Many nearshore species that inhabit subtidal rocky reefs are important both ecologically and economically. Black, blue, China, deacon, copper and quillback rockfishes, cabezon, kelp greenling, lingcod, sea urchins and abalone are examples. Investigating and sampling the fish and wildlife species that inhabit rocky reefs is thus of great interest to scientists and fishery managers. But sampling rocky reef habitats has proven to be challenging.
Bottom trawls, a sampling method widely used in soft bottom marine habitats to help assess populations of fish, cannot be used effectively in rocky habitat as the nets tend to get hung up and entangled on the rough rocky bottom. Modified trawl gear can be used in some rocky locations, but its use can dramatically alter the rocky habitat by displacing rocks along with things such as anemones and corals that live on those rocks.
A variety of visual sampling methods have been used in rocky reef habitats over the years including SCUBA and remotely operated vehicles surveys. More recently video landers developed for use in Oregon waters by ODFW staff have been utilized to sample rocky reef habitat. ODFW researchers have put out two reports on video lander work, one focused on a relatively small section of the nearshore waters off Newport, and one that compiles almost a decade of work all along the Oregon coast. Some highlights of video collected from a video lander, shown below, provide a glimpse into life in rocky reef habitat.
Every method of sampling has pluses and minuses. ODFW is using all of these visual survey techniques to sample the community of species that inhabit rocky reefs to investigate how best to use these sampling techniques to assess populations, examine the community structure, and refine our knowledge of habitat utilization by these species. A new method that combines acoustic sampling with visual sampling was also developed by ODFW researchers specifically for sampling three different Strategy Species of rockfish, Black Rockfish, Blue Rockfish, and Deacon Rockfish, that form schools in the water column above and around rocky reef habitat. More information about that work can be found in another Strategy Spotlight.