Search

Arctic char, Salvelinus alpinus (L.), captured during the summer, 1972, in Cumberland Sound, Baffin Island, fed mainly on planktonic amphipods (Parathemisto libellula, Pseudalibrotus glacialis), copepods (Calanus hyperboreus), and fish (Boreogadus saida, Myoxocephalus sp.), but failed to utilize coelenterates, planktonic gastropods, and epi- and infauna. The considerable variation in the species composition of the diet of char of different lengths was due primarily to size selection. The average length of all individuals in stomach contents and of representatives of most food species increased with the length of fish. The minimum and maximum length of frequently ingested organisms increased four and 90 times, respectively, as char increased from 4 to 85 cm. Char less than 10 cm in length captured in rivers tributary to the Sound fed mainly on larval Chironomidae (Eukiefferiella bavaria) during the summer, whereas those longer than 10 cm fed predominantly on other char. During the winter the stomachs of the smaller individuals were always empty while the diet of the large char was restricted to other fish. Most species available to the char were consumed in proportion to their relative abundance in the rivers. The dry weight of stomach contents, when expressed on a unit weight basis, decreased with the wet weight of char in both fresh and salt water. Thus, fish 10 g in weight contained approximately 1.5 times more food in their stomachs than those weighing 1000 g. The stomach contents of char captured in salt water weighed approximately 11 times more than those of char of comparable size captured simultaneously in fresh water. The fish fed at random intervals during the day and ceased feeding at night. Arctic char, at all sampling areas, had reached a length of approximately 9.6 cm after four years. Upon migrating to salt water, their growth rate increased sharply with the result that after eight years they were 26.5 cm in length, reflecting food availability. The growth rate gradually decreased in fish older than nine years so that 20 year olds were approximately 70.0 cm in length.

Bulbodacnitis alpinus sp. nov. is described from Salvelinus alpinus L. from the North Slope of Yukon and Alaska. Bulbodacnitis alpinus was found to be present in both anadromous and freshwater resident stream populations but it is absent from lake populations of S. alpinus. Specimens of B. occidentalis Smedley, 1933, B. scotti Simon, 1935, B. ampullastoma Maggenti, 1971, and B. truttae (Fabricius, 1794) were examined and comparative measurements are presented. Bulbodacnitis scotti, B. ampullastoma, and B. occidentalis are considered synonyms of B. truttae.

Cache Creek Spring provides an unusual overwintering habitat for a population of Arctic char (Salvelinus alpinus) isolated above a falls impassable to fish moving upstream. During winter, water temperatures (14–16 C) and dissolved solid concentrations (approximately 2600 ppm) are high and oxygen concentrations (0.2–6.8 ppm) are low. Arctic char in the springs differ meristically from those downstream of the falls. The former have significantly more gillrakers (mean 21.7 compared with 21.1) and parr marks (15.1 and 13.5) but fewer pyloric caeca (26.0 and 28.2) and vertebrae (64.7 and 67.1) than the latter. Growth appears similar to that of char inhabiting more typical spring habitats.

Arctic grayling, Thymallus arcticus, and Arctic char, Salvelinus alpinus, were collected by angling and seining in remote areas of northern Yukon Territory. Stomach samples were observed to test the hypothesis that fish caught by angling had eaten less food than those caught by seining. The hypothesis was supported by the data for grayling. The data for char were consistent with the hypothesis, but the results were not statistically significant. There was no difference in the sex ratio of fish caught by the two methods. Angling selected larger char than did seining, but there was no evidence of size selection in grayling.

The routine of resting oxygen consumption of Arctic char (Salvelinus alpinus) from a high arctic lake (74°42′N) was measured at 2 (acclimated) and 6 C (unacclimated). The oxygen uptake versus wet weight relation at 2 C was: Log O2 uptake = 0.7316 Log weight – 1.0944. Oxygen uptake was low, not showing any evidence of "cold adaptation," and was comparable to projections of oxygen uptake versus temperature relations of other salmonid fish from lower latitudes.The short term metabolic response to a rise in temperature of 4 C was independent of body size except with fish with yolk sacs and weighing less than 0.125 g.

