IMPORTANT LINKS
scientific studies
Presented live via Zoom on September 8, 2021. Hosted by the Leelanau Historical Society. Presented by Nicole M. Watson, Ph.D. Student, Michigan State University, Department of Fisheries and Wildlife Fisheries Ecology and Management with dual degree in Ecology, Evolution, and Behavior Nicole’s Ph.D. research examines early-life history of Arctic Grayling, and their interactions with young Brook and Brown trout. The overarching goal of her research is to clarify uncertainties to successful Grayling reintroduction to Michigan streams. It is a multifaceted study including the following: predation of Grayling fry by resident, age-1 Brook and Brown trout; competition between age-0 Grayling, Brook, and Brown trout; Grayling imprinting to home waters at early life stages; water choice; alarm cues; aspects of physiological development; predator avoidance and predator cue recognition by juvenile Grayling. Her research takes her to Alaska each spring to transport Grayling eggs back to the lab at Michigan State University. More information about Arctic Grayling reintroduction in Michigan can be found at www.migrayling.org. Nicole is part of the research team of the collaboration.
“More Catch and More Release, continued” a Chinook Salmon study by ADFG in the Kenai River, 1991
Brook Trout were exercised for 30 minutes and held out of water in a net for durations of zero, 30, 60, and 120 seconds. Afterwards, the fish were placed in a swim tube and forced to swim until they were exhausted and drifted to the end of the tube. Results showed that exercised fish held out of water longer than 60 seconds had a dramatic 75 percent decrease in swimming performance compared to the other treatments. Many were unable to swim at all. With more exercise, body fluids become more acidic and blood lactate, a metabolic waste product, increases.
Pacific salmon (Oncorhynchus spp.) can transport bioaccumulated organic pollutants to stream ecosystems where they spawn and die. We quantified PCBs, DDE, and PBDEs in resident fishes from 13 Great Lakes tributaries to assess biotransport of pollutants associated with introduced Pacific salmon. Resident fishes sampled from salmon spawning reaches had higher mean pollutant concentrations than those from upstream reaches lacking salmon but differences varied substantially among lake basins. In Lake Michigan tributaries, PCB concentrations in resident fishes from salmon reaches were over four times higher than those from salmon reaches in Lake Huron and over 30 times higher than those from Lake Superior. Moreover, resident fish pollutant concentrations were better explained by pollutant inputs from salmon than by land development/agriculture, watershed area, resident fish species, body length, or lipid content. These results suggest that pollutant dispersal to stream ecosystems via biotransport is an often overlooked consequence of salmon stocking and historical food web contamination in the Great Lakes. Our findings have implications for Great Lakes management, including dam removal and wildlife conservation.
“Research Reveals Migrating Great Lakes Salmon Carry Contaminants Upstream” Carol C. Bradley, 2012
Be careful what you eat, says University of Notre Dame stream ecologist Gary Lamberti.
If you’re catching and eating fish from a Lake Michigan tributary with a strong salmon run, the stream fish — brook trout, brown trout, panfish — may be contaminated by pollutants carried in by the salmon.
Research by Lamberti, professor and chair of biology, and his laboratory has revealed that salmon, as they travel upstream to spawn and die, carry industrial pollutants into Great Lakes streams and tributaries. The research was recently published in the journal Environmental Science and Technology.
This essay examines the environmental, political, economic, and social repercussions of the Michigan Department of Conservation's decision to reverse nearly a century of policy favoring the commercial use of Great Lakes fisheries. It shows that as early as 1959, state conservation officials began to view the recreational use of the fisheries in its Great Lakes waters as serving the greatest public good. Sport fishing and recreational tourism were offered as a means of filling the economic and cultural void created in lakeshore communities by the demise of commercial fishing and other maritime related industries. Today,it is evident that the decision to create the Great Lakes sport fishery and drastically limit or curtail commercial and subsistence fishing has had mixed social and economic effects on the lakes themselves and on inhabitants of lakeshore communities. That decision contributed to a host of unanticipated environmental, economic, and social problems that continue to pit stakeholder groups against each other and the state's conservation agency, now called the Department of Natural Resources (DNR). The result has been financially costly and socially divisive legal battles and incidents of violence and intimidation.
