A new study in the Journal of Zoology on research conducted at Norway’s Institute of Marine Research suggests jumping salmon are healthier salmon. Specifically, by jumping, salmon were found to shake off 30 percent more sea lice than other defensive methods.
Samantha Bui, the marine scientist who studied jumping salmon, said, “There’s been a lot of anecdotal evidence that salmon change their behavior when they’re exposed to coyepodids, or infective sea lice,” Bui told The Chronicle Herald in Halifax, Nova Scotia. “So we wanted to be able to design a study to capture these behaviors and the actual effect they were having on preventing lice attaching.”
To study the behaviors, Bui’s team divided salmon into three groups. One was injected with ketamine, another with saline, with the third untreated. The salmon were then put in tanks, sea lice added and their behavior studied over 30 hours.
The ketamine group were lethargic, the saline group engaged in bursts of swimming akin to a sprint and the untreated salmon acted naturally. The untreated salmon relied on natural defenses. They jumped as well as spent time motionless at the bottom of the tank.
Bui’s team determined that jumping could shake off lice before it gets a grip on the fish. They also noted that while fast-swimming fish might prevent lice from attaching itself to the animal, the act of swimming might expose the salmon to more parasites. The key observation was that those salmon allowed to act naturally “got around 30 percent less lice in the end,” said Bui.
“Anti-parasite behaviors in general is something that could be focused on and encouraged in salmon, which would improve prevention of parasitic infestation and subsequently, decrease the need for medical treatments and associated costs (and welfare implications),” Bui said. “The main thought that we have with these results is that we can show some capacity for defense in salmon, which is something that is relatively unexplored in aquacultured fish. Behavior is not yet firmly in the toolkit of aquaculture, but it should be. Knowing what the fish can do themselves within farming environments is something that can help change our perception of how we approach parasite and disease management in aquaculture.”
