Heermann's Gull heermannii

(last update: 23-01-2018 )

Coordinators:
John Cant
Mars Muusse

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1st cycle (1CY): September

OCTAVIO ABURTO USING SCIENCE TO INFLUENCE CONSERVATION

Isla Rasa: Sea birds and Sardines

The People 

Among the Midriff Islands lies Isla Rasa, a small island that’s difficult to find even on Google Maps. Though this island is uninhabited, a community nevertheless fights for and supports the conservation of Rasa. Thanks to the collaborative efforts of researchers, locals, and organizations, Isla Rasa went from an egg poaching hot spot to Mexico’s first Migratory Waterfowl sanctuary. Researchers, such as Dr. Enriqueta Verlarde, have alerted the local community of the importance of this island as a bird refuge. By using the birds' success as an indicator, researchers discovered that it  would forecast the success of the fishing season. This united the local fishermen in an effort to heed natural cues of low fishery stocks and thus prevent overfishing. 

The Resource

Though Isla Rasa measures roughly one square kilometer, over half a million birds call it home. 95% of the world’s Elegant Terns and Heermann’s gulls are among the migrating species that stop to nest on Rasa. However, it wasn’t always this way: egg and guano collectors in the mid-20th century caused the nesting colony to dwindle to a just few thousand individuals. Since then, the birds have made an amazing recovery thanks to the efforts of the collective community to designate the island as a reserve. But the abundance of birds is not solely dependent on poachers; rather, the availability of sardines also greatly impact the numbers. Collectively the birds require at least 60 tons of sardines each day, that is crucial for their health and reproduction. Unfortunately, sardines have traditionally been fished unchecked: a single fishing vessel can catch 60 tons of sardines in one night. In 20 years, appr 10.5 million tons of sardines have been fished. Clearly, sardines are important economically, and locals are learning to watch the abundance of the birds to better understand the health of the fish stock and ocean.

The Future

On occasion, these birds leave before nesting, foreshadowing a very poor fishing season. However, the frequency of these early exits appear to increase within the two decades, worrying conservationists and the local community alike. Researching why the birds are leaving and where they are going are the top priorities, as this change in behavior can speak volumes of the changing oceanographic conditions and fishery dynamics. Integrating this knowledge into sardine management is necessary to achieve a sustainable fishery, which is on the horizon: even without people inhabiting Isla Rasa, there is nevertheless a strong and persistent community fighting for it’s ecosystem.