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genetic diversity in offspring from full-sib (Al X A1) 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 diagram. A rather detailed explanation of the di-allele cross accompanies Figure 3 to explain its use in maintaining genetic diversity. If space is limited for propagation of all family lots resulting from a 5 X 5 di- allele cross, maintaining separate groups of the 5 unique family lots represented in the diagonal cells would be preferred to maintaining the 20 other matings. These 5 family lots contain the entire genetic contribution from the 10 parents. If adult fish are extremely rare and five fish of each sex cannot be obtained, factorial matings (Kapuscinski et al. 1993) will be used to increase the genetic contribution from the least numerous sex (See Box 10,Item 4). After a broodstock has been developed from a 5 X 5 cross or a factorial mating, additional wild fish should be used to supplement the genetic contribution of the parent stock until a minimum effective population size of 50 is achieved (See Box 10, Item 5). Additional lots from mating one male with one female should replace the half-sib lots in the di-allele cross to maximize the genetic contribution from the wild parents. In some situations, it may be feasible to spawn wild fish at the site of capture and return them to the habitat from where they were collected. However, in most situations, fish will be captured, transported to holding facilities, and held until they can be spawned. The stress of capture and transporting may prevent potential broodstock from spawning during the year of capture. Even if fish spawn in the year of capture or a subsequent year, wild adults may be retained at the refuge or hatchery for an additional year to ensure that F1 progeny survive from the initial spawning. VI. GUIDELINES FOR DISPOSITION OF CAPTIVE-REARED ENDANGERED AND CANDIDATE FISH A. Background. Many propagation activities may produce more fish than are needed to meet specified requirements. This additional production allows the hatchery manager to compensate for unknown or unpredictable attrition rates and ensure that specified requirements are met. These guidelines provide the protocol for disposition of such fish. Planned captive propagation minimizes the production of endangered or candidate fish that will be excess to program needs. The number of fish that are reared depends upon: 1. Captive propagation goals and objectives 2. Breeding strategy or mating system used 3. Fecundity of the fish 4. Anticipated mortality during culture 5. Method used to culture fish 6. Uncertainty of production during captive culture 7. Availability of culture facilities 24