Genetic Diversity of Wild and Hatchery Lake Trout Populations: Relevance for Management and Restoration in the Great Lakes

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

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Fish community change in Lake Superior, 1970–2000

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f03-136 ◽

2003 ◽

Vol 60 (12) ◽

pp. 1552-1574 ◽

Cited By ~ 136

Author(s):

Charles R Bronte ◽

Mark P Ebener ◽

Donald R Schreiner ◽

David S DeVault ◽

Michael M Petzold ◽

...

Keyword(s):

Great Lakes ◽

Native Species ◽

Fish Community ◽

Lake Trout ◽

Community Change ◽

Osmerus Mordax ◽

Rainbow Smelt ◽

Additional Species ◽

Community Agencies ◽

Natural Reproduction

Changes in Lake Superior's fish community are reviewed from 1970 to 2000. Lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) stocks have increased substantially and may be approaching ancestral states. Lake herring (Coregonus artedi) have also recovered, but under sporadic recruitment. Contaminant levels have declined and are in equilibrium with inputs, but toxaphene levels are higher than in all other Great Lakes. Sea lamprey (Petromyzon marinus) control, harvest limits, and stocking fostered recoveries of lake trout and allowed establishment of small nonnative salmonine populations. Natural reproduction supports most salmonine populations, therefore further stocking is not required. Nonnative salmonines will likely remain minor components of the fish community. Forage biomass has shifted from exotic rainbow smelt (Osmerus mordax) to native species, and high predation may prevent their recovery. Introductions of exotics have increased and threaten the recovering fish community. Agencies have little influence on the abundance of forage fish or the major predator, siscowet lake trout, and must now focus on habitat protection and enhancement in nearshore areas and prevent additional species introductions to further restoration. Persistence of Lake Superior's native deepwater species is in contrast to other Great Lakes where restoration will be difficult in the absence of these ecologically important fishes.

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Burbot: Ecology, Management, and Culture

Burbot: Ecology, Management, and Culture ◽

10.47886/9781888569988.ch7 ◽

2008 ◽

Keyword(s):

Population Density ◽

Great Lakes ◽

Lake Erie ◽

Lake Trout ◽

Habitat Degradation ◽

Alosa Pseudoharengus ◽

Fish Stocks ◽

Pelagic Larvae ◽

Sea Lampreys ◽

Long Term Trends

Abstract.—Burbot Lota lota populations collapsed in four of the five Laurentian Great Lakes between 1930 and the early 1960s. Collapses in Lakes Michigan, Huron, and Ontario were associated with sea lamprey Petromyzon marinus predation, whereas the collapse in Lake Erie was likely due to a combination of overexploitation, decreased water quality, and habitat degradation. We examined time series for burbot population density in all five lakes extending as far back as the early 1970s to present time and characterized the long-term trends after the initial collapses. Burbot population density in Lake Superior has remained relatively low and stable since 1978. Recovery of the burbot populations occurred in Lakes Michigan and Huron during the 1980s and in Lake Erie during the 1990s. Control of sea lampreys was a requirement for recovery of burbot populations in these three lakes. Declines in alewife Alosa pseudoharengus abundance appeared to be a second requirement for burbot recovery in Lakes Michigan and Huron. Alewives have been implicated in the decline of certain Great Lakes fish stocks that have pelagic larvae (e.g., burbot) by consuming the pelagic fry and possibly by outcompeting the fry for food. Relatively high populations of adult lake trout Salvelinus namaycush compared to burbot served as a buffer against predation by sea lampreys in Lakes Huron and Erie, which facilitated recovery of the burbot populations there. Although sea lampreys have been controlled in Lake Ontario, alewives are probably still too abundant to permit burbot recovery.

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Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea ◽

10.47886/9781888569087.ch10 ◽

1998 ◽

Keyword(s):

Great Lakes ◽

Prey Species ◽

Lake Trout ◽

Life Stage ◽

Species Variation ◽

Osmerus Mordax ◽

Alosa Pseudoharengus ◽

Rainbow Smelt ◽

Thiamine Content ◽

Lake Variation

Abstract.—Thiamine concentrations in representative Great Lakes prey fish, including alewives Alosa pseudoharengus, rainbow smelt Osmerus mordax, slimy sculpin Cottus cognatus, bloater chub Coregonus hoyi, and lake herring Coregonus artedi, and their major dietary items, including mysids Mysis relicta, amphipods Diporeia hoyi, and net macroplankton, were measured to assess their potential involvement in depressed thiamine concentrations in lake trout Salvelinus namaycush of the Great Lakes. Mean thiamine concentrations in all biota were greater than the recommended dietary intake of 3.3 nmol/g for prevention of effects on growth, although the adequacy of these concentrations for reproduction is not known. Mean thiamine concentrations decreased in the order alewives > bloater chub, herring > smelt and differed from the order of associated egg thiamine concentrations published for lake trout feeding on these species (herring > alewives, smelt). As a result, these data strongly implicate the high thiaminase content, rather than the low thiamine content, of alewives and smelt as being responsible for the low egg thiamine concentrations of Great Lakes lake trout stocks that feed heavily on these species. Variations in thiamine content among prey species did not appear to be related to levels in their diet, because thiamine concentrations in Mysis, Diporeia, and macroplankton showed little consistency between group or between lake variation. There was no lake to lake variation in mean thiamine concentrations of prey species, but considerable within species variation occurred that was unrelated to size.

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Temperature response in the physiology and growth of lake trout strains stocked in the Laurentian Great Lakes

Journal of Great Lakes Research ◽

10.1016/j.jglr.2020.01.012 ◽

2020 ◽

Vol 46 (2) ◽

pp. 366-375

Author(s):

Issac Hébert ◽

Erin S Dunlop

Keyword(s):

Great Lakes ◽

Lake Trout ◽

Temperature Response ◽

Laurentian Great Lakes

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Conservation genetics of Pitcher’s thistle (Cirsium pitcheri), an endangered Great Lakes endemic

Botany ◽

10.1139/b10-006 ◽

2010 ◽

Vol 88 (3) ◽

pp. 250-257 ◽

Cited By ~ 8

Author(s):

Martha Gauthier ◽

Emily Crowe ◽

Lindsey Hawke ◽

Neil Emery ◽

Paul Wilson ◽

...

Keyword(s):

Genetic Diversity ◽

Great Lakes ◽

Genetic Data ◽

Nuclear Data ◽

Population Connectivity ◽

Chloroplast Microsatellite ◽

Management Plans ◽

Low Levels ◽

Cirsium Pitcheri ◽

Pitcher's Thistle

Pitcher's thistle ( Cirsium pitcheri Torr. ex Eaton (Torr. & Gray)) is a Great Lakes endemic that in Canada is designated as threatened at both the provincial (Ontario) and national levels. Management plans will benefit from conservation genetic data, which can provide insight into population genetic diversity and differentiation. We obtained genetic data from nuclear and chloroplast microsatellite markers from 17 populations of C. pitcheri around the Great Lakes. The nuclear data revealed overall low levels of diversity, high levels of inbreeding, and low levels of population connectivity. The chloroplast data identified a single haplotype, which is consistent with reduced genetic diversity following postglacial colonization. The high levels of inbreeding within populations will likely pose a serious threat to populations in the short term; these have resulted from a combination of low connectivity between populations, and small and fluctuating population sizes. Future management of C. pitcheri populations should consider human-mediated dispersal of plants or seeds among sites.

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