Effects of variability in food quantity and quality on the feeding, growth, and condition of larval fish under natural field conditions.

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It has long been believed that the amount of food encountered by larval fish determines their survival in the ocean, and that year-to-year variations in the amount of food available thus lead to year-to-year variations in year-class strength in fish populations. Although supported by lab experiments, convincing evidence for this relationship under field conditions is surprisingly rare. Recently, research has shown that variations in food quality (as opposed to quantity) may also play a significant role in the growth and survival of plankton. However, very little is currently known about whether natural variations in food quality also affect the growth and survival of larval fish. This project aims to test this possibility by conducting field work that will compare the effects of food availability and food quality on the growth rates of larval fish and on various measures of their "condition", or health, under natural conditions. We will also explore the extent to which larval fish may feed upon protozoans - a group of tiny soft-bodied plankton that are not usually considered in studies of larval fish feeding (as they are rapidly digested and hard to identify), but which may be an important prey source nonetheless. Research will be conducted in coastal Newfoundland and in the Strait of Georgia.