Parasites were present in thin blood films from only 6 of 188 fishes of 11 species, collected in the Northwest Territories and northern Quebec. The haemoflagellate, Cryptobia gurneyorum (Minchin), is recorded from North America for the first time—from the type host, Esox lucius L., and from two new ones, Coregonus clupeaformis (Mitchill) and Salvelinus namaycush (Walbaum). Haemogregarina irkalukpiki n.sp., characterized by its large size (av., 17.2 by 3.2 μ) and nucleophilic habit, is described from two sea-run arctic char, Salvelinus alpinus (L.).

1. Adult Arctic char (Salvelinus alpinus), taken in summer from Hebron Fjord, Labrador, and Hudson Bay near Churchill, Manitoba, were transferred directly from salt to fresh water under fairly constant conditions.2. Decreases in blood freezing point and chloride concentration of the order of 25% were found, the char thus being like most other anadromous salmonids in this respect. The possibility of much better regulation of muscle concentrations is indicated.3. Data are presented on plasma freezing point, chloride, and potassium, muscle solids, chloride, and potassium.4. Physiological differences between populations of char are indicated.

Vättern, the second largest lake of Sweden, contains 28 species of fish, of which Arctic char (Salvelinus alpinus) and whitefish (Coregonus spp.) are the most important economically. There is both a commercial fishery and a sport fishery. The former has decreased steadily, while the latter is increasing. A modest eutrophication is occurring, due amongst other factors to an increasing input of phosphorus and resulting, for instance, in a decrease in transparency.The lake is, however, still to be characterized as typically oligotrophic. The input of polluting matters is alarming, especially as regards toxic substances. Exploitation of fish populations has on the whole increased, although the number of commercial fishermen decreases. The fishery on the char population and military activity may in the long run result in over-exploitation. An inverse correlation between the catches of char and whitefish has been explained as a result of interaction between the two species. An obvious increase in catches of the Coregonus species (whitefish and cisco) is taken to be the result of eutrophication. Introductions of "exotic" species have only resulted in one recorded case of reproduction of rainbow trout (Salmo gairdneri). Several promising experiments with the release of hatchery-reared fish, e.g. landlocked salmon (Salmo salar), have been carried out. Growth rate of several fish species in Vättern has appeared to be faster than normal.

1. 1. Molecular weights of the monomorphic serum esterases of brook trout, brown trout and Atlantic salmon were found to be 53,200, 52,100 and 54,200 respectively. 2. 2. A similar molecular weight of 54,200 was found for the Est F allele in arctic char, whereas the alternative allele in this species had a molecular weight of 89,200. 3. 3. Some biological implications of the findings are discussed.

Arctic char (Salvelinus alpinus L.) from the commercial sea run were sampled at five stations in northern Labrador. Otoliths were used for age determination. In the southern part of the range—Adlatok and Nain—commercial size is reached at 6 years and at places farther north in 7 years. There is also a tendency for older fish to occur as one proceeds north.Age, weight, and length frequencies as well as their relationship to one another were determined.Vertebral counts indicate little, if any, intermingling of populations between: Adlatok and Nain, Okkak Bay and Hebron, Adlatok and Ramah, Nain and Hebron. Fin ray counts conform with the vertebral results but indicate no significant difference between Adlatok and Nain or Nain and Okkak Bay fish.Variations in flesh colour from white to deep red is a distinct characteristic of Arctic char in northern Labrador; flesh colour has a distinct bearing on the market value of the fish.Principal food items included capelin, launce, young of mailed sculpin, Amphipoda, and Euphausiacea.

