Decline and Recovery of the Lake Superior Gull Island Reef Lake Trout (<i>Salvelinus namaycush</i>) Population and the Role of Sea Lamprey (<i>Petromyzon marinus</i>) Predation

Swanson, Bruce L.; Swedberg, Donald V.

doi:10.1139/f80-248

Cited by 53 publications

(32 citation statements)

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“…The Apostle Islands of WI-2 host a small number of native lake trout that survived stock collapse (Swanson and Swedberg 1980;Schram et al 1995). Lake trout spawning activity was not evident at many historical spawning sites in the region in the early 1960s, but lake trout reproduced around some islands (Swanson and Swedberg 1980;Schram et al 1995). After fisheries were restricted in 1962, stock abundance steadily increased, but stocks declined again by 1975 after commercial fishing was resumed in 1970 .…”

Section: Methodsmentioning

confidence: 99%

“…Annual harvests of lake trout in Lake Superior averaged 2 3 10 6 kg during 1913-1950(Baldwin et al 1979, which suggested that annual yield was sustainable. Throughout the 1940s, annual yield was sustained by increased fishing intensity and a doubling of gill-net efficiency, but lake trout abundance in southern Lake Superior declined (Hile et al 1951;Pycha and King 1975;Swanson and Swedberg 1980). Sea lampreys Petromyzon marinus invaded Lake Superior in the 1940s and reached peak abundance around 1960 (Klar and Weise 1994).…”

Section: Recruitment Dynamics Of Lake Trout In Western Lakementioning

confidence: 99%

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Recruitment Dynamics of Lake Trout in Western Lake Superior during 1988–1995

Corradin

Hansen

Schreiner

et al. 2008

N American J Fish Manag

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Stocks of lake trout Salvelinus namaycush in Lake Superior are recovering from historical collapse. Stocking, control of sea lampreys Petromyzon marinus, and harvest restrictions have aided lake trout recovery, but the contribution of stocked lake trout to contemporary recruitment has not been quantified in western Lake Superior. Using variants of the Ricker stock-recruit model, we evaluated the production of age-7 lake trout (recruits) by examining age-8 and older wild and stocked parental lake trout (spawners). We found that density of wild lake trout spawners and recruits increased during 1980-2003, whereas the density of stocked spawners decreased in all management areas. Two competing models best described recruit density of the 1988-2003 year-classes: (1) wild and stocked parents each contributed to recruitment but stocked parents contributed negatively and (2) only wild parents contributed to recruitment. Recruitment rates declined significantly with increasing spawner density in four of five management areas, which suggests that recruitment is density dependent in much of western Lake Superior. We conclude that stocked lake trout did not contribute significantly to lake trout rehabilitation in western Lake Superior during 1980-1995.

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Section: Methodsmentioning

confidence: 99%

Section: Recruitment Dynamics Of Lake Trout In Western Lakementioning

confidence: 99%

Recruitment Dynamics of Lake Trout in Western Lake Superior during 1988–1995

Corradin

Hansen

Schreiner

et al. 2008

N American J Fish Manag

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“…Lake trout stocks in Lake Superior, unable to sustain themselves in the face of intensive fishery exploitation and sea lamprey predation, collapsed by 1962 (Py-476 RICHARDS ET AL. cha and King 1975;Pycha 1980;Swanson and Swedberg 1980). Attempts to restore lake trout stocks in Lake Superior began in 1952, when stocks were declining, with the stocking of juvenile hatchery-reared lake trout (Lawrie andRahrer 1972, 1973).…”

Section: Please Scroll Down For Articlementioning

confidence: 99%

Recruitment Dynamics of the 1971–1991 Year‐Classes of Lake Trout in Michigan Waters of Lake Superior

