Age, Growth, Maturity, and Fecundity of Humper Lake Trout, Isle Royale, Lake Superior

Rahrer, Jerold F.

doi:10.1577/1548-8659(1965)94[75:agmafo]2.0.co;2

Cited by 43 publications

(17 citation statements)

References 5 publications

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“…have been described by Eschmeyer md Phillips (1965), Rahrer (1965), and Patriarche and Peck (19766 For personal use only. unique in having a very white ventral region, sometimes distended, with abnormally thin skin.…”

Section: Skcswets Half-breeds and Paperbelliesmentioning

confidence: 92%

Native Lake Trout (Salvelinus namaycush) Stocks in the Canadian Waters of Lake Superior Prior to 1955

Goodier¹

1981

Can. J. Fish. Aquat. Sci.

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Institute for Environanenlal Studies, Universiy of Toronto, Toronto, Ont. M5S dA4 GOODIER, 4. L. 1981. Native lake trout (Salvebinus namaycush) stocks in the Canadian waters of Lake Superior prior to 1955. Can. J. Fish. Aquat. Sci. 38: 1424-1734.The decline of Lake Superior lake trout (Salvelinus namaycezsh) stocks after the sea lamprey (Petromyzan marinus) population expIosion of the 1950s was both dramatic and decisive. Few native stocks remain to permit scientific data collection. However, interviews with old-time commercial fishermen suggest that there had existed many discrete or semidiscrete stocks within the lake. Historical documents in the form of government correspondence and reports, explorers' accounts, and Hudson's Bay Fur Co. records yield fuflher evidence.Possible stocks are distinguished on the basis sf anatomical features (including weight, body shape, and coloration) and behavioral differences (including seasonal movements and spawning habits). The relevance of these criteria for stock identification is discussed.Fishermen distinguished four general categories of S . narmaycush: leans, fats or siscowets, half-breeds, md humpers or paperbellies. In addition, different ""reeds" or forms of lean trout were commonly recognized. Often a form was known by a name referring to its most distinctive feature: blacks, redfins, yellowfins, grays, salmon-trout, red trout, moss trout, sand trout, and racers. These varieties are discussed and local spawning habits, grounds, and movements are summarized with maps, tables, and text. At least 200 former spawning grounds are identified, including 20 rivers which were once characterized by September runs sf lake trout. Spawning locations for the deep-water, nonlean trout variants (paperbellies, half-breeds, and siscowets) are less easily discovered. Approximately 35 fishing grounds are noted, with spawning reported at 4 of these. Consideration is given to the possible existence of phenotypically distinct stocks of siscowet.

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Section: Skcswets Half-breeds and Paperbelliesmentioning

confidence: 92%

Native Lake Trout (Salvelinus namaycush) Stocks in the Canadian Waters of Lake Superior Prior to 1955

Goodier¹

1981

Can. J. Fish. Aquat. Sci.

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“…Although considered a deep-water-type of lake charr, it is in comparison to the siscowet a leaner fish intermediate in fat content between leans and siscowets (Eschmeyer and Phillips 1965). Its small body size and high longevity (Rahrer 1965) suggest a restricted food supply. It is recognizable by its long Fig.…”

Section: Background On Formsmentioning

confidence: 99%

Differentiation of deep-water lake charr Salvelinus namaycush in North American lakes

Eshenroder

2007

Environ Biol Fish

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Deep-water morphs of lake charr, Salvelinus namaycush, are found, with one exception, in four of the largest lakes in the world: lakes Superior and Mistassini (QC) and Great Bear and Slave lakes. This paper advances a hypothesis for resource polymorphisms involving two types of deepwater morph, one of which is characteristic of the humper and the other of the siscowet charrs of Lake Superior. My hypothesis states that, first, the humper, or a humper-like morph, diverged postglacially in sympatry from the ancestral common (shallow-water) lake charr and became a feeding specialist on Mysis relicta. Second, in at least two of the four lakes the siscowet, or a siscowet-like charr, diverged as a feeding specialist on postglacially derived forms of deep-water ciscoes. In Lake Superior a successional process may have resulted in dominance of the siscowet at the expense of the humper charr. I concur with a previous inference that the one occurrence of a deep-water charr in a small lake (the above exception) represents emigration from Lake Superior. I further infer that this event involved an early humper charr, which implies that this morphotype had differentiated in Lake Superior in less than 1,900 year. I suggest that innate differences in plasticity, breeding behavior and assortive mating, and philopatry account for why Arctic charr isolate readily in small lakes whereas lake charr do not. My hypothesis assumes divergence of deep-water morphs occurred postglacially, an idea consistent with genetic and biogeographical evidence.

