“What is the cause of these cuts exactly? Government regulation or the effects of overfishing?”
Neither. It is a politically and monetarily motivated plan being flawless executed by the left for the past 40 years against all natural resource harvesters. The public pays the freight at the grocery store.
The goal is to eliminate all US natural resource harvesting other than by a certain ‘disadvantaged’ racial group entitled to do so by treaty and enshrined in the Constitution.
Add to the list of reasons, the Progressive momentum to create Marine Preserves, void of any human interaction. See “Wilderness Areas” for terrestrial examples.