Geology topics

Thomas N. Todd

Publications and source records attributed to Thomas N. Todd.

At least 19 recordsLinked to original sources

USGS2025

Archive of morphological data for the Coregonus artedi species complex of the Great Lakes, Lake Nipigon and Great Slave Lake

This publication is a user guide for an archive of morphological data recorded by various authors from North American ciscoes of the Coregonus artedi species complex (subfamily Coregoninae ). The archive is accessible from the Great Lakes Fishery Commission’s (GLFC) server, is open access, and contains data for the Laurentian Great Lakes; Lake Nipigon, Ontario; and Great Slave Lake, Northwest Territories. The archive comprises morphometrics and meristics (together metrics) for 6,700 individual Cisco of which 1,400 are accompanied by images. In addition, the archive contains metrics presented as arrays by W. N. Koelz, Coregonid fishes of the Great Lakes, Bulletin of the U.S. Bureau of Fisheries 43(2):297-643, which were based on 10,000 individuals. Spreadsheets in the Metrics folder of the archive are divided broadly into Contemporary and Historical subfolders and the Contemporary subfolder is further divided into Cisco Monograph and Extra Monograph subfolders to encourage statistical assessment of findings in GLFC Miscellaneous Publication 2023. The Images folder is organized into subfolders by lake. Tables in this user guide allow for quick determination of the availability of data by lake, subspecies, author, and year.

Laurentian↗

USGS2004

Genetic variability among lake whitefish from Isle Royale and the Upper Great Lakes

The coregonine fishes from Isle Royale National Park represent a unique group that has escaped the successional changes observed elsewhere in North America. Analysis of microsatellite DNA loci revealed significant genetic differences among samples of lake whitefish (Coregonus clupeaformis) from Isle Royale, Lake Superior, and Lake Huron. The amount of genetic variation observed is consistent with that seen in other studies of whitefishes from North America. The lake whitefish from Isle Royale had previously been assigned sub-species status, but no evidence was found to support this. The effects of common ancestry and demographics both play a role in determining the relatedness of the populations. As with other fish species from Isle Royale and the upper Great Lakes, the lake whitefish have their origins in the Mississippi refugium.

Annales Zoologici Fennici↗

USGS2004

Status of the shortjaw cisco (Coregonus zenithicus) in Lake Superior

The shortjaw cisco (Coregonus zenithicus) was historically found in Lakes Huron, Michigan, and Superior, but has been extirpated in Lakes Huron and Michigan apparently as the result of commercial overharvest. During 1999-2001, we conducted an assessment of shortjaw cisco abundance in five areas, spanning the U.S. waters of Lake Superior, and compared our results with the abundance measured at those areas in 1921-1922. The shortjaw cisco was found at four of the five areas sampled, but abundances were so low that they were not significantly different from zero. In the four areas where shortjaw ciscoes were found, abundance declined significantly by 99% from the 1920s to the present. To increase populations of this once economically and ecologically important species in Lake Superior, an interagency rehabilitation effort is needed. Population monitoring is recommended to assess population trends and to evaluate success of rehabilitation efforts.

Annales Zoologici Fennici↗

USGS2003

Update COSEWIC status report on the shortjaw cisco, Coregonus zenithicus, in Canada

Extirpated in most of the Great Lakes, the shortjaw cisco, Coregonus zenithicus, is currently found in Lakes Superior and Nipigon in addition to at least 22 Canadian lakes. The species exhibits morphological and genetic variability throughout its range and may consist of more than one distinct taxon. However, a common morph is widely distributed from the Great Lakes to the Northwest Territories, consistent with a hypothesis of preglacial origin for the species. Shortjaw ciscoes have declined because of excessive exploitation by food fisheries, habitat degradation, and predation and competition with introduced and exotic species such as alewife, Alosa pseudoharengus, and rainbow smelt, Osmerus mordax. The status of the species in most Canadian lakes is unknown, but continuing declines in those lakes that have been monitored suggest that the shortjaw cisco should be considered as threatened throughout its range.

