Is the winter period a severe bottleneck of anadromous riverine Arctic charr parr?

Abstract

– Winter growth and survival of wild individually tagged juvenile Arctic charr (1+ age) from a riverine anadromous stock, were studied in a small ice‐covered (∼6 months) ground water brook (temperature ∼1 °C) connected to Skibotnelva in subarctic northern Norway. The overall winter survival was estimated to be 68% from late October 2005 to early May 2006. The recaptured charr were not significantly different in initial length or weight compared with the nonrecaptured fish suggesting low size‐dependent mortality. The majority (98%) of the recaptured charr showed significant increase in size, with a mean increment of 62% from their initial bodyweight and 12% of the charr parr had more than doubled their weight. The mean specific growth rate was calculated to be slightly lower (0.27) than estimated values from a growth model (∼0.35). In addition, the condition factor increased significantly during the field experiment. These results are the first individual growth data on riverine anadromous Arctic charr parr under natural winter conditions, and indicate that charr can grow relatively fast during periods with low temperature and also that ground water brooks can be good over‐wintering habitat for juvenile Arctic charr. These results suggest that the winter period is perhaps a less severe bottleneck than previously recognised for the cold‐adapted Arctic charr.

Growth and mortality of Arctic charr and European whitefish reared at low temperatures

“…Aquaculture of Arctic charr in Arctic regions is mainly based on flow-through systems that experience winter water temperatures ranging between 0 and 4°C for 5-8 months a year (Brännäs & Wiklund, 1992). This study demonstrates that the growth of juvenile Arctic charr at temperatures close to zero is comparable to other reported studies of hatchery reared and wild populations of Arctic charr kept at low winter (0-4°C) temperatures (Brännäs & Wiklund, 1992;Brännäs & Linner, 2000;Siikavuopio et al, 2009). We also expected some somatic growth of whitefish at the low temperature treatment (1°C), but whitefish instead lost weight in the first period of the experiment.…”

“…Increasing length increment of wild Arctic charr has been observed during the winter period in subarctic areas (Amundsen & Knudsen, 2009;Siikavuopio et al, 2009), but no such information exists for whitefish. The differences in length growth between the two species at temperatures close to zero may possibly be related to different species-specific adaptations to Arctic conditions.…”

“…Growth of Arctic charr and whitefish populations are known to be highly variable under natural conditions in subarctic areas (Svärdson, 1976;Johnson, 1980;Hammar, 1984;Klemetsen et al, 2003a;Østbye et al, 2006). From field studies, Arctic charr seem able to feed and grow and have relatively low mortality rates during winter periods with low water temperatures (Klemetsen et al, 2003b;Byström et al, 2006;Svenning et al, 2007;Siikavuopio et al, 2009;Amundsen & Knudsen, 2009). Due to its northern distribution, Arctic charr experience considerable seasonal changes in temperature throughout the year, and are well adapted to utilise the rapid seasonal changes in resource availability in the northern areas (Johnson, 1980).…”

Divergent growth patterns between juveniles of two sympatric Arctic charr morphs with contrasting depth gradient niche preferences

“…The ability of Arctic charr to feed and grow well at temperatures close to zero, compared with other cooccurring subarctic fish species such as brown trout and whitefish (Brännäs and Wiklund 1992;Byström et al 2006;Elliott and Elliott 2010;Siikavuopio et al 2009aSiikavuopio et al , 2010, is consistent with the view that Arctic charr is a well-adapted cold-water species. Additionally, this study also indicates heritable seasonal growth performance between sympatric populations (LO-and PB-morphs).…”

Tissue-specific molecular immune response to lipopolysaccharide challenge in emaciated anadromous Arctic charr

“…We asked the question whether animals exhibiting extreme adpatations, including extended fasting as part of a life-history strategy, show the same degree of immune response to immunostimulants as fed animals. To test this, we utilized the anadromous Arctic charr (Salvelinus alpinus), the northernmost freshwater fish and considered as the most cold-adapted species in the salmonid family (Siikavuopio et al, 2009). This species makes an annual seaward migration each spring where they exhibit concentrated bouts of heavy feeding before returning to freshwater every fall to overwinter.…”