Younger sockeye salmon (Oncorhynchus nerka) have a curious habits: They bounce as much as 30 centimeters within the air, generally skimming alongside the floor for near a meter utilizing their tail fins, about 9 occasions a day on common. They even do that when no obstacles are of their method. The explanation, based on a brand new research, is that they’re infested with sea lice—and are attempting to splash them off.
Researchers already suspected that salmon leap to dislodge sea lice, a pea-size parasite that feeds on mucus, blood, and pores and skin. Fish tormented by the lice bounce out of the water 14 occasions extra usually than these which are lice-free do. However scientists didn’t know whether or not this helped rid them of the bloodsuckers.
So within the new research, researchers caught juvenile sockeye salmon infested with sea lice and separated them into two floating ocean pens in a sheltered ocean bay in British Columbia in Canada—one pen the place they had been allowed to leap, and one lined with netting simply beneath the floor. After letting the experiment run for three days, the scientists discovered that salmon that couldn’t bounce from the water had 28% extra sea lice than people who may, as they report in an article cheekily titled “Oust the Louse” within the Journal of Fish Biology.
Leaping out of the water isn’t a risk-free proposition for the salmon. It takes a median of 56 leaps to dislodge a single sea louse, throughout which period the fish might be straightforward prey for predators like seabirds. The trouble additionally drains vitality the salmon want for different issues. However for the fish, the hazard of those leaps could also be nothing in contrast with the reduction of delousing.