Diving, Research, and Tourism


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David Castro. You’ve probably seen him before, you just didn’t recognize him.

Thousands of fish coming together during reproduction courtship. In the afternoon, these fish form a massive spawning aggregation around the reefs of the National Park. The diver in the image is David Castro, a local divemaster of Cabo Pulmo who has been working together with his family, in the protection of the Park that has been close to any fishing activities for the last 17 years. This no-take marine reserve has allowed the recovery of many species and the historical abundance of predatory fish such as Bigeye travellies.
Thousands of fish coming together during reproduction courtship. In the afternoon, these fish form a massive spawning aggregation around the reefs of Cabo Pulmo National Park. Photo credit: Octavio Aburto.

That’s him right there! Yes, the small SCUBA diver next to the goliath school of jacks. This man may be most well-known for this photo and for his family’s work in Cabo Pulmo National Park in the Gulf of California. There, his father, Mario Castro, led community change from a fishing-based village to an ecotourism hot spot. After 20 years of no-take protection, Cabo Pulmo National Park has been declared one of the most successful marine reserves in the world and is known as one of the best travel destinations.

However, for David, the local divemaster at the family’s dive shop, there’s more research to be done. One of the main projects that he assists in is collecting weekly plankton samples of Cabo Pulmo to help understand what species the marine park is supporting. He has conducted plankton tows every week for the last year for CICIMAR: the samples are sent to labs at the Universidad Autónoma de Baja California Sur to be analyzed. The results surprise even David—he is amazed at both the abundance and the diversity of larvae present in the park. He communicates these findings and other bits of scientific information with his tourists as he conducts the plankton tows in between dives.

Here’s video of David working in Cabo Pulmo with Octavio Aburto in November 2016.

Another exciting project that David plays a part in is the study of grouper movement and spawning aggregations in Cabo Pulmo. This research has been ongoing for the last two years, and David lends his expertise in diving to help tag groupers and set up acoustic receivers.  With his help, the GCMP has discovered that groupers are long-term residents of Cabo Pulmo National Park, spending one to four months at El Bajo-Los Morros reef. You can read more about the study here.

Overall, the science has helped put David’s diving into perspective. Each dive has more purpose, and directly participating in the research has impacted how he interacts with his customers. David now takes tourists out on dives not just for entertainment, but also to educate them about what they may see underwater. For him, conservation begins with a conversation.

Here are some other projects that David has been involved with:

Reef Long Term Monitoring 

Red Snapper Spawning Aggregations

Turtle Nesting Conservation

Shark Tagging

Economic Value of Bull Sharks in Cabo Pulmo

Effect of Diving on Shark Behavior


Author: Astrid Hsu
Research Associate at SIO. As a recent MAS graduate in Marine Biodiversity and Conservation at Scripps Institution of Oceanography, Astrid focuses on generating interest and interdisciplinary support of marine conservation through science communications and collaborative research.

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