Conservation groups PRETOMA and Turtle Island Restoration Network found evidence that hammerhead sharks (Sphyrna lewini) were being exported from Costa Rican ports and flown to places in Hong Kong by way of stops on U.S. soil. With this evidence in hand, Turtle Island negotiated with American Airlines in recent months to convince the carrier to ban shark fin shipments on their planes.

Presented with this evidence, American Airlines took prompt, proactive action to institute a ban on shark fin shipments, but declined to publicly acknowledge this action. On April 7, American Airlines announced the ban on Twitter.

In its tweets, American Airlines announced it will no longer be shipping shark fins. This is significant because the shipments in question included fins of the Eastern Pacific Scalloped hammerhead sharks, which are listed as “endangered” under the U.S. Endangered Species Act (ESA).

The export and trade of endangered species shark fins violates the environmental law, which bans shipments of endangered species products, including “in transit” hammerhead shark fins. Read more about the evidence and shipments here.