Abalone have been harvested for hundreds of years for their meat and their decorative shells, but their remote environment previously limited the impact this had on populations (2) (3). However, the introduction of SCUBA equipment in the 1960s meant that abalone could be collected in far greater numbers, and led to the rampant over-harvesting and drastic decline of this species, to the extent that collecting this species was eventually banned over much of its range (2) (5). However, illegal poaching, which is a lucrative enterprise motivated by high demand and elevated market prices due to the species’ scarcity, continues to pose a serious threat to the northern abalone (3). Furthermore, there are law enforcement problems due to North America having large areas of uninhabited coastline, in which constant monitoring is near impossible (1).
Other important threats to the northern abalone are predation and competition. The sea otter is one of the species’ major natural predators (3), but currently the two species overlap only within the north of the northern abalone’s range. This is due to over-exploitation of the otter throughout the Western Pacific rim at the end of the 18th century, leading to its extinction in British Columbia, Washington, most of California, and much of Alaska (1). Where the two species coexist, sea otters are believed to consume northern abalone in significant numbers, and their growing numbers and rapid re-establishment due to significant conservation measures are predicted to hinder northern abalone recovery. Sea urchins out compete the northern abalone for food and space, and may also impact their numbers (1).