Coaster Brook Trout
COASTER BROOK TROUT are high-profile game fish with an international reputation. They are unique among brook trout, not only because of their large size and silvery colour, but also their migration into tributaries for spawning in the fall. Interestingly, coasters are produced by populations of typical brook trout found in these tributaries and are a variant of brook trout, rather than a unique subspecies.
Coasters are potadromous (migrating from rivers to a freshwater lake and back for spawning) brook trout that spend a portion of their life in Lake Superior. They are named for their affinity for the coastal waters of Lake Superior. Coasters are known for their large size and silvery colour while in the lake and are prized by anglers; the world record brook trout, weighing in at 14.5 pounds, was in fact a coaster brook trout caught in 1916 in the Nipigon River.
During the spawning season, coasters regain typical brook trout colouration and migrate up tributary rivers and creeks to spawn. It is at this time, when they are staging and spawning, that coaster brook trout are particularly vulnerable. Their large size and white leading edged fins make them highly visible in the tea-coloured waters of the tributaries and therefore easy targets for predators and anglers alike.
The status and range of coaster brook trout has been drastically reduced due to a variety of pressures, including habitat alteration, pollution, exploitation and competition from introduced species including Pacific salmon and brown trout. They have been extirpated from almost all of their former range (indicated in blue on the map at right) and only a handful of populations still persist. The last remaining stronghold for coaster brook trout is Nipigon Bay, which contains almost half of the known remaining coaster rivers and streams. Even here, however, coaster brook trout are still at very low numbers. This dramatic decline has prompted a demand for rehabilitation.
At present, however, knowledge of coaster brook trout is limited. The lack of basic biological data such as age of smolting, reproductive rates, life history and population demographics is greatly hampering effective conservation efforts. To date, rehabilitative efforts have focused on habitat restoration (mainly on rebuilding ďtypicalĒ brook trout habitat), and the stocking of Lake Nipigon strain hatchery brook trout. There have been multiple stockings of most of the tributaries on both the north and south shores of Lake Superior, as well as of the lake itself, but with little success. In recent years, the U.S. Fish and Wildlife Service initiated a plan ito create a coaster brook trout brood stock from remnant populations. Unfortunately, since the environmental triggers for the development of the coaster variant are unknown, this is no guarantee for coaster brook trout production.
Restoration of coaster brook trout stocks demands good science to support good management decisions. The identification of source rivers and the characteristics that make them conducive to coaster brook trout production is necessary information for recovery plans to succeed. In 2003, everyone involved in coaster rehabilitation research and management gathered to focus and prioritize efforts on both sides of the border. This diverse group, including managers, academics and representatives from Trout Unlimited and Trout Unlimited Canada, focused on the rehabilitation of coaster brook trout by identifying and filling in these information gaps. In addition, future collaborations of individuals on both sides of the border would increase the success of rehabilitation efforts.
Researchers are applying spatial analysis of aquatic habitat variables at various scales to identify differences among tributaries. In addition, they are combining multiple research tools (habitat analysis and genetic quantification of habitat-specific coaster production) to provide a testable model which will be a potent tool for identifying and prioritizing lake tributaries for rehabilitation and coaster production. Hopefully, this research also will identify possible triggers for the development of the coaster variant and, more importantly, distinguish features which can be used to identify and restore other potential coaster producing tributaries.
While this work will significantly advance our understanding of the watershed habitat variables associated with coaster brook trout, it is hoped that it may also aid in the management and restoration of other coastal trout species across Canada.
Research was undertaken between 2003-2006in order to examine the relationship between habitat parameters and coaster brook trout verses stream resident brook trout populations on the north shore of Lake Superior. Beginning in the spring of 2003 with funding grants from the Ontario Living Legacy Trust and the Canada-Ontario Agreement the project was further funded in 2004 by Fishing Forever, the Canada-Ontario Agreement and Trout Unlimited Canada. Over the first two field seasons, crews collected a variety of biotic and abiotic information on six tributaries of Nipigon Bay,Lake Superior, including temperature, flow rates, benthic invertebrate production, in-stream structure, amount of available habitat, substrate size,degree of canopy cover, species compositions. A grant from the Great Lakes Sustainability fund enabled completion of the data analysis and write-up. Based upon the field work, additional work is being proposed to develop a landscape/watershed based approach to determining key coaster brook trout streams and to identify the sensitivity of each watershed to impacts that could affect coaster brook trout.
Meanwhile, on a related note, in March 2007Trout Unlimited Canada was successful in acquiring a significant parcel of land fronting the Nipigon River which will protect an extremely important coaster brook trout spawning area adjacent to it. For more information please see the Gapenís Pool Acquisiton project.
For more information on TUCís coaster brook trout research, contact Silvia D'Amelio.
To download a copy of TUCís Coaster Brook Trout Stream Habitat technical report, click here.
To donate to the Gapenís Pool Acquisition Project, please contact TUCís National Office.