After at least nine collisions, the Hawaiian Islands Humpback Whale National Marine Sanctuary is asking boaters to navigate waters carefully in order to avoid running into the mammals, which can weight up to 40 tons.

Most of the whales reported with injuries this season are young, including calves and sub-adults, according to Ed Lyman, Natural Resource Management Specialist for the sanctuary. Many have propeller injuries, while others have superficial injuries, and one had a gouge that was not life-threatening.

“Even though we are halfway through the season, a good number of humpback whales are in the sanctuary and nearby waters,” said Lyman. “It’s still a reminder to everyone that it’s still whale season and there are a lot of whales there.”

Each year, thousands of humpback whales return to Hawaiian waters to breed, give birth and nurse their young.

Although humpback whale season in Hawaii generally runs from November through May, with the peak between January and March, whales may still be encountered in limited numbers beyond those months.

The sanctuary reminds boaters to post a lookout at all times throughout the year, and not just when whales are visiting Hawaiian waters. An extra set of eyes scanning the waters ahead and to the side of a boat can prevent collisions with marine life, obstructions, divers and other vessels.

In addition, slower speeds can reduce the risk of collisions with the animals.

Federal regulations prohibit approaching the whales within 100 yards of whales when on the water, and 1,000 feet when operating an aircraft. These apply to all ocean users, including vessel operators, kayakers, paddle boarders, windsurfers, swimmers and divers throughout the isles.

Boaters can help humpback whales by reporting injured or entangled marine animals to the NOAA Marine Mammal hotline at 888-256-9840, or to the U.S. Coast Guard on VHF channel 16.