Ocean glider helps keep an eye on marine life

March 11, 2015 - via Stanford’s Hopkins Marine Station

Scientists at Stanford’s Hopkins Marine Station are using a Liquid Robotics Wave Glider in Monterey Bay to detect when tagged animals, including great white sharks, get within range of acoustic receivers. (Courtesy of Tom O’Leary -- Stanford)

Pacific Grove - Researchers at Stanford’s Hopkins Marine Station are using an autonomous, wave-powered vehicle to keep tabs on the comings and goings of great white sharks.

The craft, called the Wave Glider, cruises on the ocean surface listening for pings coming from devices that have been attached to marine life. The vehicle has been doing figure 8s near Año Nuevo State Park since Jan. 9, a favorite feeding spot for great whites.

Scientists are using the Wave Glider, along with a network of stationary buoys, to detect when tagged animals get within range of acoustic receivers. “It’s kind of like a Smart Pass when you go through a toll,” said Barbara Block, a marine scientist at Hopkins.

Block and her colleagues at Stanford and the Monterey Bay Aquarium have tagged about 150 sharks to help create a richer picture of where the predators spend their time along the coast. They’ve found that certain sharks return to the same areas every year to feed. “Just like us, sharks have their favorite places to go,” Block said.

From elephant seals at Año Nuevo to harbor seals in Pacific Grove, the sharks seem to develop a taste for certain meals during their lifespans, she said. But scientists aren’t sure why they prefer the same spot each year. “It might be that it takes a lot of learning to catch an agile marine mammal they prefer,” Block said, adding that it may not be worth it for the animal to move to another area to learn to hunt new prey.

The Wave Glider is made by Sunnyvale-based Liquid Robotics. The company is working with Block on the project to demonstrate the vehicle’s effectiveness as a scientific tool. “Generally we sell them, but with Barb we’re just helping her out,” said Ryan Carlon, who works in business development for Liquid Robotics.

The glider has two parts, one that floats on the surface and a winged underwater portion that sits 10 to 15 feet underwater. When a wave lifts the float, the underwater wings are pulled up by a tether, propelling the craft forward.
The float has solar panels to power navigation and any scientific instruments, which are custom to each application. “It has onboard GPS and satellite communication so at any given time we can talk to it and know where it’s at,” Carlon said.

A website launched this month allows the public to take a look at the data collected by the Wave Glider. “What you really are beginning to have is an ocean animal observing system in the Monterey Bay,” Block said.

That observing system is built to detect not only great white sharks, but also any other marine life that scientists care to tag. It will allow them to study the annual patterns of those animals, too. “Every year a dining room buffet is set for whales, white sharks, makos and bluefin tuna, who come and go exactly at the same time every year,” Block said. “You can set your watch by it.”

But it doesn’t always take an acoustic tag to detect a great white. On Monday a surfer spotted a great white attacking a sea lion at Marina State Beach, and California State Parks posted an advisory for beachgoers. “When you think about the size of the Pacific and how little we really know, the importance of Monterey Bay and the sanctuary is the ability to observe some of the most majestic animals we have in the sea,” Block said. “We’re actually trying to build an awareness of how remarkable our offshore waters are here.”

The Wave Glider data, overlaid on a map, can be found at www.gtopp.org.

External link: http://www.santacruzsentinel.com/environment-and-nature/20150311/ocean-glider-helps-keep-an-eye-on-marine-life

Related Organizations:
Related Platforms:
Author:Chris Cesare