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Results for “Canadian Journal of Fisheries and Aquatic Sciences”

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At least 523 records · Page 29Linked to original sources
USGS1980

Effects of sea lamprey (Petromyzon marinus) control in the Great Lakes on aquatic plants, invertebrates and amphibians

The chemicals 3-trifluoromethyl-4-nitrophenol (TFM) or a combination of TFM and 2a??,5-dichloro-4a??-nitrosalicylanilide (Bayer 73) have been used to control the sea lamprey (Petromyzon marinus) in the Great Lakes for about 20 yr. These chemicals cause some mortalities of Oligochaeta and Hirudinea, immature forms of Ephemeroptera (Hexagenia sp.), and certain Trichoptera, Simuliidae, and Amphibia (Necturus sp.). The combination of TFM and Bayer 73 may affect some Pelecypoda and Gastropoda, but its overall effects on invertebrates are probably less than those of TFM alone. Granular Bayer 73 is likely to induce mortalities among oligochaetes, microcrustaceans, chironomids, and pelecypods. No evidence exists that the lampricides have caused the catastrophic decline or disappearance of any species. The overall impact of chemical control of sea lampreys on aquatic communities has been minor compared with the benefits derived.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1993

Sediment resuspension, redeposition, and focusing in a small dimictic reservoir

Rates of seston (dry mass) sedimentation, estimated from sediment traps (ST rates) and sediment cores (SC rates), were determined at four water depths to examine seasonal and annual sedimentation patterns in Eau Galle Reservoir, Wisconsin (USA). Annual ST rates overestimated annual SC rates at water depths less-than-or-equal-to 4 m, suggesting that sediment resuspension and redeposition in relatively shallow regions of the reservoir caused the overestimate. In contrast, annual ST and SC rates were similar at depths >4 m, suggesting minimal sediment resuspension and redeposition in deeper regions of the reservoir. Using variations in daily ST rates estimated during the autumn overturn of 1987, we developed a conceptual framework for estimating sediment resuspension, redeposition, and focusing. Resuspension of shallow sediments during this particular period accounted for over 50% of the annual ST rate at depths less-than-or-equal-to 4 m. At the same time, focusing of resuspended shallow sediments to deeper regions accounted for about 20% of the annual ST rate at depths >4 m. Our results indicate that during autumn overturn in this reservoir, peaks in sedimentation in the deep, profundal region, estimated from sediment traps, may reflect sediment focused from shallow regions rather than sediment resuspended from the profundal region.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2001

The use of marine reserves in evaluating the dive fishery for the warty sea cucumber, Parastichopus parvimensis in California, U.S.A

In this paper we describe an instance of unusual, agonistic behavior in a flock of migrant Short-billed Dowitchers (Limnodromus griseus) . We compare this behavior to that of other flocks feeding at the same time at other locations in the same estuary and then present evidence suggesting that this behavior resulted from the patchy distribution of the probable foraging resource of this flock, eggs of the horseshoe crab (Limulus polyphemus). We propose that an extremely patchy resource has increased the agonistic behavior within the flock by increasing the variation in foraging success among individuals.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1995

Population differentiation in Pacific salmon: local adaptation, genetic drift, or the environment?

Morphological, behavioral, and life-history differences between Pacific salmon (Oncorhynchus spp.) populations are commonly thought to reflect local adaptation, and it is likewise common to assume that salmon populations separated by small distances are locally adapted. Two alternatives to local adaptation exist: random genetic differentiation owing to genetic drift and founder events, and genetic homogeneity among populations, in which differences reflect differential trait expression in differing environments. Population genetics theory and simulations suggest that both alternatives are possible. With selectively neutral alleles, genetic drift can result in random differentiation despite many strays per generation. Even weak selection can prevent genetic drift in stable populations; however, founder effects can result in random differentiation despite selective pressures. Overlapping generations reduce the potential for random differentiation. Genetic homogeneity can occur despite differences in selective regimes when straying rates are high. In sum, localized differences in selection should not always result in local adaptation. Local adaptation is favored when population sizes are large and stable, selection is consistent over large areas, selective diffeentials are large, and straying rates are neither too high nor too low. Consideration of alternatives to local adaptation would improve both biological research and salmon conservation efforts.

Canadian Journal of Fisheries and Aquatic Sciences↗