POPULATION RECOVERY AND NATURAL RECRUITMENT OF LAKE TROUT AT GULL-ISLAND SHOAL, LAKE-SUPERIOR, 1964-1992

We documented an increase in the abundance of wild lake trout (Salveli nus namaycush) at Gull Island Shoal in western Lake Superior and exami ned the relationship between parental-stock size and recruitment of ag e-0 fish in 1964-1992. Abundance of adult wild female lake trout and d ensities of age-0 fish both increased during the 28-year period. A sig nificant positive, linear relationship (P = 0.0002) was found between the abundance of wild females on the spawning reef in the fall and den sity of age-0 lake trout on adjacent nursery grounds in August and Sep tember of the following year. The abundance of hatchery-origin females did not explain significant amounts (P = 0.107) of variation in recru itment. We concluded that most recruitment in 1965-1992 was the result of natural reproduction of wild females. After 28 years of recovery t he Gull Island Shoal lake trout population appears to have additional capacity to increase because the stock-recruitment relationship is sti ll linear. Therefore, restoration periods on the order of 30 years may be needed for other lake trout populations in the Great Lakes. We rec ommend that the refuge established to protect this population be maint ained to allow further study of the relationship between parental stoc k and recruitment, and to provide a major source of recruitment to the lake trout population in the surrounding waters.