Search results for "Coregonus"
showing 10 items of 73 documents
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)…
Long-term dynamics of pelagic fish density and vendace (Coregonus albula (L.)) stocks in four zones of a lake differing in trawling intensity
2001
– An 11-year time series of hydroacoustic fish density estimates and fisheries statistics of vendace (Coregonus albula (L.)) from four zones of a lake differing in trawling intensity was analyzed in order to test the hypothesis that intensive trawling has detrimental effects on pelagic fish stocks, especially vendace recruitment. The standardized fish density estimate in trawled zones showed no decrease in comparison to the non-trawled zone. No signs of recruitment failure associable with trawling intensity were found. The growth of vendace at the end of the study period was slower than that at the beginning, indicating a higher density, most clearly so in the zone with highest trawling int…
Genetic-based evaluation of management units for sustainable vendace (Coregonus albula) fisheries in a large lake system
2022
Abstract 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 ve…
Offspring performance is linked to parental identity and male breeding ornamentation in whitefish
2009
The ‘good genes’ hypothesis predicts that males advertise their quality with different sexual ornaments and that females are able to recognize the genetic quality of males by evaluating these characteristics. In the present study, we investigated the parental effects on offspring performance (feeding and swimming ability of newly-hatched larvae) and examined whether male ornamentation indicates offspring success in performance trials of whitefish (Coregonus lavaretus Linnaeus). Offspring first-feeding success had a strong paternal effect and it was also positively correlated with the size of male breeding tubercles, indicating that breeding ornamentation of males can function as an honest i…
Effects of waterborne iron overload and simulated winter conditions on acute physiological stress response of whitefish, Coregonus lavaretus
2003
Two-year-old whitefish (Coregonus lavaretus) were exposed for 30 days to episodic iron overload in iron-rich humic water (5%) supplemented with inorganic iron (5 mg FeL(-1)). Two parallel laboratory exposures were performed, one under conditions simulating winter and the other under conditions simulating spring. After exposure, some of the fish were subjected to acute handling stress in the form of a short air challenge to reveal possible modification of the primary and secondary stress responses. In whitefish sampled without additional handling, iron accumulated in the liver (under spring conditions) and gills (under winter and spring conditions); plasma catecholamine and beta-estradiol (b…
Seasonality of two gill monogeneans from two freshwater fish from an oligotrophic lake in northeast Finland.
1990
The seasonal occurrence of Dactylogyrus amphibothrium and Discocotyle sagittata from the gills of ruffe (Gymnocephalus cernuus) and whitefish (Coregonus acronius), respectively was studied in Lake Yli-Kitka, a large oligotrophic lake in Northeast Finland. The lake, located near the Arctic Circle, is ice-covered for 7-8 months of the year. The prevalence of D. amphibothrium infection was 70.7% and remained high throughout all size-classes of fish. The length distribution and developmental stages of the worms indicated two generations per year. The overwintering generation produces a summer generation which lives for only a few weeks and matures in July. Discocotyle sagittata has only one gen…