The Coast Guard says the whale was reported Saturday near Raritan Bay. A Coast Guard rescue boat and a New Jersey state police vessel were sent to enforce a safety zone.
State police reported at 2:30 p.m. Saturday that the whale had submerged and had not been relocated after 30 minutes of searching.
The Coast Guard and National Oceanic and Atmospheric Administration are asking boaters in the area to keep an eye out for the entangled whale and remember guidelines that include staying 100 yards away from whales.
Humpback whales can reach lengths of 60 feet and can weigh about 40 tons.
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