Scientists are turning to anglers and fishermen to learn more about this yet-to-be-identified parasite. Photo: VIMS

Unknown Parasite Latching onto Stripers, Other Fish

Was your Halloween sufficiently spooky? If you need another dose of the strange and unusual, these creepy Chesapeake Bay parasites are quite real—and scientists need your help to learn more about them.

During the last few months, anglers have been catching fish in the Chesapeake with parasites attached to their bellies and fins. Striped bass and sheepshead are the most frequent hosts. One sheepshead was found carrying over 20 of the unsavory hitchhikers. Some on social media believe the parasites are simply sea lice, but that is not the case.

Parasites cover the tail fins of a fish caught in Chesapeake waters. Photo: VIMS

Hamish Small, an Associate Research Scientist at the Virginia Institute of Marine Science (VIMS) who earned his doctorate in Marine Parasitology, reports that, “sea lice are parasitic copepods, and these (recent infestations) appear to be a parasitic isopod (crustacean).” Small is sequencing the DNA of these crustaceans so he can determine exactly what they are. If he had to guess, Small believes they are Livoneca redmanii, which are known to be in the Chesapeake Bay. One particularly gross version of these parasites is Cymothoa exigua, which once inside the fish’s mouth attaches to the tongue of the host fish, and eventually replaces the tongue!  

According to Small, it is not unusual to find a fish that is carrying a few of these parasites. It is the recently discovered larger numbers of parasites on individual fish that is a cause for concern. “They usually are found in small numbers (single or a pair) within the buccal cavity (mouth) or in the gill chamber of the fish they parasitize, so the current finding of multiple (over 20) on the caudal fin (tail) and caudal peduncle (the narrow part of a fish forward of the tail) of the sheepshead is somewhat unusual. Likewise, another case indicated eight parasites attached to the pelvic fins of a striped bass,” he said. 

These parasites use hooks to hold onto their hosts. That cannot be comfortable, especially in the mouth.  Heavy infections, such as on the sheepshead, can cause significant damage to the host fish. Can you eat an infected fish?  VIMS said there is no harm to humans. Personally I would donate an infected fish to science and catch another for dinner. 

“At this point we can’t really say whether this is something new.” said Small. If it is new, the scientists at VIMS don’t know the cause. If you are an angler, you can help by reporting any infected fish you catch. Try to get a photo, and call VIMS at 757 787-5834.  

-Kendall Osborne