All the mountains of stuff that we ship across the oceans comes at a price: whale blood. A recent study in the journal Science calculates just how much, reporting that — thanks to the near-total disappearance of commercial whaling — accidental ship collisions are now the leading cause of unnatural large whale deaths worldwide. Few measures have been taken to mitigate the risk, according to the report, whose authors found that while global shipping overlaps with 92% of whale ranges, fewer than 7% of the hot spots with the greatest collision risk contain any management strategies to minimize their occurrence.
The scientists mapped and quantified movement for four globally distributed large whale species — the blue, fin, humpback and sperm whales — based on 435,000 locations and then related the data to global shipping activity. Those whales share an increasingly busy ocean with shippers, whose vessels travel the equivalent of more than 4,600 times the distance to the Moon and back each year, the scientists estimated. With the ships and other human activity come risk factors and stressors like noise, pollution and now fatal meetings between the behemoths of steel and nature.
Climate change is likely to exacerbate the problem, the report noted, with melting arctic sea ice expected to draw ships further into previously unpassable areas, putting them on a collision course with whales migrating to cooler waters abundant with food.
Thankfully, this problem is easily handled, such as by adding interventions to slow ship speeds or rerouting shipping lanes out of known migration and feeding areas over as little as 2.6% of the Earth's oceanic surface area, for instance, "would be sufficient to reduce risk in all ship-strike risk hotspots," the report said.
Technological advancements could also help reduce collision risk. The study highlighted automatic identification system data and species distribution modeling in particular as useful tools that can aid ships in predicting the heavy presence of whales and avoiding those areas. And it would benefit us, too, to stop wantonly crushing cetaceans with our boats.
These great oceanic mammals have long been described as "ecosystem engineers" who stabilize marine food webs by consuming massive amounts of food, enhance the growth of phytoplankton that collectively capture 37 billion tons of CO2 per year and cycle nutrients to the deep sea when they die. Moreover, whales embody immense cultural value to many peoples, often as protectors of community and the reincarnated spirits of deceased ancestors.
"Changes in ocean ecosystems caused by the loss of historic whale populations have been hard to reverse," the report concluded. "Ship-strike risk is a ubiquitous yet solvable conservation challenge for large whales, and our results can provide a foundation for expanded management measures to protect these ocean giants."
