When Is a Blue Not a Blue

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Once thought to be a single species, Blue Rockfish are now being split into two. Photo by Dan Grolemund.
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This is a "blue-blotched" Blue Rockfish. Photo was taken off Dalli's Wall in Monterey, by Janna Nichols.
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This is a "blue-sided" Blue Rockfish. Photo was taken off Slant Rock in the Olympic Coast NMS, by Janna Nichols.

Just when you thought you had it all figured out, you realize there is more to learn. A few years ago, scientists working on Blue Rockfish genetics discovered that there were actually two species of Blues. After fishermen bagged both types off Eureka, California, and were able to correctly separate them by appearance, Drs. Tom Laidig and Milton Love wondered if they could be correctly identified by divers underwater, and in what range and depth they are found. What a perfect project for our west coast REEF surveyors.

Using photos taken by Pacific NW AAT members (Pete Naylor, Janna Nichols) in both Monterey and the Neah Bay area (on our annual REEF survey projects of these areas), they were able to determine that yes indeed, the two species of Blue Rockfish could be correctly ID’d underwater. Both species are being found along the California, Oregon and Washington coasts by fishermen. REEF surveyor Taylor Frierson has seen both species (in the same school!) while diving near Newport, Oregon. The Oregon Coast Aquarium has both species of Blue Rockfish on display in Halibut Flats – a good way to compare them.

Although the species has yet to be officially described, REEF is asking Pacific surveyors, whenever possible, to start separating the two into what for now will be called, “Blue Blotched” and “Blue Sided”. These new species are listed in the Unlisted Species section on the online data entry form. A general “Blue Rockfish” category will still exist if you’re unsure (the one listed on the Listed Species list). We are also asking surveyors who have photos from previous survey dives, to go through and if they can positively ID the species seen based on the photos, to submit the change to us at data@reef.org. Please include the survey number (if know), date, and location.

To help you ID the two species, here are some tips:

Blue Blotched:

  • Blotchy patterns on side
  • Body shape more symmetrical and rounded
  • Blue Sided:

  • More solid coloration of body
  • Lateral line more prominent
  • Body more elongated, flatter underside
  • Lower jaw juts out more
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    Comparison photos may be seen here.

    Design by Joanne Kidd, development by Ben Weintraub