A biologist at Año Nuevo Island Reserve discovered some tracking devices that had implanted in young salmon, according to a release from UC Santa Cruz. It sheds new light on what happens to young salmon after they leave our streams.
But the first logger Morris found on Año Nuevo Island told a fascinating story. Hayes and Bond implanted the logger in a hatchery-raised Coho salmon on March 15, 2006. That salmon swam down Scotts Creek to the lagoon, where it lasted 13 days. On March 28, the temperature logger records it was eaten by a warm-blooded predator. The logger emerged on top of Año Nuevo Island on March 29.
Because it showed up on top of the island, researchers can rule out the theory that an elephant seal or a harbor seal ate the Coho. Hayes and Bond say the guilty predator is probably a bird, but they can’t be sure.
"Unfortunately, the temperature loggers top out at about 25 degrees Celsius," Bond said. "The stomach temperature of the predator was much warmer than that. We never thought that we’d recover the tag of any of our fish that got eaten. We missed getting a good, precise measurement of the predator’s body temperature."
The chance discovery indicates that gulls may be a more important predator for young salmon than anyone thought.
Click below to read the press release.