerge. These strains may emerge through the simple act of domestication and restricted gene flow among farms or through breeding practices, such as selective breeding, chromosome-set manipulation (polyploidization and sex reversal), hybridization and/or gene transfer.
The strains registry can be used as a source to locate fish with specific characters, e.g., red tilapia, and to track genetic improvement technologies. However, by recording the number of breeding individuals in the strain, the registry can also serve as a watch list for potentially threatened strains, similar to the World Watch List for Domestic Animal Diversity (Scherf 1995), where endangered breeds/strains can be recorded and flagged for immediate conservation efforts.
The STRAINS table includes the following fields:
For cultured strains, the strain description is found in the STOCKS table where it is labeled Stock definition. It designates the name of a strain and describes its original year of transfer, and size of founder stock.
Country: Refers to the country where the strain is found.
|FishBase can accommodate hybrids||
StrainCode: A unique combination of letters and a 3-digit number. The first two letters refer to the first two letters of the genus; letters 3-5 refer to the first three letters of the species; letters 6-7 refer to the first two letters of the subspecies. The number is sequential. If no subspecies exists, the letters 6-7 are XX. For hybrids, the letters 6-7 are HX.
Trait: Refers to the character(s) or trait(s) that distinguish a strain from its founding stock. The choices are the same as in the GENEDAT table.
Size of founding stock: Refers to the number of founding members comprising the original population.
Breeding strategy: Refers to the method of propagation of the stock and includes chromosome manipulation (polyploidization and sex reversal), selective breeding, hybridization, gene transfer, and normal mating.
Viability (Y/N)?: Refers to whether the strain is reproductively viable. For example, a strain of all female triploid trout would not be able to reproduce.
Female: The number of female founding members in the original population.
Male: The number of male founding members in the original population.
Number of broodstock: Refers to the current number of fish used as breeders and helps determine the conservation status of and threat of extinction to the strain.
Year of first breeding: Refers to the year when the founder stocks first reproduced.
Source of founding stock: A choice list of the environment: wild or captive and the site where the founder stock came from. The Country is also given here.
StrainCode of source: Refers to the StrainCode of the stock from which the founding specimens were obtained.
Year of arrival: Refers to the year the founder stock arrived at its new site or locality.
Availability of strain: Refers to where the strain is being used and how it may be acquired.
To date, the strain registry is only preliminary: its records have not been checked and it includes only slightly over 70 strains of tilapia and carp.
Important references used so far are Khater and Smitherman (1988), Pullin (1988), Pullin and Capili (1988), Komen (1990) and Eknath et al. (1993).
We are planning to document more hybrids and improved genetic strains, following the design of the Trout Strain Registry of Kincaid and Brimm (1994).
|How to get there||
Clicking on the Biology button in the SPECIES window, the Genetics button in the BIOLOGY window, then the Strains button in the following window brings you to the STRAINS table.
If strains are recorded for a particular species, clicking on the Biology button in the SPECIES window will produce a list containing the species in general and the cultured strain(s). You get to the BIOLOGY window after selecting a particular strain.
The STRAINS table was not yet available on the Internet in November 2000.
We thank Liza Agustin, Ambekar E. Eknath, Harold Kincaid, Wolfgang Villwock and Ulricke Sienknecht for their advice on the structure and contents of this table. We thank Harold Kincaid for giving us a copy of the National Trout Strain Registry Software.
Eknath, A.E., M.M. Tayamen, M.P. de Vera, J.C. Danting, R.A. Reyes, E.E. Dionisio, J.B. Capili, H.L. Bolivar, T.A. Abella, A.V. Circa, H.B. Bentsen, B. Gjerde, T. Gjedrem and R.S.V. Pullin. 1993. Genetic improvement of farmed tilapias: the growth performance of eight strains of Oreochromis niloticus tested in different farm environments. Aquaculture 111:171-188.
Khater, A. A. and R.O. Smitherman. 1988. Cold tolerance and growth of three strains of Oreochromis niloticus, p. 215-218. In R.S.V. Pullin, T. Bhukaswan, K. Tonguthai and J.L. Maclean (eds.) The Second International Symposium on Tilapia in Aquaculture. ICLARM Conf. Proc. 15, 623 p.
Kincaid, H. and S. Brimm. 1994. National Trout Strain Registry. U.S. Fish and Wildlife Service’s Division of Fish Hatcheries, National Fishery Research and Development Laboratory and Office of Administration - Fisheries, USA.
Komen, J. 1990. Clones of common carp, Cyprinus carpio: new perspectives in fish research. Agricultural University Wageningen, Wageningen, Netherlands. PhD thesis. 169 p.
Pullin, R.S.V., Editor. 1988. Tilapia genetic resources for aquaculture. ICLARM Conf. Proc. 16, 108 p.
Pullin, R.S.V. and J.B. Capili. 1988. Genetic improvement of tilapias: problems and prospects, p. 259-266. In R.S.V. Pullin, T. Bhukaswan, K. Tonguthai and J.L. Maclean (eds.) The Second International Symposium on Tilapia in Aquaculture. ICLARM Conf. Proc. 15, 623 p.
Scherf, B.D. 1995. World Watch List for Domestic Animal Diversity. Food and Agriculture Organization of the United Nations, Rome, Italy. 769 p.
UNEP. 1992. Convention on Biological Diversity. United Nations Environment Programme, Nairobi, Kenya. 52 p.
Christine Casal and Devin Bartley