Tagged Mako Shark (NOAA)

Tracking Fish and Ships

Where do sharks and boats cross paths? What about sea turtles and whales? If we knew this, maybe we could reduce the number of vulnerable marine animals that end up entangled  or accidentally caught in fishing gear.

After years of monitoring large pelagic sea life with remote tracking devices, researchers have started to build a picture of where certain species travel throughout the year. Together with our fishing vessel maps, we have a real opportunity to minimize the deadly encounters between humans and marine life.

“This has the potential to be a really impactful application for Global Fishing Watch,” says Wessley Merten, Oceana’s data and fisheries analyst for Global Fishing Watch. “Any type of tracking data can be integrated into Global Fishing Watch, whether it be sharks, or seabirds or sea turtles or other types of fish, and a lot of that information can be pretty telling as to how those animals are interacting with boats.”

Our team is working with researchers Neil Hammershlag and Austin Gallagher from the University of Miami to track sharks throughout their migration up and down the coast of the US. Sharks have been under a lot of pressure in the Atlantic by various fisheries, and they’re heavily caught as bycatch by tuna boats.

The researchers from the University of Miami are catching the sharks and fitting them with radio-telemetry tags that send unique identification signals to satellites. Data from the tags will enable the team to track the sharks’ behavior and lead to a better understanding of where their critical habitats are at different times of the year and at different points in their lives. This is important because the size of the shark could be related to its vulnerability to fishing gear and we would want to protect areas where the sharks are more vulnerable to being captured unintentionally.

“Understanding how they utilize habitats throughout their lives may someday lead to creating dynamic management measures that adapt based on such things as where and when the sharks are breeding and how well their populations are doing,” Wess says.

Wess believes it may even be possible to design a protected area of a certain square mileage that moves with them throughout the year. The idea of such “mobile marine protected areas” is part of a fairly new concept called dynamic management. It’s being considered as a way to protect migratory and highly mobile species. Many animals, especially the larger ones, regularly travel across oceans. Endangered Atlantic Blue Fin Tuna, for example, move from the Gulf of Mexico to the Mediterranean Sea every year to spawn. The largest reptile in the world, the leatherback turtle, is known to travel between the Indian and south Atlantic Oceans where it is especially susceptible to accidental catch by longline fisheries. It is listed on the International Union for Conservation of Nature (IUCN) Red List as vulnerable.

“We have these huge marine protected areas out on the ocean,” Wess says, “but a lot of the resources within those areas are moving in and out. They’re not residing just within the marine parks. Creating a management protection scheme that caters to both the critical time and location of essential life history stages for different highly migratory species is a tough thing to do, but it could be done and likely should be done.”

It’s conceivable that a new approach to management like this may even allow for increased fishing opportunities. Rather than closing off an entire area to protect large pelagic species, managers may be able to identify a smaller critical area, perhaps just the path a specific species is traveling, or a more localized habitat during different seasons.

“We’ll need a lot of tags to be able to come up with a dynamic management scheme,” says Wess, adding that Oceana has provided 20 telemetry tags to the research team this year. “We’d like to scale that up, but twenty is a good start to begin looking at vessel tracking metrics and fish tracking metrics to calculate the areas where they’re interacting the most. It’s something that’s approachable, but it’s one of those things that’s going to take some time to get there.”