7/20/2013: Great video, but few trapped fish

I’m going to talk a little more about the video cameras and the videos in today’s blog. I already explained how the cameras are mounted on the traps and why we use cameras a little bit, but I wanted to get a little more into the specifics of my job & show a few examples of the types of habitat we are putting the traps on.

My job is primarily to deal with the data that comes in via videos. I load the SD cards into the cameras & track which card is in which camera on which trap (so we know when we bring it up exactly where it was located on the bottom of the ocean by GPS coordinates). I then mount the cameras on the traps & start them recording when we are about to deploy the traps. Once the traps are back onboard, I take the cameras out of the housings, download the videos from the SD cards & name their file with the collection number.

Sandy bottom. But still someone home

Mixy bottom

Shelly bottom. Not a lot...

Finger sponges poking through

A nice ledge

Some nice flat bottom

These videos serve two purposes. First, they give immediate feedback to the crew who was performing mapping. When they see a picture of what was on the bottom, they can better interpret the signals they are receiving from the acoustic equipment. We know that most reef fish prefer to live in areas where there are lots of rocks and that there is a higher diversity of fish in these areas. Fishermen also tend to target these areas, because this fact is well known. However, there are very large areas which have none of these features.Some areas are completely sandy, while others are flat with a sand veneer, but have algae or sponges attached to the hard rock underneath. These mixed habitats can hold some of the fish that anglers & scientist are interested in studying as well.

The ledge w/ only 20 fish caught

Another view of the same ledge

The second purpose of the videos is for scientists to get a better understanding of the fish assemblage in the area. Although traps are good at catching certain types of fish, there are many others which are either not interested in entering the traps, or actively avoid them. When a trap comes to the surface without a video camera, the scientists get no information about the species which avoided the trap. With a video camera attached, the scientists can go back & watch the video, noting all of the species of fish which were around, but didn’t go into the trap. There can be a lot of fish around that don’t like traps. For example, here’s a picture of a ledge. Watching the video, there are at least 15 different species of fish present, many in large numbers.  This trap came to the surface with a total of 20 fish from two species. Obviously, the traps are missing a fair amount of what is available within the habitat.