Have you ever heard of a barracudina? A new publication co-authored by NOAA Fisheries biologist Dr. Katherine Bemis describes a new barracudina species, Stemonosudis dianea, distinguishing it from the species Stemonosudis intermedia. This research advances our understanding of this little known but important group, which is a key source of prey for commercially and recreationally important fish species like tuna and billfish in U.S. waters.
Barracuda vs. Barracudina
Barracudina—which means “little barracuda”—are a diverse but understudied group of fish that occur across the globe. Their name is misleading, though: The two families are not actually related and live in very different habitats. There are 29 known species of barracudas, which typically dwell in shallower, reef-associated habitats. Some species can grow to more than six feet in length. Barracudina are found in more offshore environments at depths of up to 1,500 meters, and the largest species is about one foot long. However, they do share some superficial similarities, including:
- Large, sharp teeth
- Long, slender bodies
- Elongate snouts
- Dorsal fins set far back on their bodies
Barracudina haven’t received much attention since the 1950s—until recently, when biologist Dr. Hsuan-Ching (Hans) Ho began researching them in earnest. In fact, he has described 11 of the 69 known species!
A New Species in U.S. Waters
Ho first became interested in barracudina in Taiwan, where he lives and frequents fish markets. Taiwanese fish markets sell not only high commercial value species but also bycatch and non-target species. This makes them one of the best places to observe the region’s marine biodiversity—and discover new species. Ho spends a great deal of time describing (and redescribing) species that he encounters in these markets. He estimates that he and his collaborators have identified more than 60 new species this way, including four species of barracudina.
As Ho resolved taxonomic problems locally, he began to expand his focus more globally to barracudina species in the Atlantic and Caribbean. In 2024 and 2025, he traveled to the Smithsonian National Museum of Natural History in Washington, D.C. to explore their fish collection. There, he connected with Dr. Katherine Bemis, a research zoologist with NOAA Fisheries’ National Systematics Laboratory.
While browsing, Ho discovered an exciting specimen: a barracudina collected in 2011 in the Caribbean Sea, which was deposited at the Smithsonian Institution. It had only been identified down to the family level, but Ho believed it was likely a new species and enlisted Bemis’ help in describing it. As Ho and Bemis further explored museum collections, they found additional specimens, including some off the U.S. east coast.
The new species, Stemonosudis dianea, is named for Diane Pitassy, the collection manager of Fishes at the Smithsonian Institution National Museum of Natural History. Pitassy and Ho are longtime colleagues. “I promised her that I’d name a fish after her someday,” Ho laughs. “The name is especially appropriate because Diane curated the specimens from the expedition. She also supported my research with the museum and made these specimens available to researchers worldwide.”
A Key Food Source for Top Predators
Through their research, Bemis and Ho uncovered evidence that barracudina play important roles as both predators and prey in their ecosystems. As part of their study, they X-rayed barracudina specimens to count their vertebrae. They found this to be an effective way to distinguish Stemonosudis dianea from closely related species.
While X-raying, Ho discovered that three specimens of the new species had other species of barracudina in their stomach. This suggests that barracudina are preying on each other. We don’t yet know whether they mostly cannibalize their own species, other species within the family, or both.
Barracudina are an important food link in the food web as prey items, particularly for large predators like tuna, swordfish, and lancetfish. Some of the barracudina specimens used to describe Stemonosudis dianea were actually from the stomachs of tuna and lancetfish. They were collected by former NOAA biologist Dr. Bruce Collette in 1957 onboard the NOAA Ship Oregon. These specimens, deposited by Collette at the Smithsonian Institution for future researchers, have remained unidentified to the species level until now.
A story from Bemis’ colleague at Woods Hole Oceanographic Institution, Dr. Martin C. Arostegui, provided additional support for the importance of barracudina as prey. He told Bemis and Ho about swordfish caught in the North Atlantic as part of his ongoing research on the diets of top predators like tuna and swordfish. When he opened up the stomachs of the swordfish, they were all packed with barracudina. Research by NOAA biologists has shown that barracudina are important prey for marine mammals like Sowerby’s beaked whales, as well.
To manage economically and ecologically important predators, we have to understand what they’re eating, Bemis emphasizes. “In many scientific papers that list barracudinas as prey, the barracudinas are not identified to the species level. Because they are not identified, we’re not sure if only one or two species of barracudina are important prey items, or if the entire family is. That’s why the ability to identify each species—like Stemonosudis dianea—is so valuable.”
Bemis says that this research is an example of the ways that museum collections bring things together—both specimens and people. “We were able to identify this new species that occurs in U.S. waters because of Hans [Ho]’s expertise,” she says. “For me, this was an exciting opportunity to learn from the world authority on barracudina, and now in the field I look much more closely at each barracudina we collect. That’s one reason it’s so valuable to build relationships with people around the world. Their understanding of their local fisheries and ecosystems helps us better understand our own.”
