No abstract

No abstract

One hundred and fifteen US Air Force male officers and airmen were evaluated on a 12-minute field performance test and on a treadmill maximal-oxygen-consumption test. The correlation of the field-test data with the l aboratory\x=req-\ determined oxygen-consumption data was 0.897. The significance of this relationship makes it possible to estimate with considerable accuracy the maximal oxygen consumption from only the results of the 12-minute performance test. This test is readily adaptable to large groups, requires minimum equipment, and appears to be a better indicator of cardiovascular fitness than the more commonly accepted 600-yard run. Because of the high correlation with maximal oxygen consumption, it can be assumed that the 12-minute field performance test is an objective measure of physical fitness reflecting the cardiovascular status of an individual.When assessing fitness for prolonged physical activity, one must expose the subject to continuous hard work in order to test him accu¬ rately. This procedure is required primarily because the easier the work, the smaller and less regular are the differences between the fit and the unfit.1

No abstract

The Yakima River Spring Chinook Salmon Supplementation Project in Washington State is one of the most ambitious efforts to enhance a natural salmon population currently under way in the United States. Over the past 5 years we have conducted research to characterize the developmental physiology of natural and hatchery‐reared wild progeny spring Chinook salmon Oncorhynchus tshawytscha in the Yakima River basin. Fish were sampled at the main hatchery in Cle Elum, at remote acclimation sites, and, during smolt migration, at downstream dams. Throughout these studies, we characterized the maturational state of all fish using combinations of visual and histological analyses of testes, computation of gonadosomatic indices, and measurement of plasma 11‐ketotestosterone (11‐KT). We established that a plasma 11‐KT threshold of 0.8 ng/mL can be used to designate male fish as either immature or precociously maturing approximately 8 months prior to final maturation (1–2 months prior to release as “smolts”). Our analyses revealed that 37–49% of the hatchery‐reared males from this program undergo precocious maturation at 2 years of age and that a portion of these fish appear to residualize in the upper Yakima River basin throughout the summer. An unnaturally high incidence of precocious male maturation may result in the loss of returning anadromous adults, the skewing of female : male sex ratios, and ecological and genetic impacts on wild populations and other native species. As precocious male maturation is significantly influenced by the growth rate at specific times of year, in future studies we will alter maturation rates through seasonal growth rate manipulations.