April 05, 2017
Four hundred river miles might seem like a walk in the park compared to the 1,000-mile voyage often undertaken by spawning Pacific salmon. The comparison serves as a sort of myth buster, however, when the former figure is attributed to channel catfish, a supposed sedentary species to many folks.
It turns out, channel catfish are movers, and have a lot more happening between their pectoral fins than most folks think. Like that their sense of smell is on par with or exceeds every other freshwater fish, including salmon, which sniff their way back to the rivers of their birth. Of course, catfish aren't anadromous and need not navigate the ocean back to their natal streams. But both species certainly do use their acute senses of smell to identify and home in on spawning sites as well as home ranges.
Both species can detect certain amino acids at extremely dilute levels. Catfish can detect concentrations to one part per 100 million, or about an ounce of substance dissolved in 100,000 railroad tank cars worth of water. Comparatively, evidence suggests salmon can smell to at least one part per 10 million. Such an intense sense of smell explains how cats can find cutbait 100 yards upstream in a turbid river at night.
We're beginning to learn that smell not only gives channel cats the ability to find an acorn in a dark world, but also the ability to migrate great distances in moving water, just as chemoreception enables salmon to travel up large rivers against strong current and long odds.
Red River Tracking
What began as conversation between University of Nebraska-Lincoln (UNL) fish ecologist Mark Pegg and Manitoba biologists at the 2010 Catfish Symposium developed into a thesis subject for UNL graduate student Stephen Siddons, and eventually, one of the more ambitious tracking studies in the ictalurid world to date. Launched in 2012, the study aims to follow channel catfish in the Red River of the North for a number of years. The importance of the survey has made it a cooperative effort between UNL and the Manitoba Fisheries Branch, with further collaboration with the Minnesota Department of Natural Resources and the North Dakota Game and Fish Department.
As perhaps North America's archetypal channel catfish stream, the Red flows approximately 550 miles from its headwaters near Breckenridge, Minnesota, north to Lake Winnipeg in Manitoba. Like many large North American rivers, the Red has been altered by the construction of dams, levees, and flood-diversion canals. Attempts to diminish the impacts of nine obstructions to fish migration have prompted the removal or modification of all but three of them. Remaining dams (St. Andrews in Manitoba, and at Drayton and Grand Forks, North Dakota) are not total barriers, but may prevent fish movement at lower discharge levels.
For the past several years, Siddons, Pegg, and a team of biologists have fished for and placed anchor tags in about 15,000 channel catfish, mostly near Lockport, Manitoba. Pegg says another 120 catfish carry radio transmitters, with a vast grid of listening stations (receivers) set up throughout the river's Canadian course and into Lake Winnipeg, as well as three additional stations on the U.S. side of the Red. To date, his team has downloaded a fair volume of preliminary data, though it's still too early to draw solid conclusions. Fortunately, the transmitters have at least a six-year lifespan.
According to Siddons' thesis, channel cats older than 20 years are common in the Red, with fish up to age-27 observed. Moreover, Red River catfish boast an exceedingly low (11 percent) annual mortality rate; harvest rate is 6 percent in Manitoba and 22 percent in the U.S. portion of the river. Manitoba has a more restrictive regulation, prohibiting harvest of any catfish over 24 inches. New tracking data will continue to be gathered for at least the next several years.
In the meantime, tag returns have already revealed surprising results regarding Red River catfish migration. Siddons' dissertation, Population Dynamics and Movement of Channel Catfish in the Red River of the North, reports 553 tagged fish recaptured by anglers. Remarkably, Siddons found that 88 percent of the fish that passed the dam in Lockport were recaptured upstream in the U.S.
Other findings showed that only larger catfish (greater than 24 inches) moved upstream through St. Andrews Dam at Lockport, while 79 percent of catfish that moved downstream to Lake Winnipeg were smaller than 26 inches. The greatest distance traveled by a single catfish was 703 km (436 miles), from Selkirk, Manitoba, to the Sheyenne River near Harwood, North Dakota. Siddons also reported a trend showing catfish longer than 24 inches traveled farther than smaller individuals, possibly related to spawning migration. Upstream migrations were far more common that downstream movements. Overall, 19 percent of tag recaptures occurred in the U.S. portion of the river.
Last summer, my buddy Brad Durick, likely the busiest catfish guide on the entire river, started telling me about the tagged fish he was catching in the upper reaches of the Red. "Through last season, we'd caught about 40 tagged catfish between Grand Forks and Drayton, North Dakota," Durick said. "Each tag is imprinted with a phone number and unique identification number. So when you call in the ID number, you can find out where the fish was tagged. Turned out, just three of those 40 fish were tagged in Grand Forks and another 1 or 2 were from Drayton, North Dakota. The remaining 35 or so were all fish tagged about 350 river miles downstream (north) around Lockport, Manitoba.
Durick says a catfish can swim twice its body length per second. "Biologists tell me cats are capable of this speed routinely," he says. "If they're migrating, they're likely capable of swimming much faster. With this in mind, a 36-inch channel cat could theoretically swim the 90 or so river miles between Grand Forks and Drayton in about a day and a half."
Apparently, they can and do swim that distance — at least inside a month — as evidenced by one tagged fish Durick's clients caught twice last year. "We caught a tagged fish last May 14 near the Drayton dam. Then on June 12, another client caught the same fish near Grand Forks, 92 river miles upstream." According to Durick, a deluge of precipitation raised river levels substantially, perhaps prompting a significant upstream migration.