These three lakes of the Aare Valley in Switzerland have been subjected to increasingly intense fisheries exploitation in recent decades. Fishing intensities have been roughly comparable in the three lakes in any particular year. Attempts at introducing non-native species have been made in all lakes but none of the attempts have had appreciable effect. Nutrient loading, due to domestic wastes predominantly, has been much greater with the downstream Bielersee than the upper two lakes, and somewhat greater in the Thunersee than the highest lake, Brienzersee. But even the latter is now showing symptoms of nutrient stress, in that populations of indicator phytoplankters have recently erupted.Ecological effects ascribed to the fishery include a marked reduction in stocks of Arctic char due to angling and pelagic coregonines due to commercial gillnetting. The latter taxa have recently shown pronounced fluctuations in year-class abundance. An energetic hatchery program has mitigated exploitation effects to some extent.Total stocks of fishes have increased due to eutrophication with initial increases in all fish taxa, except perhaps Arctic char. The cyprinids, percids, and esocids have increased in the Bielersee to a far greater extent than the salmonids with a result that the latter are now contributing smaller proportions of the catches. The cyprinids have little economic value and their burgeoning stocks are creating ecological and economic problems in the Bielersee as well as many other Swiss lakes. The cyprinids apparently cannot be effectively controlled by piscivores such as esocids, even where the latter are assisted by a hatchery program.

1. 1. Electrophoretic patterns of five protein groups from seven geographically isolated populations of Salvelinus alpinus were compared. 2. 2. Muscle protein patterns of S. alpinus, S. aureolus and S. oquassa revealed no interspecific variations. 3. 3. Eye lens proteins, liver LDH and liver esterase demonstrated interpopulation variations which may be useful as population markers. 4. 4. A liver esterase polymorphism was found within the population from Matamek Lake, Quebec.

Two isolated populations of Arctic char (Salvelinus alpinus) in spring-fed tributaries of the Canning River, Alaska, had meristic characters that corresponded to those of the Western Arctic–Bering Sea form of Arctic char. The two populations demonstrated slight differences in growth rates, age at maturity, longevity, and food habits. The fish were characterized by small size (maximum 235 mm), low growth rates, low fecundities (maximum 199 eggs), and annual spawning after maturity. Mature fish were darkly pigmented and parr marks were retained throughout life. The spawning season appeared to be sometime in November, when the eggs of mature females averaged 3.8 mm in diameter.

Many important, recently glaciated oligotrophic lakes that lie in coastal regions around the northern rim of the Pacific Ocean produce anadromous populations of sockeye salmon, Oncorhynchus nerka. This paper describes the limnology and fish ecology of two such lakes in British Columbia, five in Alaska, and one in Kamchatka. Then we discuss the following general topics: the biogenic eutrophication of nursery lakes from the nutrients released from salmon carcasses wherein during years of highest numbers of spawners, lake phosphate balances in Lakes Babine, Iliamna, and Dalnee are significantly affected; the use of nursery lakes by young sockeye that reveals five patterns related to size and configuration of lake basins and the distribution of spawning areas; the interactions between various life history stages of sockeye salmon and such resident predators, competitors, and prey as Arctic char, lake trout, Dolly Varden, cutthroat trout, lake whitefish, pygmy whitefish, pond smelt, sticklebacks, and sculpins; the self-regulation of sockeye salmon abundance in these nursery lakes as controlled by density-dependent processes; the interrelations between young sockeye salmon biomass and growth rates, and zooplankton abundance in Babine Lake; and finally, the diel, vertical, pelagial migratory behavior of young sockeye in Babine Lake and the new hypothesis dealing with bioenergetic conservation.

