Summer osmoregulatory capacity of the world's northernmost living salmonid

Anadromous Arctic charr (Salvelinus alpinus L.) were caught on their way to and from the sea with the use of a fish trap placed in the Dieset watercourse located on the Spitsbergen Island (79 degrees 10' Northern latitude) within the high-Arctic Svalbard archipelago. When subjected to a seawater challenge test (34 parts/thousand at 4-5 degrees C), charr on their way to the sea showed only minor and temporary changes in blood plasma osmolality and Na+ and Mg2+ concentrations. The seawater tests also revealed good hypoosmoregulatory capacity for Arctic charr returning from the marine environment 4 wk later. A progressive decrease in seawater tolerance was first documented 7-11 days after their return to the freshwater habitat. Thus the Svalbard charr, being the northernmost anadromous salmonid and probably a direct descendant from the first Salvelinus immigrants to freshwater systems, undergoes a preparatory increase of hypoosmoregulatory capacity (smoltification) before entering the oceanic water bodies. Furthermore, the termination of their short annual seawater stay is probably elicited by factors controlling body systems other than osmoregulation.

Download Full-text

Annual Variations in Rheotactic Behaviour and Seawater Adaptability in Landlocked Arctic Char (Salvelinus alpinus)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f92-052 ◽

1992 ◽

Vol 49 (3) ◽

pp. 448-452 ◽

Cited By ~ 21

Author(s):

Monika Schmitz

Keyword(s):

Seasonal Changes ◽

Salvelinus Alpinus ◽

Challenge Test ◽

Early Summer ◽

Rapid Decrease ◽

Arctic Char ◽

Migratory Behaviour ◽

Annual Variations ◽

Seawater Tolerance ◽

Seawater Challenge

The existence of basic smoltification characteristics, measured by means of seasonal changes in rheotactic behaviour and seawater adaptability, was studied from February to November in 1- and 2-yr-old landlocked Arctic char (Salvelinus alpinus). Up- and downstream directed movements were monitored in an annular stream tank at a water velocity of 0.2 m/s. A 48-h seawater challenge test using 25‰ seawater was performed at monthly intervals throughout the year to assess seawater adaptability. The 1-yr-old char displayed mainly nondirectional behaviour during spring, but from August onwards the movements were predominantly against the current. Seawater performance improved slightly in this group in May and June. The 2-yr-old char progressively developed a downstream behaviour and exhibited an increased seawater adaptability during spring and early summer. In late August, a marked reversal in rheotactic behaviour occurred, followed by a rapid decrease in seawater tolerance. The results demonstrate that seasonal changes in seawater adaptability and changes in migratory behaviour which were directionally consistent with smolting still exist in a population of Arctic char that has been landlocked for about 6000 yr.

Download Full-text

Population structure, ecological segregation and reproduction in non-anadromous Arctic charr, Salvelinus alpinus (L), in four unexploited lakes in the Canadian high Arctic

Journal of Fish Biology ◽

10.1111/j.1095-8649.1991.tb03098.x ◽

1991 ◽

Vol 38 (1) ◽

pp. 123-147 ◽

Cited By ~ 52

Author(s):

H. H. Parker ◽

L. Johnson

Keyword(s):

Population Structure ◽

Salvelinus Alpinus ◽

Arctic Charr ◽

High Arctic ◽

Canadian High Arctic ◽

Ecological Segregation ◽

Anadromous Arctic Charr

Download Full-text

Seawater tolerance in first-time migrants of anadromous Arctic charr (Salvelinus alpinus)

Polar Biology ◽

10.1007/s003000000208 ◽

2001 ◽

Vol 24 (4) ◽

pp. 270-275 ◽

Cited By ~ 10

Author(s):

Odd A. Gulseth ◽

Kjell J. Nilssen ◽

Martin Iversen ◽

Bengt Finstad

Keyword(s):

Salvelinus Alpinus ◽

Arctic Charr ◽

Anadromous Arctic Charr ◽

Seawater Tolerance ◽

First Time

Download Full-text

Development of Hypoosmoregulatory Capacity in Arctic char (Salvelinus alpinus) Reared under either Continuous Light or Natural Photoperiod

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f92-027 ◽

1992 ◽

Vol 49 (2) ◽

pp. 229-237 ◽

Cited By ~ 47

Author(s):

Arne M. Arnesen ◽

Morten Halvorsen ◽

Kjell J. Nilssen

Keyword(s):

Water Content ◽

Salvelinus Alpinus ◽

Plasma Osmolality ◽

Continuous Light ◽

Arctic Char ◽

Direct Transfer ◽

Seawater Tolerance ◽

Natural Photoperiod ◽

Muscle Water Content ◽

Muscle Water

Two groups of Arctic char (Salvelinus alpinus) were reared in freshwater (5–6 °C) under either continuous light (LDL) from first feeding (March) or LDL until July and then natural photoperiod (NDL, 70°N). Direct transfer to seawater (5.5 °C, 35 ppt) in February resulted in both groups exhibiting increases in blood plasma osmolality, Na+, and Mg2+ concentrations and a significant decrease in muscle water content. When tested in May, an improvement in seawater tolerance was evident in both groups. In June, only the NDL fish showed further improvements in hypoosmoregulatory capacity, since they exhibited only minor fluctuations in plasma constituents and muscle water content following direct transfer to seawater. Increased body size could partially explain the improved seawater tolerance in the experimental groups. Acclimation to brackish water prior to transfer to 35 ppt seawater in June improved seawater tolerance only in fish reared under continuous light. The results indicate that the seasonal increase in photoperiod stimulates the development of hypoosmoregulatory capacity whilst the fish are still resident in freshwater.

Download Full-text