Osa Peninsula Chronicles

By Brooke Bessesen

Golfo Dulce (“sweet gulf”) is held between the mainland and Osa Peninsula in S. Pacific Costa Rica. It is one of only four tropical fiords in the world. This curved embayment, approximately 50km in length and 10-15km wide, is utilized by an abundance of marine life, including large shoals of fish and several species of sharks, dolphins and sea turtles. It was recently recognized that whale sharks, the world’s largest fishes, seasonally migrate to the gulf waters and Humpback whales from both the northern and southern hemispheres spend time inside the gulf during their breeding and birthing seasons.

Indeed, Golfo Dulce is renowned for its biodiversity! Yet a tuna farm—the very first to raise yellow fin—has been slated for development near the mouth of the gulf, just beyond the southeastern shores of Punta Banco. Should that commercial “experiment” move forward, Golfo Dulce is sure to transform.

Underwater cages will not only consume space, encroaching on existing wildlife and blocking entrance to calm mineral-rich gulf waters, but organic waste produced by captive fish is likely to alter water quality, potentially influencing delicate ecosystems. A wide array of species may be affected by entanglement and introduced disease. And endangered sea turtle hatchlings drawn to the cage marker lights may fall prey to hungry tuna.

Human populations, too, face impacts. The gulf may be less conducive to traditional fishing practices and pollutants may modify ecological interest from the international community for surfing, sport fishing and eco-travel creating long-term changes in industry.

Friends of the Osa recently supported a research effort to collect baseline data about the types of species that enter or reside in Golfo Dulce during the dry season. Read the project report from that investigation. Perhaps a more distinct understanding of the unique gulf habitat will inspire conservation initiatives—before it’s too late.