Resilience and stability of north Labrador Arctic charr, Salvelinus alpinus, subject to exploitation and environmental variability

Abstract

There are relatively few studies that have examined in detail the effects of long term exploitation on population characteristics of Arctic charr, Salvelinus alpinus, coincident with natural changes in environmental conditions. This is particularly the case for anadromous charr despite their widespread use and importance in areas such as northern Canada. Here, the response of north Labrador charr to major reductions in commercial exploitation following long periods of intense fishing is described for three stock complexes with emphasis on changes in size, growth, and age configurations. Changes in age and size distribution, specifically long-term declines in weight, are linked with periods of intensive exploitation and possibly with variability in the climate of the northwest Atlantic that resulted in identifiable diet shifts during the early 1990s. Despite observed changes in some metrics, populations have maintained relatively stable length compositions with variations in weight showing resilience to return to earlier configurations as exploitation was reduced and environmental conditions ameliorated. Results of the long-term investigations challenge traditional beliefs associated with the inability of all anadromous charr to withstand periods of intense exploitation.

Dwarfs and cannibals in the Arctic: production of Arctic char (Salvelinus alpinus (L.)) at two trophic levels

“…The splitting into morphs like dwarfs and cannibals appears to be a universal trait of landlocked Arctic char populations in northern areas, but under identical hatchery conditions offspring of dwarf and cannibalistic char does not grow differently in speed or maximum size (Janhunen et al, 2010). However, management is critical dependent whether the mechanism underpinning life-history choice is purely dynamic and flexible (Nordeng, 1961;Johnson, 1980;Claessen et al, 2000Claessen et al, , 2002Dempson et al, 2008;Svanbäck et al, 2009) or if there are various levels of genetic control (Hindar et al, 1986;Svenning, 1993;Gislason et al, 1999). In a worst-case scenario from a management perspective, large-growing forms may represent unique genotypes and thereby a distinct management entity from small growing forms.…”

“…Evenset et al, 2004Evenset et al, , 2005Gewurtz et al, 2009) to harvesting of natural resources (e.g. Balikci, 1980;Dempson et al, 2008). Arctic char is also a valued resource, particularly in systems with large-growing forms (Aas & Skurdal, 1996).…”

The role of Salvelinus in contemporary studies of evolution, trophic ecology and anthropogenic change

“…Dempson, 1995;Dempson et al, 2008;Gallagher & Dick, 2010), there have been relatively few investigations focusing directly on human-charr interactions. The emergence of biotelemetry technologies has enabled researchers to document how undisturbed organisms interact with each other and their environment in real time (Cooke et al, 2004) and has great potential for applied research into human interactions with charrs.…”

Changes in growth patterns of wild Arctic charr (Salvelinus alpinus (L.)) in response to fluctuating environmental conditions

“…In particular, significant relationships between climatic variables and the mean size and age of Arctic charr captured on the Labrador shelf were noted for exploited stock complexes in the region (e.g. Dempson, 1995;Power et al, 2000;Dempson et al, 2008). Trends were established primarily between year-to-year variability in temperature and the mean size of charr in annual catches.…”

“…In addition to the impacts on marine species, changes were also observed in stock characteristics of anadromous Arctic charr (Salvelinus alpinus, Linneaus) in the Labrador region (Dempson, 1995;Power et al, 2000;Dempson et al, 2002Dempson et al, , 2008. In particular, significant relationships between climatic variables and the mean size and age of Arctic charr captured on the Labrador shelf were noted for exploited stock complexes in the region (e.g.…”