Freckled guitarfish: the challenge of studying a rare species with binational distribution

Studying the guitarfish, Pseudobatos lentiginosus, across its range in the Gulf of Mexico basin is a challenge. So far, it is known to be the only ray species of the family Rhinobatidae that inhabits this gulf, as far northwest as North Carolina in the Northwest Atlantic Ocean. Like other family members, these species are bottom dwellers in sandy, weedy, or muddy shallow waters, extending from the shore to approximately 30 m in depth, where they are buried in the bottom sediments. Seasonally migrate to shallower waters and bays to give birth and mate.

Updated records of Freckled Guitarfish through the Gulf of Mexico and the East Coast of the United States. Locations provided by Southeast Area Monitoring and Assessment Program (SEAMAP-SA), SEAMAP-Gulf of Mexico, Texas Parks & Wildlife Department (TP&WD), Marine Megafauna Foundation, Research Consortium of the Gulf of Mexico (CIGOM), and the Instituto Mexicano de Investigación en Pesca y Acuacultura Sustentables (IMIPAS). Complemented data from digital databases such as Global Biodiversity Information Facility (GBIF) and iNaturalist.

The freckled guitarfish has a maximum total length (TL) of 76 cm; however, it is commonly caught by fisheries between 50 and 60 cm TL, making it a medium-sized member among guitarfish species. Due to its small size, it’s not a species of interest for artisanal and industrial fisheries. In both Mexico and the United States (US), it is caught incidentally in industrial shrimp fisheries. Nevertheless, in Mexico, it is caught in artisanal fishing that targets shrimp and other elasmobranch species, including sharks and rays, which hold a higher economic value in the market. However, most of the time, it’s released in the capture zone, regardless of its condition, whether alive or damaged by nets. At the end of the shark and ray fisheries season in Mexico, when the abundances of other elasmobranch species decrease, the guitarfish can be marketed at a low economic value. Based on annual catch records from fisheries-dependent and independent sources, an updated map of the freckled guitarfish distribution shows that this species has been commonly recorded on the Florida coast and the southern GoM but has still rarely been seen or caught over the continental shelf of the northern GoM. We are therefore interested in studying its ecology and the environmental conditions of the area to understand why it does not inhabit this region.

Fishing camp in Ciudad del Carmen, Campeche, México. Photo © Raúl Lara | Instituto Mexicano de Investigación Pesquera y Acuacultura Sustentable

In vulnerable species such as the Freckled Guitarfish, evaluating population status and implementing appropriate regulations for fisheries are essential for their conservation, enabling populations to recover or at least mitigating the risk of further depletion. This requires robust life history and habitat use data to estimate life history parameters and determine the locations of nursery areas. It is important to note that the demographic and ecological parameters, including age, growth, longevity, seasonal reproductive cycle, habitat use, and nursery areas of the Freckled Guitarfish remain unknown. The main challenge for our project is to collect sufficient whole organisms from fisheries throughout their distribution, given the extensive area of the GoM. To achieve the objectives, it has been key to establish an extensive collaboration network with other researchers interested in sampling this species, as well as colleagues from governmental and academic institutions, civil associations, and, most importantly, local fishermen.

Bycatch in a shrimp trawl in the southern Gulf of Mexico. Photo © Raúl Lara | Instituto Mexicano de Investigación Pesquera y Acuacultura Sustentables

Artisanal fisherman sorting the shrimp and bycatch in Ciudad del Carmen, Campeche, Mexico. Photo © Raúl Lara | Instituto Mexicano de Investigación Pesquera y Acuacultura Sustentables