Researchers discover migration patterns of marine predators

(Press-News.org) Ian Jonsen, a research associate and adjunct professor in the Department of Biology at Dalhousie University and co-lead investigator of the Future of Marine Animal Populations Project (FMAP), has teamed up with Barbara Block at Stanford University and several other American researchers to conclude a two year study entitled, "Tracking apex marine predator movements in a dynamic ocean" published in the science journal Nature released June 22.

The study summarized the results from a ten year tagging program called the Tagging of Pacific Predators (TOPP). The TOPP program deployed 4,306 tags on 23 species in the North Pacific Ocean resulting in data that covers 265, 386 days-an extraordinary scale by industry standards. Both TOPP and FMAP were projects under the recently concluded Census of Marine Life program.

TOPP scientists have been tagging marine predators for ten years. Species like sharks, whales, tuna, seals and marine turtles are caught, tagged with an electronic device that keeps track of the animals' location, and released back into their natural habitat. Their movements are then monitored by researchers at several institutions in California. Dr. Jonsen helped synthesize that data over the last 2 years right here at Dalhousie.

"We wanted to be able to build a story on behalf of these marine predators. Tagging allows us to answer questions like, 'where are they going', 'how long are they there for', and 'how long does it take them to get there.' By tracking the movements of marine predators, we can build a map of the important 'traffic routes' in the ocean, something we haven't been able to do until now," Dr. Jonsen explains.

What the scientists discovered through this study was that that the California Current large marine ecosystem is a significant habitat for species like tunas, sharks, salmon and sea turtles.

The data collected also indicates these species are quite predictable in their movements and time their migrations so they arrive in the California Current when it is most productive. Species, such as tunas and sharks, residing in the California Current migrate north and south seasonally within this region as it warms and cools.

The study also indicates that predators, like the leatherback turtle, travel back and forth from Indonesia and Monterey Bay, California each year like clockwork.

Jonsen believes that although there is still a lot more work left to be done on predicting the movements of marine predators, this study is a step in the right direction.

"Knowing where and when species overlap is important information that can be used to manage and protect these large predators and their ecosystems from human activities."

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