Equilibrium yield of the cutthroat trout, Salmo clarki lewisi Girard, in Yellowstone Lake, Wyo., is determined from data on catch and spawning runs from 1945 to 1961. Changes in growth rate, spawning runs, mortality rates, and year-class strength are related to differences in total catch. Three stages of exploitation of the stock are defined and the maximum safe catch or equilibrium yield is estimated at 325,000 trout. Management of the sport fishery according to equilibrium yield is discussed with reference to regulations, distribution of fishing pressure, planting, and interspecific competition. The Yellowstone River fishery is treated briefly.

Life histories of Daphnia galeata mendotae, D. retrocurva, D. parvula, D. ambigua, and D. schoedleri are compared with year class strength and food of threadfin shad in Bull Shoals Reservoir from 1965 to 1967. Maximum population density of daphnids was in April, May, and June. Populations declined to insignificant densities throughout the rest of the year. Declines coincided with the inclusion of Daphnia in the diets of threadfin shad smaller than 14 mm. Declines in the summer of 1967 coincided with both young shad predation and high Leptodora kindtii density. Population changes associated with declining year class strength of threadfin shad were an increase of the large D. schoedleri and Leptodora kindtii from nondetectable or trace densities to relatively large populations, and increase from nondetectable densities of daphnids in the summer to detectable densities, and a twofold to threefold increase in the summer standing crops of Bosmina longirostris.

A study area in the Bahia de Palmas, was established and predatory behavior in some Gulf of California shore fishes was studied to define certain general activity patterns.

A literature search, starting from scratch, is expensive in terms of time spend in comparison with information gathered. This bibliography includes earlier references by Hunn (1959, 1960) that provide some information to anyone seeking a range of "normal" blood values for fish blood chemistry as well as additional literature that attempts to evaluate the physiological responses of fish to changes in their environment.