As in so much else advances in science are finding ways to advance our knowledge and understanding of fish, which in this part of the world frequently concerns salmon. In my hometown of Campbell River one example of this became front-page news recently in the local paper – it may have been a slow news week but I for one was pleased to see the exposure this initiative received.
The story (www.campbellrivermirror.com/news/409575025.html) concerns a study intended to find out if size-specific pairings of chinook salmon being used for broodstock at the Quinsam River hatchery can result in offspring better or best suited to spawn naturally in the Campbell River, the much shorter but wider system into which the Quinsam flows. The Campbell River itself once hosted some of the largest chinook salmon found on the south coast, fish that were the foundation of the communities’ recreational salmon fishing reputation over 100 years ago. Such were the large size of these fish that the Tyee Club
(www.tyeeclub.org), membership of which requires the landing of a fish 30 pounds or more under club rules, was founded in 1924.
It is thought that this specific stock of chinook salmon evolved in response to the river habitat which features high flows and large gravel, requiring bigger than average fish to spawn successfully there. The history of changes to this rivers’ habitat are outside the scope of this column but efforts are ongoing to ensure the future sustainability of this chinook stock and, to the extent possible, replicate the traits that made them what they were.
Declining size-at-age in the 21st century is a feature common to all salmon, not just to Campbell River chinook, likely caused by a combination of factors possibly including less favorable rearing conditions at sea, increased competition between hatchery and wild origin fish and the long-term effects of fishing, but nobody knows for sure. The fact that Campbell River chinooks still have the capability of becoming very large in a fairly short period of time was confirmed in 2013 when a 61.5-pound chinook landed under Tyee Club rules was found to be a 5-year old fish.
Starting a couple of years ago a small tissue sample from the tail fin is taken from all chinook and coho used as broodstock at DFO production hatcheries to provide DNA. This program is known as Parental Based Tagging and has a variety of applications, including sampling in at-sea fisheries, but in combination with the size-specific (large by large, small by large etc.) pairing study being conducted at Quinsam hatchery is at the center of efforts to restore Campbell River chinook to something of their former greatness. As soon as the eggs from these pairings become eyed-up they are transferred from the hatchery into in-stream incubators in the Campbell River itself, maximizing the imprint time of the river on the resulting juveniles. Emerging as fry from the incubators they will spend approximately 3 months rearing as essentially wild fish before becoming smolts and heading to sea.
Tissue samples taken from returning adults in future years will be analyzed to find out if their parents were part of this program and, in combination with the usual stock assessment data (sex, length, age) collected each year, will inform the study as to what, if any, specific size-pairings create larger chinook. Being long lived salmon, typically 4 – 6 years for Campbell River chinook, the answers won’t come quickly but the study is underway so that’s the important thing.
One genetics study on chinook salmon has already come up with some answers and it has raised some big questions about previously held assumptions on the migration range of chinook originating from BC and southern US (Washington, Oregon & Idaho) rivers. The fact that chinook from the southern part of their range often migrate up the coast has been well understood for decades but it was thought that BC origin fish usually didn’t migrate past the top end of the Alaska Panhandle. This was the basis for Cape Suckling as the upper geographic boundary of the Pacific Salmon Commission area of responsibility when the Canada/US salmon treaty was first negotiated in 1985.
Now a study by the state of Alaska ( https://fnonlinenews.blogspot.ca/ ) sampling the genetics of chinook caught in both sport and commercial fisheries around Kodiak Island, further southwest across the Gulf Of Alaska, has found that in some years half the chinook caught there originate from BC, including fish from the inner south coast such as Quinsam/Campbell chinook. Also included in the mix of fish found there are chinook salmon originating from Russia, albeit in much smaller numbers, but this study is sure to initiate a serious rethink of chinook ocean distribution patterns with possible implications for high-level fisheries management arrangements. Almost certainly this apparent change is a result of salmon, and not just chinooks, responding to a warming ocean.
Much closer to home the results of a study using genetics to determine the general stock composition of chum salmon encountered in commercial fisheries in Johnstone Strait and the San Juan Island – Point Roberts area in Washington State has been released. Funded by the Pacific Salmon Commission Southern Endowment Fund and sampling nearly 5,000 fish a joint Canada/US team of researchers has determined that more than 95% of chums encountered in Johnstone Strait are of Canadian origin, mostly from the Fraser River and east coast of Vancouver Island rivers.
In US management areas 7 and 7A the majority of the chums taken there originate from the Fraser River, with the percentages varying depending on timing and which exact area, with 7A being closest to the border. As well Vancouver Island chums from rivers like the Cowichan and Nanaimo contribute significantly to the commercial fisheries there.
For those with an interest in salmon these new understandings derived from genetic sampling are exciting and represent only the tip of the proverbial iceberg in where this field of research will go. Likely the biggest constraint to additional research is the cost of analyzing the tissue samples – about $15 each currently – but provided it can be funded all kinds of new and informative information about salmon will be forthcoming in the not so distant future.