1960s Up to 400,000 dolphins are crushed or drowned each year in purse seines. Ocean activists and consumers boycott canned tuna to protest the dolphin slaughter. The U.S. Congress passes the Marine Mammal Protection Act, which puts observers on tuna boats and makes U.S. boats change fishing methods to minimize dolphin kill. 1980s Foreign boats, which don't have to protect dolphins, take over most tuna fishing. The U.S. bans imports of tuna from nations that encircle dolphins.
More fishers start to use log sets so their tuna can be sold as dolphin-safe.
1995 Research reveals that log sets kill tremendous amounts of juvenile tuna, sharks, other fishes and sea turtles. Some argue that the ecological cost of killing so many tons of fish and other animals in a log set is worse than killing just a few dolphins. Others argue that killing any dolphins is unacceptable. 1999 NMFS preliminary study finds no significant adverse impact if fishers apply the new encirclement techniques that release dolphins. Accidental kill is no longer allowed, but setting nets around dolphins is permitted, as long as the dolphins are released unharmed.