Chinook by the Numbers
U-Idaho graduate Josh McCormick’s research informs management of Idaho salmon fisheries
Spring is here, Chinook salmon are swimming from the Pacific Ocean to the Idaho hatcheries and rivers where they were born – and anglers are waiting for them. But how do state management agencies balance the need for adequate numbers of Chinook in the fisheries against anglers’ desire to stock their larders?
Thanks to Josh McCormick, a recent graduate of the University of Idaho College of Natural Resources, the Idaho Department of Fish and Game, or IDFG, now has improved tools for managing Idaho’s Chinook salmon population.
In recognition of his groundbreaking work, the college named McCormick its outstanding researcher, and the Department of Fish and Wildlife named him its outstanding fisheries graduate student.
Using an ambitious observation study, McCormick worked closely with IDFG to develop improved sampling designs for creel surveys, in which IDFG “creel clerks” ask anglers at designated times and places throughout the season simple questions about what they caught, how long it took them and what they kept.
“When you collect data you have a snapshot in time and space of what’s happening to fish and wildlife,” says McCormick, who now works for the Oregon Department of Fish and Wildlife as a fishery biometrician, a scientist who analyzes data used to make decisions on natural resources.
Since IDFG can’t keep an eye on every single angler, creel surveys help the department estimate the numbers of Chinook being caught. As harvest numbers approach the quota – carefully determined before the beginning of the season — IDFG can decide when to close the Chinook season.
“With bad survey design, you are potentially making bad inferences about what the population is doing,” McCormick says. “The better design you have, the more likely you are to make correct inferences and decisions, and the better you can defend the decision you made.”
If creel surveys underestimate the number of fish harvested, too few could return to the hatchery to spawn. This could have a profound impact on the species’ recovery and on the industry, which annually brings in upwards of $253 million to the state while supporting thousands of jobs.
But if creel surveys overestimate the harvest, IDFG could shut down the season prematurely, denying anglers their opportunity to harvest salmon.
To get a clearer picture of what was actually happening during the Chinook salmon season, McCormick designed a study that included a complete census of portions of Chinook fisheries across Idaho.
Over two summers, he spent about 60 days in the field using binoculars to observe anglers from before sunup to after sundown, recording the time they spent fishing and number of fish they caught. Finding observation points was challenging because he had to be able to get a good look at a wide area without being noticed by the anglers.
“It’s really expensive and time-consuming for natural resource planners to get this kind of data,” said McCormick. “It’s probably the kind of thing only a graduate student would do. It hasn’t been done a lot.”
Michael Quist – College of Natural Resources associate professor, assistant leader of the Idaho Cooperative Fish and Wildlife Research Unit and McCormick’s adviser, says it takes a devoted scientist to take on such research.
“Creel surveys are one of the main tools in our toolbox, but they are not fun,” he says. “They are not the sexy part of fisheries research and management. So, the importance of it is often neglected – particularly with regard to the sample design.”
Once McCormick had real numbers to work with, he ran simulations of various creel survey designs until he developed one that would provide the most accurate results, while taking into account the time and monetary constraints faced by Idaho’s fishery managers.
McCormick’s work is particularly important because it focuses on Chinook salmon.
Creel surveys are used to manage all kinds of fisheries, and IDFG was using the best available science to establish harvest quotas prior to McCormick’s research, Quist says. However, virtually all of the scientific literature on such surveys at the time focused on inland recreational fisheries for species such as walleye and black bass, which are harvested year-round.
Chinook salmon, however, are different. They are only available for short periods of time as they move up the river. The pressure to harvest them is so intense that anglers often line up shoulder-to-shoulder, competing for their chance at a fish – a practice that’s been termed “combat fishing.” Even an angler who fishes all day long may never catch a prized Chinook.
McCormick’s designs have now been used by IDFG for two seasons.
“Josh’s work has really provided a guide to the profession in general, in Idaho and around the world, on how to sample short-duration, high-intensity fisheries,” Quist says. “It’s going to take some time to realize the full impact. But within the region, it has already programmatically changed how people are thinking about creel surveys and harvest estimates.
His research represents the very best the College of Natural Resources and the University of Idaho have to offer – and he’s not done yet.”
In fact, he’s only beginning. McCormick is now putting his sampling design genius to work helping Oregon’s state fish and game agency to improve management of the state’s fisheries.
By Jill Maxwell