Shaping the Management of Northern Dolly Varden Charr
Protecting and conserving our fisheries resources are key priorities of Fisheries and Oceans Canada. The Department relies on credible, science-based information to support Canadian fisheries. In the case of the northern Dolly Varden charr (Salvelinus malma), genomics research has played an important role in the management and conservation of this Arctic species.
A Co-Managed Species
Northern Dolly Varden charr (S. malma malma) live in the river systems and coastal areas of the Yukon and the Northwest Territories. Some of the populations are found in two settled land claims in the area, the Inuvialuit Settlement Region and the Gwich’in Settlement Area. Northern Dolly Varden charr are harvested by the Inuvialuit and Gwich’in peoples and are an important part of their diet, tradition and culture. The management of this species is a collaborative effort between the Fisheries Joint Management Committee (Inuvialuit), the Gwich’in Renewable Resources Board, Fisheries and Oceans Canada and the resource users (community hunters, trappers, and renewable resource committees).
A Complex and Sensitive Fish
Northern Dolly Varden charr are a complex species -- at least six distinct populations exist in the rivers of the northwestern Arctic. In addition, they exhibit three life history forms:
- sea-run fish, which are large and preferred by fishers;
- riverine fish, which are small, remain in fresh water and spawn with the sea-run form; and,
- small stream fish, which are isolated upstream by impassable water falls.
Northern Dolly Varden charr are also a sensitive fish that are vulnerable to a variety of impacts. They mature later than many other species, are particularly vulnerable to habitat changes, exist in small populations, and do not recover from stress as readily as other species. Climate change, local earthquakes, exploitation and lower water levels are taking a toll on the northern Dolly Varden charr and their habitats. Two populations have been depleted to critical levels and, although fisheries in some river systems have been banned for years, coastal fisheries continue in the region. This can have unknown consequences for the depleted populations because they mix with the other populations in the coastal areas. A better understanding of the classification complexity, genetic diversity and coastal mixing of populations is needed to manage this species well.
With funding through the Genomics Research and Development Initiative, scientists at Fisheries and Oceans Canada, led by Dr. Jim Reist, have been examining the genomic complexity of the northern Dolly Varden charr. By studying fragments of DNA called microsatellites, the scientists were able to distinguish the subspecies and populations of northern Dolly Varden as distinct groups. The genetic markers also provided essential information for estimating how much of the fish are harvested at sea.
"Greater knowledge of diversity in northern fishes, such as the Dolly Varden Charr, is critical to the sustainable management of these species. Genetic and genomic research is key to that understanding, especially as significant changes occur throughout the Arctic."
— Dr. Jim Reist, Fisheries and Oceans Canada Scientist
Impacts on Conservation
The genetic findings have changed how the Department and its co-management partners manage the species. In terms of conservation, the findings enabled the Committee on the Status of Endangered Wildlife in Canada to assess that the northern Dolly Varden charr is a sensitive species; it is now listed as a species of ‘special concern’ in Canada. This led the co-management partners to develop new sustainable management policies to help guide conservation and management strategies for the species.
Impacts on Fishery Decisions
The genetic findings have also informed important fishery management actions. For example, the genetic markers were used to determine the effective population size (a vital parameter for conservation) of one of the depleted populations of northern Dolly Varden charr, the Big Fish River population of the Northwest Territories. This information contributed to a Canadian Science Advisory Secretariat assessment (2009-2011), which concluded that there are no immediate conservation concerns for that particular population. This was an important finding, as it directly influenced the decision to re-open the Big Fish River fishery, which had been closed for over 10 years. The genetic findings are also being used to determine the yearly harvest levels for the Big Fish River populations in coastal and inland waters.
Because of the status of northern Dolly Varden charr as a species of special concern, and its importance to the Inuvialuit and Gwich'in peoples, well-founded science advice is regularly required to effectively manage the species and to ensure its long-term sustainability. The Fisheries Joint Management Committee and Gwich'in Renewable Resources Board have requested continued genetic analysis (for an additional two years) to assist them with assessing the stability of their fisheries. This knowledge is used by community resource groups in making management decisions.
"We fully support the genetics work that is being conducted at Shingle Point since summer 2011. The genetics work (…) has helped with understanding more about Dolly Varden charr stock components and provided useful information to management decisions on the species in the Aklavik area."
— The Aklavik Hunters and Trappers Association Committee
Going forward, researchers plan to use genetic tools to estimate the sizes of the other populations of northern Dolly Varden charr (as was done for the Big Fish River population) and to further examine the relationships among the life history forms (sea-run, riverine and small stream fish). Collaboration with Alaskan researchers will increase our knowledge of the migratory behaviours of these fish. Future conservation and management actions (such as setting of harvest levels and recovery needs) will directly benefit from this work.
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