Composition and conservation status of rays sold in Baja California Sur, Mexico

October 2025

Isabella C. Ossiander, Giacomo Bernardi, Marta D. Palacios, Donald A. Croll, Kelly M. Zilliacus, Abel Trejo-Ramirez, May B. Roberts, Adrian Munguia-Vega, Xchel A. Perez-Palafox, Pablo Ahuja, Rogelio Gonzalez-Armas & Melissa R. Cronin

Keywords: Baja California • Conservation • DNA Barcode Sequencing • Elasmobranchs • Fishing Regulations • Mexico • Mobulids • Seafood Labelling • Threatened Species • Traceability

Summary: Sharks, skates, and rays (elasmobranchs) are declining globally, with unsustainable fishing and market mislabelling exacerbating threats to vulnerable populations. In La Paz, Baja California Sur, Mexico, DNA barcode sequencing revealed 131 ray samples from 36 locations, representing 14 species across eight families. Most were sold under broad commercial names such as mantarraya, masking identity. Notably, over 78% were threatened species, including two devil rays (Mobula munkiana and Mobula thurstoni), both federally protected. Expanding species-level identification at markets is critical to support mobulid conservation, improve traceability, and guide sustainable management of these mobulid species.

Abstract

“Sharks, skates, and rays (elasmobranchs) are experiencing global population declines, leading to heightened concern regarding the impacts of target and bycatch fishing on their populations. Globally, market mislabeling of unsustainably harvested fish can lead to confusion about species identity and origin, mask unsustainable fishing practices, and inhibit recovery of depleted populations. Therefore, it is important to increase transparency about the identity of species sold to address the potential impact of mislabeled or illegally harvested threatened elasmobranchs. We used DNA barcode sequencing to identify the species composition of rays sold in fish markets and supermarkets in La Paz, Baja California Sur, Mexico, an important market for small-scale fisheries in Northwestern Mexico. We identified 131 samples from 36 market locations collected between 2020 and 2022 representing 14 species belonging to eight families. None of the samples were labeled using local names for individual species by the seller; instead, they were sold under four categories: mantarraya, pescado seco, machaca, and cubana seca. The most common species identified by genetic analyses were diamond stingray (Hypanus dipterurus) (n = 47), longtail stingray (H. longus) (n = 37), and California butterfly ray (Gymnura marmorata) (n = 11). Greater than 78% of the samples identified are considered threatened by the IUCN Red List. This included two species of devil ray (Mobula munkiana and Mobula thurstoni), both of which are federally protected in Mexico. The use of overly broad seafood commercial names for threatened ray species is concerning, given that most species exhibit vulnerable life history characteristics and have documented population declines. We recommend expanding point of purchase identification for fresh products weighed and packaged in markets with Mexican authorities to better understand the extent of elasmobranch fishing and to identify which fisheries and species require increased action for their conservation in the Mexican Pacific.”

Full publication

Author Affiliations

  • University of California Santa Cruz

  • Mobula Conservation

  • The Manta Trust

  • Applied Genomics Lab

  • The University of Arizona

  • Mar Libre

  • Instituto Politécnico Nacional

  • University of Massachusetts Dartmouth

Funding

  • Koret Foundation Koret Research Scholarship

  • The Manta Trust Cyclone Grant

  • GoFundMe