Returns of Hatchery-Reared Lake Trout in Southern Lake Superior, 1955–62

1967 ◽  
Vol 24 (2) ◽  
pp. 281-298 ◽  
Author(s):  
Richard L. Pycha ◽  
George R. King
Keyword(s):  
Lake Trout ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Salvelinus Namaycush ◽  
Osmerus Mordax ◽  
Commercial Fishery ◽  
Sea Lampreys ◽  
Average Size ◽  
Better Than ◽  
Made In

Experimental plantings of fin-clipped lake trout (Salvelinus namaycush) of various ages have been made in southern Lake Superior since 1952. The catch of planted lake trout by the commercial fishery was used to measure the success of stocking. Estimates of total returns were based on samples of 8.2 to 21.2% of the Wisconsin catches in 1955–62 and 36.4 to 46.8% of the Michigan catches in 1959–62. Marked lake trout were assigned to various plantings according to the fin mark, length of fish, readings of age from scales, and locations of capture.Estimated returns from Wisconsin plantings of 9-month-old lake trout varied from 2.1 to 6.4%. Wisconsin releases of 16-month-old fish yielded returns of 5.7 to 37.3%. Returns from plantings in Michigan were 0.3% for 9-month-old fish and 1.5 to 3.8% for 16-month-old fish. The ratios of the returns from plantings of 16-month-old fish to those of 9-month-old fish were 3.9:1 for Wisconsin releases and 6.7:1 for Michigan releases. Lake trout planted in Wisconsin generally survived better than those released in Michigan. Returns from fish planted at ages of 17 to 40 months in Michigan in 1958–59 were far greater than those from 16-month-old fish released in Michigan, but were not as high as from the most successful plantings of 16-month-old fish in Wisconsin. Lake trout released in 1960 from shore and from boats survived equally well.Average size of lake trout at release was more closely related to survival than any other factor. All except 1 of 10 highly successful releases were of fish larger than 22 per lb, and all 6 poor releases were of fish smaller than 34 per lb. Fish that ran 22 to 33 per lb survived only moderately well. A size of 17 to 20 fish per lb appears to be close to optimum.Abundance of native lake trout, American smelt (Osmerus mordax), and sea lampreys (Petromyzon marinus) all appeared to be unrelated to stocking success. The only apparent method of rapidly improving the success of stocking is to rear all lake trout to an average size of 17 to 20 per lb.

Evaluating the growth potential of sea lampreys (Petromyzon marinus) feeding on siscowet lake trout (Salvelinus namaycush) in Lake Superior

2011 ◽  
Vol 37 (2) ◽  
pp. 343-348 ◽  
Author(s):  
Eric K. Moody ◽  
Brian C. Weidel ◽  
Tyler D. Ahrenstorff ◽  
William P. Mattes ◽  
James F. Kitchell
Keyword(s):  
Lake Trout ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Salvelinus Namaycush ◽  
Growth Potential ◽  
Sea Lampreys

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

Dynamics and Exploitation of Mature Walleyes, Stizostedion vitreum vitreum, in the Nipigon Bay Region of Lake Superior

1968 ◽  
Vol 25 (7) ◽  
pp. 1347-1376 ◽  
Author(s):  
R. A. Ryder
Keyword(s):  
Lake Trout ◽  
Lake Superior ◽  
Total Mortality ◽  
Inland Waters ◽  
Commercial Fishery ◽  
Sea Lampreys ◽  
Wood Fibres ◽  
High Concentrations ◽  
Trout Fishery ◽  
Hexagenia Limbata

Walleye stocks in Nipigon Bay of Lake Superior were homogeneous with those in tributary inland waters but were discrete from Black Bay stocks. Returns from 2200 tagged walleyes in Lake Superior and tributary inland waters between 1955 and 1958 varied from 7.8 to 31.0% for 2 years after release. The commercial fishery in Lake Superior recovered 64.9% of the tags, the sports fishery in inland waters captured 27.6%. Fish tagged in the Nipigon River travelled a mean distance of 11.8 miles from the point of release and were recovered in 191 days (average). Total mortality rates for Nipigon Bay walleyes were 55.0% (1955–57). Mature walleyes on the spawning grounds in the Nipigon River in 1957 were estimated at 22,000, and fish in Nipigon Bay over 14 inches (total length) the same year at 41,000. All male walleyes were mature at 15 inches and females at 18 inches. Walleyes exploitation rates increased with the decline of the lake trout fishery. Wounding and scarring rates by sea lampreys increased during 1955–57 but never exceeded 1.0% on adult walleyes. Severe pollution on the west side of Nipigon Bay originated from a kraft mill. High concentrations of total solids and dense sedimentation of wood fibres created an environment unfavourable to Hexagenia limbata and Pontoporeia affinis. The recent elimination of the walleye fishery in Nipigon Bay is most likely attributable to industrial pollution rather than to overexploitation or sea lamprey predation.

