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John M. Dettmers

Publications and source records attributed to John M. Dettmers.

28 records · Page 2Linked to original sources

Do intracoelomic telemetry transmitters alter the post-release behaviour of migratory fish?

Electronic tags have become a common tool in fish research, enhancing our understanding of how fish interact with their environment and move among different habitats, for estimating mortality and recording internal physiological states. An often-untested assumption of electronic tagging studies is that tagged fish are representative of untagged conspecifics and thus show ‘normal’ behaviour (e.g. movement rates, swimming activity, feeding). Here, we use a unique data set for potamadromous walleye (Sander vitreus) in Lake Huron and Lake Erie tributaries to assess whether the lack of appropriate controls in electronic tagging could seriously affect behavioural data. We used fish tagged in previous years and compared their migratory behaviour during the spawning season to fish tagged in a current year at the same location. The objective of the study was to determine whether intracoelomic acoustic tag implantation altered downstream movement of walleye after spawning. Fish tagged in a given season travelled slower downstream from two river spawning sites than fish tagged in previous years. Fish tagged one or two years earlier showed no differences between each other in downstream travel time, in contrast to fish tagged in a given year. Our results support notions that standard collection and intracoelomic tagging procedures can alter short-term behaviour (i.e. days, weeks, months), and as such, researchers should use caution when interpreting data collected over such time periods. Further, whenever possible, researchers should also explicitly evaluate post-tagging effects on behaviour as part of their experimental objectives.

Maumee Bay, Saginaw Bay↗

Seasonal thermal ecology of adult walleye (Sander vitreus) in Lake Huron and Lake Erie

The purpose of this study was to characterize thermal patterns and generate occupancy models for adult walleye from lakes Erie and Huron with internally implanted biologgers coupled with a telemetry study to assess the effects of sex, fish size, diel periods, and lake. Sex, size, and diel periods had no effect on thermal occupancy of adult walleye in either lake. Thermal occupancy differed between lakes and seasons. Walleye from Lake Erie generally experienced higher temperatures throughout the spring and summer months than did walleye in Lake Huron, due to limnological differences between the lakes. Tagged walleye that remained in Saginaw Bay, Lake Huron (i.e., adjacent to the release location), as opposed to those migrating to the main basin of Lake Huron, experienced higher temperatures, and thus accumulated more thermal units (the amount of temperature units amassed over time) throughout the year. Walleye that migrated toward the southern end of Lake Huron occupied higher temperatures than those that moved toward the north. Consequently, walleye that emigrated from Saginaw Bay experienced thermal environments that were more favorable for growth as they spent more time within their thermal optimas than those that remained in Saginaw Bay. Results presented in this paper provide information on the thermal experience of wild fish in a large lake, and could be used to refine sex- and lake-specific bioenergetics models of walleye in the Great Lakes to enable the testing of ecological hypotheses.

Journal of Thermal Biology↗

Acoustic telemetry reveals large-scale migration patterns of walleye in Lake Huron

Fish migration in large freshwater lacustrine systems such as the Laurentian Great Lakes is not well understood. The walleye ( Sander vitreus ) is an economically and ecologically important native fish species throughout the Great Lakes. In Lake Huron walleye has recently undergone a population expansion as a result of recovery of the primary stock, stemming from changing food web dynamics. During 2011 and 2012, we used acoustic telemetry to document the timing and spatial scale of walleye migration in Lake Huron and Saginaw Bay. Spawning walleye ( n = 199) collected from a tributary of Saginaw Bay were implanted with acoustic tags and their migrations were documented using acoustic receivers ( n = 140) deployed throughout U.S. nearshore waters of Lake Huron. Three migration pathways were described using multistate mark-recapture models. Models were evaluated using the Akaike Information Criterion. Fish sex did not influence migratory behavior but did affect migration rate and walleye were detected on all acoustic receiver lines. Most (95%) tagged fish migrated downstream from the riverine tagging and release location to Saginaw Bay, and 37% of these fish emigrated from Saginaw Bay into Lake Huron. Remarkably, 8% of walleye that emigrated from Saginaw Bay were detected at the acoustic receiver line located farthest from the release location more than 350 km away. Most (64%) walleye returned to the Saginaw River in 2012, presumably for spawning. Our findings reveal that fish from this stock use virtually the entirety of U.S. nearshore waters of Lake Huron.

Michigan, Ontario↗

Mercury accumulation in sea lamprey ( Petromyzon marinus ) from Lake Huron

We determined whole-fish total mercury (Hg) concentrations of 40 male and 40 female adult sea lampreys ( Petromyzon marinus ) captured in the Cheboygan River, a tributary to Lake Huron, during May 2011. In addition, bioenergetics modeling was used to explore the effects of sex-related differences in activity and resting (standard) metabolic rate (SMR) on mercury accumulation. The grand mean for Hg concentrations was 519 ng/g (standard error of the mean = 46 ng/g). On average, males were 16% higher in Hg concentration than females. Bioenergetics modeling results indicated that 14% higher activity and SMR in males would account for this observed sex difference in Hg concentrations. We concluded that the higher Hg concentration in males was most likely due to higher rate of energy expenditure in males, stemming from greater activity and SMR. Our findings have implications for estimating the effects of sea lamprey populations on mercury cycling within ecosystems, as well as for the proposed opening of sea lamprey fisheries. Eventually, our results may prove useful in improving control of sea lamprey, a pest responsible for substantial damage to fisheries in lakes where it is not native.

