Persistence of Infection by Metacercariae of Apophallus sp., Neascus sp., and Nanophyetus salmincola Plus Two Myxozoans (Myxobolus insidiosus and Myxobolus fryeri) in Coho Salmon Oncorhynchus kisutch
ABSTRACT We evaluated the ability of 5 muscle- or skin-dwelling parasites to persist in naturally infected coho salmon, Oncorhynchus kisutch, from the West Fork Smith River, Oregon, by holding them in captivity from late summer to early spring (parr stage to the typical time of smoltification). These parasites included metacercariae of 3 digeneans, Nanophyetus salmincola, Apophallus sp., and neascus sp., and 2 myxozoans, Myxobolus insidiosus and Myxobolus fryeri. Two groups of wild-caught fish were evaluated in the laboratory, i.e., heavily infected fish from the lower main stem and less severely infected fish collected from tributaries of this river. All parasites survived in these fish for the 7-month experiment. Only 2 parasites had a statistically significant lower median abundance between host life stages. The mean abundance of N. salmincola declined 45% in the tributary fish and Apophallus sp. declined 43% in the lower main stem fish. However, more than 50% of each species persisted until the end of the study, with smolts still harboring relatively high infections.
- SourceAvailable from: Camille A.-L. Leblanc
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- "Muscle and kidney samples were thawed and the entire amount of tissue weighed. We placed a subsample of muscle tissue (4.5–6.3 g) or the entire posterior kidney (0.02–0.24 g) between two pieces of Plexiglas with a small amount of water, and applied pressure to create a wet mount (Ferguson et al. 2010). We then examined the slide under a compound microscope to identify and enumerate parasites. "
ABSTRACT: Anadromous salmonids are viewed as a prized commodity and cultural symbol throughout the Pacific coast of North America. Unfortunately, several native salmonid populations are threatened or at risk of extinction. Despite this, little is known about the behavior and survival of these fish as the juveniles transition from freshwater to the ocean. Our primary objectives were to estimate survival of juvenile steel-head migrating between trapping sites and the ocean and evaluate whether survival in the estuary varies temporally (within a year) or spatially (within and between estuaries) within the same distinct population segment. We also evaluated whether flow or fork length were correlated with survival and collected information on variables that have been demonstrated to affect smolt survival in other studies to lend insight regarding differences in survival estimates between basins. We compared run timing, migration rate, sur-vival, condition factor, age composition and time of residence in the estuary for steelhead outmigrants from each basin and measured parasite loads in outmigrat-ing steelhead to evaluate potential differences in par-asite density and parasite community between basins. In 2009, we implanted acoustic transmitters in 139 wild steelhead smolts in two small rivers on the Ore-gon Coast. In general, only 40–50 % of the wild steelhead smolts tagged at upstream smolt traps were detected entering the ocean. The majority of mortality occurred in the lower estuary near the ocean. Wild steelhead smolts typically spent less than 1 day in Environ Biol FishEnvironmental Biology of Fishes 05/2013; 96:849-863. DOI:10.1007/s10641-012-0080-8 · 1.36 Impact Factor
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ABSTRACT: Population viability analysis (PVA) can guide conservation management and research by identifying the cheapest and most effective actions required to conserve populations and by prioritising research. The usefulness of a very preliminary PVA model is illustrated here for managing New Zealand mainland colonies of sooty shearwaters Puffinus griseus, a long-lived seabird that is preyed on by small carnivores and harvested by Maori for food. The model suggests that chicks can be safely cropped for transfer to depleted colonies, or for human consumption from the two large Otago colonies with populations exceeding the most conservative MVP of 520 individuals. The model also helps direct managers to where and when predator control will be most efficient. It predicts that predation of adults is more likely to have a greater effect on growth rates and MVPs than chick predation. Therefore, funding should be directed towards predator control at the beginning of the season when adults are most vulnerable. However, the model cannot determine population trends, nor rightly assure conservation managers that predator control is essential or even sufficient to prevent extinction. Preliminary models can assist by formalising how uncertain our current understanding is, but should not be expected to work a miracle of divining certainty from a lack of field information that still may take decades to collect. Less reliance should be placed on the predictions of population trends or extinction probabilities than on the model's guidance to the relative efficacy of different management actions.Biological Conservation 01/1995; 73(2-73):107-117. DOI:10.1016/0006-3207(95)90033-0 · 4.04 Impact Factor
Conference Paper: SIMD optimization in COINS compiler infrastructure[Show abstract] [Hide abstract]
ABSTRACT: COINS is a compiler infrastructure that makes it easy to construct a new compiler by adding/modifying only part of the COINS of compiling/optimization features. SIMD optimization is a major advantage. We present an overview of COINS and some topics on its SIMD optimization.Innovative Architecture for Future Generation High-Performance Processors and Systems, 2005; 02/2005