Rescuing Cold-Stunned Ocean Sunfish off Cape Cod

The New England Coastal Wildlife Alliance (NECWA) is a volunteer nonprofit that focuses on marine wildlife off New England. Since 2005, we have maintained a community-sighting network for basking sharks and ocean sunfish in the waters off New England. Each fall, we now respond to stranded ocean sunfish along the north shores of Cape Cod or in back bay areas.

Ocean sunfish are the heaviest bony fish in the world and can reach lengths of over 10 feet. They migrate to our cold waters each summer to feed on jellyfish. As winter approaches, they head south to spend their winters in warmer, more tropical waters. However, some individuals get trapped in the arm of Cape Cod and become cold-stunned as water temperatures continue to drop.

For live ocean sunfish that strand, NECWA staff and interns push them back into the water. When responding to carcasses, we conduct a necropsy to learn more about their biology and eoclogy. NECWA now has the largest database on ocean sunfish off Cape Cod including the largest tissue bank that we share with other researchers worldwide.

This fall we created a portable weighing tripod that allows us to weigh ocean sunfish carcasses that wash up on beaches. So far, we have been able to collect weights on 3 carcasses with weights ranging from 350 to 650 pounds.

When rescuing live, cold-stunned ocean sunfish, the act of pushing them back into the water is not productive since they will more than likey re-strand sometime in the future. To assist these animals on their southerly migration, we need to relocate them to the southern side of Cape Cod or get them to the Cape Cod Canal. To do this, we need to make a portable sling that can be used to tow a live, cold-stunned ocean sunfish behind a small boat. Even though these fish are quite large, they can be easily moved given their hydrodynamic body shape. And since they are cold-stunned, they are not that active when handled.

We also need to come up with a way to tag all rescued sunfish with some type of metal dart tag. Tags would display NECWA’s contact information to allow anyone finding a rescued sunfish to contact NECWA about its condition and location. This would help us determine the level of our success regarding the relocation of cold-stunned ocean sunfish.

Financiado pelo capítulo Boston, MA (August 2012)

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