Inter-Research > MEPS > v678 > p95-107  
MEPS
Marine Ecology Progress Series

via Mailchimp

MEPS 678:95-107 (2021)  -  DOI: https://doi.org/10.3354/meps13897

Seasonal aggregations of blacktip sharks Carcharhinus limbatus at a marine protected area in the Gulf of California, assessed by unoccupied aerial vehicle surveys

Kathryn A. Ayres1,2, James T. Ketchum2,3,4,*, Rogelio González-Armas1, Felipe Galván-Magaña1, Alex Hearn4,5, Fernando R. Elorriaga-Verplancken1, Raúl O. Martínez-Rincón6, Edgar M. Hoyos-Padilla2,4,7, Stephen M. Kajiura8

1Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, 23096 La Paz, Mexico
2Pelagios Kakunjá A.C, 23070 La Paz, Mexico
3Centro de Investigaciones Biológicas del Noroeste (CIBNOR), 23096 La Paz, Mexico
4MigraMar, Olema, California 94950, USA
5Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Diego de Robles y Vía Interoceánica, EC 170157 Quito, Ecuador
6CONACYT-Centro de Investigaciones Biológicas del Noroeste SC, 23060 La Paz, Mexico
7Fins Attached: Marine Research and Conservation, Colorado Springs, Colorado 80908, USA
8Florida Atlantic University, Boca Raton, Florida 33431, USA
*Corresponding author:

ABSTRACT: No-take marine protected areas (MPAs) can provide spatial refuge for species throughout all or part of their life cycles. Cabo Pulmo National Park (CPNP) is a no-take MPA located on the south-east coast of the Baja California Peninsula, Mexico, where there has been an increase in the abundance and diversity of elasmobranch species since its closure to fishing. An unoccupied aerial vehicle was used to complete weekly aerial surveys over sandy habitat in CPNP to determine the relative abundance of blacktip sharks Carcharhinus limbatus over a 1 yr period in 2019. C. limbatus were only observed during winter months, and abundance per survey ranged between 7 and 1086 sharks (289 ± 59, mean ± SE), yielding a maximum density of 4827 ind. km-2. A generalized additive model determined that sea surface temperature (SST), time of day, photoperiod and wind speed were significant influencers of C. limbatus abundance. According to this model, higher abundance is expected when SST is lower than 25°C, during the afternoon, at low wind speeds (<4 knots) and when photoperiod is between 12 and 13 h. The close proximity of C. limbatus to the shoreline is likely a result of a refuging behaviour, with sharks utilising the shallow sandy habitat to behaviourally thermoregulate and/or to avoid predators.


KEY WORDS: Aerial survey · Drone · Unoccupied aerial system · Generalized additive model · Elasmobranch · Cabo Pulmo National Park · Environmental factors · Refuging


Full text in pdf format
Supplementary material 
Cite this article as: Ayres KA, Ketchum JT, González-Armas R, Galván-Magaña F and others (2021) Seasonal aggregations of blacktip sharks Carcharhinus limbatus at a marine protected area in the Gulf of California, assessed by unoccupied aerial vehicle surveys. Mar Ecol Prog Ser 678:95-107. https://doi.org/10.3354/meps13897

Export citation
Mail this link - Contents Mailing Lists - RSS
Facebook - - linkedIn