New Jersey State Troopers from the Marine Services Bureau responded to the Route 36 bridge over the Shrewsbury River for the report of the whale around 9:25 a.m., police said.
Additional NJSP officials arrived to assess the whale's condition.
"Preliminarily, the whale appears to be healthy and feeding," state police said. "We understand it may be tempting to get close for a better look or picture, but at this time, we are advising boaters to avoid the area."
Additional boat traffic may scare the whale and prevent it from leaving the river or negatively impact its health, officials said.
"We will continue to monitor the situation," NJSP said. "Hopefully, it will return to sea healthy and with a full belly."
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