Ignorance is not bliss: what we don’t know about Atlantic guitarfish will hurt them

When I tell you that the Atlantic guitarfish (Pseudobatos lentiginosus) is understudied, what exactly do I mean?

Researchers love when we can claim that our topic or species is “understudied” as a way of communicating its importance and garnering support for the work, although perhaps to the point where its widespread use may even come across as a cliché. While there are almost infinite scientific topics that remain to be investigated, the word is thrown about without clarity on what, if anything, should ever be considered “well-studied.”

A small biopsy of muscle tissue is sampled for stable isotope analysis, a method that uses the predictable flow of carbon and nitrogen isotopes through marine food webs to estimate important diet groups and foraging habitats. Photo © John Hlavin | University of Miami Shark Research and Conservation Program

In many contexts, “understudied” is implied to mean less-studied relative to other more popular species or topics, but in the case of the Atlantic guitarfish, no comparison is needed to justify this claim. A quick Web of Science search for either of its recent scientific names (i.e., “Pseudobatos lentiginosus OR Rhinobatos lentiginosus”) returns just 13 results. Seven of the 13 concern anatomical or physiological descriptions of the heart, olfaction, vision, locomotion, feeding mechanics, and litter size. Five of the remaining six concern observations of infection or parasites. The last result describes the vulnerability of the Atlantic guitarfish to the Mexican shrimp trawl fishery in the Gulf of Mexico. In another Save Our Seas Foundation funded project, Bryan Huerta-Beltrán is investigating the occurrence of the Atlantic guitarfish and its congeners in Mexico’s cultural medicinal market. Not a single study to date, however, investigates the movement, habitat use, or trophic ecology of the Atlantic guitarfish.

A guitarfish is measured while an active dredge pipe can be seen depositing sand in the background, emblematic of the risk of human disturbance facing the guitarfish’s nearshore habitats. Dredging is often part of coastal management projects innocuously called “beach nourishment” aimed at combatting erosion and maintaining recreational value of manmade beaches. Photo © Nicole Bozkurt | University of Miami Shark Research and Conservation Program

In terms of species conservation, ignorance is not bliss and what we don’t know can indeed hurt wildlife. There is a saying that is true for computational modelling in science and may hold true for wildlife management as well: “garbage in, garbage out.” Without quality data to identify the conservation needs for a threatened species like the Atlantic guitarfish, we cannot expect to succeed in protecting them. While the east coast of the United States may be a potential refuge from fishing pressure for the Atlantic guitarfish, they are not free from the human-caused pressures of development, urbanisation, and the ecosystem and habitat disturbances that accompany them.

The guitarfish’s cloaca is swabbed to collect trace amounts of fecal DNA which will be sequenced using a method called metabarcoding to identify what taxa are present in their diet. Photo © Jason Hill | University of Miami Shark Research and Conservation Program

Guitarfish species are considered to form a link in the food web between benthic species like worms and small fish, and upper-level consumers. On the east coast of Florida, they may serve as an important prey species for the Critically Endangered great hammerhead, a predator famous for hunting rays. Maintaining healthy guitarfish populations in support of this flow of energy through the ecosystem requires ensuring they have continued access to their own important prey and the habitats where they forage. It is for that exact purpose that we are applying minimally invasive techniques, including stable isotope analysis of muscle and plasma and fecal DNA metabarcoding, to approximate the guitarfish’s dietary niche, trophic level, and foraging habitats, and to identify prey taxa. Only armed with these data and more can we hope for “good data in, good management out.”