Early ocean residence is assumed to be a critical period for juvenile Pacific salmon Oncorhynchus spp. However, the specific mechanisms influencing growth and survival in the ocean have not been identified for most populations. Therefore, three hypotheses regarding the relationship between early marine residence and subsequent survival of mid-upper Columbia...
The Northern California Current (NCC) ecosystem exhibits extreme seasonal, interannual and interdecadal shifts in the abiotic environment and shifts in primary and higher production. This variability is also apparent in the spatial structure of the ecosystem with nearshore-shelf waters (<150 m isobath) being highly productive and having a different community...
The pigeon guillemot (Cepphus columba) population in Prince William Sound has failed to recover from declines that occurred both before and after the Exxon Valdez Oil Spill (EVOS). Post-spill studies of pigeon guillemot breeding biology have identified three potential factors limiting recovery: (1) predation on eggs and nestlings; (2) declines...
Effective and sustainable fisheries management not only depends on identifying and defining stocks (fundamental unit of management), but also on having knowledge of factors influencing the abundance, distribution and connectivity of stocks. Population structure of Pacific cod (Gadus macrocephalus) in the southeastern Bering Sea (EBS) remains unresolved although genetic data...
The lingcod (Ophiodon elongatus) is an important groundfish species in both recreational and commercial fisheries of the Northeastern Pacific. It is a large, fast-growing, generalist predator of invertebrates and fishes. In response to concerns that lingcod may limit populations of rockfishes (Sebastes spp.), I compared the diets of 375 adult...
Understanding how populations within a species interact across various geographic and temporal scales is fundamental to developing appropriate conservation strategies. I examined the geographic variation in genetic and meristic characters of coastal cutthroat trout (Oncorhynchus clarki clarki) based on
approximately 1,400 fish sampled from 54 populations spanning their distributional range...
Transferrin of Columbian black-tailed deer (Odocoileus
hemionus columbianus) displayed two types of polymorphism. One
type involved differences in sialic acid content. The nature of the
other polymorphism is not known. A hypothesis for three codominant
alleles at a common locus was proposed and tested by using the
Hardy-Weinberg Principle. The...
A study conducted May 1978-December 1980 determined that the present geographic range of Columbian white-tailed deer, Odocoileus virginianus leucurus, (CWTD) in Douglas County, Oregon encompassed 1199km2. The area was predominately a Quercus woodland community, typical of the Interior Valley Zone of western Oregon. The CWTD distribution
was not contiguous throughout...
The early marine phase following freshwater emigration has been identified as a critical period in salmonid (Oncorhynchus spp.) life history, characterized by high but variable mortality. Consistent with the “growth-mortality” and “bigger-is-better” hypotheses, at least some of the mortality during the critical period appears to be size-dependent – with smaller...
To begin to understand freshwater seasonal floodplain fish communities in the context of human alteration of the physical system, species introductions and wetland restoration efforts, I studied fish assemblages in fifteen seasonal floodplain wetlands within four geographic regions (coastal, upper Columbia River estuary, Puget Sound and eastern Oregon/Washington) in the...
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William J. Liss
To begin to understand freshwater seasonal floodplain fish communities in