50 CFR § 600.610 - Factual findings for Federal preemption.
(a) The two factual findings for Federal preemption of state management authority over a fishery are:
(1) The fishing in a fishery that is covered by an FMP implemented under the Magnuson-Stevens Act is engaged in predominately within the EEZ and beyond such zone.
(2) A state has taken any action, or omitted to take any action, the results of which will substantially and adversely affect the carrying out of such FMP.
(b) Whether fishing is engaged in “predominately” within or beyond the EEZ will be determined after consideration of relevant factors, including but not limited to, the catch (based on numbers, value, or weight of fish caught, or other relevant factors) or fishing effort during the appropriate period, and in light of historical patterns of the distribution of catch or fishing effort for such stock or stocks of fish.
(c) Whether relevant effects are substantial will be determined after consideration of the magnitude of such actual or potential effects. Relevant to this determination are various factors, including but not limited to, the proportion of the fishery (stock or stocks of fish and fishing for such stocks) that is subject to the effects of a particular state's action or omission, the characteristics and status (including migratory patterns and biological condition) of the stock or stocks of fish in the fishery, and the similarity or dissimilarity between the goals, objectives, or policies of the state's action or omission and the management goals or objectives specified in the FMP for the fishery or between the state and Federal conservation and management measures of the fishery.