We know these incredible fish are born in rivers, migrate to the ocean and eventually return to the river of their birth to produce a new generation.  But under that broad overview, what’s really going on? How do these incredible fish perform this massive cyclical journey? 

Biologists have struggled to answer these questions in large part because its been impossible to track individual fish through the entire cycle – or even through significant parts of the cycle. Until now.

The Pacific Ocean Shelf Tracking Project (POST) has developed new technologies and new techniques to shed new light on the secret’s of salmon.

The Pacific Ocean Shelf Tracking Project is a non-profit organization facilitating the development and coordination of a large-scale acoustic telemetry network along the entire length of the West Coast of North America. It works operationally through contractors engineering and deploying the array, and collaboratively through principle investigators conducting specific research projects using the array. 

Scientists working with POST developed and refined miniature tagging and tracking processes that allow them to follow salmon through vast distances and highly dissimilar waters – from as far as the Rocky Mountain headwaters of USA’s Columbia River through the ocean to the coast of Alaska.

Across to POST’s reports, “In 2006, researchers implanted the new tags in 1,000 juvenile Chinook salmon (www.eol.org/taxa/17154704) roughly the same length and half the weight of a frankfurter hot dog – 14 centimeters long, 20-30 grams weight – for a study in the Columbia and Fraser Rivers, and followed their journeys. 

“Among the many studied, two tagged juveniles survived a 2,500 km trip that took more than three months – from the upper reaches of the Snake River (a tributary of the Columbia River) in Idaho, out to sea then north along the continental shelf to Alaska. ”

“The two swam about the same distance as from London to Istanbul or Moscow, from Auckland to Melbourne, from Beijing to Hanoi, or from New York City to Austin, Texas.”

The research unveiled some incredible new findings. For instance, the report says, two species of juvenile salmon migrating through the Columbia River’s eight dams survived the freshwater and early marine portions of their journey to the ocean as well as those in the un-dammed Fraser River, challenging widely-held notions about factors affecting salmon abundance.

In fact, more survived in the Columbia once distance or travel time was taken into account – and survival was greater during migration within the hydropower system than below the dammed section. 

Evidence does not yet suffice to tell whether the Fraser has a problem that cuts salmon survival to that of a heavily dammed river, or whether factors other than dams play a larger, unsuspected role in salmon survival. 

 The full summary of POST report, with links to the data, can be found here.