Bomb radiocarbon chronologies in the Arctic, with implications for the age validation of lake trout (Salvelinus namaycush) and other Arctic species

2008 ◽  
Vol 65 (4) ◽  
pp. 733-743 ◽  
Author(s):  
Steven E Campana ◽  
John M Casselman ◽  
Cynthia M Jones

Radiocarbon generated by atmospheric testing of nuclear weapons (bomb radiocarbon) produced a strong signal with an abrupt onset in the 1950s, which serves as a dated marker for tracing oceanic circulation and confirming age in animals forming growth bands. Here, we report the first prebomb and postbomb radiocarbon chronologies for marine and freshwater environments in the Canadian Arctic, extend the radiocarbon chronology for the northwest Atlantic Ocean, and use the onset of the bomb signal to validate our age interpretations of lake trout (Salvelinus namaycush) in Arctic lakes. Both surface and deepwater Arctic chronologies became detectable on or around 1958, similar to the year of onset elsewhere in the world. In contrast, the freshwater Arctic chronology increased sharply in 1957, with a peak value sixfold higher than the adjacent marine environment. The radiocarbon content of the adult otolith core validated our age interpretation criteria for Arctic lake trout to an age of at least 50 years. Otolith growth in such slow-growing fish was so low as to be unresolvable under conventional examination with a dissecting microscope. With these new radiocarbon reference chronologies, age validation of a large number of Arctic organisms should now be possible.


2019 ◽  
Vol 70 (12) ◽  
pp. 1781 ◽  
Author(s):  
John M. Casselman ◽  
Cynthia M. Jones ◽  
Steven E. Campana

The growth rates of freshwater fish in the Arctic would be expected to be very low, but some previous studies of lake whitefish (Coregonus clupeaformis) have reported relatively rapid growth and longevity estimates of less than 15 years. We used bomb radiocarbon chronologies to validate an ageing method based on otolith sections for lake whitefish in both an unexploited Arctic lake (MacAlpine Lake; longevity 50 years) and a lightly exploited temperate population (Lake Simcoe; longevity 49 years). Our results confirm previous suggestions that other ageing methods can seriously underestimate lake whitefish age after ~5–8 years. A Chapman–Robson estimate of instantaneous natural mortality rate (M) of 0.12 in the unfished Arctic lake was one-quarter of that measured in other Arctic lake whitefish populations, and one-third of that predicted by Pauly’s (1980) growth–temperature equation. The high estimates of M reported in other whitefish studies and by Pauly’s equation are almost certainly due to their being based on (incorrect) scale or surface otolith ages. Radiocarbon dating confirms that any attempt at predicting sustainable production for long-lived freshwater fishes like lake whitefish will need to be based on accurate ages derived from otolith sections.



2010 ◽  
Vol 67 (5) ◽  
pp. 842-853 ◽  
Author(s):  
Heidi K. Swanson ◽  
Karen A. Kidd ◽  
John A. Babaluk ◽  
Rick J. Wastle ◽  
Panseok P. Yang ◽  
...  

In the family Salmonidae, lake trout ( Salvelinus namaycush ) are considered the least tolerant of salt water. There are, however, sporadic reports of lake trout in coastal, brackish habitats in the Canadian Arctic. Otolith microchemistry analyses conducted on lake trout and Arctic char ( Salvelinus alpinus ) from four Arctic lakes in the West Kitikmeot region of Nunavut, Canada, revealed that 37 of 135 (27%) lake trout made annual marine migrations. Anadromous lake trout were in significantly better condition (K = 1.17) and had significantly higher C:N ratios (3.71) than resident lake trout (K = 1.05 and C:N = 3.34). Anadromous lake trout also had significantly higher δ15N (mean = 16.4‰), δ13C (mean = –22.3‰), and δ34S (mean = 13.43‰) isotope ratios than resident lake trout (means = 12.84‰, –26.21‰, and 1.93‰ for δ15N, δ13C, and δ34S, respectively); results were similar for Arctic char and agree with results from previous studies. Mean age of first migration for lake trout was 13 years, which was significantly older than that for Arctic char (5 years). This could be a reflection of size-dependent salinity tolerance in lake trout, but further research is required. These are the first detailed scientific data documenting anadromy in lake trout.



1978 ◽  
Vol 35 (1) ◽  
pp. 53-59 ◽  
Author(s):  
G. Power

Existing theories attempting to account for the predominance of older, larger individuals and the often observed bimodal character of the length-frequency distribution of unexploited northern fish populations were evaluated and rejected. The error in interpretation appears to result from problems in age determination of northern lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis). An alternative explanation of the observed structure of arctic lake fish populations is proposed. Growth of fish in these populations is relatively rapid until first maturity, when it becomes slow through a life span that may exceed 50 yr. Mortality declines rapidly through early life and stabilizes at a very low level through much of the life span. The combination of these growth and mortality patterns produces a population containing many small, few intermediate, and many large fish. Selection by gill nets provides a unimodal sample of large fish or a bimodal sample of large and smaller fish from such populations. A model is developed to demonstrate this and compared with results obtained from several northern Quebec lakes. Key words: Salvelinus namaycush, Coregonus clupeaformis, age, population structure, arctic lakes



Author(s):  
Alexander Gatch ◽  
Dimitry Gorsky ◽  
Zy Biesinger ◽  
Eric Bruestle ◽  
Kelley Lee ◽  
...  


