A new publication co-authored by scientists from NOAA Fisheries redescribes the freckled stargazer, Xenocephalus egregius. In the paper, the authors expand the range of this species and document the anatomical changes that occur throughout its lifespan. This research demonstrates the combined value of fisheries surveys and museum collections for enhancing our understanding of marine species. This in turn improves our overall understanding of our nation’s biodiversity and fisheries.
Wrong Place, Right Time
Each fall and spring, the NOAA Ship Henry B. Bigelow heads out to sea for the Northeast Fisheries Bottom Trawl Survey. The survey spans the Gulf of Maine to Cape Lookout, North Carolina. The species that scientists encounter during surveys are similar from year to year, often including black sea bass, summer flounder, and scup.
But in 2014, NOAA Fisheries biologist John Galbraith came upon an unusual specimen off New Jersey during the survey. It immediately caught his attention—in part because it was so massive, but also because he believed it belonged to a genus called Xenocephalus. Fish in this group are known as stargazers because of their distinctive top-mounted eyes. They are deepwater ambush predators, dwelling at depths of 100–400 meters.
Encountering this genus of stargazer during the survey was uncommon. Species of Xenocephalus live in deep water, so they are rarely seen and we know very little about them, making this specimen particularly valuable. Galbraith collected the stargazer and deposited it at the Museum of Comparative Zoology at Harvard University.
In 2015, Galbraith and Dr. Katherine Bemis of NOAA Fisheries’ National Systematics Laboratory collected two more stargazers on the bottom trawl survey. Bemis and her colleague Dr. Matthew Girard of the Smithsonian’s National Museum of Natural History collected two more in 2022.
“Matt [Girard] and I were working to photograph as many North Atlantic species as we could, which was why we initially decided to collect those specimens,” Bemis says. But they also wanted to save them for further investigation by Leo MacLeod, a Ph.D. candidate at Howard University studying stargazers.
MacLeod joined Bemis, Galbraith, and Girard on the Northeast Bottom Trawl Survey in 2023. The group discussed their shared experiences of collecting stargazers from the genus Xenocephalus in the North Atlantic, which piqued MacLeod’s interest. “Everything I’d read about this group of fish said they only occurred between Texas and Florida,” he says.
MacLeod realized then that they had multiple records out of range, and a comprehensive dataset to prove it. “I was so excited that I actually started writing the paper on the Bigelow during the survey,” MacLeod laughs.
MacLeod positively identified the specimens collected by Galbraith, Bemis, and Girard as freckled stargazers, Xenocephalus egregius, using specimens from:
- Smithsonian Institution National Museum of Natural History
- Museum of Comparative Zoology at Harvard University
- California Academy of Sciences
- Universidad Nacional Autónoma de México
This meant that the range of this species was more expansive than previously thought, spanning the Gulf and along the U.S. East Coast into the Atlantic Ocean.
The freckled stargazer is the only member of the genus Xenocephalus found in the Atlantic Ocean; the rest occur in the Indo-Pacific. “We now realize that this species has a very broad range, which is amazing,” MacLeod says. “Stargazers are not like tunas that make long migrations. Instead, they bury themselves in the sand and really just stay put.”
Changing Its Spots
MacLeod began his research with a focus on the range expansion of the freckled stargazer. He quickly became aware of and interested in problems with identifying this species during surveys. “People were collecting it but seemed to not know what it was,” he says.
As MacLeod continued his work, he found a variety of factors contributing to the confusion around this species. One of the most significant was the fact that this species undergoes notable physical changes as it matures. Like fawns that lose their spots as they grow into adult deer, juvenile and adult freckled stargazers can appear drastically different. MacLeod observed that juveniles typically have blue or green spots or streaks—a stark contrast from the yellow-gold coloration and namesake “freckles” of adults.
However, this transformation can lead to misidentification if these changes are not well documented in species guides or biologists are unfamiliar with all life stages of the species. MacLeod also notes that most guidebooks for the western Atlantic Ocean don’t contain the freckled stargazer. This would leave a scientist stumped if they were trying to match a specimen using a key. “Not only do you have a fish that changes a lot throughout its life, it’s also appearing where it’s not supposed to appear,” MacLeod says.
Hidden in the Data
This paper highlights how questions initiated by sailing on fisheries surveys can be explored using museum collections. The information can tell a more complete story about the natural history of an organism. “This is a success story, and a reminder, of why we do these surveys over a long time series. It gives us the ability to build comparative datasets that, even for rarely encountered species like Xenocephalus egregius, start to add up,” says Bemis.
NOAA scientists collected stargazers and deposited them in the Smithsonian Institution as early as the 1960s. These samples helped them to positively identify the more recent specimens and provided additional support for the range expansion of the freckled stargazer. “Some of the data we needed was already there in museum collections; we just didn’t know it was there until we looked more closely,” MacLeod adds.
“Being at the National Systematics Lab positions us at the intersection of fisheries datasets and museum specimens, and enables us to use both for systematic studies,” Bemis says. “It’s really exciting to have graduate students like Leo involved in both, and also a great example of the way the National Systematics Lab supports the next generation of scientists.”
While these findings have enhanced our understanding of stargazers, MacLeod remains focused on questions we still have about these species and what we can learn from this discovery. “The amount of specimens and data—and access to them—is now so much greater than when this species was described in 1905. We’re able to extract new insights from data that we’ve been building from surveys and in museums.”
