Growth, reproduction, food habits, and parasites of pile perch were investigated in Yaquina Bay, Oregon between April 1966 and July 1967. The research disclosed that pile perch live at least 10 years. Males and females of given ages are close to the same size up to age IV, after which females are increasingly larger than males. The diet varies between seasons and localities. Pile perch are carnivorous feeders, obtaining food from the bottom or protruding surfaces in the littoral zone. Principal foods are barnacles, mussels, the bay clams, crabs, mud shrimp and tube dwelling amphipod. None of the pile perch examined was heavily parasitized. Infestations of gill copepods vary seasonally.

Studies on two hemoflagellates of fish were carried out to determine biological parameters: host range, vector relations, in vivo culture, in vitro culture, pathogenicit, and cryogenic preservation.

A bibliography comprising annotated citations of 2037 scientific and technical publications from ten series issued by the U.S. Fish and Wildlife Service. Includes a six-page introduction containing a history of the Service and a description of the research and development series.

Abundance increased and was highest in the lower third of the reservoir while it was filling, whereas it decreased and was generally highest in the upper two-thirds of the reservoir after it was filled. Abundance of species produced in littoral areas was greater wwhile the reservoir was filling -- particularly in years when spring water levels covered vegetation, fluctuated little, and were maintained through May or longer -- than after the reservoir was filled.

Significant changes have occurred in the distribution of trout in streams of Great Smoky Mountains National Park since 1900. By the mid-1970's the original range of the native brook trout had been reduced by about 70% and the species was relegated to suboptimal habitat in head water streams. Most of the stream sections lost by brook trout became the territory of the introduced rainbow trout, which in 1977 occupied about 80% of the Park waters. After 1950, brown trout introduced in State waters outside the Park established reproducing populations in some 50 miles of stream formerly occupied only by rainbow trout. If current trends continue, the recovery of brook trout in Park water may be difficult, if not impossible, and brown trout may occupy much of the territory now held by rainbow trout.

The time and location of spawning, food and larvae, and habitats used as nursery areas by young-of-the-year fishes were studied from 1972 to 1975 in South Dakota waters of Lake Oahe, a main stem Missouri River reservoir. Sampling locations were in the tributary rivres -- the Grand Moreau, and Cheyenne -- and their embayments. Year-class strength of river-spawning species was strongly correlated with river flow rates during the spawning season. Success of reservoir-spawning species was primarily dependent on above-average water levels, which inundated terrestrial vegetation to provide a substrate for egg deposition and cover for larvae. Preserving adequate streamflow and enhancing reservoir shoreline areas by managing water levels, seeding vegetation, and eliminating grazing alongshore would probably ensure adequate reproduction of most areas.

Manipulation of photoperiods, combined with modifications by other environmental conditions such as temperature and salinity, can alter growth, smoltification, and sexual maturation of salmonid fishes by way of a neuroendocrine pathway. The extent of responses of salmonids to environmental changes, however, is restricted by circadian endogenous metabolic rhythms that cannot be completely overcome by external factors. The success of the manipulation of photoperiod depends primarily on four factors: the daily length and the duration of the light treatment; the season and time of day during which fish are exposed to light; the age, sex, size and species of fish; and the type of physiological response under consideration. Although gaps remain in the available information, salmonids apparently need systematically changing, intermittent periods of darkness for optimum long-term stimulation of growth, reproduction, and migration.

The percentage body weight contributed by the ovaries and frequency distributions of ovarian egg diameters were reliable indicators of the spawning season of largemouth bass, in West Point Reservoir in 1977.