Larkin's Predation Model of Lake Trout (Salvelinus namaycush) Extinction with Harvesting and Sea Lamprey (Petromyzon marinus) Predation: A Qualitative Analysis

1994 ◽  
Vol 51 (4) ◽  
pp. 942-945 ◽  
Author(s):  
A. L. Jensen
Keyword(s):  
Qualitative Analysis ◽  
Great Lakes ◽  
Lake Trout ◽  
Petromyzon Marinus ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Volterra Model ◽  
Model Parameters ◽  
Relative Importance ◽  
Simple Models

After invasion of the Great Lakes by the parasitic marine sea lamprey (Petromyzon marinus), lake trout (Salvelinus namaycush) populations crashed, but there remains some uncertainty concerning the relative importance of sea lamprey predation and harvesting in destruction of the fisheries. Some investigators believe overharvest was important; others think that the sea lamprey alone was enough. Simple models of predation assume monophagous predators and do not predict extinction of prey, but Larkin's modification of the Lotka–Volterra model results in extinction under some circumstances. The dynamics of sea lamprey predation on lake trout were investigated using Larkin's model, and crude estimates of the model parameters indicate that extinction is a likely outcome with or without a fishery.

Classification of Sea Lamprey (Petromyzon marinus) Attack Marks on Great Lakes Lake Trout (Salvelinus namaycush)

1980 ◽  
Vol 37 (11) ◽  
pp. 1989-2006 ◽  
Author(s):  
Everett Louis King Jr.
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Petromyzon Marinus ◽  
Attachment Site ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Oral Disc ◽  
Field Assessment ◽  
Sea Lampreys

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

On Evaluating Measures to Rehabilitate Lake Trout (Salvelinus namaycush) of Lake Superior

1980 ◽  
Vol 37 (11) ◽  
pp. 2057-2062 ◽  
Author(s):  
A. H. Lawrie ◽  
W. MacCallum
Keyword(s):  
Lake Trout ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Control Program ◽  
Mortality Rates ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Planting Density ◽  
Hatchery Fish ◽  
Natural Recruitment

The Lake Superior lake trout (Salvelinus namaycush) population is being rebuilt following its collapse in the early 1950s. Estimates are presented of the contributions to this recovery provided directly by the artificial recruitment of hatchery fish, a demonstrable amelioration in mortality rates and a resurgence, lately, of natural recruitment. Of the increased lake trout abundance, 55% on the average was owing to trebling the planting density, 40% to improved survival, and 5% to increasing recruitment of native lake trout. The precise contribution of the sea lamprey (Petromyzon marinus) control program could not be defined for lack of sufficient early data.Key words: lake trout, sea lamprey, rehabilitation, natural recruitment, hatchery stocking

Responses of Lake Trout (Salvelinus namaycush) to Harvesting, Stocking, and Lamprey Reduction

1980 ◽  
Vol 37 (11) ◽  
pp. 2133-2145 ◽  
Author(s):  
Carl J. Walters ◽  
Greg Steer ◽  
George Spangler
Keyword(s):  
Simple Model ◽  
Policy Analysis ◽  
Great Lakes ◽  
Population Regulation ◽  
Lake Trout ◽  
Normal Population ◽  
Lake Superior ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Density Dependent

Sustained yields, declines, and recovery of lake trout (Salvelinus namaycush) can be explained by a simple model that hypothesizes normal population regulation through density dependent body growth, coupled with depensatory lamprey mortality. The model indicates that either lamprey or fishing alone could have caused the Lake Superior decline, though they apparently operated in concert. The presence of depensatory lamprey mortality leads to a "cliff edge" in the system's dynamics, such that catastrophic changes may be repeated in the future. It is not unlikely that Lake Superior is on the verge of a second collapse. Options for dealing with potential disasters include conservative harvesting policies, development of more sensitive monitoring indicators, and modified stocking policies that may speed the coevolution of a viable lamprey/trout association.Key words: lake trout, sea lamprey, simulation, Great Lakes, policy analysis

Assessment of Sea Lamprey (Petromyzon marinus) Predation by Recovery of Dead Lake Trout (Salvelinus namaycush) from Lake Ontario, 1982–85

1988 ◽  
Vol 45 (8) ◽  
pp. 1406-1410 ◽  
Author(s):  
Roger A. Bergstedt ◽  
Clifford P. Schneider
Keyword(s):  
Lake Trout ◽  
Stock Assessment ◽  
Petromyzon Marinus ◽  
Lake Ontario ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Fish Stock ◽  
Annual Fish ◽  
Dead Fish ◽  
Fish Stock Assessment

During 1982–85, 89 dead fake trout (Salvelinus namaycush) were recovered with bottom trawls in U.S. waters of Lake Ontario: 28 incidentally during four annual fish-stock assessment surveys and 61 during fall surveys for dead fish. During the assessment surveys, no dead lake trout were recovered in April–June, one was recovered in August, and 27 were recovered in October or November, implying that most mortality from causes other than fishing occurred in the fall. The estimated numbers of dead lake trout between the 30- and 100-m depth contours in U.S. waters ranged from 16 000 (0.08 carcass/ha) in 1983 to 94 000 (0.46 carcass/ha) in 1982. Of 76 carcasses fresh enough to enable recognition of sea lamprey (Petromyzon marinus) wounds, 75 bore fresh wounds. Assuming that sea lamprey wounding rates on dead fish were the same as on live ones of the same length range (430–740 mm), the probability of 75 of the 76 dead lake trout bearing sea lamprey wounds was 3.5 × 10−63 if death was independent of sea lamprey attack, thus strongly implicating sea lampreys as the primary cause of death of fish in the sample. The recovery of only one unwounded dead lake trout also suggested that natural mortality from causes other than sea lamprey attacks is negligible.

