Matt O’Neill is managing a survival training camp of sorts for imperiled native fish. The Arizona Game and Fish Department biologist says the small bonytail chub and razorback sucker are being eaten into extinction by non-native game fish like flathead catfish, largemouth bass and stripers that are swimming in their Colorado River home. But one of the biggest problems is that the little fish do not even know they are big fish food. In fact, they move toward hungry predators. O’Neill says they consider them school mates.
“It’s not a good recipe for success,” he said. “Not only are they naïve as hatchery fish, but they also are naïve in the sense they didn’t evolve with these predators. And so to kind of explain that naiveté, if you put that bass into a tank with bonytail, half of those bonytail will leave whatever cover they have to go swim under the bass, so we’re not just trying to fight naiveté, we’re also trying to fight fish that are actively stupid. So that’s the scale of the problem that we’re dealing with.”
So in his watery lab at the Aquatic Research and Conservation Center near Cornville, O’Neill has designed experiments that he hopes will result in a predator-prey game changer. His research involves the same botulism toxin used to make Botox for humans and the native fish’s own natural stress pheromones.
Here is how his project works: O’Neill creates a concentrated strain of botulism and injects it near the gills in the underbelly of his lab fish, like a largemouth bass. This temporarily paralyzes the muscles of the lower jaw so it cannot suck in a small fish, but it can still catch food pellets and survive until the toxin wears off.
“It stops the bass from being able to capture a fish, but they still behave normally and try to hunt bonytail.”
Meanwhile, he mixes up a concoction of stress pheromones in a blender. These are chemicals that are released from the skin of native fish when they are in trouble, which act as a warning to the other fish.
“We introduce a bass at the same time as we add that pheromone into a tank of bonytail or into a tank of razorbacks, and we let the bass swim around in the water with the pheromone for a few minutes – five minutes actually – and that will then teach the bonytail that the bass are dangerous.”
O’Neill then gives the trained fish and some unfortunate untrained fish what he calls the “24-hour survival challenge.” They all go into a concrete pond with hungry non-native game fish.
“It’s the most harsh survival challenge that we could think of,” he explained. “We found that the training improves survival by at least 30 percent for both bonytail and razorbacks against both channel catfish and largemouth bass as predators.”
As is the case with most experiments, O’Neil has learned from trial and error. Early on, he tried tying the mouth of a bass shut so it would not be able to eat in the training process. “Some of the bass just laid on their side and that wasn’t exactly the visual cue we wanted to give our prey fish, so instead we used the type A toxin.”
So now that he has demonstrated that fish can be trained to recognize predators and that recognition will improve survival in a lab setting, O’Neill wants to test his trainees in a bigger pond for a longer period of time. He is working with Valley Vista Golf Course in Kingman, where six ponds have been created for fish research on the greens. The native fish will have to survive that challenge course for 30 days.
“Our efforts are aimed at trying to improve the stocking success of native fish back into their natural habitat,” said O’Neill.
Bonytail and the razorback are both “critically, critically endangered,” he said. All bonytail chubs now raised in fish hatcheries are descendants of just 11 fish that were captured by biologists in the 1970s and ‘80s who realized the species was crashing.
The Aquatic Research and Conservation Center, formerly the Bubbling Ponds Fish Hatchery, is a federally funded facility run by the Arizona Game and Fish Department to conserve imperiled desert fishes. FBN
By Bonnie Stevens
Photo by Bonnie Stevens