Here’s the link with a case from 2005 about a charter operator who wanted to fish Canadian waters with his customers. This information was passed on to me by Bellingham Port Director with U.S. Customs and Border Protection, Anthony Zumpano.
Zumpano sent me the below paragraph today.
The final holding of the ruling states, “Pursuant to applicable laws and regulations vessels, such as the one under consideration, which travel to the waters of a foreign country, come to rest or engage in an activity in foreign waters, and return to the U.S. are required to obtain vessel clearance, report arrival, and make formal vessel entry”. Private vessels would be exempt the requirement to obtain clearance and make formal vessel entry pursuant to 19 USC 1441, but even that exemption requires that pleasure vessels comply with the requirement to report arrival.
In short, sports anglers who leave U.S. waters MUST call U.S. Customs & Border Patrol and “Report Arrival” into U.S. waters. And to properly do that an I-68 or Nexus card is required for proper entry and reporting.
Fishing Canadian waters is really simple once you have the I-68 or Nexus. Upon entering Canadian waters make your call to Canadian authorities, get a clearance number and fish. Upon re-entering U.S. waters call U.S. authorities, get a clearance number and be done for the day.