BI 3063 J. Mork H08

1. Genetic and biologic stock management Hallerman Ch. 14 Hatchery supplementation programs BI 3063 J. Mork H08 "Stocking" has a long history in salmonid species, both Atlantic and Pacific salmonids. In Scandinavia, the permission to build dams and hydroelectric power plants usually came with an obligation to compensate for the lost habitats and local river fry production by stocking the affected rivers with young salmon fry reared artificially in hatcheries. During the first days of this activity, knowledge was poor among the acteurs, and a lot of grave violations were made to the genetic principles for such acitivity. Today, the acticity has a new role, namely to preserve or restore natural populations which have been depressed, in a way which also conserves the genetic resources. It is now calles supplementation.

2. Genetic and biologic stock management Hallerman Ch. 14 Hatchery supplementation programs BI 3063 J. Mork H08 • Genetic concepts relevant to hatchery programs • Extinction • Loss of within-population genetic variation • Loss of between-population variation • Domestication selection

3. Genetic and biologic stock management Hallerman Ch. 14 Hatchery supplementation programs BI 3063 J. Mork H08

4. Genetic and biologic stock management Hallerman Ch. 14 Hatchery supplementation programs BI 3063 J. Mork H08 Genetic guideline for hatchery programs

5. Genetic and biologic stock management Hallerman Ch. 14 Hatchery supplementation programs BI 3063 J. Mork H08 Choise of donor population Choose the donor population that, compared with the population targeted for management, shows the greatest possible similarity in terms of genetic lineage, life history patterns, and ecology of originating environment.

6. Genetic and biologic stock management Hallerman Ch. 14 Hatchery supplementation programs BI 3063 J. Mork H08 Collection of broodstock Collect an appropriate number of fish to minimize genetic differences between the hatchery- and wild-spawning subpopulations and, ultimately, to minimize genetic alterations of the overall population.

7. Genetic and biologic stock management BI 3063 J. Mork H08 Hallerman Ch. 14 Hatchery supple- mentation programs

8. Genetic and biologic stock management BI 3063 J. Mork H08 Hallerman Ch. 14 Hatchery supple- mentation programs

9. Genetic and biologic stock management BI 3063 J. Mork H08 Hallerman Ch. 14 Hatchery supple- mentation programs • Collect a minimum of 50 spawners, preferably with equal numbers of males • and females, to reduce loss of rare alleles. • Collect less than 50% of the wild spawners if minimum size requirements • can be met easily. • Generally exclude hatchery returns from broodstock collections but • reevaluate this practice and the entire supplementation progarm if hatchery • returns exhibit low fitness on spawning grounds. • Collect adults for broodstock so that they constitute an unbiased sample of • the naturally spawning donor population with respect to spawning timing, • size, age, sex ratio, and any other traits identified as important for long- • term fitness. • Consider a captive brood stock if the target population is critically low • Maintain a broodstock for only one generation.

10. Genetic and biologic stock management BI 3063 J. Mork H08 Hallerman Ch. 14 Hatchery supple- mentation programs • Spawning • Within each group of adults that are ripe for spawning on a given day, randomize matings with respect to size and other phenotypic traits. • For all fish collected as a hatchery broodstock, choose the mating scheme that will maximize Ne (cf Figure left).

11. Genetic and biologic stock management BI 3063 J. Mork H08 Hallerman Ch. 14 Hatchery supple- mentation programs • Rearing • Produce fish that are qualitatively similar to wild fish of the targeted population in • size, mophology, behaviour, physiological status, health, and other ecological • attributes important for fitness in the wild. • Simulate the natural environment in the hatchery conditions • Rear all fish of a given population under the same conditions (which may be variable) • Mix families randomly as soon as possible, taking into consideration plans to mark • families (physically or genetically)

12. Genetic and biologic stock management BI 3063 J. Mork H08 Hallerman Ch. 14 Hatchery supple- mentation programs • Release • The sum of the numbers of hatchery fish released and naturally reproduced fish • (with none displaced) should be equal to or less than the estimated carrying • capacity of the environment for juvenile fish • Release at the earliest life stage possible considering the trade-off between adult • return rate and genetic risks • Release fish in locations where the target populations naturally produced fish • occur at the same life stage • Disperse release sites • Acclimate juveniles by exposing them to water from the target stream • Allow volitional movement of juveniles to the target stream

13. Genetic and biologic stock management Hallerman Ch. 14 Hatchery supplementation programs BI 3063 J. Mork H08

14. Genetic and biologic stock management Hallerman Ch. 14 Hatchery supplementation programs BI 3063 J. Mork H08

15. Genetic and biologic stock management Hallerman Ch. 14 Hatchery supplementation programs BI 3063 J. Mork H08