Blue whales off the U.S. west coast enjoy feeding in areas that are usually used for shipping lanes, a practice that puts their existence at risk, according to a new study.

The study, which was led by Oregon State University and the University of California, Santa Cruz, was published on July 23 in the journal PLOS ONE.

For the study, researchers tagged 171 blue whales off the coast of California from 1993 to 2008.

Blue whales were tagged using air-powered guns and crossbows and then tracked by scientists through satellite and radio for 15 years, according to the study.

During that time period it became clear to the researchers that the whales favor the area where freight ships travel in order to get food, putting them in direct danger.

"It's not really our place to make management decision, but we can inform policy-makers and in this case it is pretty straightforward," said one of the co-authors of the study, Daniel Palacios in a statement. "You will eliminate many of the ship strikes on blue whales by moving the shipping lanes south of the northern Channel Islands."

Researchers have since asked policy makers to move shipping lanes in order to preserve the species.

Around 10,000 and 25,000 of these whales can be found in the world's oceans today. Their numbers have not increased much in recent decades, according to the study.

 "We've pointed out that our new data should be useful to the shipping industry and to the various agencies concerned with the lanes that lead to San Francisco and Los Angeles," Palacios said. "But we're not out beating the drums, because it's not our job to decide how those lanes should be moved. That's up to all the stakeholders."

Blue whales can live 80 to 90 years on average, and their 100-foot long bodies can weight close to 20 tons.

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