Salmon Biodiversity and Survival Impacted by Ocean Changes Caused by Climate

It turns out that salmon may be in trouble due to climate change. Scientists have tracked the survival of Chinook and coho salmon from hatcheries in North America between 1980 and 2006 and have found that  these salmon are being impacted by changing climate.

Before the 1990s, ocean survival rates of the two species varied separately from each other. However, these survival rates became increasingly similar as time moved forward.

"Two species that historically have had different responses and seem to be very different in their coastal-wide patterns now appear to be more synchronized," said Patrick Kilduff, lead author of the new study, in a news release. "When salmon populations are synchronized, it's either good for everyone or bad for everyone-similar to the stock market."

This synchronous response to ocean conditions actually represents a loss in biological diversity that cannot be addressed directly by freshwater management actions. It's not currently well understood what is causing the increasing similarity, but the researchers said it could reflect a change in coastal ocean food-web linkages or perhaps a change in the salmon species themselves.

The new study actually found that the coho and Chinook survival rates along the West Coast are strongly linked to the North Pacific Gyre Oscillation (NPGO). This means that environmental changes can drastically impact salmon populations.

"Changes in equatorial conditions lead to more of the large-scale Pacific Ocean variability being explained by North Pacific Gyre Oscillation, and it's influencing the survival of salmon from Vancouver Island south to California," said Kilduff.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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