Undergrad helps reel in elusive shark species

"You know the feeling when you get to the top part of the roller coaster and you're looking down at the drop? Waiting for a shark on the line is kind of like that," wrote natural sciences major Catherine Spangler in an account of her ANSEP internship last summer. "When a shark did come up, everything started flying."

Through the internship, Spangler had the opportunity to work with Markus Horning, Ph.D., at Wildlife Technology Frontiers on a research project aimed at studying Pacific sleeper sharks (Somniosus pacificus).

Typically dwelling deep underwater, the slow-moving sleeper sharks are some of the most elusive and least understood fish in Alaska's waters. NOAA Fisheries once referred to the Pacific sleeper shark as "Alaska's largest, most mysterious shark." Wildlife Technology Frontiers' project aimed to shed light on the species by using a Deep Submersible Camera Trap (DSCT) to capture footage of the shark at depths of more than 200 meters below the surface of Resurrection Bay. Later in Prince William Sound, Spangler and the project's other team members captured, measured, tagged and released sharks for further study.

'Smile!': Snapshots from submersible cameras

The team completed a total of eight drops with the DSCT in Resurrection Bay to capture footage of underwater creatures. The team affectionately gave the DSCT the nickname of 'Cyclops' as "it only has one camera like an eye," Spangler recalled.

One of Spangler's primary responsibilities on the team was analyzing video captured by the DSCT, noting both the presence and behavior of sleeper sharks. Spangler ultimately watched over 200 hours of red-light footage to scan for sharks, and her efforts were not unrewarded. The DSCT captured footage of Pacific sleeper sharks seven out of the eight times it was deployed; some drops captured multiple shark sightings. Surprisingly, the camera captured a greater number of sleeper sharks at shallower depths, with three sleeper sharks spotted at a depth of only 171 meters. Spangler also identified other sea creatures on the red-light footage, including fish like cod, halibut, rockfish and skates, and invertebrates like crab, shrimp and jellyfish.

Proving that sleeper sharks can be monitored via underwater cameras was a major accomplishment for the project. Spangler explained that "this demonstrates that [underwater remote video systems] such as the DSCT are an effective, non-extractive method for detecting species presence and conducting behavioral observations on large benthic fish."

Sharking in the Sound

Next, the team spent two weeks on the waters of Prince William Sound, working to reel in Pacific sleeper sharks for direct observation. Working from a 15-foot skiff, the team, now joined by UAA's Amy Bishop, Ph.D., set and dropped long-lines down to the bottom of the Sound at select locations. The team checked each line every four hours to see if a shark had bitten. The team used salmon heads as bait for the sharks and experimented with different gummies for 'good luck.'

"Over the two weeks, we found that Life Savers gummies had the highest success rate to catch sharks," Spangler recalled.

Fortunately, the team was able to catch four Pacific sleeper sharks during their time on the Sound. Pulling the sharks to the surface from deep underwater can cause significant stress on the animals, so the team aimed to keep each shark for less than 45 minutes before release. The team transferred each shark to a smaller skiff to measure them.

The team attached tracking devices to the four sharks, including a conductivity, temperature and depth (CTD) tag, a pop-up archival transmitting tag (MiniPAT) for tracking location, and a SomniVision, which Spangler described as "a shark GoPro." The sensors are designed to "pop up from the animals and float up to the surface for retrieval after a set date," Spangler explained.

"My job was to be the person who would receive the shark on the skiff to transfer over to the stretcher," said Spangler. "There's just something about being so close to an animal that minutes ago was over 1,000 feet underwater, and seeing them in person after only seeing them over video footage for two months."

The data collected during the project is helping Wildlife Technology Frontiers with the goal of better understanding the sharks' behavior and physiology, including their preferred temperature and depth range and their migration patterns.

This summer, Spangler is off on a different maritime adventure. After being accepted into a Research Experience for Undergrads (REU) opportunity at Mystic Aquarium in Mystic, Connecticut, Spangler is working on a project studying beluga whales. "I am aiming to explore the differences in beluga whale population microbiomes between the aquarium population and wild populations from the north shore of Alaska, and Churchill, Canada," said Spangler, who is looking for "notable differences in microbiome diversity and proportion of percentages through our DNA extractions."