Join Dr. Shawn Larson, curator of conservation research at the Seattle Aquarium, as she shares the latest on one of our many field research efforts in this special two-part guest post.
Neah Bay, Washington: the northwesternmost tip of the United States and the entrance to the Strait of Juan de Fuca. This is where all the waters entering Puget Sound to the south (U.S.) and the Strait of Georgia to the north (Canada) exchange four times a day, twice moving massive amounts of water to the east during flood tides and twice to the west during ebb tides. There is so much water movement that divers say it never really stops moving in this area. Regardless, four Seattle Aquarium divers were in and around Neah Bay last August trying to dive during the “sweet water,” or slack current, when there is very little water movement.
The goal was to conduct ecosystem surveys, so diving on the slack tide was essential. Why? Because they had to find a cinder block, measuring a mere one foot by six inches, at 60–70 feet (18–21 meters) of depth on rocky reef systems in those wild waters.
Day 1: August 24
August 2019 marked the Aquarium’s 15th year within Makah Nation waters at Neah Bay, conducting 328-foot (100-meter) scuba-based surveys at five reef systems to document changes in fish abundance and diversity as well as to capture changes of all the reefs’ flora and fauna. (We operate under a permit from the Nation to enter their land/waters to conduct research.) The dive team consisted of me, Shawn Larson, curator of conservation research; Joel Hollander, assistant dive safety officer and Aquarium biologist; Amy Olsen, Aquarium lab specialist; and Chris Van Damme, senior aquarist; plus a dedicated boat driver and dive safety officer, Jeff Christiansen.
Every year is the same: The divers start at the same point, a cinder block at depth, which has its GPS coordinates recorded by the boat above once the block is found. Once at the block, or start point, one diver runs a transect tape and another runs an underwater camera alongside to film the reef. They swim a total of 328 feet (100 meters) and then turn around to get a reverse look of the transect with the tape in the video camera view. That way they can see if fish behavior changes with divers and gear in the water.
The goal is two round-trip, 328-foot (100-meter) transects, totaling 656 feet (200 meters) of video without gear in the field of view and 656 feet (200 meters) with. The divers swim a minimum of 1,312 feet (400 meters), which is a lot if they miss the “sweet water” and have to fight the current. (This does happen to at least some of the dive team every year.) The video is then taken back to the Aquarium, where it can be viewed on a big-screen monitor and slowed down and even paused to document fish, invertebrates and kelp cover on the reef systems. The researchers try to dive the same way each year in the same area to control for some variables because they know they can’t control for changes in ocean conditions.
This year we started our dives the afternoon we arrived in Neah Bay. First we checked out the Aquarium’s research vessel that had been moored at Makah Marina since June. Once we were assured that it was in working order and ready to go, we headed to our first survey at Site 5, the site closest to the marina, only a 10-minute boat ride. Upon arrival at the site we found, as usually happens, that the predicted current wasn’t matching the water conditions, so we waited to see which way the wind, waves and current pushed the boat to determine the best time to drop our divers—and if we even should.
We decided that diving was a go, and we dropped three divers at Site 5: one camera operator, one reel operator and one diver in training who hadn’t dived these sites before. They had a little trouble finding the cinder block, as the current was strong and they had to swim against it over two reef systems. They fought hard and found it, but by that time they had enough air left for just half a transect. That just meant we’d have to revisit the site later.
Read part two in this series, in which Shawn and the team reconnect with an old friend below the surface!