Changes in Mortality of Lake Trout (Salvelinus namaycush) in Michigan Waters of Lake Superior in Relation to Sea Lamprey (Petromyzon marinus) Predation, 1968–78

1980 ◽  
Vol 37 (11) ◽  
pp. 2063-2073 ◽  
Author(s):  
Richard L. Pycha
Keyword(s):  
Fishery Management ◽  
Lake Trout ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Total Mortality ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Catch Per Unit Effort ◽  
Instantaneous Rate ◽  
Unit Effort

Total mortality rates of lake trout (Salvelinus namaycush) of age VII and older from eastern Lake Superior were estimated from catch curves of age distributions each year in 1968–78. The instantaneous rate of total mortality Z varied from 0.62 to 2.31 in close synchrony with sea lamprey (Petromyzon marinus) wounding rates on lake trout. The regression of transformed Z on the index of lamprey wounding, accounted for over 89% of the variation in lake trout mortality (r2 = 0.893). An iterative method of estimating rates of exploitation u, instantaneous rates of fishing mortality F, K (a constant relating sample catch per unit effort to population size), instantaneous normal natural mortality rate M, and instantaneous rate of mortality due to sea lamprey predation L from the sample catch per unit effort and total catch by the fishery is presented. A second method using the results of a 1970–71 tagging study to estimate the mean F in 1970–77 yielded closely similar results to the above and is presented as corroboration. The estimates of u, F, and M appear to be reasonable. F ranged from 0.17 in 1974 to 0.42 in 1969 and M was estimated at 0.26. L varied from 0.21 in 1974 to 1.70 in 1968. Management implications of various policies concerning sea lamprey control, exploitation, and stocking are discussed.Key words: lake trout, sea lamprey, lamprey control, mortality, predation, Lake Superior, fishery, management

Changes in Mortality of Lake Trout (Salvelinus namaycush) in Relation to Increased Sea Lamprey (Petromyzon marinus) Abundance in Green Bay, 1974–78

1980 ◽  
Vol 37 (11) ◽  
pp. 2052-2056 ◽  
Author(s):  
J. D. Moore ◽  
T. J. Lychwick
Keyword(s):  
Lake Michigan ◽  
Lake Trout ◽  
Petromyzon Marinus ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Green Bay ◽  
Methods Of Measurement

Increased sea lamprey (Petromyzon marinus) abundance in Green Bay during 1977 is documented utilizing sea lamprey counts and lake trout (Salvelinus namaycush) wounding as methods of measurement. Since lake trout rehabilitation began in 1965, sea lamprey predation has been consistently higher in Green Bay and Northern Lake Michigan than other areas of the lake. It appears that increased sea lamprey predation in Green Bay, above the former high levels, resulted in decreased abundance and increased mortality of lake trout. The increase in lampreys is related to the colonization of the Peshtigo River, Marinette County, Wisconsin.Key words: Green Bay, sea lamprey increases, Peshtigo River, lake trout, increased mortality

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

1980 ◽  
Vol 37 (11) ◽  
pp. 2074-2080 ◽  
Author(s):  
Bruce L. Swanson ◽  
Donald V. Swedberg
Keyword(s):  
Lake Trout ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Total Mortality ◽  
Mortality Rates ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Steady Increase ◽  
Egg Deposition

The Gull Island Reef lake trout (Salvelinus namaycush) population was one of the few in Lake Superior that was not annihilated by the combined effects of excessive fishing and sea lamprey (Petromyzon marinus) predation. Following control of the lamprey in the early 1960s, this population of lake trout began a slow but steady increase in the average age and numbers of lake trout. Total annual mortality rates for spawning lake trout were 32% for age VI fish, 48% for ages VII–VIII, and 75% for ages IX and older. These total mortality rates included a 7.3% exploitation rate u, a 20% natural mortality n, and annual lamprey-induced mortalities of 6% for ages V–VI, 24%, for ages VII–VIII, and 56% for ages IX and older fish. The estimated number of lake trout eggs deposited annually on Gull Island Reef from 1964 to 1979 ranged from 3.3 million eggs in 1965 to 28 million eggs in 1979, with a mean of 9 million eggs per year. At present levels of lamprey predation, the estimated egg to spawning fish return rate on Gull Island Reef is 0.18%.Key words: lake trout, sea lamprey, survival, population structure, egg deposition

Survival from Sea Lamprey (Petromyzon marinus) Predation by Two Strains of Lake Trout (Salvelinus namaycush)

