LONG BEACH, Calif. — A minke whale that was spotted by locals last week in the shallow waters of Long Beach's Rainbow Harbor was found dead, and the National Oceanic and Atmospheric Administration Fisheries is working Monday to determine a cause of death.

The whale was discovered dead Sunday morning, and the NOAA was examining the body for potential injuries or illnesses, according to media reports.

Justin Viezbicke of NOAA Fisheries told a local news station the theory was that a bridge above the harbor was to blame for the whale's refusal to swim back into the deeper ocean waters.

"You know, this is a very surface-visual animal and when you come out of that little area and you look up, there's this very large structure that's overhead, and whales are not used to having things over them," he told a local news station.

On Thursday, harbor crews on boats were seen maneuvering booms in the water in an apparent effort to guide the whale back towards the ocean and the Aquarium of the Pacific officials had been monitoring the situation.

Minke whales are small whales that grow up to about 35 feet, and are largely found near the West Coast of North America.