ASA/CAA '05 Meeting, Vancouver, BC

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POST: Pacific Ocean Shelf Tracking Project

Tiny Acoustic Transmitters Help Map Salmon Tracks in the Ocean

David W. Welch
Chief Scientist, Census of Marine Life Project POST, Kintama Research Corp., 4737 Vista View Crescent, Nanaimo, BC, Canada V9V 1N8

Popular version of paper 2aAO1
Presented Tuesday morning, May 17, 2005
Joint ASA/CAA Meeting, Vancouver, BC

Want to know the true story behind the 1.3 million missing sockeye from the Fraser River? Is cleaning up our rivers enough to save the salmon? Are changes in ocean conditions affecting the fish populations? Can we do better than just guess at what happens after the fish left the rivers?

Yes, now we can. The Pacific Ocean Shelf Tracking project (POST) uses tiny transmitters in young salmon to tell conservationists about their fate.

POST is one of the 13 field projects under the Census of Marine Life (, which is a decade long program involving scientists from more than 70 countries, designed to assess the diversity, distribution and abundance of ocean life.

Acoustic tracking
POST is putting tiny acoustic transmitters in thousands of young salmon and following their journey from freshwater to sea. It is like assigning barcodes to individual fish. As they pass over sensors installed on the seafloor, they are telling scientists where they are at what time.We no longer have to guess where the fish went, but will have precise factual records.

Making the transmitters and sensors work is challenging. Scientists have to worry about how long the batteries last in the mini transmitters. To conserve battery life, some transmitters are programmed to go to sleep after the fish move out to the deep ocean, and start beeping again at the time of home migration to find out how many return. The sensors on the seabed have to withstand the ocean conditions, and be equipped with a modem to send data to boats passing overhead, or to satellites.

Biologists have to be exceptionally skilled in inserting the transmitters into thousands of young fish in a matter of days, working by the side of streams and rivers in MASH-style operations.

Going boldly where no one goes before
The grand scale of the system, however, is its most remarkable aspect and has never been attempted before. Imagine 2000 sensors sitting permanently on the ocean floor, along 30 listening lines, each extending from shore seawards for 50 km, from Baja to the Bering Sea, listening to more than 250,000 animals at one time. The concept worked remarkably well in a demonstration in the Salish Sea region in 2004 which yielded the first mapping of the migration corridors of 14 stocks of salmon. POST will have the continental-scale system completely in place by 2010.

Dr. David Welch, Chief Scientist of POST, will be discussing the findings in the Salish Sea study in his presentation (2aAO1) at the meeting of the Acoustical Society of America,May 17, 2005 in Vancouver. He will explain the data showing the sockeye moved very quickly out to the open ocean while the coho appeared to stay around close to shore. Also, the fact that a lot more of the steelhead stocks made it to the deep ocean (15-31%) than expected, challenges the conventional belief that the historical record of 2-4% return of these fish is mainly due to die-offs at the river mouths.

More than just tracking fish
What is even more exciting is that the seabed array can also host temperature, salinity, current or other oceanographic sensors. Knowing this information, scientists can relate where animals go and their survival, to changes in the ocean.

POST is a powerful science tool, which carries a relatively low overhead, and is generating high expectations from managers and policy makers responsible for marine resource conservation.

Map of marine life highways
POST will not only track salmon. Scientists are beginning to use the technology on sturgeon, rockfish, squid and other marine animals. Thanks to POST, we are on the way to having the first ever map of the marine life highways. POST will serve as the prototype for similar systems in other parts of Canada and the world.

For further information please contact:

Chief Scientist, David Welch
Tel: 1-250-714-3526

Executive Director, Peggy Tsang
Tel: 1-604-659-3587

POST Secretariat Vancouver Aquarium Marine Science Centre P.O. Box 3232, Vancouver, B.C. V6B 3X8
Tel: 604-659-3587

The 2,000 sensors on the ocean floor along the west coast of North America

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