Predicting Year-class Abundance of Yellowstone Lake Cutthroat Trout


Book Description

Fluctuations in strength of year classes from 1945 to 1956 of Yellowstone Lake cutthroat from Pelican and Chipmunk Creeks are compared with the parental stock and several climatically influenced factors of the environment. Variations in year-class strength in the two tributaries were highly correlated with fluctuations in lake water levels. Strong year classes occurred in yeas of low water. Female spawner escapement, timing of the runs, and summer air temperatures were not significant factors. A formula based on water levels is presented for predicting year-class strength in Pelican Creek and in the Fishing Bridge area fishery. Stocking of fry in years of high water is suggested as a means of supplementing natural production. A method of forecasting lake water levels several months in advance of their occurrence is discussed.




Equilibrium Yield and Management of Cutthroat Trout in Yellowstone Lake


Book Description

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.




Research Report


Book Description




Research Report


Book Description







Effects of Accumulated Excretory Products on Hatchery-reared Salmonids


Book Description

In experiments at the Bureau's Salmon-Cultural Laboratory, to determine the excretory products of significance in rearing ponds and the possible effect of these products on fingerling chinook salmon (Oncorhynchus tshawytscha), the results demonstrated that ammonia and urea are the principal products. The relative amounts of these products vary with the concentration of fish and with their metabolic activity. Ammonia assumes dominance in an unfavorable environment. Water temperature, pH, and pond type affect the toxicity of ammonia solutions. Continuous exposure to levels of ammonia normally encountered in rearing ponds produced extensive hyperplasia of the gill epithelium in controlled experiments.




A Device for Stamina Measurement of Fingerling Salmonids


Book Description

A stamina tunnel was developed to measure differences in physical performance of salmonid fingerlings. By subjecting fish samples to controlled patterns of water velocity, it has proved possible to demonstrate differences in fish stamina imparted by disease, nutrition, and environment.







Food Habits of Striped Marlin and Sailfish Off Mexico and Southern California


Book Description

Stomach contents of 924 striped marlin landed in the sport catches at Mazatlan, Sinaloa, and Buena Vista, Baja California, Sur, Mexico, and San Diego, California, and of 197 sailfish from Mazatlan and Buena Vista were examined. The striped marlin and sailfish fed primarily on pelagic fishes and cephalopods. By volume the major foods were squid (principally Dosidicus gigas) for striped marlin at Mazatlan and for striped marlin and sailfish at Buena Vista, northern anchovy for striped marlin at San Diego, and threadfin for sailfish at Mazatlan. Locally differences in food habits were pronounced, and some seasonal and yearly differences were found.




Review of Fishery Studies on Missouri River Main Stem Reservoirs


Book Description

The six main stem Missouri River reservoirs are described, and information available through 1964 on plankton, water chemistry, fish populations, and water management is discussed. At maximum pool, these reservoirs have a capacity of 76 million acre-feet and a surface area of 1.2 million acres. Each of the upper reservoirs is larger in capacity and area than the sum of the lower three reservoirs. Fishes common in this system are bigmouth buffalo, carp, river carpsucker, yellow perch, goldeye, northern pike, sauger, walleye, white crappie, black crappie, and freshwater drum. Available information on growth rates, year-class strength, and relative abundance of common species is described. Limiting factors of the environments are the turbidities, wind, and fine soils. Research needs and problems relative to fish production are discussed.