This study analyzed the effects on rainbow trout in the Green River in Utah after consuming New Zealand mud snails. “We observed a sharp annual increase in the number of brown and rainbow trout consuming NZMSs between 2001 and 2005 in the Green River, Utah, downstream from Flaming Gorge Dam; moreover, the condition of brown and rainbow trout with NZMSs in their guts was significantly lower than that of fish without NZMSs in their stomachs. Our results confirm that North American trout fisheries face potential negative impacts from NZMS invasion.”
This study concluded that at high densities, New Zealand mud snails compete for food and space with native fauna.
This study of the effects of Great Lakes connectivity on resident populations of brook and brown trout concludes that the potential introduction of Pacific salmonids would likely harm existing populations of wild brook trout. “Brook trout, typically being competitively inferior to brown trout (Fausch & White, 1981; Waters, 1983) and introduced Pacific salmonids (Fausch & White, 1986), may suffer the greatest loss when a reach is made accessible to Great Lakes salmonids.”
This study of the potential effects of the introduction of steelhead into the Boardman River concludes that steelhead likely would out-compete brook trout. “There is clear evidence from field measurements and lab and field experiments that juvenile rainbow trout and steelhead can cause decreases in growth and survival of juvenile brook trout, and of juvenile brown trout which have a similar life history and ecology in tributaries of the Great Lakes.”
This study found that juvenile rainbow trout out-compete and push brook trout out of their native habitat. “We found that juvenile rainbow trout showed a higher growth rate than its two sister species (brook trout and Atlantic salmon), revealing its ability to effectively exploit resources.”
This study found that brook trout decreased in length following the emergence of larval rainbow trout. “For brook trout, mean food size increased, and amount consumed decreased, after the emergence of rainbow trout larvae. Growth reduction during the first summer, an outcome of interspecific competition for food and space, may result in increased overwintering mortality of fish at high latitudes, and be a mechanism by which brook trout are excluded by rainbow trout.”
This study discusses how brook trout have been pushed into the headwaters of New York tributaries of Lake Ontario by adult Pacific salmonids. “The decline of brook trout (Salvelinus fontinalis) populations throughout much of their native range in eastern North America is well documented and has received considerable attention. . . . Among the many factors that are thought to have contributed to the decline of brook trout is interspecific interactions with introduced non-native salmonids, particularly brown trout and rainbow trout.”
This study assessed the compatibility of non-native brook trout and Arctic grayling. Its conclusion: “We found little evidence that nonnative brook trout negatively affected microhabitat use or growth of native Arctic grayling.”
This study analyzed the compatibility of brown trout and brook trout. It notes that brown trout compete “closely with brook trout (both spawn in the fall and inhabit similar stream types), but the brown trout has the edge since it is more carnivorous, grows much larger, is more aggressive (monopolizes choice pools), and is more wary of anglers.”
This study analyzed the effect of removing brown trout from two southeastern Minnesota streams — Hemmingway Creek and Coolridge Creek. It found that “brook trout abundance steadily increased throughout the three year time period after brown trout removal.” The study also cautioned: “Due to the large amount of work involved in eradicating nonnative salmonids, removals may only be justified and achievable in small streams with brook trout populations of greatest concern.”
This study analyzed competition for stream position between brook trout and brown trout in the East Branch of Michigan’s Au Sable River. It found that brook and brown trout “competed for preferred resting positions, a critical and scarce resource, and that brown trout were the dominant competitor bccause brook trout expanded their use of resources to include more advantageous rehting positions when released from interspecific competition.”
