BC Salmon Ocean Migration Pattern

Ocean tagging has shown that most Pacific salmon spend their sea-lives within these boundaries. A few adventurous fish have ranged further — a sockeye tagged as a mature fish at 177° West was recovered in the Nass River in the same year, and a sockeye tagged as an immature fish at 177° East was recovered in Rivers Inlet two years later — but these are exceptional.

Salmon on the High Sea

Research scientist Dr. David Welch of the Pacific Biological Station in Nanaimo, BC, has researched the mystery of the salmon migration into the mid-Pacific Ocean. Each year juvenile salmon pour into the Pacific Ocean all along the North American coast, from northern California all the way around the arc of the Gulf of Alaska and into the Bering Sea. An estimated 10 billon salmon smolts enter the Gulf of Alaska from surrounding rivers each year. Where do the young salmon go, and why must they migrate away from the coastal waters near their home rivers, are some of the most intensely interesting questions fisheries scientists need to address.

As part of the vast migration from coastal waters, many of the young salmon appear to have migrated past the northern part of the Alaska panhandle in the coastal current by early October, and are already well to the west. Not only are the young salmon migrating, they do so in a very smart way - by staying in the centre of the coastal current they are carried far away from the continental shelf off BC and the Alaska panhandle at speeds up to 10 times what the young salmon could achieve on their own. While some salmon are swept by the coastal current far out to the west, away from their summer feeding grounds and natal rivers, it is clear that some BC salmon are not simply swept away by the currents - some stocks of chinook and coho remain on the shelf year round. But not the sockeye, chums, or pinks.

Whatever the conditions driving this migration, they must be extremely important to the survival of the salmon; for why else do all sockeye, pink, and chum undertake a migration of thousands of miles? So an important unresolved issue is to determine where the salmon go, and why they migrate out of the coastal waters off BC and Alaska. Are the majority of the 10 billion salmon smolts that leave the coastal zone of BC and SE Alaska each year driven by the end to find lower winter temperatures, or higher levels of food, or simply to position themselves for their subsequent migration into the offshore Pacific?

See full article by David W. Welch and H. Richard (Dick) Carlson