Report↗

USGS2002

Sequence analysis of the mitochondrial DNA control region of ciscoes (genus Coregonus ): Taxonomic implications for the Great Lakes species flock

Sequence variation in the control region (D-loop) of the mitochondrial DNA (mtDNA) was examined to assess the genetic distinctiveness of the shortjaw cisco ( Coregonus zenithicus ). Individuals from within the Great Lakes Basin as well as inland lakes outside the basin were sampled. DNA fragments containing the entire D-loop were amplified by PCR from specimens of C. zenithicus and the related species C. artedi , C. hoyi , C. kiyi , and C. clupeaformis . DNA sequence analysis revealed high similarity within and among species and shared polymorphism for length variants. Based on this analysis, the shortjaw cisco is not genetically distinct from other cisco species.

Molecular Ecology↗

USGS2002

Application of truss analysis for the quantification of changes in fish condition

Conservation of skeletal structure and unique body ratios in fishes facilitated the development of truss analysis as a taxonomic tool to separate physically-similar species. The methodology is predicated on the measurement of across-body distances from a sequential series of connected polygons. Changes in body shape or condition among members of the same species can be quantified with the same technique, and we conducted a feeding experiment using yellow perch ( Perca flavescens ) to examine the utility of this approach. Ration size was used as a surrogate for fish condition, with fish receiving either a high (3.0% body wt/d) or a low ration (0.5%). Sequentially over our 11-week experiment, replicate ration groups of fish were removed and photographed while control fish were repeatedly weighed and measured. Standard indices of condition (total lipids, weight-length ratios, Fulton's condition) were compared to truss measurements determined from digitized pictures of fish. Condition indices showed similarity between rations while truss measures from the caudal region were important for quantifying changing body shape. These findings identify truss analysis as having use beyond traditional applications. It can potentially be used as a cheap, accurate, and precise descriptor of fish condition in the lab as shown here, and we hypothesize that it would be applicable in field studies.

Journal of Aquatic Ecosystem Stress and Recovery↗

USGS1999

Functional convergence among pelagic sculpins of Lake Baikal and deepwater ciscoes of the Great Lakes

The vast, well-oxygenated hypolimnia of Lake Baikal and the Great Lakes were both dominated by endemic planktivorous fishes. These dominants, two species of sculpins ( Comephorus, Comephoridae ) in Lake Baikal and six species of deepwater ciscoes ( Coregonus, Salmonidae ) in the Great Lakes, although distant taxonomically, have morphologies suggesting a surprising degree of functional convergence. Here it is proposed that the same two buoyancy-regulation strategies observed in Baikal sculpins also arose in the deepwater ciscoes of the Great Lakes. One strategy favors hydrostatic lift (generated by low specific gravity) and is characterized by fatter, larger-bodied fish with smaller paired fins; the second strategy favors hydrodynamic lift (generated by swimming) and is characterized by leaner, smaller-bodied fish with larger paired fins. Both types likely evolved to feed on a single species of ecologically analogous, vertically migrating macrozooplankter: Macrohectopus branickii in Lake Baikal and Mysis relicta in the Great Lakes. It is suggested that Coregonus did not diversify and proliferate in Lake Baikal as they did in the Great Lakes because by the time Coregonus colonized Lake Baikal, pelagic sculpins were already dominant.

