How do dolphin-safe tuna nets work?

So, how do they build a net that lets the big dolphins go but catches the little fishies?

From Senate report 104-373


Following this voluntary action, the Dolphin Protection Consumer Information Act was introduced and later added as an amendment to the Fishery Conservation Amendments of 1990, to codify criteria for labeling tuna and tuna products as dolphin-safe. To qualify as dolphin-safe, tuna caught in the ETP must have been caught either by a vessel too small to deploy nets around dolphins, or, for larger vessels, be accompanied by certification from a qualified observer that no `dolphin sets’ were made for the entire fishing trip. This Act further specified that tuna caught in driftnets could not qualify for the dolphin-safe label.

One solution is to not use nets; they catch the tuna on hook and line instead.

The problem is that dolphins and tuna are roughly the same size; you can’t use a mesh that will trap tuna but allow the dolphins to escape. So other means are required. One solution is to have nets that can be lowered at the top to allow dolphins to escape (dolphins, as air-breathers, are near the surface). Another is selective fishing - dolphins swim with yellowfin tuna but not with albacore, so going after a different kind of tuna can reduce or eliminate dolphin by-catch.

Middle and South American fisherman petitioned under NAFTA to force North American tuna canners to buy their fish, making the argument that the Dolphin Safe laws did not apply to them (since they aren’t bound by the laws of the USA), yet their refusal to purchase their tuna (whose dolphin safety was esentially unknown) was an unfair barrier to free trade.

An eventual balance was struck whereby “Dolphin Safe” tuna must be made up of some percentage of verified dolphin safe tuna (I think the figure was 80%). Good in theory. In practice, there’d be a cyclic process where the “unsafe” tuna would be mixed with safe tuna, and thereby become certified dolphin safe. That lot of now 100% dolphin safe tuna would then become the new 80% to be mixed with more “unsafe” tuna… lather rinse repeat.

In any event, these aren’t cute intelligent bottlenose dolphins we’re talking about here.

“…In any event, these aren’t cute intelligent bottlenose dolphins we’re talking about here.”

I guess these are the mentally-challenged “I’ve been locked up in a tank in the Florida Keys” dolphins that try to fuck swimmer who dare go in the tank with them. If you guys knew how half of the shit you eat was treated BEFORE it made it to your local store, you’d eat tree leaves. Shit, even orange soda doesn’t have oranges in it. Peace.