Unlocking Secrets About
Ocean Temperatures and Oxygen Levels
Deckhand Logan Browning on the F/V Lady Lee deploys an oceanographic mooring into the Cape Falcon Marine Reserve in May.
On-going ocean monitoring in Oregon’s Marine Reserves is unlocking secrets about temperatures and oxygen levels known to impact groundfish and invertebrate activities, create stresses on ecosystems and even alter sport anglers’ catches. Some of the data go back two decades at what is now the Cape Perpetua Marine Reserve near Yachats and are buoyed by oceanography monitoring in recent years at the state’s four other marine reserves.
The phenomenon is called hypoxia, and data collected in the reserves is showing an apparent trend in size and length of these episodes, and that they differ throughout the Oregon Coast. “In some places we’ve never looked until recently, we’re starting to see our first glimpses of it,” said Dr. Lindsay Aylesworth, the Marine Reserves Program Leader.
The program’s main oceanography monitoring began this month with the placement of special moorings in the Cape Falcon Marine Reserve as well as in a nearby comparison area off Cape Meares. The moorings, which were deployed by the Garibaldi-based F/V Lady Lee hired by the program, contain sensors that track ocean temperature and oxygen levels through early fall, when they will be removed.
Ecological team members and Oregon State University collaborators deploying oceanographic moorings in early May.
So, what do these data tell us so far?
Collectively, early data show a relationship between oxygen levels, wind direction and water temperatures. North winds, desired for good ocean nutrient conditions, routinely coincide with decreases in sea surface temperature and periods of low oxygen levels, which can plunge to hypoxic levels. These zones disperse with the return of south winds that bring warmer water and higher oxygen levels to the surface.
The size of these low-oxygen zones come and go and vary across state waters, but they have grown and persisted for longer durations of time in recent years. Low oxygen levels, particularly when they plunge to levels of hypoxia, are known to place stress on fish, invertebrates, and underwater ecosystems.
Along the coast, the south has seen the fewest episodes of hypoxia, when compared to central and north coast conditions. During days of high levels of dissolved oxygen, catch rates during the marine reserves’ hook-and-line surveys show better catches of groundfish, data show. Days with low oxygen levels correspond to relatively poor catch rates among survey volunteers.
Oregon State Police during a marine reserves enforcement flight.
Oregon State Police troopers have seen a marked increase in compliance with Oregon Marine Reserves laws since restrictions began in 2012, and nothing has helped that more than a little rules clarification two years ago.
Historically, troopers regularly had trouble investigating whether some crab pots were either set illegally inside a reserve or legally just outside of its boundary. Sometimes a pot’s buoy would float into the reserve waters, forcing an investigating trooper to determine whether the pot was inside or outside the line. But a 2021 rules clarification made it clear that all fishing gear, including a pot buoy, must be outside of reserve boundaries.
“That has helped our enforcement ten-fold,” said OSP marine fisheries Sgt. Heather Van Meter, who oversees marine reserves enforcement. “So much so that we didn’t have a case this year. It has dramatically reduced the complaints,” Van Meter said. “But we still get people setting pots in the reserves.”
All fishing and crabbing as well as invertebrate removal from marine reserves is prohibited under Oregon law.
Troopers continue to grapple with the occasional crab pot that’s blown into a reserve, with the Cape Perpetua Marine Reserve remaining the most common area for that, Van Meter said. For recreational fisher complaints, the Cascade Head Marine Reserve still garners the lion’s share, particularly out of the Roads End State Recreation Site in Lincoln City, she said. Roads End is a common launch point close to the reserve.
This new infographic now summarizes the findings of law-enforcement data found within the 10-year Marine Reserves Program Synthesis Report issued in 2022.
Watch out for that…Orca?
Transient orca whales encountered during SCUBA surveys in May 2023.
Our ecological monitoring and SCUBA dive team started their research season with a little lesson in ocean right-of-way: Apex predators always get to go first. During the first dive of the field season, the SCUBA team waited patiently for a small pod of transient orcas to meander out of the Otter Rock Marine Reserve so divers could safely access transect locations.
It was one of the more unusual moments of the start of this year’s field season, which kicked off in April. The full field season includes SCUBA, remotely operated vehicle (ROV), and hook-and-line surveys, along with the deployment of oceanographic moorings and SMURFs at marine reserves sites and comparison areas.
Volunteer divers trained and led by the Oregon Coast Aquarium completed 20 dives this month to collect data on fish, invertebrates, and algae in the Otter Rock Marine Reserve and its nearby comparison area.
Updates From the Field
Ecological team members and Oregon State University collaborators preparing to deploy SMURFS in May.
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Hook-and-line: Teams of volunteers fished for groundfish in the Cape Falcon Marine Reserve as well as its comparison area during two hook-and-line survey trips out of Garibaldi under a contract with the F/V Norwester. Two trips were cancelled because of bad weather. The revised schedule has the final spring trip set for June 6. Another round of hook-and-line surveys are planned to begin in early fall. |
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Remotely Operated Vehicle: The ROV team successfully completed 4 days of surveys in the Cascade Head Marine Reserve and its nearby comparison areas earlier this month under a contract with the R/V Pacific Surveyor. Maximum underwater visibility during this trip was between 15-20 ft! |
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Oceanographic Moorings: Oceanography buoys were deployed successfully at the Cascade Head Marine Reserve as well as at the Cape Falcon Marine Reserve and its nearby comparison area at Cape Meares. Those moorings will collect data on ocean temperature and oxygen levels until they are retrieved in early fall. |
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SMURFs: Standard Monitoring Units for Recruitment of Fishes, or SMURFs for short, are planned for release at the Redfish Rocks Marine Reserve within the week. The deployments were done with help from Oregon State University as well as the Oregon Coast Aquarium. |
Our Ecological Monitoring Team has added a new member for the 2023 field season! Meet Emmah Johannes, who is our Ecological Research Assistant.
She has her bachelor’s degree in Fish, Wildlife, and Conservation Biology from Colorado State University (go rams!). She grew up in Colorado where her love for the outdoors and fish was born. During her time in Oregon, she has worked on a juvenile salmon passage study and on multiple projects with ODFW including chinook spawning ground surveys on the Siuslaw river. In her free time, you can find her fishing and hiking with her dog Oli.
Help us welcome Emmah to our team!
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