Richard J. Beamish

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Projected shifts in climate forcing variables such as temperature and precipitation are of great relevance to arctic freshwater ecosystems and biota. These will result in many direct and indirect effects upon the ecosystems and fish present therein. Shifts projected for fish populations will range from positive to negative in overall effect, differ among(More)
Arctic freshwater and diadromous fish species will respond to the various effects of climate change in many ways. For wide-ranging species, many of which are key components of northern aquatic ecosystems and fisheries, there is a large range of possible responses due to inter- and intra-specific variation, differences in the effects of climate drivers(More)
We hypothesise that salmon year class strength is determined in two stages during the first year in the ocean. There is an early natural mortality that is mostly related to predation, which is followed by a physiologically-based mortality. Juvenile salmon that fail to reach a critical size by the end of their first marine summer do not survive the following(More)
Otoliths, or ‘ear stones’, are calcium carbonate structures found in all vertebrates. In teleosts, they have a number of sensory functions, including hearing. Daily growth increments of these structures have permitted advanced age and population studies of teleosts. Whereas ‘normal’ otoliths are composed of crystals imbedded within a protein matrix as(More)
Karyotypes prepared from tissues of gills, gonads, fins, liver, and spleen, yielded the following diploid numbers: all Esox spp. 50, all Umbra spp. (excluding U. krameri) 22, Novumbra hubbsi 48, Dallia pectoralis 78. DNA measurements from Feulgen stain content of erythrocytes, indicated that the species could be divided into two categories: 30–39% of(More)
Sable®sh (Anoplopoma ®mbria) were recaptured up to 20 years after being injected with oxytetracycline (OTC). After 20 years the OTC mark is clear in most otoliths. Our examination of these otoliths con®rmed that sable®sh are long-lived and grow slowly after maturity. Annuli that formed beyond the OTC mark could be dif®cult to interpret in broken and burnt(More)
Histological techniques and immunohistochemistry with antisera against insulin and somatostatin were used in a study of the identification and the distribution of endocrine pancreatic tissue in adults of four species of lampreys in British Columbia. The fine structure of the pancreatic cells of one of the species was also examined. The four species(More)
Pacific salmon abundance along the West Coast of Canada has been in sharp decline since the early 1990s. Declines have been most severe for coho and chinook salmon despite large additions of hatchery-reared fry and smolts. There is particular concern for populations of wild coho because, in addition to low abundance, up to 80% of the juvenile coho in the(More)
It is well known that current equilibrium-based models fall short as predictive descriptions of natural ecosystems, and particularly of fisheries systems that exhibit nonlinear dynamics. For example, model parameters assumed to be fixed constants may actually vary in time, models may fit well to existing data but lack out-of-sample predictive skill, and key(More)
Stable oxygen and carbon isotope ratios ( 18O and 13C) from archived otoliths of Pacific halibut, Hippoglossus stenolepis, were measured to examine the most recent regime shifts in British Columbia and the Gulf of Alaska. 18O values of these otoliths ranged from −1.5 to +2.8‰ VPDB, and were consistent with the life stages and migration behavior of halibut.(More)