Column: Is Colorado River’s flourishing flathead catfish population being loved to death?

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 of more than 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 all of the big fish he saw during 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.”

The Arizona Game and Fish Department first introduced flathead catfish into the lower Colorado River in 1962 (600 fish released at Imperial Dam near Yuma) and 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 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 for 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.

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 so many of the 40- to 60-pounders being kept by anglers and 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 more than 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 below 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 largest fish in the 2015 surveys was a 67-pounder captured and released in the lower stretch, while the big 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 their data mostly shows the population was healthy and not how trophy flatheads were 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 was concerned about 50 flatheads of 20 pounds or more being harvested in just a couple of weeks could mean angler pressure was – as he phrased 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 suggested more anglers think about releasing the 30- to 60-pounders to make sure the best spawners stay in the river and the odds of one living long enough to break 100-pound mark becomes a reality.

Pierce suggests anglers keep the eight- to 15-pounders to eat and then photograph and release everything else except “a wall hanger, a personal-best fish.” He just thinks it’s odd a 70-pounder hasn’t been caught since 2003. More catfish anglers releasing the big fish will end the drought, Pierce believes.

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