Puffins as samplers of juvenile pollock and other forage fish in the Gulf of Alaska

Abstract

Nestling diets of tufted puffins Fratercula cirrhata and horned puffins F. corniculata were sampled at colonies from the N-central Gulf of Alaska to the E Aleutian Islands, Alaska. Overall, tufted puffins consumed (by weight) 41% sandlance Ammodytes hexapterus, 22% capelin Mallotus villosus, 19% walleye pollock Theragra chalcogramma, 13% other fish, and 5% invertebrates. Horned puffins took 85% sandlance, 4% capelin, 2% pollock, 8% other fish, and <1% invertebrates. All pollock consumed were young of the year, whereas four year-classes of capelin were present, from young of the year through spawning adults. Puffins took mostly first-year sandlance, but fish in their second year or older were also common at colonies near Kodiak, Alaska. The importance of juvenile pollock in the diet of tufted puffins varied geographically from little or no use in the N-central Gulf and Kodiak areas to moderate use (5-20%) in the Semidi and Shumagin Islands to heavy use (25-75%) in the Sandman Reefs and E Aleutians. An estimated 11 billion pollock were consumed by tufted puffins throughout the region in 1986. The proportion of pollock in puffin diets in the Semidi Islands was strongly correlated with independent estimates of cohort strength in three years. Puffins may thus provide a useful index of distribution and year-class abundance of first-year pollock, a species that currently supports an important commercial fishery in the Gulf of Alaska. -Authors