Spot prawns from British Columbia are your "Best Choice" as their populations are healthy and abundant.
Prawn, Spot Shrimp, Amaebi
Spot prawns are very large shrimp sold frozen, fresh and live. The term "shrimp" and "prawn" are used interchangeably. When prepared for sushi, spot prawns are known by the Japanese name, amaebi.
Spot prawns are the largest shrimp on the West Coast. The population status for spot prawns from British Columbia is healthy, while overfishing is occurring in the Alaskan fishery. Little data are collected on spot prawns in California, Oregon and Washington, so population status is unknown.
Spot prawns are caught with traps , which have relatively low bycatch and habitat impacts. Traps are submerged wire or wood cages that attract fish and hold them alive until fishermen return to haul in the gear. As spot prawns are typically found in hard-bottom habitats, home to fragile glass sponges and corals, the traps likely cause some habitat damage when large ocean swells and tides bounce them around. Hauling in a row of traps may also drag the cages along the seafloor, causing some habitat damage.