Endohelminths of salmonids from two localities in eastern Lake Michigan, with emphasis on Echinorhynchus salmonis

1989 ◽  
Vol 67 (6) ◽  
pp. 1604-1607 ◽  
Author(s):  
Patrick M. Muzzall
Keyword(s):  
Chinook Salmon ◽  
Salmo Trutta ◽  
Lake Michigan ◽  
Oncorhynchus Tshawytscha ◽  
Lake Trout ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Salvelinus Namaycush ◽  
Salmo Gairdneri ◽  
Brown Trout Salmo Trutta

Adult salmonids (101 chinook salmon, Oncorhynchus tshawytscha; 7 coho salmon, Oncorhynchus kisutch; 56 lake trout, Salvelinus namaycush; 6 steelhead, Salmo gairdneri; and 2 brown trout, Salmo trutta) were collected from eastern Lake Michigan (Ludington and Manistee, Michigan) in July–September 1986, and examined for helminths. Eight species (three Cestoda, three Nematoda, two Acanthocephala) were found in the digestive tract and other viscera. Echinorhynchus salmonis and Eubothrium salvelini were the most common helminths found. The intensity of E. salmonis significantly increased as chinook salmon became older and longer.

An examination of the PCB: lipid relationship among individual fish

1997 ◽  
Vol 54 (5) ◽  
pp. 1031-1038
Author(s):  
C A Stow ◽  
L J Jackson ◽  
J F Amrhein
Keyword(s):  
Salmo Trutta ◽  
Lake Michigan ◽  
Oncorhynchus Tshawytscha ◽  
Lake Trout ◽  
Coho Salmon ◽  
Salvelinus Namaycush ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Strong Linear Correlation ◽  
Brown Trout Salmo Trutta ◽  
The Relationship

We examined data from 1984 to 1994 for five species of Lake Michigan salmonids to explore the relationship between total PCB concentration and percent lipid. When we compared mean species lipid and PCB values, we found a strong linear correlation. When we compared values among individuals, we found modest positive PCB:lipid associations in brown trout (Salmo trutta), chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and rainbow trout (Oncorhynchus mykiss) collected during spawning, but positive associations were not apparent among nonspawning individuals. Lake trout (Salvelinus namaycush) exhibited no discernible PCB:lipid relationship. Our results are not incompatible with previous observations that contaminants are differentially partitioned into lipids within a fish, but these results do suggest that lipids are not a major factor influencing contaminant uptake.

Predation and Production by Salmonine Fishes in Lake Michigan, 1978–88

1991 ◽  
Vol 48 (5) ◽  
pp. 909-922 ◽  
Author(s):  
Donald J. Stewart ◽  
Myriam Ibarra
Keyword(s):  
Conversion Efficiency ◽  
Chinook Salmon ◽  
Salmo Trutta ◽  
Lake Michigan ◽  
Lake Trout ◽  
Biomass Conversion ◽  
Average Weight ◽  
Alosa Pseudoharengus ◽  
Brown Trout Salmo Trutta ◽  
Diet Shifts

A marked decline of alewife (Alosa pseudoharengus) in Lake Michigan during 1981–83 led to diet shifts by coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) from feeding primarily on large alewife to eating proportionately more immature alewives and other prey. Diets of lake trout (Salvelinus namaycush) did not change greatly during that period. Population biomass conversion efficiency averaged 24.5% for coho and 16.6% for lake trout. Chinook salmon suffered an apparent 20% decline in gross conversion efficiency of biomass (25.1 to 20.8%) and a 25% decline in average weight of sport-caught fish. We infer that chinook salmon growth was inhibited by insufficient forage available to them. A simulation of chinook salmon feeding on bloater (Coregonus hoyi) at 8 °C suggested that such behavior could lead to further declines in growth rates. Extension of modeling results to include approximations for brown trout (Salmo trutta) and rainbow trout (O. mykiss) revealed peaks in total annual salmonine predation of 71 000 t in 1983 and 76 000 t in 1987. The alewife was 70% of all prey eaten by salmonines in 1987–88. Lakewide gross production by salmonines was 15 300 t (or 0.27 g∙m−2) in 1987. Ratios of annual gross production to average monthly population biomass were 1.6 for chinook, 1.15 for coho, and only 0.6 for lake trout.