1986 ◽  
Vol 43 (12) ◽  
pp. 2528-2531 ◽  
Author(s):  
William D. Swink ◽  
Lee H. Hanson
Keyword(s):  
Survival Rate ◽  
Lake Trout ◽  
Petromyzon Marinus ◽  
Lake Ontario ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Direct Result ◽  
Environmental Preferences ◽  
Significant Difference ◽  
Lake Fish

We tested the hypothesis that the better survival of the Seneca Lake strain of lake trout (Salvelinus namaycush) in Lake Ontario resulted from their greater resistance than other stocked strains to sea lamprey (Petromyzon marinus) predation. No significant difference was found in the survival of Marquette and Seneca Lake strains of Lake trout subjected to single sea lamprey attacks in the laboratory. Of 85 Marquette strain lake trout, 44% died as a direct result of sea lamprey predation, 20% died of undetermined causes, and 36% survived; for 90 lake trout of the Seneca Lake strain, the respective percentages were 39, 21, and 40. The location of sea lamprey attachment on the lake trout was not a factor in mortality, which was significantly higher at water temperatures of 15.6–17.8 °C than at 0.6–15.6 °C. Our study suggested that the seemingly greater survival rate of Seneca Lake fish in Lake Ontario probably resulted from differences in behavior or environmental preferences that decreased their exposure to sea lamprey attacks.

New estimates of lethality of sea lamprey (Petromyzon marinus) attacks on lake trout (Salvelinus namaycush): implications for fisheries management

2008 ◽  
Vol 65 (3) ◽  
pp. 535-542 ◽  
Author(s):  
Charles P Madenjian ◽  
Brian D Chipman ◽  
J Ellen Marsden
Keyword(s):  
Fisheries Management ◽  
Lake Trout ◽  
Petromyzon Marinus ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Freshwater Ecosystems ◽  
Control Measures ◽  
Lake Huron ◽  
Lake Champlain ◽  
And Control

Sea lamprey (Petromyzon marinus) control in North America costs millions of dollars each year, and control measures are guided by assessment of lamprey-induced damage to fisheries. The favored prey of sea lamprey in freshwater ecosystems has been lake trout (Salvelinus namaycush). A key parameter in assessing sea lamprey damage, as well as managing lake trout fisheries, is the probability of an adult lake trout surviving a lamprey attack. The conventional value for this parameter has been 0.55, based on laboratory experiments. In contrast, based on catch curve analysis, mark–recapture techniques, and observed wounding rates, we estimated that adult lake trout in Lake Champlain have a 0.74 probability of surviving a lamprey attack. Although sea lamprey growth in Lake Champlain was lower than that observed in Lake Huron, application of an individual-based model to both lakes indicated that the probability of surviving an attack in Lake Champlain was only 1.1 times higher than that in Lake Huron. Thus, we estimated that lake trout survive a lamprey attack in Lake Huron with a probability of 0.66. Therefore, our results suggested that lethality of a sea lamprey attack on lake trout has been overestimated in previous model applications used in fisheries management.

Changes in Biological Characteristics of the Sea Lamprey (Petromyzon marinus) as Related to Lamprey Abundance, Prey Abundance, and Sea Lamprey Control

1980 ◽  
Vol 37 (11) ◽  
pp. 1861-1871 ◽  
Author(s):  
John W. Heinrich ◽  
Jerry G. Weise ◽  
Bernard R. Smith
Keyword(s):  
Great Lakes ◽  
Chemical Control ◽  
Lake Trout ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Control Program ◽  
Sea Lamprey ◽  
Biological Characteristics ◽  
Prey Abundance ◽  
Sea Lampreys

Biological characteristics of adult sea lampreys, Petromyzon marinus, in the Great Lakes changed in response to lamprey and prey abundance and the chemical control program. Sea lampreys collected as early as 1947, through 1978, from southern Lake Superior, northwestern Lake Michigan, the Ocqueoc River and Canadian shore of Lake Huron, and the Humber River of Lake Ontario were analyzed. Generally, abundance of sea lampreys peaked in each lake before the chemical control program began. The annual mean lengths and weights were relatively low when lampreys were abundant and increased as the numbers were reduced by the control efforts. As an indication of the change in sea lamprey weight per unit change in length, annual log10 weight on log10 length equations were solved at the arbitrary length of 410 mm. The values were plotted against years for each lake and interpreted with respect to chemical treatment periods. All slopes were negative before the control period and positive thereafter. Sea lamprey lengths and weights were low when fish stocks in the Great Lakes were near depletion. As salmonids again became abundant through stocking, lampreys grew larger. In Lake Superior, where detailed records on lake trout abundance have been available since 1959, a significant relation exists between the changes in the sea lamprey estimated weight values at 410 mm and in lake trout abundance (P < 0.01). Male sea lampreys were the dominant sex when populations of the parasite were high. A shift to a preponderance of females occurred as lamprey abundance declined.Key words: Petromyzon marinus, Salvelinus namaycush, abundance, sex ratio, weight–length relationship, chemical control

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