This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Filmmaker and outdoorsperson Quinn Barabash recently made headlines when he found a swordfish carcass nearly two meters (6.6 feet) long on the remote shores of Haida Gwaii in northern British Columbia. Swordfish are large-bodied, highly migratory fish typically found in temperate and warmer tropical waters far south of Haida Gwaii.
They are thought to have been documented in B.C. only twice before, so it's a rare find. Long-term ocean warming alongside the developing El Niño may be making B.C.'s waters more attractive to these warm-water species. While this sighting is unusual and exciting, it also serves as a reminder that our oceans are rapidly changing and we need to adapt to these changes.
This isn't the first time a warm-water species has appeared along B.C.'s coast. During the 2014–16 marine heat wave known as "the Blob," ocean sunfish, Humboldt squid and triggerfish were all sighted off B.C. More recently, tropical barracuda and even a great white shark have been spotted.
Marine species can move to new locations as they follow favorable ocean conditions. During extreme events like marine heat waves, these shifts can bring species far outside their normal ranges. These sightings make good headlines, but the bigger story is what ocean warming and environmental extremes mean for marine ecosystems and the fisheries and communities that depend on them.
Our recent global study published in Nature Communications analyzed three decades of data covering 1,246 species across 254 regions. We found that unusually high ocean temperatures and very low primary production can substantially increase the likelihood of extremely low fish catches. The risk was even greater when these extremes occurred together or across multiple years.
Two consecutive years of extreme temperatures increased the likelihood of extremely low catches by 40% globally. Extreme events can abruptly disrupt marine food webs and the productivity of fish stocks, and the effects can last years after the water cools. A warming ocean changes what species are caught and how predictable the catch is from year to year.
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