Young salmon may leap to 'oust the louse'

August 10, 2018

A study by Simon Fraser University aquatic ecologists Emma Atkinson and John Reynolds reveals that young salmon may jump out of water to remove sea lice.

"Ideas about why fish leap include getting over obstacles during their upstream migration as adults, catching food and avoiding predators," says Atkinson.

"However, these reasons may not apply to young salmon since their diet is composed almost exclusively of underwater zooplankton and their tendency is to scatter rather than leap when escaping from predators."

Atkinson hypothesized that the leaping behaviour could be the fish's way of removing parasitic sea lice, which is a common condition for wild and penned salmon off the B.C. coast. Heavy sea-louse infestation is correlated with reduced growth, impaired swimming and competitive foraging ability for young salmon.

To test her hypothesis, Atkinson and her team caught wild juvenile sockeye salmon during their coastal migration away from the Fraser River. They held the fish in flow-through net-pen enclosures, half of which were covered with netting to prevent leaping and the other half were left uncovered to allow leaping. After three days, the team counted the lice on each fish.

The researchers found that, on average, the salmon that were allowed to leap in the uncovered pen had 22 per cent fewer sea lice compared to those that weren't allowed to leap in the covered pen.

The researchers also found that it may take more than 50 leaps for a young salmon to dislodge a sea lice, which Atkinson acknowledges is a substantial amount of energy to expend. She says these costs may be offset by the benefits of successfully removing sea lice, but will have to be investigated in another study.
-end-
Atkinson's study was recently published in the Journal of Fish Biology.

Simon Fraser University

Related Salmon Articles from Brightsurf:

Alaska's salmon are getting smaller, affecting people and ecosystems
The size of salmon returning to rivers in Alaska has declined dramatically over the past 60 years because they are spending fewer years at sea, scientists report.

Chinook salmon declines related to changes in freshwater conditions
A new University of Alaska-led study provides the first evidence that declines in many of Alaska's chinook salmon populations can be attributed in part to climate-driven changes in their freshwater habitats.

Size matters in the sex life of salmon
For Atlantic salmon, size matters when it comes to love.

What does drought mean for endangered California salmon?
Droughts threatens California's endangered salmon population -- but pools that serve as drought refuges could make the difference between life and death for these vulnerable fish.

Salmon provide nutrients to Alaskan streambanks
Nutrient cycling of stream ecosystems dependent on portion of salmons' lifecycle.

Melting glaciers will challenge some salmon populations and benefit others
A new Simon Fraser University-led study looking at the effects that glacier retreat will have on western North American Pacific salmon predicts that while some salmon populations may struggle, others may benefit.

Bigger doesn't mean better for hatchery-released salmon
A recent study in the Ecological Society of America's journal Ecosphere examines hatchery practices in regards to how Chinook salmon hatcheries in the PNW are affecting wild populations over the past decades.

Salmon get a major athletic boost via a single enzyme
A single enzyme anchored to the walls of salmons' blood vessels helps reduce how hard their hearts have to work during exercise by up to 27%.

Salmon are shrinking and it shows in their genes
Male salmon are maturing earlier and becoming smaller, and it shows in their genes.

Young salmon may leap to 'oust the louse'
A study by Simon Fraser University aquatic ecologists Emma Atkinson and John Reynolds reveals that young salmon may jump out of water to remove sea lice.

Read More: Salmon News and Salmon Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.