Beyond lessons learned regarding the amazing distances traveled by these catfish, Durick has been heartened by the overarching, positive implications for catch-and-release fishing. "Last May, my buddy Charlie caught one around Drayton with a tag, which I called in for him. Turns out, I'd caught the same fish 100 yards from where he'd caught it on September 28, 2015, which was the third time the tag had been reported. This was another Lockport fish originally tagged in August 2014. If this doesn't prove catch-and-release works, nothing does."
Additionally, several other tagged fish caught by Durick have been recaptured by other anglers up to three additional times. Siddons reported that 28 tagged catfish were recaptured twice, while at least three more fish were recaptured at least three times.
Learning the origins of tagged fish and their migration habits also has helped Durick confirm a suspicion he's long held regarding fish perhaps born in the far lower (Canadian) reaches of the river, as opposed to those hatched well upstream.
Among veteran Red River anglers, it's long been apparent that average and top-end size of channel catfish increases as you travel downstream, closer to Lockport, Manitoba. Although some of this discrepancy could be related to the catch-and-release rule for all catfish over 24 inches in Manitoba (1 fish over 24 inches is allowed daily on the U.S. side), perhaps the river's physical size and increased carrying capacity grows larger fish in the river's lower stretches.
"I feel lower-river fish looks physically different than those spawned in the southern (upstream) third," Durick says. "The Canadian tagged fish I've caught are shorter and heavier with thicker tails."
When Durick shows you the difference between a so-called U.S. catfish and a Canadian one, the physical variation seems subtle. But it's also tough to argue with a guide who handles upward of 1,500 catfish each season.
"We saw tons of Canadian fish in the Grand Forks to Drayton stretch last fall," he says. "A big influx of water in June may have had something to do with it. All of a sudden we started catching big fish and also caught a couple Canadian tagged fish around Grand Forks.
"Whereas low current spreads fish out, high water gets catfish moving. More current makes them more predictable. They stack below dams. Or if heavy localized rain inundates a tributary, you get a big push of catfish into that stream. We see it happen in the Sheyenne, Assiniboine, and other Red River tributaries all the time." To Durick, it's more proof that channel catfish move, perhaps much more than we know, particularly during prespawn and again in early to late fall.
Pegg concurs, reporting that some of the catfish have been reported a couple hundred miles from their tagging locations, well up the Assiniboine River, which feeds the Red in downtown Winnipeg. "The ability of catfish to move is impressive," Pegg says. "Entering this study, I expected to find fish moving maybe 50 miles, but we've been intrigued to find them moving all the way from Lockport upstream over 300 miles, close to the Red River's headwaters."
Lake to River Migrations
While data on far-ranging catfish offer positive implications for anglers on the U.S. side of the river, Pegg says dramatic north-to-south upstream migration trends have raised eyebrows among fish managers in Manitoba. "So far, we've only observed one tagged catfish that traveled upstream to the U.S. side that returned to Lockport, where it was tagged. There's been subsequent interest from Manitoba concerning harvest management, given the discrepancy in catfish regulations between borders.
"I suspect over time, we'll see fish coming back to Canada," Pegg adds. "But there's so little fishing pressure on the lower reaches of the river that tag returns may never reflect it."
Pegg and colleagues plan to examine the chemistry of tagged catfish to determine where they've lingered longest. "Each waterbody — Red River, Lake Winnipeg, and other lakes and rivers — exhibits a different chemical signature that shows up in the skeletons of catfish," he says. "So if a fish is born in Lake Winnipeg, but spends most of its life in the upper reaches of the river, we'll see it."
It points to one of the more compelling questions in this complex waterway: Are Red River channel catfish feeding, spawning, wintering, or migrating to or from Lake Winnipeg in any significant way?
Siddons' work reveals, among tagged catfish, no downstream movement through the St. Andrews Dam at Lockport. He noted that four catfish tagged in the Red River below the dam were recaptured in Lake Winnipeg in September 2014. Pegg adds that a different fish, tagged near Selkirk in June, immediately traveled downstream into Lake Winnipeg, swam 93 miles around the lake's southern basin, and returned to the river in October.
"We had initially speculated catfish might enter Lake Winnipeg to take advantage of additional food sources, or to seek deep, still water for a winter refuge," Pegg says. "For now, the jury's still out."
Worthy of watching, too, is the role of commercial catfish harvest in Lake Winnipeg. Catfish are commonly caught there in gillnets by commercial fishers seeking walleyes. Given the current uncertainly of the Lake Winnipeg commercial walleye fishery, it's been speculated that netters may turn to catfish as a means of making up for a shortfall of other species. If this happens, it could have an impact on the world-class catfishery up and down the river.
Siddons continues: "Our results suggest the Manitoba portion of the Red River may be functioning as a source population for the upstream fishery. The complex nature of channel catfish movements in the Red River, across international borders, and the resulting implications suggest management of this fishery should focus on the entire watershed.
"If downstream movement from the U.S. doesn't occur, as we have seen here, or is limited, then the channel catfish fishery in the Red River could be functioning as a source-sink system. Eventually, unidirectional movements could lead to degradation of the trophy channel catfish fishery in the lower Red River. We have no evidence that such depletion is occurring, but it would be worth monitoring to ensure viable populations on both sides of the international border."
Pegg and I agreed that if such a "source-sink" situation is indeed at play, it hasn't so far impacted the world-class fishery on either side of the border for many decades. However, it will be interesting to follow this study to its conclusion, to see whether tagged fish recaptured in the U.S. eventually return downstream to where they were tagged, or whether the lower river is responsible for breeding more catfish. Further, results from the radiotelemetry portion of the study will soon begin to emerge, providing a more complete picture and ultimately offering more tantalizing glimpses into the secret lives of channel catfish.
*In-Fisherman Field Editor Cory Schmidt contributes to all In-Fisherman publications, often uncovering the latest science connections to fisheries and fishing.