Search

Your search keyword '"McKern JL"' showing total 2 results
Start Over Author "McKern JL"
2 results on '"McKern JL"'

1. Sexual cycles and food of the doves Streptopelia chinensis and S. senegalensis in Australia

Author

Frith, HJ, McKern, JL, and Braithwaite, LW

Abstract

The sexual cycles, food and feeding habits of S. chinensis in Sydney, NSW, Melbourne, Vic., and Perth, WA, and those of S. senegalensis in Perth have been examined. In S. chinensis in each city and in S. senegalensis in Perth, many males were producing abundant sperm and many females had enlarged ovarian follicles in each month of the year. Nevertheless there were cycles of gonadal size in each city. The gonads were greatest in spring and summer and least in autumn and winter but in S. chinensis the phase of the cycle differed between the cities. There was reason to believe that the food, waste grain and bread, was abundant at all times and that its availability Was not greatly influenced by rainfall and other environmental factors. Supply of food probably was not the sole cause of the difference in phase of the cycles. Some of the difference in phase would have been caused by different genetic composition of the populations in the three cities.

Published
1976
Full Text
View/download PDF

2. Estuarine and early-marine survival of transported and in-river migrant Snake River spring Chinook salmon smolts.

Author

Rechisky EL, Welch DW, Porter AD, Jacobs-Scott MC, Winchell PM, and McKern JL

Subjects
Animals, Canada, Ecosystem, Fisheries methods, Fisheries statistics & numerical data, Geography, Marine Biology methods, Marine Biology statistics & numerical data, Pacific Ocean, Population Density, Population Dynamics, Rivers, Salmon growth & development, Survival Analysis, Telemetry methods, Time Factors, United States, Adaptation, Physiological physiology, Animal Migration physiology, Estuaries, Salmon physiology
Abstract

Many juvenile Snake River Chinook salmon are transported downriver to avoid hydroelectric dams in the Columbia River basin. As mortality to the final dam is ∼50%, transported fish should return as adults at roughly double the rate of nontransported fish; however, the benefit of transportation has not been realized consistently. "Delayed" mortality caused by transportation-induced stress is one hypothesis to explain reduced returns of transported fish. Differential timing of ocean entry is another. We used a large-scale acoustic telemetry array to test whether survival of transported juvenile spring Chinook is reduced relative to in-river migrant control groups after synchronizing ocean entry timing. During the initial 750 km, 1 month long migration after release, we found no evidence of decreased estuarine or ocean survival of transported groups; therefore, decreased survival to adulthood for transported Chinook is likely caused by factors other than delayed effects of transportation, such as earlier ocean entry.

Published
2012
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results