Sharp Decline of Bull Kelp Colonies in the Salish Sea
June 9, 4:30 PM
Starting in the 1970s and continuing through modern heatwaves, bull kelp colonies in the northern Salish Sea (British Columbia) have experienced a dramatic reduction, according to a new study. The most significant loss of kelp beds occurred between 1972 and 1984, driven by climate change and the resulting degradation of the ecosystem.
Researchers analyzed data from maps, aerial photos, and underwater surveys dating back to 1972. In 2023, they conducted follow-up studies to compare findings over a 50-year span. Previously, bull kelp beds near Comox and Denman Island spanned more than 5.5 square kilometers (550 hectares)—ten times the earlier baseline for the area. By 2023, however, not a trace of these beds remained.
Ecological Fallout and Urgent Need for Action
By the late 1970s, water temperatures in the Salish Sea were already warmer than at the start of the 20th century. At depth, populations of cold-tolerant kelp and red algae declined by 60 to 99 percent. No warm-water species moved in to replace them, worsening the ecological imbalance. This habitat loss has led to food shortages for commercial fish such as herring, rockfish, and salmon.
'Humanity has a distorted view of what a “normal” ocean looks like, because the current baseline is based on an already damaged system.'
The decline of bull kelp in the Salish Sea has serious consequences not only for local ecosystems but also for fisheries and the broader food web. The loss of these underwater forests threatens fish populations and other marine life that rely on them for shelter and food. As climate change accelerates, protecting and restoring marine ecosystems is critical to maintaining biodiversity and economic stability in the region.