Ecology, behaviour and conservation of the charrs, genus Salvelinus

Salvelinus species are one of the most thoroughly studied groups of fishes. Many reasons explain this intense interest in charr biology. Charrs have a Holarctic distribution encompassing many Asian, North American, and European countries and occupy diverse marine and freshwater environments. Furthermore, the current distribution of charr includes areas that were directly influenced by climate and topographic change associated with the many Pleistocene glaciations. Undoubtedly, these conditions have promoted much of the tremendous morphological, ecological, and genetic variability and plasticity within Salvelinus species and they make charr very good models to study evolutionary processes 'in action'. Many charr species also exhibit demographic characteristics such as slow growth, late maturity, and life in extreme environments, that may increase their susceptibility to extinction from habitat changes and overexploitation, especially in depauperate aquatic habitats. This vulnerability makes understanding their biology of great relevance to biodiversity and conservation. Finally, charr are of great cultural, commercial, and recreational significance to many communities, and their intimate linkage with human societies has stimulated much interest in this enigmatic genus. This volume comprises a selection of papers presented at the fourth International Charr Symposium held in Trois-Rivières (Québec, Canada), from 26 June to 1 July 2000. It includes 31 papers on ecological interactions and behaviour, trophic polymorphism, movement and migration, ecophysiology and evolutionary genetics, ecological parasitology, environmental stress and conservation. These studies cannot cover all recent developments in the ecology, behaviour and conservation of Salvelinus species, but collecting them into a special volume should bring attention to current research on this important genus and stimulate further work on Salvelinus species.

Prelude.- Developments in the ecology, evolution, and behaviour of the charrs, genus Salvelinus: relevance for their management and conservation.- Keynote.- Charrs, glaciations and seasonal ice.- 1. Ecological interactions and behaviour.- Takvatn through 20 years: long-term effects of an experimental mass removal of Arctic charr, Salvelinus alpinus, from a subarctic lake.- Spatial and temporal variability in the diet of anadromous Arctic charr, Salvelinus alpines, in northern Labrador.- The relationship between spatial distribution and diet of Arctic charr, Salvelinus alpines, in Loch Ness, U.K..- Growth and dietary niche in Salvelinus alpinus and Salvelinus fontinalis as revealed by stable isotope analysis.- Does the refuge availability influence the spawning behavior of mature male parr in salmonids? A test in the Miyabe charr.- 2. Trophic polymorphism.- Diversification, sympatric speciation, and trophic polymorphism of Arctic charr, Salvelinus alpinus complex, in Transbaikalia.- The biology of Arctic charr, Salvelinus alpinus, of Gander Lake, a large, deep, oligotrophic lake in Newfoundland, Canada.- Physiological performance of two forms of lacustrine brook charr, Salvelinus fontinalis, in the open-water habitat.- 3. Movements and migrations.- Why do foraging stream salmonids move during summer?.- Local movement as a measure of habitat quality in stream salmonids.- Adaptations to stochastic environmental variations: the effects of seasonal temperatures on the migratory window of Svalbard Arctic charr.- Seasonal timing and diel activity of lacustrine brook charr, Salvelinus fontinalis, spawning in a lake outlet.- 4. Ecophysiology and evolutionary genetics.- Seasonal changes in osmotic and ionic regulation in Arctic charr. Salvelinus alpinus. From a high- and a sub-arctic anadromous population.- The effect of acute stress and temperature on plasma cortisol and ion concentrations and growth of Lake Inari Arctic charr, Salvelinus alpinus.- Phenotypic differences in buoyancy and energetics of lean and siscowet lake charr in Lake Superior.- A sex-linked microsatellite locus isolated from the Y chromosome of lake charr, Salvelinus namaycush.- Interspecific relationships among charrs based on phylogenetic analysis of nuclear growth hormone intron sequences.- Characterization of charr chromosomes using fluorescence in situ hybridization.- Physiological, endocrine, and genetic bases of anadromy in the brook charr, Salvelinus fontinalis, of the LavaI River (Québec. Canada).- 5. Ecological parasitology.- A comparative study of Eubothrium salvelini and E. crassum (Cestoda: Pseudophyllidea) parasites of Arctic charr and brown trout in alpine lakes.- Parasite-induced host mortality: indirect evidence from a long-term study.- 6. Environmental stress and conservation.- A comparison of Floy and soft Vlalpha tags on hatchery Arctic charr, with emphasis on tag retention, growth and survival.- The effect of Carlin tags on survival and growth of anadromous Arctic charr. Salvelinus alpinus.- Abundance, annual survival, and recruitment of unexploited and exploited lake charr, Salvelinus namaycush, populations at the Experimental Lakes Area, northwestern Ontario.- Biomass and production of lake charr during the acidification and pH recovery of a small Ontario lake.- Assessment of the feasibility of preventing reproduction of lake charr, Salvelinus namaycush, in shallow areas of reservoirs affected by drawdowns.- The relevance of individual size to management of Arctic charr, Salvelinus alpines, populations.- Decline of the migratory form in bull charr,Salvelinus confluentus, and implications for conservation.- Factors affecting redd site selection, hatching, and emergence of brook charr, Salvelinus fontinalis, in an artificially enhanced site.- Impact of the 1998 El Niño event on a lake charr, Salvelinus namaycush, population recovering from acidification.- Species and subject index.