BODY WEIGHT and GROWTH OF JUVENILE MALE NORTHERN FUR SEALS, CALLORHINUS URSINUS

A mark-recapture study conducted in 1987–1992 provided weight measurements of juvenile male northern fur seals ( Callorhinus ursinus ) on St. Paul Island, Alaska, at ages ranging from approximately 1.5 mo to 5 yr. Males born in 1987 tended to weigh less at ages 3 and 4 yr than those born in other years. Weights of individuals at ages 2, 3, and 4 yr were significantly correlated with their weights as pups ( P < 0.05). Weights at ages 2 and 3, 3 and 4, and 4 and 5 yr were significantly correlated ( P < 0.001), although weight changes with age were highly variable. Data indicate that larger than average male pups born during 1987–1990 were more likely to survive, but this effect was less evident than among pups born during 1960–1965 when average pup weights were lower.