Declining lake trout (Salvelinus namaycush) energy density: are there too many salmonid predators in the Great Lakes?

2009 ◽  
Vol 66 (6) ◽  
pp. 919-932 ◽  
Author(s):  
Gordon Paterson ◽  
D. Michael Whittle ◽  
Kenneth G. Drouillard ◽  
G. Douglas Haffner
Keyword(s):  
Energy Density ◽  
Great Lakes ◽  
Body Mass ◽  
Lake Trout ◽  
Growth Models ◽  
Temporal Trends ◽  
Salvelinus Namaycush ◽  
Average Body Mass ◽  
Native Salmonids

This study used long-term biomonitoring data on lake trout ( Salvelinus namaycush ) collected from Lakes Erie, Ontario, Huron, and Superior between 1995 and 2004 to investigate latitudinal and temporal trends in body mass and energy density of this top predator in the Great Lakes. Lake trout average body mass and energy density were observed to have negative relationships with latitude that primarily reflected patterns in lake productivities. Temporal declines in energy density occurred for >80% of all lake trout age classes collected from each of the four lakes between 1995 and 2004. von Bertalanffy (VBL) growth models describing the relationships between fish energy density and age demonstrated decreased growth of lake trout energy density during 2000–2004 relative to 1995–1999. VBL growth coefficients (k) and the slopes describing the rates of change in lake trout energy density were negatively correlated with the total number of lake trout and salmonid individuals released into these lakes during this study. We hypothesize that the temporal declines in lake trout body mass and energy density are a manifestation of a bioenergetic bottleneck for this species due to their inability to efficiently compete with non-native salmonids for depleted prey populations.

Concentrations and Long-Term Temporal Trends of Hexabromocyclododecanes (HBCDD) in Lake Trout and Walleye from the Great Lakes

2020 ◽  
Vol 54 (10) ◽  
pp. 6134-6141 ◽  
Author(s):  
Bita Alipour Parvizian ◽  
Chuanlong Zhou ◽  
Sujan Fernando ◽  
Bernard S. Crimmins ◽  
Philip K. Hopke ◽  
...  
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Temporal Trends

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

Long-term suppression of the Lake Trout (Salvelinus namaycush) population in Lake Pend Oreille, Idaho

Hydrobiologia ◽  
2019 ◽  
Vol 840 (1) ◽  
pp. 335-349 ◽  
Author(s):  
Michael J. Hansen ◽  
Matthew P. Corsi ◽  
Andrew M. Dux
Keyword(s):  
Lake Trout ◽  
Salvelinus Namaycush

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

Long-Term Effects of Diet on the Biology of the Lake Trout and the Fishery in Lake Opeongo, Ontario

1970 ◽  
Vol 27 (1) ◽  
pp. 125-146 ◽  
Author(s):  
N. V. Martin
Keyword(s):  
Lake Trout ◽  
Feeding Activity ◽  
Salvelinus Namaycush ◽  
Point Of View ◽  
Average Weight ◽  
Coregonus Clupeaformis ◽  
Long Term Effects ◽  
Food Content ◽  
Coregonus Artedii

From 1936 to 1965 food content was examined in 17,171 Lake Opeongo lake trout (Salvelinus namaycush). The diet is analysed from the point of view of frequency of occurrence of foods, their weight, feeding activity of trout, size of trout and size of food, and seasonal and annual changes in food habits.In the late 1940's and early 1950's perch, Perca flavescens, largely disappeared from the diet. The lake trout initially turned to lake whitefish, Coregonus clupeaformis, and then to the cisco, Coregonus artedii, introduced into Lake Opeongo in 1948.As a result of these dietary changes lake trout are now heavier and rate of growth has improved. Age and size at maturity is later and there are fewer infertile fish. Egg counts, egg size, and ovary weights are now greater, particularly in the medium-sized lake trout.In the fishery the average weight of individual trout taken has almost doubled. About 25% more of the immature stock is exploited by the recent fishery. The harvest and catchability of lake trout has remained generally constant on a numerical basis but show an improvement on a poundage basis in the more recent years. The possible effects of these changes on the character of the fishery are discussed.

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

scholarly journals 1249Trends and disparities in adult body mass index across 47 prefectures in Japan, 1975–2018

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Nayu Ikeda ◽  
Tomoki Nakaya ◽  
James Bennett ◽  
Majid Ezzati ◽  
Nobuo Nishi
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Temporal Trends ◽  
Poor Performance ◽  
Bayesian Hierarchical ◽  
Adult Body Mass ◽  
Adult Body ◽  
Adult Body Mass Index ◽  
Spatio Temporal

Abstract Background Consistent and comparable health information across prefectures is necessary for monitoring progress in improving population health and reducing geographic health disparities in Japan. We aimed to examine long-term trends and variations in adult body mass index (BMI) by prefecture. Methods We obtained a total sample of 233,988 males and 261,086 females aged 20–79 years with anthropometric measurements from National Health and Nutrition Surveys conducted annually during 1975–2018. We applied a spatio-temporal Bayesian hierarchical model to estimate the annual time series of prefectural mean BMI by 20-year age group and sex. Results Prefectural mean BMI consistently increased in males regardless of age but decreased in younger females. It increased in older females until starting to decrease in the early 2000s. Mean BMI was noticeably higher in Okinawa, the southernmost prefecture, than in other prefectures from 1975 in males and from the 1990s in females. The interquartile range of mean BMI across prefectures was consistently higher in females than in males. It decreased over time to plateau during the 2000s in both sexes. Conclusions Mean BMI increased in males across prefectures and there is a need for stimulating a further reduction in geographic disparities particularly for females. Okinawa once ranked first in longevity but has shown relatively poor performance in recent years, which may be partly attributable to the distinctive trends in adult BMI. Key messages Bayesian hierarchical modelling is useful for reconstructing long-term spatio-temporal trends of mean BMI by integrating small-size survey samples.

Toxicity of chlorinated bornane (toxaphene) residues isolated from Great Lakes Lake trout (salvelinus namaycush)

1987 ◽  
Vol 16 (3) ◽  
pp. 349-355 ◽  
Author(s):  
Jay W. Gooch ◽  
Fumio Matsumura
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Salvelinus Namaycush
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