Indices of prey availability near the Seal Island CEMP site: 1990 through 1996

Four indices of prey availability are calculated for prey surveys conducted in the vicinity of the Seal Island CEMP site during the austral summers of 1990-96. The indices are measures of average prey density, depth, distance from Seal Island, and persistence over time. Acoustic data from two AMLR surveys each year were sub-sampled to include the foraging range of predators breeding at Seal Island. The average depth of the prey field and its average distance from Seal Island were positively correlated; no other relationships between the indices were apparent. Indices of prey availability were compared with indices of predator performance at Seal Island. The depth of the prey field and its distance from Seal Island appear to have a positive effect on the duration of chinstrap foraging trips, but not on breeding success. The distance of the prey field from Seal Island appears to be negatively correlated with both the duration of fur seal foraging trips and pup growth rate.