Fig. 9. Sea temperatures in Bristol Bay and southeastern Bering Sea in mid-June and early July of 1967 and 1971 (from Straty 1974).
• The most apparent predation by marine birds on fish is on fish large or mature enough that some hard body parts persist and can be found in the stomach samples of birds.
• Little is known of the extent of bird predation on the pelagic eggs and larvae of demersal fish and shellfish in the Bering Sea because of lack of investigation and the rapid digestion of eggs and larvae by birds.
• Predation by marine birds on juvenile salmon is not well documented because of the lack of investigation in areas where both birds and fish are present.
• Marine birds and commercial fish eat similar zooplankton and fish in the eastern Bering Sea. The food exploited by both generally reflects the relative abundance of the types of food in the area, but food preference is displayed by some species of fish and birds.
• More is known about the food habits of the commercial fish than of the marine birds of the Bering Sea.
• Sea water temperature may be a major environmental factor in the Bering Sea since it influences both the extent to which fish are vulnerable to predation and the amount of competition with marine birds. Sea temperatures may vary greatly from year to year in the Bering Sea, and this may result in variations in the magnitude of predation and competition between birds and fish.