Carleton University Researcher Reveals New Findings on Ferocious Fish

While most people like to admire barracuda from afar, Amanda O’Toole thought she would take the plunge and study this ferocious fish up close and personal.

As part of her master’s degree in science at Carleton University in Ottawa, Canada, O’Toole journeyed to the Bahamas to learn more about these toothy creatures.

“Strangely, there is very little known about barracuda biology despite the fact that they are widely regarded as important predators in tropical marine waters,” says Steven Cooke, one of O’Toole’s two thesis advisers. “Amanda’s work is an important first-step in managing and conserving these fish.”

In order to collect her data, O’Toole became the first person to surgically implant telemetry transmitters in barracuda to study their movements.

“We were intrigued to find out that many of the fish were homebodies, staying close to where they were tagged,” says O’Toole. “However, just a few weeks ago, a barracuda that I tagged in 2007 was detected near Nassau, so that fish had swum more than 100 kilometres from where it was originally tagged.” O’Toole’s work also showed that barracuda would typically move offshore during the day and return to near shore habitats around dusk. “That’s good news for daytime swimmers,” shares the researcher.

As part of her research Amanda also studied what happens to barracuda when they are captured by recreational fishers. “We found that all fish that were landed survived the angling experience and were vigorous at the time of their release. But several barracuda were attacked by other predators while they were being reeled in.”

Although most fishers release barracuda, they are eaten in some areas despite the potential for poisoning from ciguatera. “This toxin can cause neurological problems and even death,” shares O’Toole. Working with researchers from the United States Marine Biotoxin Program, the Carleton student developed a technique to take blood samples from barracuda without killing them and validated that ciguatera could be detected in fish blood. She then took samples of blood from the fish, tagged and released them. “I found that the toxin levels in the blood of the tagged fish were associated with how mobile they were,” says O’Toole.

O’Toole’s co-supervisors, Dr. Andy Danylchuk at the University of Massachusetts Amherst and Dr. Cooke at Carleton, intend to conduct additional research on barracuda that will involve use of satellite tags to track fish over larger distances. Cooke’s Carleton lab is a world leader in the use of telemetry to track aquatic animals. “Our team wants to ensure that fisheries are sustainable while providing students with the opportunity to address real-world problems,” says Cooke.

O’Toole says she is thrilled that her work has revealed new information about barracuda biology. “These are fascinating fish that deserve a better future than following the trend of global declines in marine predatory fish,” remarked O’Toole.