Sharks unveiled: Comparing impact of management measures on two shark species in different grounds in southern Spain

Abstract

Sharks face multiple threats such as overfishing, IUU (Illegal, Unreported, and Unregulated) fishing, habitat degradation, and climate change, threatening their survival and abundance globally. Spain ranks among the top nations in shark catch, with Andalusia, covering the Gulf of Cádiz (Atlantic) and Alborán Sea (Mediterranean Sea), being a significant fishing region. This study assesses the commercialization of tope shark (Galeorhinus galeus) (Linnaeus, 1758) and common smooth-hound shark (Mustelus mustelus) (Linnaeus, 1758) by the Andalusian fleet from 2000 to 2022, using data from the Junta de Andalucía Fisheries Information System. Both tope shark and common smooth-hound shark rank among the top ten most caught elasmobranch species in the region, contributing 12.13% and 4.35% to the total historical landings, respectively. Stable market values in the Atlantic and Mediterranean suggest perceived equivalence between the species, influenced by supply, regulations, and consumer preferences rather than species identity. Change-point analysis revealed significant fluctuations in their landings. Digitalization efforts in Andalusia have progressed in tandem with the decline in tope shark landings. In the Atlantic ground, an increase in common smooth-hound landings has been observed, which may suggest resource substitution and previous species misidentification. In the Mediterranean, landings for both species are declining. A negative cross-correlation in the landings of the two species was observed, indicating alternating patterns potentially driven by market dynamics, ecological factors, regional variations in ecosystem behavior, fishing pressure, or management practices. This underscores the importance of Andalusian fish market data for managing vulnerable stocks. Collaboration among scientists, managers, and fishers is crucial for tailored conservation strategies and enhanced management practices to sustain these economically vital highly threatened species.