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

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

Growth potential and host mortality of the parasitic phase of the sea lamprey (Petromyzon marinus) in Lake Superior

2005 ◽  
Vol 62 (10) ◽  
pp. 2343-2353 ◽  
Author(s):  
Jeffrey C Jorgensen ◽  
James F Kitchell
Keyword(s):  
Oncorhynchus Tshawytscha ◽  
Lake Trout ◽  
Pacific Salmon ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Maximum Size ◽  
Sea Lamprey ◽  
Growth Potential ◽  
Sea Lampreys ◽  
Host Mortality

Landlocked Lake Superior sea lampreys (Petromyzon marinus) cause a significant but uncertain amount of mortality on host species. We used a sea lamprey bioenergetics model to examine the scope of host sizes vulnerable to death as a consequence of sea lamprey feeding and incorporated the bimodal lake-ward migration of parasitic sea lampreys. At their peak feeding rate and maximum size (P = 1.0, proportion of maximum consumption), spring migrants were capable of killing lean lake trout (Salvelinus namaycush) hosts ≤ 2.0 kg, which was larger than fall migrants (1.8 kg). Spring migrants feeding on Pacific salmon (coho (Oncorhynchus kisutch), Chinook (Oncorhynchus tshawytscha), and steelhead (Oncorhynchus mykiss)) killed hosts ≤ 2.0 kg, but fall migrants killed hosts as large as 2.8 kg. Although there is no direct empirical evidence, bioenergetics modeling suggests that it is plausible that some of the largest sea lampreys in Lake Superior spent more than one summer as parasites. Two-summer parasites readily attained sizes of sea-run adult anadromous sea lampreys and killed hosts from 3 to >5.5 kg in size. The maximum upper limit number of 2-kg hosts killed by two-summer parasites was nearly twice that of one-summer parasites.

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

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

1981 ◽  
Vol 38 (12) ◽  
pp. 1724-1737 ◽  
Author(s):  
John L. Goodier
Keyword(s):  
Body Shape ◽  
Lake Trout ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Salvelinus Namaycush ◽  
Scientific Data ◽  
Stock Identification ◽  
Behavioral Differences ◽  
Anatomical Features ◽  
Form Of Government

The decline of Lake Superior lake trout (Salvelinus namaycush) stocks after the sea lamprey (Petromyzon marinus) population explosion 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 semi-discrete stocks within the lake. Historical documents in the form of government correspondence and reports, explorers' accounts, and Hudson's Bay Fur Co. records yield further evidence.Possible stocks are distinguished on the basis of 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. namaycush: leans, fats or siscowets, half-breeds, and humpers or paperbellies. In addition, different "breeds" 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 of 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.Key words: lake trout, Salvelinus namaycush; stocks, anatomical features, behavioral differences

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

System Simulation of the Predatory Activities of Sea Lampreys (Petromyzon marinus) on Lake Trout (Salvelinus namaycush)

1975 ◽  
Vol 32 (5) ◽  
pp. 623-631 ◽  
Author(s):  
Patrick F. Lett ◽  
F. W. H. Beamish ◽  
G. J. Farmer
Keyword(s):  
Lake Trout ◽  
Petromyzon Marinus ◽  
Salvelinus Namaycush ◽  
Commercial Fishing ◽  
Stochastic Dynamic ◽  
Age Classes ◽  
Trout Population ◽  
Sea Lampreys ◽  
Population Structures ◽  
The Mean

A stochastic dynamic model was developed to evaluate the simulated and empirical interactions between sea lampreys (Petromyzon marinus) and two lake trout (Salvelinus namaycush) population structures, one without and the other with previous lamprey predation.An arithmetic increase in lampreys induced a geometric decline in trout, which was dependent on the number of age-classes and the mean weight of trout. Large trout, when present, were subject to most of the lamprey predation allowing survival of smaller trout. Lethality increased exponentially with lamprey size resulting in peak lake trout mortality during fall near the end of the lamprey’s feeding period. Lake trout scarring data could be used only as an index of lamprey abundance when trout:lamprey ratios and trout population structures were known. The simulation suggested that sea lampreys and lake trout could coexist if large trout are not removed by commercial fishing and if some exogenous factor controlled lamprey abundance.

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