This study analyzed the trout population in Minnesota’s Valley Creek between 1965 and 1980, during which time the population changed from 100% brook trout to predominantly brown trout. It found that “the change in species composition clearly occurred during a period of unsettled hydrological conditions that included floods and siltation, with consequent deleterious effects on trout reproductive success and food production. Several factors may be postulated to account for the brown trout's apparent ability to compete successfully against the brook trout under these stressed conditions, including greater aggressiveness in foraging and use of spawning areas, higher growth rate, survival to larger size, greater resistance to predation and angling, greater use of other fishes as food (sculpins in this case), and use of different habitat in their early life history.”
This study reports on the alarming decline in brook trout populations across their historic eastern U.S. range, from Maine to Georgia. “The assessment revealed wild brook trout populations in the eastern United States are impaired. Intact stream populations of brook trout, where wild brook trout occupy >90% of historical habitat, exist in only 5% of the watersheds assessed. Populations of streamdwelling brook trout are greatly reduced or have been extirpated from nearly half of the watersheds in their native range. The vast majority of historically occupied large rivers no longer support self-reproducing populations of brook trout.”
Boardman River Assessment — Final Report, August 2018
This report assesses the overall health of the Boardman River watershed. Its findings include the observation that native brook and brown trout are undersized when compared with trout in other Northwest Michigan trout streams due to “a paucity of instream habitat.”
Brown Bridge Dam Failure Report
This report analyzes the causes of a catastrophic accident on October 6, 2012, during the removal of the Brown Bridge Dam. During the drawdown of the 190-acre Brown Bridge Pond, 66 downstream Boardman River residences were flooded by a cascade of water.
Boardman River Natural River Plan, February 1976 (revised March 12, 2002)
This report shows that, for decades, the Michigan DNR has envisioned the Boardman as a premier steelhead and salmon fishery: “Were it not for Boardman Dam, Sabin Dam and a few other minor obstacles in the lower Boardman, the river between Brown Bridge Dam and its mouth would, without a doubt, be one of Michigan’s finest steelhead and salmon streams.”
BROOK TROUT, grayling and fish conservation LINKS
State of the Trout 2015, a report from Trout Unlimited
American Expedition: Brook Trout Information, Photos and Facts
Orvis News, Fish Facts: Brook Trout
U.S. Fish and Wildlife Service, Brook Trout
Michigan Department of Natural Resources, Brook Trout
The Wild Trout Trust, Trout Lifecycle
“Disappearing Native: The Brook Trout”
National Wildlife Federation, Brook Trout
A BTC white paper on the plight of the brook trout
Artic Grayling Reintroduction Research in Michigan
essays, videos, resolutions and letters
dnr’s plan to send steelhead up the boardman river
Following are comments made by DNR officials during a January 3, 2018, meeting with members of the Brook Trout Coalition, the Adams Chapter of Trout Unlimited, and other groups opposed to the DNR’s plan to send steelhead up the Boardman:
“The only way you can bring nutrients back into that system, in a useable form, is through fish from the Great Lakes. It’s the only way you can improve your size structure, it’s the only way to get a better fishery out of the Boardman River. . . . You’re stuck perpetually with what you have now.” — Jay Wesley, DNR Lake Michigan Basin Coordinator
“Even though steelhead are not native here, they can adjust to their ecosystem a lot better than we can (by) throwing a hatchery product out there.” — Jay Wesley
“Suckers are probably the largest mover of energy – far and away.” — Gary Whelan, DNR Fisheries Division Program Manager, when asked whether the DNR’s goal of “connectivity” between the Boardman River and Lake Michigan could be achieved by allowing suckers and other native species to pass into the Boardman without allowing steelhead, salmonids and non-native species to enter the river.
“Floods and droughts are likely the main causes of population changes for brook trout. Overharvesting can also present a threat to populations of this fish. Additionally, non-native fish that have been stocked in ponds and streams for fishermen are often more aggressive than brook trout and create a risk for this species.””