Colorado River flathead catfish population flourishing, but is it being loved to death?
By JIM MATTHEWS
Since Memorial Day weekend, Robert Pierce at Walter’s Camp on the lower Colorado River south of Palo Verde, said there have been at least 50 flathead catfish topping 20 pounds caught by anglers -- including two over 50 pounds.
Pierce, the long-time manager at Walter’s Camp, is both thrilled and frustrated. On one hand, he’s excited the big flatheads are finally getting the attention they deserve as great gamefish. On the other hand, he’s concerned the heavy harvest on the really big fish is going to negatively impact the fishery.
“I’m just concerned that if these guys keep hammering these big fish, they’re not going to continue to be here,” said Pierce, noting that all of the big fish he saw over the past few weeks have been kept by anglers. “I’ve always said that you keep the eight to 15 pounders to be eaten, and that the bigger fish -- the breeding stock -- you let go. But that’s not what a lot of these guys are doing today.”
Flathead catfish were first introduced into the lower Colorado River by the Arizona Game and Fish Department in 1962 (600 fish released at Imperial Dam near Yuma), and they have been surveyed and monitored extensively almost every year since those first releases were made. Since flatheads can live at least to 25 years old, the fish didn’t start reaching their full size potential until the 1980s, and it was until the late 1980s and early 1990s that the first 50-pounders were caught. From the late 1980s through the early 2000s, there had been a steady string of bigger and bigger flatheads landed by anglers, and the volume of big fish just seemed to keep increasing. The California state record is a 72-pound, 14-ounce fish caught in 2003, while Arizona lists a 74-pounder caught in 1988 as the biggest flathead from the river. (The photo below is of Tinker Lewis at Walter's Camp in the early 1980s with one of the first flatheads topping 50 pounds ever caught from the Colorado River.)
Russ Engel, the fishery program supervisor for the Yuma office of the Arizona Game and Fish Department, said the biggest flathead ever recorded in their annual surveys on the Colorado River was an 89.4-pound flathead electro-fished several years ago.
The world record is a 123-pounder caught in Kansas, and most Colorado River anglers believe the could and should be flatheads in the 100-pound range living in the river, but Pierce wonders if there are so many of the 40 to 60-pounders being kept by anglers that the potential for truly giant fish is disappearing.
With more than 20 years of data to draw from, Engel said he hasn’t “seen any indications we’re having an impact [on flathead numbers]. Our survey data shows the population is stable or actually increasing.”
Engle said they extensively survey two stretches of the Colorado River each spring. The stretch from the Palo Verde Diversion Dam (north of Blythe) to Cibola Lake (opposite Walter’s Camp) is the upper survey area. The stretch from Cibola Lake to Morelos Dam at Yuma is the lower stretch. Using electro-fishing equipment, they capture and classify over 1,000 flatheads from both stretches. Engle said they call the upper stretch the “nursery area” because it has mostly smaller fish, with 93 percent under the 20-inch mark. The lower stretch is where the bulk of the bigger fish live, with 20 percent of the surveyed fish topping the 20-inch mark. The biggest fish in in the 2015 surveys was a 67-pounder captured and released in the lower stretch, while the biggest fish in the upper stretch was a mere 21-pounder.
This mirrors what anglers see: The biggest flathead catfish are in the unchanneled stretch of the river. The channelizing ends at the mouth of the Palo Verde Lagoon, where Walter’s Camp is located. Below that point the river has mostly natural banks and winds between deep pools and long riffles, all naturally carved by the river’s flow.
This stretch of the river has the best habitat for big flatheads, which prefer big, deep, slow pools with some kind of structure where they can take cover, ambush prey, and spawn. Unlike other catfish, flatheads are aggressive predators and eat only live prey, mostly panfish, and the big pools are ideal homes. Engel said that in a survey many years ago, bigger flathead were fitted with sonic tags so their locations and movements could be tracked. Most of the fish, which were released at a common tagging site, moved back to the exact locations where they were captured in the Colorado River.
Engel admitted that their data mostly shows the population is healthy and not how trophy flatheads are faring. He said it would be interesting to have more data on harvest rates on big flatheads and information on how often fish are caught and released before being kept. The relatively small percent of big fish in the population means fishing pressure on the big fish could keep trophy fish numbers suppressed. In the lower river stretch, 1,226 flatheads were sampled in 2015. Of those, only 32 were longer than 28 inches.
Pierce’s concern that 50 flatheads over 20 pounds harvested in just a couple of weeks could mean angler pressure is -- as he puts it -- “putting the hurt on the trophy population.”
That may or may not be the case and without better data no one is suggesting that bag limits be changed or slot limits instituted on flatheads right now. However, long-time flathead anglers like Pierce are suggesting that more anglers think about releasing the 30 to 60-pounders to make sure the best spawners stay in the river and that the odds of one living long enough to break that 100-pound mark becomes a reality.
Pierce suggests that anglers keep the eight to 15-pounders to eat, and then photograph and release everything else except “a wall hanger, a personal-best fish.”
Pierce just thinks it’s odd that a 70-pounder hasn’t been caught since 2003, and he believes more catfish anglers releasing the big fish will change that.
Diamond Valley Lake has an
untouched flathead population
Survey data on Diamond Valley Lake shows there were at least 6,000 flatheads in the lake. Since they are suspected to have been in the lake only since 2004 or 2005, the oldest fish in the population are only 10 to 12 years old and weigh around 15 pounds. Fifty pounders can be expected in a decade or less.
The problem is that anglers can’t use what would be the best baits for these trophy fish -- small bluegill or gold fish. While bluegill and gold fish are legal bait in the Colorado River system, they are verboten baits for Diamond Valley.
An alternative? Anglers can dip net live threadfin shad from Diamond Valley have viable and legal flathead baits. [Ed note: An earlier version of this story said anglers could also use dip-netted silversides and sculpin for catfish bait. That is NOT the case. Those two baits are also illegal. Only shad are legal bait, and only if they are dip-netted from the lake where the angler is fishing.]
[Jim Matthews is a syndicated Southern California-based outdoor reporter and columnist. He can be reached via e-mail at email@example.com or by phone at 909-887-3444.]