UI graduate student researches migration of Amazonian catfish
After studying abroad in Brazil and being enthralled by the wildlife and culture that exists there, University of Idaho doctoral candidate Jens Hegg knew he had to return to the Amazon again someday.
“I’ve always wanted to go to the jungle,” Hegg said.
Hegg said he was interested in the migration patterns of Amazonian catfish, so he performed a pilot study on it and wrote a report with his partners Tommaso Giarrizzo and Brian Kennedy. He said the pilot study was done “on a shoe string,” with minimal funding, and they can use the research results to apply for grants.
During their study Hegg said they used a smaller sample of 25 catfish and experimented to see if they could recreate the same sort of migration pattern seen in their species throughout the Amazon River. He said they found that they could recreate the pattern.
Hegg said Kennedy was able to track the catfish in the Amazon through isotopes found in the bones in their ears.
“I saw that and thought that was a super cool technology that fish have this little flight data recorder that you can track every movement that they’ve made,” he said.
Hegg said they found that the migration pattern for Amazon catfish is more complex and interesting than many people know. The fish lay their eggs in near the Andes Mountains, and the young fish float down the river to an estuary on the other side within two weeks. Then when they’re older they head all the way back upstream to lay their eggs and the process begins again.
Hegg said proof in this conclusion can be seen in where certain catfish are caught along the river.
“We know all of this from the time and the size all the fish are when they’re caught,” he said. “We know the fish in the estuary tend to be smaller, that at some point the larger fish disappear and start appearing upstream.”
Amazonian catfish are continually overfished, Hegg said. There has also been more pressure on governments to instill dams in the Amazon, which may cause a population crash for the catfish since the young fish simply float down the river and many dams don’t have sufficient fish ladders.
Hegg said by having a better understanding about the species and their migration patterns they may be able to help.
“Knowing how the fish migrate, and then understanding that in terms of the fishing pressure and the dams, might give us a way to figure out how to lessen the impact of both of those things,” he said.
Hegg said he mainly wants to continue his research and visit the Amazon again. He said they will need to develop a proposal for a grant, but for now he is content with developing his knowledge about what he called a “keystone species” of the Amazon.
“These fish are really important,” Hegg said. “They’re the only fish that migrate the entire length of the Amazon, and the only animal at all to use the entire Amazon Basin to complete their life cycle. They’re kind of a keystone species.”
Erin Bamer can be reached at [email protected] or on Twitter @ErinBamer