Both anadromous and freshwater-resident populations of Arctic char (Salvelinus alpinus) occur in the Sagavanirktok River drainage, Alaska. A comparison of the gill-raker and pyloric-caeca counts of populations of the two types revealed that anadromous fish had lower gill-raker and pyloric-caeca counts than freshwater-resident fish. Freshwater-resident populations correspond meristically to McPhail's Eastern Arctic form, and anadromous population scor-respond to his Western Arctic–Bering Sea form (McPhail, J. Fish. Res. Bd. Canada 18: 793–816, 1961). It is suggested that the former was the original inhabitant of the area but has been replaced by the latter except in inaccessible, headwater lakes.

In 1956 fisheries studies were concentrated in the Mackenzie Delta region between Herschel Island and Tuktoyaktuk, where fishes are relatively varied and abundant. ... In addition to substantial beluga and ringed seal collections which were made for the mammal investigations, about 11,000 fish were sampled in all. ... a preliminary survey of fish stocks in Pelly and Garry lakes of the Back River system was undertaken .... The lakes, which are shallow (20-30 feet), were found to support sufficient stocks of whitefishes and lake trout to permit organized subsistence fishing should this be necessary. ... In 1957 one party carried out fisheries studies up the Mackenzie River from Aklavik to Fort Norman, and another surveyed fish stocks at Coppermine, N.W.T. An intensive study was made of the char run in Rowley River on Rowley Island, Foxe Basin by the M .V. Calanus and in northern Hudson Bay by whaleboat and by peterhead from Coral Harbour. Forty-five walrus were tagged in the latter area, and 20 were examined in detail. In Foxe Basin 60 walrus and 220 seals were sampled. The reproductive cycle, ages at maturity, and life expectancy have to a large extent been clarified by work on aging from growth layers in the cementum of molar teeth and in tusk development. ... In 1956 and 1957, a continued increase in the fishery for pilot whales in Newfoundland (1956 catch, about 10,000) led to emphasis on population studies. Investigations were begun as well on minke whales or lesser rorquals, with a small fishery at Dildo, Newfoundland as the source of material. ... During a 12-month period beginning in September 1955, collecting of plankton, benthos and hydrographic samples was carried out in northern Foxe Basin from the M.V. Calanus, based at Igloolik. Biological samples included net plankton, microplankton, bottom fauna and intertidal collections. Hydrographic sections were run across Fury and Hecla Strait, and between Jens Munk and Koch, Koch and Rowley, Koch and Baffin, Baffin and Bray, and Bray and Rowley Islands. Additional stations were occupied and water temperature, salinity, oxygen and phosphate values were determined. It thus has been possible to follow through a complete yearly cycle of hydrography and productivity in Foxe Basin. ...

The Geographical Branch of the Department of Mines and Technical Surveys was created in 1947. Under its terms of references, part of its responsibility is the collection and analysis of geographical information on northern Canada, in particular the territories under the jurisdiction of the federal government. In the decade since the Branch's inauguration, geographers have carried out various kinds of field surveys in the Canadian Arctic and subarctic, from the northern coast of Ellesmere Island to the Hudson Bay coastal plain in Ontario, and from the Alaska boundary to Labrador. These surveys have varied from parties formed entirely of geographers to individual shipboard observers or representatives on collaborative teams of scientists. The collection of basic information on the vast unknown expanses of the Arctic is peculiarly suited to the application of geographic methods. Utilizing the trimetrogon and vertical photography carried out since World War II, geographers have applied sampling techniques in interpreting larger areas, making intensive field studies of representative terrain types and expanding them by use of the air photos in delimiting, describing and analysing physiographic regions. Studies in physical geography have been the backbone of the work of the Branch in the Arctic. Air photo interpretation keys have been prepared for 14 areas: Alert, Eureka, Mould Bay, Resolute, Mackenzie Delta, Darnley Bay, Coppermine, Bathurst Inlet, Boothia Isthmus, Wager Bay, Southampton Island, Kaniapiskau-Koksoak Rivers in Ungava, the Hudson Bay Railway, and the Kenogami River. Reports on the human geography of various areas were included in the field reports and are mainly unpublished; several studies in historical geography also resulted from the field surveys. ...