Contaminant trends in lake trout (Salvelinus namaycush) from the Upper Great Lakes

1986 ◽  
Vol 15 (4) ◽  
pp. 349-356 ◽  
Author(s):  
David S. DeVault ◽  
Wayne A. Willford ◽  
Robert J. Hesselberg ◽  
David A. Nortrupt ◽  
Eric G. S. Rundberg ◽  
...  
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Upper Great Lakes

An Evaluation of Lake Trout (Salvelinus namaycush) Hooking Mortality in the Upper Great Lakes

1988 ◽  
Vol 45 (8) ◽  
pp. 1473-1479 ◽  
Author(s):  
Andrew J. Loftus ◽  
William W. Taylor ◽  
Myrl Keller
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Fishing Mortality ◽  
Temperature Differential ◽  
Sport Fishing ◽  
Upper Great Lakes ◽  
Lower Jaw ◽  
Impact On Survival ◽  
Size Limits

Investigation of lake trout (Salvelinus namaycush) hooking mortality was conducted in Lakes Michigan, Huron, and Superior during 1984 and 1985. Fish were caught and handled by charterboat operators and sport fishermen. Mortality was estimated by returning hooked fish to the lake after tethering them to a line–buoy system. Overall hooking mortality was estimated to be 14.9% (95% C.I. = 7.4–25.7). Significantly higher mortalities occurred in fish that were not discovered to have been hooked and in fish of smaller size classes. In addition, lake trout that were hooked in internal regions produced a mortality of 71.4% whereas those hooked in the upper or lower jaw had a mortality of 6.9%. The depth from which the fish was angled, the temperature differential from this depth to the surface, gear type, and handling times had no significant impact on survival. These results support the use of size limits, creel limits, and season restrictions as effective methods to reduce sport fishing mortality of lake trout.

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

Effects of coancestry on accuracy of individual assignments to population of origin: examples using Great Lakes lake trout (Salvelinus namaycush)

Genetica ◽  
2006 ◽  
Vol 127 (1-3) ◽  
pp. 329-340 ◽  
Author(s):  
Bruno Guinand ◽  
Kim T. Scribner ◽  
Kevin S. Page ◽  
Kristi Filcek ◽  
Laura Main ◽  
...  
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Salvelinus Namaycush

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

Paenibacillus thiaminolyticus is not the cause of thiamine deficiency impeding lake trout (Salvelinus namaycush) recruitment in the Great Lakes

2012 ◽  
Vol 69 (6) ◽  
pp. 1056-1064 ◽  
Author(s):  
Catherine A. Richter ◽  
Allison N. Evans ◽  
Maureen K. Wright-Osment ◽  
James L. Zajicek ◽  
Scott A. Heppell ◽  
...  
Keyword(s):  
Great Lakes ◽  
Thiamine Deficiency ◽  
Lake Trout ◽  
Bacterial Species ◽  
Primary Source ◽  
Salvelinus Namaycush ◽  
Trophic Levels ◽  
Thiaminase I ◽  
Global Concern ◽  
Paenibacillus Thiaminolyticus

Thiamine (vitamin B1) deficiency is a global concern affecting wildlife, livestock, and humans. In Great Lakes salmonines, thiamine deficiency causes embryo mortality and is an impediment to restoration of native lake trout ( Salvelinus namaycush ) stocks. Thiamine deficiency in fish may result from a diet of prey with high levels of thiaminase I. The discoveries that the bacterial species Paenibacillus thiaminolyticus produces thiaminase I, is found in viscera of thiaminase-containing prey fish, and causes mortality when fed to lake trout in the laboratory provided circumstantial evidence implicating P. thiaminolyticus. This study quantified the contribution of P. thiaminolyticus to the total thiaminase I activity in multiple trophic levels of Great Lakes food webs. Unexpectedly, no relationship between thiaminase activity and either the amount of P. thiaminolyticus thiaminase I protein or the abundance of P. thiaminolyticus cells was found. These results demonstrate that P. thiaminolyticus is not the primary source of thiaminase activity affecting Great Lakes salmonines and calls into question the long-standing assumption that P. thiaminolyticus is the source of thiaminase in other wild and domestic animals.

New insight into the spawning behavior of lake trout, Salvelinus namaycush, from a recovering population in the Laurentian Great Lakes

2014 ◽  
Vol 98 (1) ◽  
pp. 173-181 ◽  
Author(s):  
T. R. Binder ◽  
H. T. Thompson ◽  
A. M. Muir ◽  
S. C. Riley ◽  
J. E. Marsden ◽  
...  
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Laurentian Great Lakes ◽  
Spawning Behavior ◽  
Insight Into

Lake Trout, Sea Lampreys, and Overfishing in the Upper Great Lakes: A Review and Reanalysis

1990 ◽  
Vol 119 (6) ◽  
pp. 985-995 ◽  
Author(s):  
Daniel W. Coble ◽  
Richard E. Bruesewitz ◽  
Thomas W. Fratt ◽  
Jeffrey W. Scheirer
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Upper Great Lakes ◽  
Sea Lampreys

Taxonomy of a Swimbladder Nematode, Cystidicola stigmatura (Leidy), and Evidence of its Decline in the Great Lakes

1983 ◽  
Vol 40 (5) ◽  
pp. 643-647 ◽  
Author(s):  
Geoff A. Black
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Valid Species ◽  
Museum Specimens

Cystidicola stigmatura (Leidy, 1886) Ward and Magath, 1917 is considered a valid species after examination of specimens from Leidy's collection. Cystidicola cristivomeri White, 1941 is considered a synonym of C. stigmatura. Cystidicola stigmatura is distinguished from the only other species in the genus, namely C. farionis Fischer, 1798, by the presence of lateral lobes on the eggs rather than filaments. A neotype of F. stigmatura is designated. Cystidicola stigmatura has not been found in fishes in the Great Lakes since 1925. The parasite was found in museum specimens of lake trout (Salvelinus namaycush) collected before 1925, suggesting that the species became rare or disappeared with the decline of lake trout in these lakes.

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