Journal of Great Lakes Research↗

USGS1998

Competition between larval lake herring (Coregonus artedi) and lake whitefish (Coregonus clupeaformis) for zooplankton

Diet and growth of larval lake herring (Coregonus artedi) and lake whitefish (Coregonus clupeaformis) were compared in mesocosm experiments in a small mesotrophic lake in southeastern Michigan. Fish were sampled from single-species and mixed assemblages in 2-m 3 cages for 8 weeks during April and May. Both species initially ate mostly cyclopoid copepodites and small cladocerans (Bosmia spp.). Schoener's index of diet overlap showed considerable overlap (70-90%). Lake whitefish ate Daphnia spp. and adult copepods about 2 weeks earlier than did lake herring, perhaps related to their larger mean mouth gape. Lake whitefish were consistently larger than lake herring until the eighth week, especially in the sympatric treatments. Lake whitefish appeared to have a negative effect on the growth of lake herring, as lake herring in mixed-species treatments were smaller and weighed less than lake herring reared in single-species treatments. The diet similarities of lake whitefish and lake herring larvae could make them competitors for food in the Great Lakes. The greater initial size of lake whitefish could allow them to eat larger prey earlier and thereby limit availability of these prey to lake herring at a crucial period of development.

Michigan↗

USGS1998

Environmental modification of gillraker number in coregonine fishes

Gillraker number, one of the most important taxonomic characters in the Coregoninae, has been considered genetically determined and not environmentally modifiable. However, laboratory-reared progeny of Coregonus alpenae , C. artedi , C. clupeaformis , C. hoyi , C. kiyi , C. zenithicus , and Prosopium cylindraceum generally had fewer gillrakers than the wild parents from which eggs were taken for hatching and rearing. Of 19 experimental groups hatched and reared between 1957 and 1996, only progeny from C. alpenae , C. zenithicus , and one group of C. clupeaformis had gillraker counts similar to their parents. All other groups had three to six gillrakers less than their wild parents. Most species were hatched and reared under similar conditions including similar temperatures, except for three groups of C. hoyi and several groups of C. clupeaformis and C. artedi . Incubation of C. hoyi eggs at 2°, 4°, and 8° C produced fish with five to six fewer gillrakers on average than their wild parental source in Lake Michigan. Warmer rearing temperatures produced higher gillraker counts in C. clupeaformis , and perhaps the discrepancies observed between wild and laboratory-reared fish in these experiments resulted from colder rearing temperatures in the laboratory than those experienced by wild fish.

Book chapter↗

USGS1995

Genetic contribution of hatchery fish to walleye stocks in Saginaw Bay, Michigan

Stocks of walleye ( Stizostedion vitreum ) were severely depressed in Saginaw Bay in the 1970s. In 1979, the Michigan Department of Natural Resources began intensive stocking of walleye fingerlings to bolster fish populations. Subsequent to stocking, the walleye fishery has recovered. The study objective was to determine if recovery was due to the stocking program or natural reproduction. Inherent genetic differences between hatchery fish and endemic walleyes were used to determine the effect and contribution of hatchery fish to Saginaw Bay.

Michigan↗

USGS1995

Effects of fish density and relative abundance on competition between larval lake herring and lake whitefish for zooplankton

Competition for zooplankton between larval lake herring ( Coregonus artedi ) and lake whitefish ( C. clupeaformis ) was compared in mesocosm experiments in a small lake. Both species were combined in test enclosures at relative abundances of 1:1 or 1:4 lake herring to lake whitefish at densities of 500; 1, 000; and 2, 000 fish per cage, and were allowed to feed ad libitum on available zooplankton. After 60 days, at 500 fish per cage and a 1:1 ratio, lake whitfish were significantly larger than lake herring. At 1, 000 and 2, 000 fish per cage, lake herring and lake whitefish exhibited similar depressed growth rates. Survival was lower (30-50%) in the nets with 2, 000 fish than in the lower fish densities. We suspect that diet similarities of juvenile lake herring and lake whitefish in addition to the larger size and more aggressive behavior of larval lake whitefish resulted in the depressed growth and poorer survival for lake herring.

