Migratory Bird Act of 1918.
To expand on RNATB’s post The case Missouri v. Holland held that a treaty could overrule state law and later it was ruled that a treaty cannot effectually change the Constitution in Ried v. Covert. IMO it basically boils down to the argument that under the right circumstances, the Feds can go beyond their enumerated powers and not conflict with the 10th Amendment (e.g. South Dakota v. Dole).
All I know is that the tuna doesn’t taste as good as it used to. Must have been the dolphin…
Maybe try mixing some Liver with your Tuna to get that faux-dolphin taste? 
“In Taiji, the fishermen say that dolphin tastes like venison or beef. But eaten raw with a dab of ginger and soy sauce, the glistening dark flesh resembles liver with a coppery aftertaste that lingers on the roof of the mouth long after you’ve chewed it past your protesting taste buds.”
I’d say it boils down to the Feds have an enumerated power to make treaties and those treaties overrule state law.
Kind of what I said. The Feds had tried many times to limit migratory bird hunting but was shot down because it is not an enumerated power and violated the 10th Amendment. They decide to do the same thing via treaty and the states called foul saying you can’t do an end-around the Constitution via a treaty. Missouri v Holland said yeah they can because that’s the right way of getting around the 10th Amendment.