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J. Breeding Strategy for Caotive Propagation when Small Numbers of Fish are Available. If the number of available adult wild fish is low, mating 5 males and 5 females using a 5 X 5 breeding matrix (Figure 3) is reasonable (Box 10, Item 3). The 5 X 5 breeding matrix should be used as the basic minimal breeding Box 10. Recommended strategies to maximize the effective population size in the captive propagation of listed and candidate fish. (Listed in priority order) 1. To maximize genetic contribution from the wild stock and reduce rate of inbreeding, mate one male with one female (as wild fish.. are available) until an effective population size of 50 is achieved. 2. Pair mate as many adults as feasible in a given year until an effective population size of 50 is reached. If 25 families cannot be obtained during one spawning season,continue in the subsequent years until 25 paired matings have been attained. It is important that all 50 fish used in the matings are different individuals so that all family lots are unique. 3. If numbers of adult fish are low, use the 5 X 5 breeding matrix or di-allele cross to develop a broodstock (Figure 3). Resulting half-sib family lots provide a safeguard against potential catastrophic loss of genetic contribution from any parents. 4. When wild fish are extremely rare and represented by unequal sexes, use factorial matings to capture the genetic contribution from all fish of the least numerous sex. For example, if three males and one female were available, three family lots should be produced by mating all three males with the single female. This example will result in three half-sib family lots. strategy model. The genetic contribution from mating 5 males and.5 females is represented in the diagonal cells (upper left to lower right). The remaining 20 crosses are various combinations of the 10 parental genotypes. Pedigreed matings of this nature (a single uniquely-marked male mated with a single uniquely-marked female) ensure that every possible genotype is produced and each parent is genetically represented in the next generation (Kapuscinski et al. 1993). The mating of ten unrelated parents in the illustration of a di-allele cross (Figure 3) will maintain the genetic contributions of all parents. Note the genetic diversity in offspring from full-sib (Al X Al) or half-sib (Al X A2) crosses. The resulting offspring of the full-sib cross is illustrated in the lower left diagram and the half-sib cross is illustrated in the lower center 22 L •