Ocean sunfish commonly strand along our New England beaches in the fall and early winter. The majority of strandings occur along the northern shores of Cape Cod, those that border Cape Cod Bay, and in shallow bays and inlets of Buzzards Bay. Most of the animals are dead when they wash ashore, but some fish are still alive. From our work with stranded individuals, we believe that ocean sunfish can strand anytime during the spring, summer, and fall, and for a number of reasons which we will list below.
- vessel and boat collisions
- fishing gear interactions
- trapped in shallow tidal areas as tide is going out
- cold-stunned in the fall and early winter
In the summer and early fall, ocean sunfish are attracted into our coastal waters as they feed on jellyfish, ctenophores, and other gelatinous organisms. As winter approaches, ocean sunfish begin their migration south to warmer, more tropical waters. However some ocean sunfish become trapped by the physical presence of Cape Cod and Buzzards Bay. Stuck inside Cape Cod Bay and unable to continue south, these animals can not survive for long as water temperatures continue to fall. Eventually these trapped individuals will become cold-stunned and wash ashore on our sandy beaches and rocky shorelines.
The staff of NEBShark and NEOSunfish have created a rescue and stranding effort on behalf of these amazing animals. Each fall, we respond to hundreds of calls from local organizations as well as from members of the public who find a stranded animal on our shores. If the animal is still alive and in shallow water, we attempt to move the fish into deeper water to keep it from stranding. If the animal has beached itself, then we are limited in our response given the immense weight of this creature. We are hopeful that we or one of our associates will devise a method of moving a fish weighing close to 800 pounds back across the tidal flats and into deep water.
Ocean Sunfish StrandingsFor ocean sunfish that strand dead, we conduct external and internal examinations in the hopes of learning more about this species. It is very sad when such a beautiful fish dies and we wish we could save them all, but that is not possible. What is possible is to collect information from stranded animals that can help us better understand and protect the living ocean sunfish in our New England waters. NECWA is sharing this information with researchers in the New England area as well as those in Europe and Asia.
Level A Examinations For Level A Examinations, NECWA records and collects:
- carcass position
- carcass weight
- body measurements
- skin plugs (skin, reticulated collagen, muscle)
- external parasites
- sex determination
- internal parasites
- whole eyes
- upper and lower jaw
- vertebra section
- liver sample
- muscle sample
One project focuses on determining the age of ocean sunfish that strand in our area. Looking at the size of the carcasses that wash ashore, typically 7 feet long, we assume that these are juvenile ocean sunfish that are not reproductively mature. To determine this, we collect otoliths, gonads, and sections of vertebra for use in aging studies. Dr. Rich McBride and his team from NOAA's Age and Growth Lab, Woods Hole, have examined gonad (ovary and teste) tissue and determined that all of the samples represent reproductively immature fish who have not spawned.
The Ocean Coconut
We also conduct necropsies or internal examinations on all ocean sunfish carcasses that are reported to NEOSunfish, our community-sighting network. We must dissect the carcass to determine its gender or sex and we collect a number of tissues for future analysis. One of the interesting structures that ocean sunfish have is a thick layer of reticulated collagen just under the very thin, rough skin. This white tissues is hard and surrounds the body cavity of the fish. No one is sure of the function of this tissues, but you have to cut through this tissue to access any internal structures. We now have a new nickname for the ocean sunfish, we call it the "ocean coconut."
If you see a dead ocean sunfish on the beach, look to see if there is a colored cable tie through the leading edge of its dorsal fin and its anal fin. We use a variety of colored cable ties to tag the carcasses that we have examined. Please call us about the carcass and let us know what color you observed. Better yet, send in a sighting report to NEOSunfish and include some photos.
Who Reports Strandings?
Ocean sunfish can strand anytime during the spring, summer, and fall, but the majority of strandings occur from August through December. Reports of stranded animals are called into NECWA from a number of different sources that include:
- Wellfleet Bay Wildlife Sanctuary
- Internal Fund for Animal Welfare (IFAW)
- New England Aquarium
- Town Animal Control Officers
- Natural Resource Officers
- Harbor Masters
- Public Citizens