Book chapter↗

USGS1995

Biology and status of the shortnose cisco Coregonus reighardi Koelz in the Laurentian Great Lakes

The shortnose cisco, Coregonus reighardi , a member of the endemic species assemblage of Coregoninae in the Laurentian Great Lakes, was commercially important until overfishing and competition pressures from induced planktivores extirpated the species in Lakes Michigan and Ontario. Spawning shortnose ciscoes have been collected from Lake Huron and Georgian Bay of Lake Huron since 1956, however, no individuals have been collected from these habitats since 1985. Shortnose ciscoes were not collected during surveys of the cisco fishery of Georgian Bay during the summer of 1992 and spring of 1993. The lack of captures in the last eight years coupled with captures of only lone individuals in the last 16 years suggests the species may be extinct in all of the Laurentian system. The life history traits examined for Lake Huron shortnose ciscoes were similar to the conditions recorded for Lake Michigan and Ontario shortnose ciscoes, although Lake Huron fish were smaller.

Great Lakes↗

USGS1994

Effects of pulsed turbidity and vessel traffic on lake herring eggs and larvae

Proposals to extend commercial shipping in the St. Marys River (connecting Lakes Superior and Huron) to include winter months have raised concerns regarding its effect on lake herring ( Coregonus artedi ). Because lake herring spawn in fall and their eggs overwinter in the river and hatch in spring, their hatching success could be impacted by early opening of the locks in spring. Our laboratory studies showed that under the range of turbidities expected in the river due to vessel traffic, lake herring eggs hatched and larvae fed adequately. Field incubation studies produced about 75% survival and 70% hatching success of lake herring eggs at two of three study sites. Collections in the river throughout the month following ice-out showed that sufficient plankton of appropriate size were available to ensure growth and survival of larval lake herring. We did not detect any negative impacts on the early life stages of lake herring as a result of sedimentation in the laboratory or field. However, detailing the spawning sites of lake herring and defining the normal survival-to-hatch in these areas are necessary before making accurate predictions of the effects of early season vessel traffic on lake herring hatching success.

Journal of Great Lakes Research↗

USGS1993

Genetic and tagging evidence for movement of walleyes between Lake Erie and Lake St. Clair

Walleyes ( Stizostedion vitreum vitreum ) from Lake Erie differed in allele frequencies from walleyes in Lake St. Clair (N = 1,680; 25 loci); however, only slight differences were found among walleyes from different spawning sites in each lake. Analyses of allele frequency data from samples of nonspawning walleyes taken in Lake St. Clair provided conditional maximum likelihood estimates that 86% of these walleyes were from Lake St. Clair and 14% from Lake Erie (SD = 19.7%) in 1983 and that 63% were from Lake St. Clair and 37% were from Lake Erie (SD = 20.0%) in 1984. About 30% of 1,159 recoveries of walleyes tagged in Lake Erie were taken from the Detroit River northward to southern Lake Huron, thus demonstrating extensive mixing of stocks from Lake Erie and Lake St. Clair. Additionally, tags recovered from the upper half of the St. Clair River provided an estimate of mixed stock composition of 76% Lake St. Clair fish and 24% Lake Erie fish. Analyses of tags returned during successive spawning seasons showed that walleyes strongly tended to return to suspected natal spawning areas. The tagging data thus corroborate the genetic evidence that walleye stocks from Lake St. Clair and Lake Erie are different, and that large numbers of Lake Erie walleyes enter Lake St. Clair during nonspawning seasons and return to their Lake Erie spawning sites each year. Western Lake Erie and Lake St. Clair walleyes should be considered as separate stocks for management purposes.

Journal of Great Lakes Research↗

USGS1993

Genetic variability and glacial origins of yellow perch ( Perca flavescens ) in North America

