Study: Shipping Can Avoid Endangered-Species Habitat at Minimal Cost
In a study aimed at demonstrating that shipping can support marine conservation efforts without significantly increasing costs, researchers in the UK found that rerouting vessels around whale shark aggregation sites added at most one percent to fuel consumption on voyages of more than six days. On voyages lasting more than 12 days, the penalty was smaller still, at less than 0.5 percent.
For shorter crossings, slowing down inside the aggregation areas was the more fuel-efficient option, limiting the extra fuel burn to less than one percent for slower ships while still reducing the risk of striking the endangered sharks.
In the study, University of Southampton researchers simulated eight port-to-port voyages for each of two vessel classes: a 336-meter crude oil tanker and a 366-meter container ship. Each voyage was run under three routing scenarios: a baseline optimized route, a 10-knot speed limit within core whale shark habitat, and complete avoidance of those areas. Across all routes, the change in fuel use ranged from a 0.13 percent decrease to a 9.65 percent increase, and most long-distance voyages saw increases of less than one percent.
To run the simulations, the team loaded maps of known whale shark aggregation sites into T-VOS (Theyr Voyage Optimization Solution), a routing tool used by commercial shipping operators. The results showed that speed reduction works best on short voyages, while steering clear of the areas entirely makes more sense on longer ones.
The team chose routes originating in the Arabian Gulf and the U.S. Gulf because of their proximity to whale shark aggregation sites. The routes also cover a range of voyage lengths and destinations, which allowed the researchers to compare how speed reduction and area avoidance affect fuel consumption and distance traveled.
The study, titled “Optimizing voyages for biodiversity: rerouting vessels around ocean giants can have minimal impact on shipping,” was published in the journal Royal Society Open Science. It comes as the shipping industry faces growing criticism over vessel strikes on large marine animals. Strikes have been documented in at least 75 marine species, from whales, dolphins and manatees to sharks, sea turtles, seals and even penguins. Off Southern California alone, ships killed an estimated 23 blue, fin and humpback whales each summer between 2012 and 2018, according to research cited in the study.
“Our research shows how incorporating species-specific habitat data into voyage planning could mitigate the risk of ship strikes with negligible disruption to global trade,” said Ryan Reisinger, an associate professor of marine biology and ecology at the University of Southampton, who led the research. “We demonstrated this with whale sharks, but it could be applied to other large sea creatures at risk of ship strikes, such as whales and dolphins.”
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The authors conclude that by building biodiversity data into voyage planning, merchant shipping can help reduce vessel strikes and protect vulnerable species without sacrificing the efficient movement of goods.
Top image: A whale shark in the Andaman Sea (Abe Khao Lak / CC BY SA 4.0)