1997 ◽  
Vol 54 (5) ◽  
pp. 1031-1038
Author(s):  
C A Stow ◽  
L J Jackson ◽  
J F Amrhein

We examined data from 1984 to 1994 for five species of Lake Michigan salmonids to explore the relationship between total PCB concentration and percent lipid. When we compared mean species lipid and PCB values, we found a strong linear correlation. When we compared values among individuals, we found modest positive PCB:lipid associations in brown trout (Salmo trutta), chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and rainbow trout (Oncorhynchus mykiss) collected during spawning, but positive associations were not apparent among nonspawning individuals. Lake trout (Salvelinus namaycush) exhibited no discernible PCB:lipid relationship. Our results are not incompatible with previous observations that contaminants are differentially partitioned into lipids within a fish, but these results do suggest that lipids are not a major factor influencing contaminant uptake.



1980 ◽  
Vol 37 (11) ◽  
pp. 1989-2006 ◽  
Author(s):  
Everett Louis King Jr.

Criteria for the classification of marks inflicted by sea lamprey (Petromyzon marinus) into nine categories were developed from laboratory studies in an attempt to refine the classification system used in field assessment work. These criteria were based on characteristics of the attachment site that could be identified under field conditions by unaided visual means and by touching the attachment site. Healing of these marks was somewhat variable and was influenced by the size of lamprey, duration of attachment, severity of the wound at lamprey detachment, season and water temperature, and by other less obvious factors. Even under laboratory conditions staging of some wounds was difficult, especially at low water temperatures. If these criteria are to be used effectively and with precision in the field, close examination of individual fish may be required. If the feeding and density of specific year-classes of sea lampreys are to be accurately assessed on an annual basis, close attention to the wound size (as it reflects the size of the lamprey's oral disc) and character of wounds on fish will be required as well as consideration of the season of the year in which they are observed.Key words: sea lamprey, attack marks, lake trout, Great Lakes



1989 ◽  
Vol 46 (3) ◽  
pp. 384-388 ◽  
Author(s):  
F. W. H. Beamish ◽  
J. C. Howlett ◽  
T. E. Medland

Juvenile lake trout, Salvelinus namaycush, of similar size were fed one of three isocaloric diets, each differing in protein and lipid content. Oxygen consumption and swimming performance were measured in a recirculating water flume at intervals throughout the 70-d feeding trials (10 °C). Swimming speed was increased by stepwise velocity increments (5 cm∙s−1) and oxygen consumption was measured at each velocity between 20 and 45 cm∙s−1. Oxygen consumption for a given speed did not differ significantly throughout the feeding trial nor among the diets implying a similarity in the quality and quantity of substrate catabolized for energy. Basal metabolism (0 cm∙s−1) was also independent of diet and feeding interval. Critical swimming speed increased with dietary and carcass protein content to suggest a direct association with muscle mass and number of myofilaments.



1997 ◽  
Vol 54 (6) ◽  
pp. 1299-1305 ◽  
Author(s):  
Robert France

The purpose of the present study was to determine if riparian deforestation would expose lake surfaces to stronger winds and therefore bring about deepening of thermoclines and resulting habitat losses for cold stenotherms such as lake trout (Salvelinus namaycush). Removal of protective riparian trees through wind blowdown and two wildfires was found to triple the overwater windspeeds and produce thermocline deepening in two lakes at the Experimental Lakes Area. A survey of thermal stratification patterns in 63 northwestern Ontario lakes showed that lakes around which riparian trees had been removed a decade before through either clearcutting or by a wildfire were found to have thermocline depths over 2 m deeper per unit fetch length compared with lakes surrounded by mature forests. Riparian tree removal will therefore exacerbate hypolimnion habitat losses for cold stenotherms that have already been documented to be occurring as a result of lake acidification, eutrophication, and climate warming.



2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Shauna M. Baillie ◽  
Andrew M. Muir ◽  
Michael J. Hansen ◽  
Charles C. Krueger ◽  
Paul Bentzen


1981 ◽  
Vol 38 (12) ◽  
pp. 1738-1746 ◽  
Author(s):  
Terrence R. Dehring ◽  
Anne F. Brown ◽  
Charles H. Daugherty ◽  
Stevan R. Phelps

Patterns of genetic variation among lake trout (Salvelinus namaycush) of eastern Lake Superior were examined using starch gel electrophoresis. We used 484 individuals sampled from three areas, representing three morphological types (leans, humpers, and siscowets). Of 50 loci examined, 44 were monomorphic in all groups sampled. Genetic variation occurs at six loci AAT-1,2, MDH-3,4, ME-1, and SOD-1. The average heterozygosity found (H = 0.015) is low relative to other salmonid species. A significant amount of heterogeneity exists among the 10 lake trout samples. These differences are due to variation within as well as between morphological types. The significance and management implications of these data are discussed.Key words: genetic variation, lake trout, Salvelinus namaycush, Lake Superior



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