We’ve had GoPro cameras out at two occupied and two unoccupied octopus dens for the last month or so, recording one photograph every 10 minutes.
Here’s a time-lapse video of an unoccupied den, sped up to one real hour = one video second. The thing to note is the lack of permanent fish. You’ll see the occasional lingcod (Ophiodon elongatus) near the bottom, or Puget Sound rockfish (Sebastes emphaeus) flitting through, but no resident fish.
Next, here’s a video from an occupied den. Note the copper rockfish (Sebastes caurinus) that just sit there near the den for hours at a time. These are resident individuals that come here day after day.
Our analysis of these photos show that the two unoccupied dens had very infrequent copper rockfish visitations. One of the two occupied dens had several resident copper rockfish. However, the photos from the second occupied den did not show resident rockfish. I think this is a function of the position of the camera, rather than a lack of fish. The following video shows that this den has two major entrances, one from the side (that the GoPro sees) and one from above (that is not visible to the GoPro). The video starts looking down from above, and then moves down to end with the view the GoPro has. You can see two copper rockfish sitting in the den, with the large brown head of the octopus below them.
Every time we visit this den to change out the batteries, we always see two or three rockfish in the den, but these individuals are not visible from the position of the GoPro. We’re working on solving this problem, and will be moving the cameras to a new position soon.
Here’s a copy of the poster I presented at WSN. My coathors are: Derek Smith (Ph.D. student in Ken Sebens’ lab, working with me on this project), Michelle (Izzie) Brant (undergraduate student at FHL this quarter, helping analyze the photos), and Ken Sebens (my advisor).