Nav: Home

Salmon smolts find safety in numbers

May 09, 2016

Using tags surgically implanted into thousands of juvenile salmon, UBC researchers have discovered that many fish die within the first few days of migration from their birthplace to the ocean.

"We knew that on average 10 to 40 million smolts leave Chilko Lake every year and only about 1.5 million return as adults two years later," said Nathan Furey, researcher and a PhD candidate in the faculty of forestry. "It's always been a mystery about what happens in between."

Researchers from the Pacific Salmon Ecology and Conservation Laboratory at UBC followed the migration of one of B.C.'s largest sockeye populations from Chilko Lake, in British Columbia's Cariboo region, to the ocean. Each spring, juvenile salmon known as smolts leave this central B.C. lake and migrate downstream through the Chilko, Chilcotin, and Fraser rivers and into the Salish Sea.

To follow the juvenile salmon, researchers implanted small electronic tags into the tiny 12-centimetre fish as they were leaving Chilko Lake. As the smolts made the 1,000-kilometre journey to the Pacific Ocean, acoustic receivers picked up the signals from the tags to monitor how many fish survived the migration.

More than 2,000 salmon were tracked over four years and researchers found that survival was poor in the clear and slow-moving Chilko River, where predators were feeding intensely on the smolts. Once in the murky and fast-flowing Fraser River, the salmon travelled day and night, covering up to 220 km per day, and experienced nearly 100 per cent survival. The researchers believe that in these waters, predators have difficulty finding and getting to the fish.

In a followup study, Furey found that juvenile salmon were more likely to survive the perilous days in the Chilko River if they traveled with lots of other fish. Survival was as low as 40 per cent for salmon that left the lake in small numbers compared to times of peak migration where survival rates increased to more than 90 per cent. The results confirm the old adage that there is safety in numbers and that salmon use this strategy, known as predator swamping, to avoid predators early in life.

"Our studies may help fisheries managers better understand why numbers of adults that return to spawn may be so low in some years," said Furey.
-end-
This research program is led by professor Scott Hinch and is a large collaboration involving Timothy Clarke, a former member of the Pacific Salmon Ecology and Conservation Laboratory, and industry, and Fisheries and Oceans Canada (DFO) and Kintama Ltd. partners. Results were recently published in two articles in Ecological Applications and the Journal of Animal Ecology. The research was funded by Canada's Ocean Tracking Network and the Pacific Salmon Foundation.

University of British Columbia

Related Salmon Articles:

Study: Floodplain farm fields benefit juvenile salmon
Central Valley rice fields managed as floodplains during the winter can create surrogate wetland habitat for native fish, study shows.
Salmon with side effects
Tasty, versatile, and rich in essential omega-3 fatty acids: salmon is one of the most popular edible fish of all.
Happy salmon swim bette
What makes young salmon decide to leave their rivers and head out to Sea has been a hot topic for decades now.
Discovery of new bacteria complicates problem with salmon poisoning in dogs
Researchers have identified for the first time another bacterium that can cause symptoms similar to 'salmon poisoning' in dogs -- and may complicate the efforts of Pacific Northwest pet owners to keep their dogs protected and healthy.
How will salmon survive in a flooded future?
As torrential rain descends on the Pacific Northwest, new research published in Global Change Biology provides a glimpse of how salmon rivers might fare in a future with larger floods.
Pipelines affect health, fitness of salmon, study finds
Pipelines carrying crude oil to ports in British Columbia may spell bad news for salmon, according to a new University of Guelph-led study.
UM study: Kodiak bears track salmon runs in Alaska
Research from the University of Montana found bears greatly extend their use of salmon resources by migrating from one run to another.
Salmon smolts find safety in numbers
Using tags surgically implanted into thousands of juvenile salmon, UBC researchers have discovered that many fish die within the first few days of migration from their birthplace to the ocean.
Climate change may reduce vulnerable salmon populations
New research in north-central Mongolia illuminates the effects of global climate change on certain vulnerable species of salmon.
Salmon are less aggressive in tanks with darker backgrounds
Coho salmon may be four times less aggressive in tanks with darker backgrounds than in tanks with light backgrounds, according to a study published March 30, 2016, in the open-access journal PLOS ONE by Leigh Gaffney from the University of British Columbia, Canada, and colleagues.

Related Salmon Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#532 A Class Conversation
This week we take a look at the sociology of class. What factors create and impact class? How do we try and study it? How does class play out differently in different countries like the US and the UK? How does it impact the political system? We talk with Daniel Laurison, Assistant Professor of Sociology at Swarthmore College and coauthor of the book "The Class Ceiling: Why it Pays to be Privileged", about class and its impacts on people and our systems.