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“…The occurrence of sympatric morphotypes of lake trout therefore extends beyond the Laurentian Great Lakes. A few studies have compared life history (in terms of patterns in age, growth, and maturity) among lake trout morphotypes from the Great Lakes (e.g., Rahrer 1965;Burnham-Curtis and Bronte 1996). However, life history characteristics have not been compared between the newly described sympatric lake trout morphotypes that occur elsewhere in North America.…”

mentioning

confidence: 99%

“…Lake trout were classified as either humper or lean based on the characteristics described by Zimmerman et al (2007). We expected to find that humpers and leans in the lightly exploited Lake Mistassini would be older in age (due to low mortality), slower growing, and later maturing than exploited populations (Johnson 1972(Johnson , 1976 but would differ in life history characteristics (age, growth, survival, and maturity) because of the different habitat use (food and temperature) in Lake Mistassini than in the Laurentian Great Lakes (Rahrer 1965;Burnham-Curtis and Bronte 1996).…”

mentioning

confidence: 99%

Age, Growth, Survival, and Maturity of Lake Trout Morphotypes in Lake Mistassini, Quebec

et al. 2012

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Life history characteristics (age, growth, survival, and maturity) were compared between the deepwater “humper” and shallow‐water “lean” forms of lake trout Salvelinus namaycush in Lake Mistassini, Quebec, to determine whether the two morphotypes may represent resource polymorphism. Lake trout were sampled using graded‐mesh (range = 51–114 mm stretch) gill nets set in deep and shallow waters. Humpers were typically caught in deep waters (>50 m) and averaged 474 mm TL (range = 389–616 mm) and 852 g in weight (range = 470–1,710 g), whereas leans were typically caught in shallow waters (<50 m) and averaged 525 mm TL (range = 301–865 mm) and 1,210 g in weight (range = 200–6,500 g). Humpers and leans did not differ in weight–length relationships and grew slimmer with length over a common TL range (389–616 mm). Average age of humpers was 27 years (range = 13–49 years); average age of leans was 21 years (range = 6–42 years). The two forms did not differ in total annual mortality (A) of fish older than 17 years, the first age beyond which numbers declined with age for both morphs (A = 5.1%; 95% confidence interval = 2.4–7.8%). Humpers grew slower (annual growth rate ω = 53 mm/year) than leans (ω = 68 mm/year) and to a shorter mean asymptotic length (L∞ = 514 mm) than leans (L∞ = 605 mm). Mature humpers (mean TL = 475 mm, SE = 9.0; N = 58) were shorter on average than mature leans (mean TL = 539 mm, SE = 8.5; N = 65); mature humpers (mean age = 27 years, SE = 1.0; N = 56) were also older on average than mature leans (mean age = 23 years, SE = 0.98; N = 61). We conclude that lean and humper forms of lake trout in Lake Mistassini differed in age, growth, and maturity; this is consistent with the resource polymorphism that has been observed for other lake trout populations and other char species.

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Age, Growth, Maturity, and Fecundity of Humper Lake Trout, Isle Royale, Lake Superior

Cited by 43 publications

References 5 publications

Native Lake Trout (Salvelinus namaycush) Stocks in the Canadian Waters of Lake Superior Prior to 1955

Native Lake Trout (Salvelinus namaycush) Stocks in the Canadian Waters of Lake Superior Prior to 1955

Differentiation of deep-water lake charr Salvelinus namaycush in North American lakes

Age, Growth, Survival, and Maturity of Lake Trout Morphotypes in Lake Mistassini, Quebec

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