Starch–gel electrophoresis was used to analyze muscle and liver tissue for variation in 13 enzymes representing 31 presumptive loci in yellow perch ( Perca flavescens ) from 13 localities scattered throughout the natural geographic range of the species in North America. Ten loci were polymorphic, but only three, alcohol dehydrogenase ( ADH-1 *), glucose-6-phosphate isomerase ( GPI-1 *), and phosphoglucomutase ( PGM-2 *), exhibited polymorphisms at relatively high frequencies across localities. Western populations were fixed for one allele at ADH-1 *, eastern populations were fixed for another allele, and populations from intermediate locations in Lake Ontario and Pennsylvania had both alleles. The distributions of alleles at GPI-1 * and PGM-2 *were similar to that of ADH-1 *, exhibiting strong differences between eastern and western populations, although the delineation was not as clear. Western populations were much less variable than eastern populations, and the distribution of alleles indicated that the two groups were derived from Mississippi and Atlantic glacial refugia. Populations near the physiographic discontinuity between the Mississippi and Atlantic drainages in western New York and Pennsylvania exhibited an admixture of typically western and eastern alleles. Such observations are consistent with the mixed faunal history of the region and limited postglacial dispersal of western and eastern populations across the boundary.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS1992

A review of differentiation in Great Lakes ciscoes

Seven species of ciscoes (Coregonus, subgenus Leucichthys) were found in the Great Lakes as recently as the early 1950's. Variation within and among species of Great Lakes ciscoes indicates that much of the divergence occurred within lakes. Following postglacial colonization by perhaps two or three species, population differentiation began with homing and reproduction at different localities and times. Physiological interaction between temperature (depth) and maturation time, as well as behavioral tendencies to home to spawning grounds and mate with related individuals, are the basis of premating reproductive separation. Phenotypic differences between populations indicate that ecological character displacement has been an important mechanism in the divergence. Introgression has obscured morphological species boundaries at the same time as intralacustrine speciation has created local subgroups, providing an unresolvable conflict between species definitions based on morphological and other characters and definitions dominated by inferred reproductive isolation. Species should be considered as the smallest diagnosable units within a phylogenetic framework, in which diagnoses are strictly by derived characters. Ecological and seasonal species could be recognized by application of a trinomial, equivalent to the subspecies trinomial.

Polskie Archiwum Hydrobiologii↗

USGS1990

Genetic differentiation of walleye stocks in Lake St. Clair and western Lake Erie

Allozyme data from six spawning sites of walleyes (Stizostedion vitreum vitreum) in western Lake Erie and two in Lake St. Clair demonstrated significant differences between allelic frequencies in fish from the two lakes. In contrast, differences were only slight between walleyes from different spawning sites within each lake. Of 21 presumptive genetic loci assayed electrophoretically, 4 were polymorphic enough to differentiate the populations. Allelic frequencies differentiating the stocks were stable between year classes, sexes, and sample years, showing that fry hatched in a particular area were returning there to spawn. These findings support other evidence for homing in Great Lakes walleyes.

Fish and Wildlife Technical Report↗

USGS1989

Hybridization of ciscoes ( Coregonus spp.) in Lake Huron

Gill raker number and length were compared for lake herring, Coregonus artedii LeSueur, and bloater, Coregonus hoyi (Gill), collected in 1917, 1956, and 1984-1985 at four locations in western Lake Huron to examine the effects of suspected introgressive hybridization on these distinctive species characters. Gill raker length showed no change from 1917 to 1984-1985, but gill raker number became similar in the two species over that period. Between 1917 and 1984-1985, mean gill raker counts decreased from 48.0 to 45.8 in lake herring, but increased from 41.8 to 43.1 in bloaters. The modal count for both species was 43 in 1984-1985. Intermediate gill raker counts were consistent with the hypothesis of hybridization. Bloater abundance increased greatly in the 1980's, but lake herring remained scarce. Under these circumstances, the rare lake herring would be increasingly likely to encounter abundant ripe bloaters during the overlapping spawning seasons of these species, increasing the probability for hybridization. Basic biological differences between the species, such as lower vulnerability of bloaters to commercial harvest, better survival of bloater fry, or greater fecundity of bloaters, may have contributed to the substantially better success of bloaters. Cisco populations are fragile; only the bloater has ever made a strong and sustained recovery after a severe decline. Hybridization with bloaters may impede the recovery of lake herring in Lake Huron.

Canadian Journal of Zoology↗