Geology topics

Charles A. Bowen

Publications and source records attributed to Charles A. Bowen.

7 recordsLinked to original sources

USGS2004

Status of lake trout rehabilitation on Six Fathom Bank and Yankee Reef in Lake Huron

Six Fathom Bank, an offshore reef in the central region of Lake Huron's main basin, was stocked annually with hatchery-reared lake trout Salvelinus namaycush during 1985–1998, and nearby Yankee Reef was stocked with hatchery-reared lake trout in 1992, 1997, and annually during 1999–2001. We conducted gill-net surveys during spring and fall to evaluate performances of each of the various strains of lake trout, as well as the performance of the entire lake trout population (all strains pooled), on these two offshore reefs during 1992–2000. Criteria to evaluate performance included the proportion of “wild” fish within the population, spawner density, adult survival, growth, maturity, and wounding rate by sea lamprey Petromyzon marinus . Although naturally reproduced age-0 lake trout fry were caught on Six Fathom Bank and Yankee Reef, wild lake trout did not recruit to the adult population to any detectable degree. The density of spawning lake trout on Six Fathom Bank (>100 fish/305 m of gill net) during 1995–1998 appeared to be sufficiently high to initiate a self-sustaining population. However, annual mortality estimates for all lake trout strains pooled from catch curve analyses ranged from 0.48 to 0.62, well exceeding the target level of 0.40 suggested for lake trout rehabilitation. Annual mortality rate for the Seneca Lake strain (0.34) was significantly lower than that for the Superior–Marquette (0.69) and Lewis Lake (0.69) strains. This disparity in survival among strains was probably attributable to the lower sea-lamprey-induced mortality experienced by the Seneca Lake strain. The relatively high mortality experienced by adult lake trout partly contributed to the lack of successful natural recruitment to the adult population on these offshore reefs, but other factors were probably also involved. We recommend that both stocking of the Seneca Lake strain and enhanced efforts to reduce sea lamprey abundance in Lake Huron be continued.

North American Journal of Fisheries Management↗

USGS2002

Parasites of the slimy sculpin, Cottus cognatus Richardson, 1836, from Lake Huron, U.S.A

One hundred slimy sculpins, Cottus cognatus (Cottidae), collected from Six Fathom Bank Lake Trout Refuge in Lake Huron in June 1995 were examined for parasites. A total of 17 parasite species (3 Digenea, 2 Monogenea, 3 Cestoda, 3 Nematoda, 2 Acanthocephala, 2 Ciliophora, 1 Microspora, and 1 Myxosporea) were found to infect sculpins. Tetracotyle sp. had the highest prevalence, mean intensity, and mean abundance, followed by Diplostomum sp. The most common gastrointestinal helminth species was Echinorhynchus salmonis . Epistylis sp. occurred on the gills of 79 sculpins. The mean parasite species richness ± SD and mean helminth abundance ± SD were 5.4 ± 1.6 and 242.6 ± 264.5, respectively. The mean Brillouin's diversity and evenness values were 0.5773 ± 0.1915 and 0.5248 ± 0.1892, respectively. Although the helminth community of slimy sculpins is dominated by larval trematodes that mature in piscivorous birds, it is believed that few slimy sculpins are eaten by birds at this location.

Comparative Parasitology↗

USGS2002

Northwestward range extension for Diacyclops harryi (Crustacea: Copepoda)

A recent find of the groundwater-inhabiting copepod crustacean Diacyclops harryi extended the known range of this species far northwestward, to include northern Ohio and the drainage basin of the Laurentian Great Lakes. The species was previously collected in drainages of the Atlantic Slope from New York to North Carolina. Ostracodes tentatively identified as ? Nannocandona n. sp., and amphipods belonging to the subterranean species Bactrurus mucronatus were also found at the Ohio locality.

Northeastern Naturalist↗

USGS2000

Helminths in an intensively stocked population of lake trout, Salvelinus namaycush, from Lake Huron

Eighty stocked lake trout Salvelinus namaycush (Salmonidae), collected from 2 locations in Lake Huron in May 1995, were examined for parasites. The parasite fauna of this top predator in Lake Huron was characterized by only 6 helminth species. Echinorhynchus salmonis infected all lake trout with a mean intensity of 163.9. The intensity of this acanthocephalan species significantly increased with host length and weight. Eubothrium salvelini infected 78 lake trout with a maximum number of 81 scoleces counted. Diplostomum sp., Cyathocephalus truncatus, Capillaria salvelini, and Neoechinorhynchus sp. infrequently infected lake trout. The low parasite species richness in these lake trout is believed to be due to their large size at stocking and to the loss of historical enzootic host–parasite relationships that followed the absence of this fish species in Lake Huron for 26 yr.

Michigan, Ontario↗

USGS1990

Host-parasite relationships and geographic distribution of Salmincola corpulentus (Copepoda: Lernaeopodidae) on bloater ( Coregonus hoyi ) stocks in Lake Huron

Examination of the branchial cavities of 8347 adult bloaters ( Coregonus hoyi ) collected from seven locations in Lake Huron for parasitic copepods yielded only the lernaeopodid Salmincola corpulentus ; its distribution was limited to bloaters collected in the southern two-thirds of the lake. The infections were highest off Au Sable Point and on Six Fathom Bank, where 12 and 22%, of the bloaters examined were infected, respectively. All copepods seen were sexually mature females. The dorsal anterior portion of the branchial rim was the preferred site of attachment. The prevalence of S . corpulentus increased with length of the bloaters, reaching a maximum of 40% in fish longer than 330&ensp;mm; none were seen in bloaters shorter than 182&ensp;mm. The mean intensity of S . corpulentus was unusually low (1.0–1.9) for a lernaeopodid copepod and the maximum number of copepods found on a single bloater was five. Prevalences of copepods differed significantly ( P &ensp;<&ensp;0.05) between bloaters collected at different geographic locations, suggesting that S . corpulentus may be of value in bloater stock determination.

Canadian Journal of Zoology↗

USGS1987

Discrepancies between ages determined from scales and otoliths for alewives from the Great Lakes

Discrepancies between ages determined from otoliths and those determined from scales were common and, sometimes, quite large in alewives Alosa pseudoharengus collected in fall 1983 from Lakes Ontario, Huron, and Michigan. Among fish with 'otolith ages' of 4 or more, the percentages having identical 'scale ages' were 1% in Lake Ontario, 35% in Lake Huron, and 56% in Lake Michigan. Among alewives with different otolith and scale ages, the percentages with discrepancies of 3 years or more were 51% in Lake Ontario, 23% in Lake Huron, and 6% in Lake Michigan. Among the three populations, variation in the magnitude of age disagreements were perhaps due to the different mortality rates in each lake, whereas variation in the frequency of disagreements appeared to be due to different ratios of food to fish in each lake. Previously reported age compositions and rates of mortality and production for Great Lakes alewives derived from scales have probably been inaccurate to various degrees.

Book chapter↗

USGS1985

Introduction and spread of the threespine stickleback ( Gasterosteus aculeatus ) in Lakes Huron and Michigan

The threespine stickleback ( Gasterosteus aculeatus ) was not known to occur in the Great Lakes above Niagara Falls until 1980, when it was collected in South Bay, Manitoulin Island, in the Lake Huron basin. By 1984 this species had been found in tributaries of Lakes Huron and Michigan, and in the open waters of both lakes. All specimens identified were the completely plated morph that is most prevalent in fresh water along the east coast of North America. The status of this species in Lakes Huron and Michigan appears to be “Possibly Established.” If threespine stickleback increase in abundance they may eventually provide additional forage for large salmonids.

Journal of Great Lakes Research↗