Mobula habitat overlaps with the main tuna fishing grounds in the Eastern Pacific Ocean. The tropical tuna purse seine fishery captures the highest numbers of Mobulas per year (on average, 1,200 individuals) compared with other purse seine fisheries.
This fishery uses different strategies for finding tunas depending on how the set is performed:
1) school sets (schools of tunas detected by sonar marks, breezers, radar, or jumps)
2) dolphin sets (schools of tuna associated with group of dolphins) and
3) drifting fish aggregating devices (FAD) sets (school of tuna associated and aggregated around floating objects).
Mobula rays are often caught in dolphin and school sets, showing less association with FAD sets.
Species Distribution modeling
Our work is to identify the main areas of importance for each species and understand the habitat conditions where these species are usually captured. The use of species distribution models (SDMs) helps to identify important spatial and temporal regions, and at the same time provides first steps to advise tuna fisheries on potential spatial management strategies.
Collaborative Solutions to Reduce Mobula Bycatch Mortality in Purse Seine Fisheries
We host or cooperative workshops with purse-seine skippers, crew, mechanics and observers to incentivize the design, testing, and onboard implementation of feasible, scalable techniques for safely removing rays from vessel decks. These workshops allow scientists and tuna fishers to work together to collaboratively problem-solve. Workshops began in January 2021 in Ecuador and will continue through the year. As part of this work, we are distributing posters for vessels to hang on board to help with onboard species identification and proper handling and release techniques.
Analyses of Mobula bycatch data from observer programs in purse-seine fisheries surveys
Species Distribution Models
Cooperative workshops with the purse-seine crew to find solutions to reduce mobula bycatch mortality in purse seine fisheries
In the Field
Spatio-temporal distribution of spinetail devil ray Mobula mobular in the eastern tropical Atlantic Ocean