The Coast Guard is asking cargo ships to slow down due to more whales making their way to the San Francisco coast.

The blue water beneath the Golden Gate Bridge lately has been a hot spot for large schools of fish. Marine experts said the large schools of fish near the coast is a concern because whales are following them and getting into shipping lanes that large cargo ships pass through daily.

"Wherever the fish are is where you'll find the whales," said Mary Jane Schram with the National Oceanic and Atmospheric Administration.

Video provided by NOAA shows a humpback whale slapping its tail on the water near San Francisco this week.

"It's a delight to see, but it's concerning to us," Schram said.

The Coast Guard in response has asked cargo ship to voluntarily slow down to 10 knots or slower -- about 11 miles per hour.

"If a ship is moving a little bit slower it may give the edge of time for the whale to move out of its way," Schram said.

Schram said there have been no reports of whale deaths near the Golden Gate straight this season, but said that does not mean it has not happened.

"We can't hope to eliminate ship strike altogether, but we are hoping to minimize how lethal those strikes are when they do occur," Schram said.