Richards

Hansen

Bronte

et al. 2004

N American J Fish Manag

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In the 1950s, populations of lake trout Salvelinus namaycush in Lake Superior collapsed because of excessive exploitation and predation by sea lampreys Petromyzon marinus. Restoration began in the 1950s with the stocking of juvenile, hatchery‐reared lake trout and controls on fisheries and sea lampreys. Partial restoration was declared in 1996 because wild fish made up most of the populations in many areas, especially in Michigan waters, so stocking was dramatically curtailed in most areas. We evaluated the production of age‐7 lake trout (recruits) by age‐8 and older wild and stocked parental lake trout (spawners). Using Ricker stock–recruitment models, we also evaluated the effects of large‐mesh (114‐mm stretch measure) gill‐net effort on wild lake trout recruitment in Michigan waters of Lake Superior during 1970–1998. In general, the density of wild lake trout spawners increased, whereas that of stocked lake trout spawners decreased in all management areas investigated. The density of recruits was best described by the combined density of wild and stocked parents, which suggested similar reproductive contributions for both. Recruitment rates declined significantly with increasing spawner density in four of the five management areas and suggested that carrying capacities were reached and exceeded, which may serve as an indicator of population restoration. We conclude that both wild and stocked lake trout have contributed to the recruitment of lake trout in Michigan waters of Lake Superior. Large‐mesh gill‐net fishing effort varied in all Michigan management areas but did not account for the significant variation in wild lake trout recruitment. We conclude that levels of large‐mesh gill‐net fishing effort during 1970–1998 were not having an appreciable effect on wild lake trout recruitment in Michigan waters of Lake Superior.

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“…Management agencies later reopened restricted recreational and commercial fisheries as lake trout stocks began to recover (Hansen et al, 1995). In Wisconsin waters, two refugia were also designated to protect lake trout (Swanson and Swedberg, 1980;Hansen et al, 1995). The Lake Superior Technical Committee (LSTC) set the sustainable limit of total annual mortality for lake trout at 42%, based on the work of Healey (1978) (LSLTTC, 1986), but how this limit was intended to apply to an age-structured population was not made explicit.…”

Section: Introductionmentioning

confidence: 99%

Modeling the sustainability of lake trout fisheries in eastern Wisconsin waters of Lake Superior

Nieland¹,

Hansen²,

Seider³

et al. 2008

Fisheries Research

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a b s t r a c tLake trout Salvelinus namaycush stocks in Lake Superior collapsed in the 1950s due to overfishing and sea lamprey Petromyzon marinus predation. Stocks were rehabilitated through stocking, sea lamprey control, and fishery regulation, but concern over lake trout population sustainability still exists because commercial and recreational fishing demand is high relative to productivity, and the currently accepted 42% total annual mortality rate has not been tested for sustainability. Our objective was to estimate the maximum sustainable (i.e., likely not to cause extirpation) fishing mortality and total annual mortality rates for lake trout in eastern Wisconsin waters of Lake Superior. We developed a dynamic, age-structured population model to predict future lake trout abundance. The simulation model included parameter uncertainty and autocorrelated process error in the stock-recruitment relationship and in sea lamprey mortality, and accounted for assessment and implementation error. We used mean abundance, mean total annual mortality rate, mean catch for the commercial and recreational fisheries, and probability of decline as performance metrics to evaluate a range of commercial and recreational fishing mortality rates and different assessment and implementation errors. Increasing assessment error led to undesirable outcomes (e.g., low mean abundance). However, varying implementation error had almost no effect on performance metrics. Increased commercial fishing had larger effects on performance metrics than recreational fishing. Combinations of commercial and recreational fishing mortality rates corresponding to total annual mortality rates of approximately 40% may be sustainable, and so the currently accepted 42% total annual mortality rate is also likely sustainable. However, we recommend that the amount of assessment error be more accurately quantified, low spawner abundance be avoided through the use of threshold management strategies, and commercial fishing quotas be closely monitored and enforced.

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Decline and Recovery of the Lake Superior Gull Island Reef Lake Trout (Salvelinus namaycush) Population and the Role of Sea Lamprey (Petromyzon marinus) Predation

Cited by 53 publications

References 0 publications

Recruitment Dynamics of Lake Trout in Western Lake Superior during 1988–1995

Recruitment Dynamics of Lake Trout in Western Lake Superior during 1988–1995

Recruitment Dynamics of the 1971–1991 Year‐Classes of Lake Trout in Michigan Waters of Lake Superior

Modeling the sustainability of lake trout fisheries in eastern Wisconsin waters of Lake Superior

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