Search results for "Oregon"
showing 10 items of 88 documents
HELMINTH ASSEMBLAGES OF WHITEFISH (COREGONUS LAVARETUS) IN INTERCONNECTED LAKES: SIMILARITY AS A FUNCTION OF SPECIES SPECIFIC PARASITES AND GEOGRAPHI…
2004
This article examined the composition of parasite assemblages of whitefish (Coregonus lavaretus) in 8 interconnected lakes in northeastern Finland and evaluated the role of coregonid specific parasites and the geographical distance between populations in determining the similarity of the assemblages. Parasite assemblages were compared using the Jaccard qualitative similarity index and a quantitative similarity index and by incorporating the allogenic-autogenic species concept and the effects of 2 corresponding measures of geographical distance between the lakes. The majority of the parasite species found (10 of 14) were specific to salmonids. Similarity of assemblages of autogenic parasites…
Oxygen consumption of burbot, Lota lota(L.), fed different rations of vendace, Coregonus albula L.
2000
Summary The oxygen consumption of adult burbot, Lota lota (L.), was examined to determine the effects of fasting and meal ration on oxygen consumption rates. The temperature (2.1 °C) was selected to represent ambient conditions for burbot in winter. The average pre-feeding oxygen consumption rate was 29.5 mg kg−1 h−1. Feeding affected the oxygen consumption rates since the apparent heat increment correlated significantly with the meal ration. However, the meal ration (i.e. vendace, Coregonus albula L.) did not affect the proportion of the ingested meal energy used in the apparent heat increment. When the meal ration was increased, peak oxygen consumption ranged from 1.2 to 2.2 times higher …
Occurrence of Yersinia ruckeri infection in farmed whitefish, Coregonus peled Gmelin and Coregonus muksun Pallas, and Atlantic salmon, Salmo salar L.…
1986
Yersinia ruckeri, the aetiological agent of enteric redmouth disease (ERM), is now generally recognized to be distributed worldwide. The pathology and epizootiology of the disease was first described by Rucker (1966) and although rainbow trout, Salmo gairdneri Richardson, has been the most frequently affected species, all salmonids are now considered to be potential hosts for the organism (McDaniel 1979). The present paper reports the first confirmed occurrence of Y. ruckeri infection in farmed whitefish and Atlantic salmon, Salmo salar L., in Finland, with the known host range being extended to include the whitefish Coregonus peled Gmelin and Coregonus muksun Pallas . The outbreaks of infe…
Dietary plasticity of Arctic charr (Salvelinus alpinus) facilitates coexistence with competitively superior European whitefish (Coregonus lavaretus)
2011
– Habitat use and diet of Arctic charr (Salvelinus alpinus) coexisting with European whitefish (Coregonus lavaretus) and grayling (Thymallus thymallus) were studied in one deep and two relatively shallow subarctic lakes in northern Norway. Stomach content and stable isotope analyses revealed clear and temporally stable resource partitioning between the species in all three lakes. Arctic charr had a wide and flexible trophic niche and was the only piscivorous species. In contrast, whitefish and grayling had remarkably stable planktivorous and benthivorous niches, respectively. In the deepest lake, Arctic charr together with grayling mainly utilised littoral benthos, while piscivory was more…
The Adaptation of Professional Fishing to Diminished Vendace Stocks: The Case of Finnish Inland Waters
1999
Abstract The large number of lakes covering 10% of Finland's surface area provide an opportunity for both full-time and part-time professional fishing. However, the development of the fishing industry is hindered by unpredictable fluctuations in fish stocks, by the elaborate hierarchy of the fisheries system, as well as by certain features of Finnish professional fishing, such as the small size of fishing enterprises, the scattered pattern of production, and long transportation distances to the core demand areas. According to Finnish catch statistics, the stock of vendace Coregonus albula has clearly diminished since the mid 1980s. Our results show that full-time professional fishermen diff…
Acanthocephala in fish from the Bothnian Bay, Finland
1990
A sample of 7266 fish from 31 species was obtained from the north-eastern Bothnian Bay, Baltic Sea, from 1975 to 1982. Twenty-six fish species were found to be infected with seven acanthocephalan species identified as Echinorhynchus salmonis, E. bothniensis, E. borealis, E. gadi, Acanthocephalus anguillae, A. lucii and Neoechinorhynchus rutili. Acanthocephalus lucii was the only acanthocephalan not to attain sexual maturity M at least one species of fish. Fourteen new host records were found for E. bothniensis. A total of 1576 acanthocephalan infections was found; in most cases these were single species infections, but in 108 cases infections of two, and in two cases of three species were o…
Lifting the Vendace, Coregonus albula, on the Life Table : Survival, Growth and Reproduction in Different Life-Stages during Very High and Low Abunda…
2021
We analyzed the variability in vendace population parameters in the context of a life table. Parameters related to growth, fecundity and survival were estimated for post-recruitment (age > 1 growing season) life stages of Lake Southern Konnevesi vendace in both very high and low population abundance regimes. Pre-recruitment survival producing population stability was then determined. We found a very strong compensatory density dependence in growth, fecundity and survival: during low abundance, a lifetime reproductive output of a female was almost 20 times that of the abundant regime. To maintain the low abundance regime, pre-recruitment survival must counterbalance it by decreasing to a ver…
The use of fish bile metabolite analyses as exposure biomarkers to pulp and paper mill effluents
1998
The exposure of caged one-year-old whitefish (Coregonus lavaretus) to wood extractives and chlorophenolics from pulp and paper mill effluents in Lake Saimaa (SE Finland) was investigated. Whitefish were exposed at 17 locations affected by effluents from pulp and paper mills and at 5 reference areas. Resin and fatty acids and chlorophenolics in bile were analysed by GC and GC-MS. Cholesterol concentration in bile was also measured. Results show that despite of process changes to ECF and waste water treatment improvements employed by the pulp and paper industry in the study area, it is still possible to detect elevated concentrations of these substances in the bile of fish exposed in the vici…
Eye fluke infection and lens size reduction in fish: a quantitative analysis.
2008
Parasites have a variety of harmful effects on their hosts, some of which may be overlapping or complementary and thus easily overlooked but which are still important for the overall severity of infection. We investigated the effect of Diplostomum sp. eye fluke infection on the size of the eye lens in a range of wild and farmed fish species and those exposed to controlled parasite infection. We found that asymmetry in intensity of infection between the right and left lens of an individual fish affected lens size such that the lens with the higher intensity of infection was smaller. Interestingly, however, this was observed only in 3 of the 10 species studied (whitefish, smelt and sea trout)…
Genetic-based evaluation of management units for sustainable vendace (Coregonus albula) fisheries in a large lake system
2022
The goal of the processing industry, trade and consumers is to get eco-labelled freshwater fish products from sustainable fisheries into the market as soon as possible. The fourth largest natural lake system in Europe, the Saimaa lake system supports a fishery for vendace (Coregonus albula). Certification of the fishery requires an understanding of population structure to help determine the number and spatial extent of management units. In this study, we analysed the genetic diversity of local vendace populations in the Saimaa lake system and aimed to identify the conservation and management units of vendace. Within the Saimaa, the genetic divergence between local populations of vendace was…