CHATHAM — Officials say a minke whale that spent last Thursday in Stage Harbor before dying in the Oyster River apparently had an underlying health condition that caused it to become stranded.
The 18-foot long whale was first spotted in the area of the Eldredge trap dock before 6 a.m. Thursday, and onlookers watched in amazement as it swam under the floats at Old Mill Boat Yard. When it emerged from under the concrete, barnacle-encrusted floats, the whale's dorsal side was injured and bleeding.
By 9 a.m., it had beached on a tidal flat about 50 feet away from the floats. Marine mammal rescuers from the International Fund for Animal Welfare (IFAW) watched as the whale freed itself from the flat on the incoming tide and began to swim in counterclockwise circles in the harbor.
Many bystanders, including members of a sailing class at nearby Stage Harbor Yacht Club, stood on the shoreline and watched the whale, snapping cell phone pictures and pointing.
Throughout the morning, the whale swam circles in the harbor, its powerful fluke causing the water to bubble up in telltale patterns. It surfaced every minute or two to breathe.
The whale was likely drawn to the harbor by the presence of pogies or menhaden, a species of bait fish that congregates in tight schools at this time of year.
“A team of experts found that the whale was an immature female with remnants of fish in her stomach, indicating she fed recently,” IFAW spokeswoman Melanie Mahoney wrote in an email to The Chronicle. “We are not sure at this time how the whale came to be in the harbor. It could be for a variety of reasons,” she wrote.
The whale continued circling in the harbor during the day Thursday, thwarting efforts of IFAW and Chatham harbor patrol staff to herd it back to open water. Officials opted to return to the harbor Friday morning to reevaluate the animal, but were alerted early that morning that it died and was beached about a mile and a half away in the Oyster River, a short distance upstream from the oyster shanties at Barn Hill Landing.
Officials loaded the animal on a flatbed trailer and took it to Harwich for a postmortem examination.
“Gross necropsy findings indicate that she had [an] underlying health condition that likely caused the stranding,” Mahoney wrote. “No evidence of trauma from entanglement or vessel interaction was found.” The wounds visible on the animal were likely caused by its stranding and its contact with piers and floats, not a collision with a boat.
“It may be several weeks or months before laboratory results from tissues collected can confirm a diagnosis,” she added.
Though they are legally protected like other marine mammals, minke whales are not rare and have stable population numbers. They can live up to 50 years, growing 35 feet in length or longer. It is one of the smallest members of the baleen whale family.