Residues of DDT in Lake Trout (Salvelinus namaycush) and Coho Salmon (Oncorhynchus kisutch) from the Great Lakes

1974 ◽  
Vol 31 (2) ◽  
pp. 191-199 ◽  
Author(s):  
Robert E. Reinert ◽  
Harold L. Bergman
Keyword(s):  
Lake Erie ◽  
Lake Michigan ◽  
Lake Trout ◽  
Coho Salmon ◽  
Marked Decrease ◽  
Life Stage ◽  
Oncorhynchus Kisutch ◽  
Salvelinus Namaycush ◽  
Spawning Season ◽  
Spawning Run

Concentrations of DDT residues were higher in lake trout (Salvelinus namaycush) from southern Lake Michigan in 1966–70 (average 18.1 ppm in fish 558–684 mm long) than in lake trout of the same size-class from Lake Superior in 1968–69 (4.4 ppm), and higher in adult coho salmon (Oncorhynchus kisutch) from Lake Michigan in 1968–71 (averages for different year-classes, 9.9–14.0 ppm) than in those from Lake Erie in 1969 (2.2 ppm). Residues were significantly higher in lake trout from southern Lake Michigan than in those from the northern part of the lake. In lakes Michigan and Superior, the levels increased with length of fish and percentage oil. In Lake Michigan coho salmon, the residues remained nearly stable (2–4 ppm) from September of the 1st yr of lake residence through May or early June of the 2nd yr, but increased three to four times in the next 3 mo. Residues in Lake Erie coho salmon did not increase during this period, which preceded the spawning season. Although the concentrations of total residues in whole, maturing Lake Michigan coho salmon remained unchanged from August 1968 until near the end of the spawning season in January 1969, the residues were redistributed in the tissues of the spawning-run fish; concentrations in the loin and brain were markedly higher in January than in August. This relocation of DDT residues accompanied a marked decrease in the percentage of oil in the fish, from 13.2 in August to 2.8 in January. Concentrations of residues were relatively high in eggs of both lake trout (4.6 ppm) and coho salmon (7.4–10.2 ppm) from Lake Michigan. The percentage composition of the residues (p,p′DDE, o,p′/DDT, p,p′DDT, and p,p′DDT) did not differ significantly with life stage, size, age, or locality, or date of collection of lake trout or coho salmon.

The relationship between the size of some salmonid fishes and the intensity of their acanthocephalan infections

1985 ◽  
Vol 63 (4) ◽  
pp. 924-927 ◽  
Author(s):  
Omar M. Amin
Keyword(s):  
Lake Michigan ◽  
Oncorhynchus Tshawytscha ◽  
Lake Trout ◽  
Coho Salmon ◽  
Linear Regression Analysis ◽  
Partial Replacement ◽  
Steady Increase ◽  
Host Feeding ◽  
Host Age ◽  
Maximal Increase

Of the complex factors affecting the abundance of acanthocephalan infections in their definitive fish hosts, those related to fish age are considered. In Lake Michigan, the abundance of some 8000 worms, mostly Echinorhynchus salmonis (Müller, 1784), was independent of the age (weight) of coho salmon, Oncorhynchus kisutch (Walbaum), chinook salmon, Oncorhynchus tshawytscha (Walbaum), and lake trout, Salvelinus namaycush (Walbaum), using linear regression analysis. Other E. salmonis infection patterns include steady increase in abundance with host age and a maximal increase in midage. A decrease in abundance with host age was demonstrated in other acanthocephalan species. The above patterns were primarily related to host feeding behavior as well as spatial and seasonal distribution of invertebrate and vertebrate larval hosts. A progressive increase in the abundance of Echinorhynchus through midage or through life is associated with a stable intake of an invertebrate diet, including the infected intermediate host, in larger volumes by older fish. Loss of the latter two patterns is affected by destabilizing the above trend through total or partial replacement of the invertebrate diet with a piscivorous one.