Michigan↗

Binational ecological risk assessment of bigheaded carps (Hypophthalmichthys spp.) for the Great Lakes Basin.

Bigheaded carps (Bighead and Silver carps) are considered a potential threat to the Great Lakes basin. A binational ecological risk assessment was conducted to provide scientifically defensible advice for managers and decision-makers in Canada and the United States. This risk assessment looked at the likelihood of arrival, survival, establishment, and spread of bigheaded carps to obtain an overall probability of introduction. Arrival routes assessed were physical connections and human-mediated releases. The risk assessment ranked physical connections (specifically the Chicago Area Waterway System) as the most likely route for arrival into the Great Lakes basin. Results of the risk assessment show that there is enough food and habitat for bigheaded carp survival in the Great Lakes, especially in Lake Erie and productive embayments in the other lakes. Analyses of tributaries around the Canadian Great Lakes and the American waters of Lake Erie indicate that there are many suitable tributaries for bigheaded carp spawning. Should bigheaded carps establish in the Great Lakes, their spread would not likely be limited and several ecological consequences can be expected to occur. These consequences include competition for planktonic food leading to reduced growth rates, recruitment and abundance of planktivores. Subsequently this would lead to reduced stocks of piscivores and abundance of fishes with pelagic, early life stages. Overall risk is highest for lakes Michigan, Huron, and Erie, followed by Lake Ontario then Lake Superior. To avoid the trajectory of the invasion process and prevent or minimize anticipated consequences, it is important to continue to focus efforts on reducing the probability of introduction of these species at either the arrival, survival, establishment, or spread stage (depending on location).

Great Lakes Basin↗

Evaluation of two forms of electroanesthesia and carbon dioxide for short-term anesthesia in walleye

Anesthetics immobilize fish, reducing physical damage and stress during aquaculture practices, stock assessment, and experimental procedures. Currently, only tricaine methanesulfonate (MS-222) is approved for use as an anesthetic for food fish in Canada and the United States; however, MS-222 can only be used with certain fish species, and treated fish must be held for a specified period of time before release into the wild. Two forms of electroanesthesia and carbon dioxide (CO 2 ) were evaluated as anesthetics for adult walleye Sander vitreus to determine their suitability for use before intracoelomic implantation of telemetry transmitters. Walleyes were subjected to one of three treatment groups: constant direct current (CDC), pulsed direct current (PDC), and CO 2 . Fish subjected to these treatments were monitored for induction (where appropriate) and recovery time and whether these forms of anesthesia were conducive to implanting telemetry transmitters, that is, whether they fit a surgery threshold range of 250–350 s. Additionally, all fish were monitored for posttrial survival, and radiographs were taken to determine whether any vertebral damage was associated with the electroanesthesia treatments. Although all anesthetic treatments successfully immobilized fish for enough time to implant a transmitter, PDC electroanesthesia is recommended because of its immediate induction time, quick recovery, high immediate and short-term survival, and lack of evidence of vertebral abnormalities.

North American Journal of Fisheries Management↗

Estimating mortality rates of adult fish from entrainment through the propellers of river towboats

We developed a method to estimate mortality rates of adult fish caused by entrainment through the propellers of commercial towboats operating in river channels. The method combines trawling while following towboats (to recover a fraction of the kills) and application of a hydrodynamic model of diffusion (to estimate the fraction of the total kills collected in the trawls). The sampling problem is unusual and required quantifying relatively rare events. We first examined key statistical properties of the entrainment mortality rate estimators using Monte Carlo simulation, which demonstrated that a design-based estimator and a new ad hoc estimator are both unbiased and converge to the true value as the sample size becomes large. Next, we estimated the entrainment mortality rates of adult fishes in Pool 26 of the Mississippi River and the Alton Pool of the Illinois River, where we observed kills that we attributed to entrainment. Our estimates of entrainment mortality rates were 2.52 fish/km of towboat travel (80% confidence interval, 1.00–6.09 fish/km) for gizzard shad Dorosoma cepedianum , 0.13 fish/km (0.00–0.41) for skipjack herring Alosa chrysochloris , and 0.53 fish/km (0.00–1.33) for both shovelnose sturgeon Scaphirhynchus platorynchus and smallmouth buffalo Ictiobus bubalus . Our approach applies more broadly to commercial vessels operating in confined channels, including other large rivers and intracoastal waterways.

Illinois, Missouri↗

Changes in seasonal energy dynamics of alewife ( Alosa pseudoharengus ) in Lake Michigan after invasion of dreissenid mussels

The dreissenid mussel invasion of Lake Michigan during the 1990s has been linked to a concomitant decrease in the abundance of the amphipod Diporeia . We tracked the seasonal energy dynamics of alewife ( Alosa pseudoharengus ) in Lake Michigan during 2002–2004 and compared our findings with previously published results for years 1979–1981. Adult alewife energy density exhibited a pronounced seasonal cycle during both the pre-invasion and post-invasion periods, with energy density in October or November nearly twice as high as that in early summer. However, on average, adult alewife energy density was 23% lower during the post-invasion period compared with the pre-invasion period. This significant decline in energy density was attributable to decreased importance of Diporeia in adult alewife diet. In contrast, energy density of juvenile alewives did not significantly differ between the pre-invasion and post-invasion periods. To attain a weight of 8 kg by age 4, bioenergetics modeling indicated that a Chinook salmon ( Oncorhynchus tshawytscha ) in Lake Michigan would have to consume 22.1% more alewives during the post-invasion period compared with the pre-invasion period.

Canadian Journal of Fisheries and Aquatic Sciences↗