Spatiotemporal patterns in trophic niche overlap among five salmonines in Lake Michigan, USA

2020 ◽  
Vol 77 (6) ◽  
pp. 1059-1075 ◽  
Author(s):  
Matthew S. Kornis ◽  
David B. Bunnell ◽  
Heidi K. Swanson ◽  
Charles R. Bronte
Keyword(s):  
Brown Trout ◽  
Chinook Salmon ◽  
Lake Michigan ◽  
Lake Trout ◽  
Coho Salmon ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Ecosystem Change ◽  
Forage Base ◽  
Overlap Analysis

Native lake trout (Salvelinus namaycush) and introduced Chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), steelhead (Oncorhynchus mykiss), and brown trout (Salmo trutta) are major predators in Lake Michigan’s complex ecosystem and collectively support a valuable recreational fishery, but declines in their primary prey, alewife (Alosa pseudoharengus), have raised ecological and management concerns about competition and prey allocation. We applied niche overlap analysis to evaluate competition among salmonine predators during rapid forage base change in Lake Michigan. δ13C and δ15N stable isotope ratios indicated that lake trout had a unique trophic niche from inclusion of offshore and benthic prey, with <29% lake-wide niche overlap with Chinook salmon, coho salmon, and steelhead. Brown trout had moderate overlap with other species (45%–91%), while Chinook salmon, coho salmon, and steelhead had high overlap (71%–98%). Regional differences in isotopic signatures highlighted the potential importance of subsystem differences in fish diets in large aquatic systems. The uniqueness of the lake trout niche, and broadness of brown trout and steelhead niches, suggest these species may be resilient to forage base changes. This study further demonstrates how niche overlap analysis can be applied to tease apart competitive interactions and their response to ecosystem change.

Prey fish exploitation, salmonine production, and pelagic food web efficiency in Lake Ontario

1998 ◽  
Vol 55 (2) ◽  
pp. 318-327 ◽  
Author(s):  
Peter S Rand ◽  
Donald J Stewart
Keyword(s):  
Food Web ◽  
Lake Michigan ◽  
Oncorhynchus Tshawytscha ◽  
Lake Trout ◽  
Coho Salmon ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Prey Fish ◽  
Rainbow Smelt ◽  
Time Model

Estimates of production and predation rates from bioenergetic models of chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and lake trout (Salvelinus namaycush) suggest a long-term decline in their gross conversion efficiency (gross production/prey consumption) and the gross production to biomass ratio in Lake Ontario during 1978-1994. The former pattern was caused primarily by a declining trend in adult alewife (Alosa pseudoharengus) energy density during 1978-1985; the latter pattern resulted from reductions in growth rates (coho salmon) and a buildup of the older age-classes in the population (lake trout) over time. Model results suggest that over 100 and 25% of the annual production of adult alewife and rainbow smelt (Osmerus mordax), respectively, was consumed by salmonines during 1990 in Lake Ontario; hence, we claim that recent observations of reduced salmonine growth in Lake Ontario may be a result of prey limitation. Energy transfer from primary production to salmonines appeared to be more efficient in Lake Ontario than in Lake Michigan, probably due to higher stocking levels per unit area and higher densities of preferred prey fish in Lake Ontario. Through separate analyses, we arrived at conflicting conclusions concerning the sustainability of the food web configuration in Lake Ontario during 1990.

Phoma herbarum, a Fungal Plant Saprophyte, as a Fish Pathogen

1975 ◽  
Vol 32 (9) ◽  
pp. 1648-1652 ◽  
Author(s):  
A. J. Ross ◽  
W. T. Yasutake ◽  
Steve Leek
Keyword(s):  
Rainbow Trout ◽  
Chinook Salmon ◽  
Coho Salmon ◽  
Histopathological Examination ◽  
Oncorhynchus Kisutch ◽  
Salmo Gairdneri ◽  
Fish Pathogen ◽  
Experimental Infections ◽  
Phoma Herbarum ◽  
Low Incidence

Phoma herbarum, a fungal plant saprophyte, was isolated from diseased hatchery-reared coho salmon (Oncorhynchus kisutch), chinook salmon (O. tshawytscha), and rainbow trout (Salmo gairdneri). The disease was observed at 10 national fish hatcheries in Washington and Oregon, but the low incidence of experimental infections indicate that it is only weakly contagious. Histopathological examination suggests that the air bladder is one of the primary organs infected. The visceral organs are also affected in both natural and experimental infections.

Sign in / Sign up

Export Citation Format

Share Document