7/23/2013: Safety first

Last night’s weather was pretty rough. The wind monitor on the bridge was reading upwards of 35 knots and the seas were a solid 5 feet, with larger ones mixed in as well. When we got up this morning the seas were 5-7 feet and the wind was still blowing at least 25 knots. These are conditions that the boat handles quite well.  This vessel is much more stable than many I have worked on before, deceptively so. The back deck is almost 8 feet off of the water, so when the seas are 7 feet high, they are barely coming up to where you are standing. However, retrieving gear is not easy under these conditions.  We delayed putting traps in the water until almost 10 am. This gave time for the sun to come up higher & provide more light to the cameras on the bottom. The combination of traps and cameras give us 3 different types of information.

1.       Traps bring fish to the boat. We can then select the fish we are most interested in studying & keep those for further study.

2.       Cameras give us information about the species which are more trap-wary.

3.       Cameras also give us “groundtruth” information about the types of habitat that are present in the area.

When the chevron traps are sitting still, they work for all three of these purposes. However, if the current or wind is too strong, or the seas are too rough, the traps will move along the bottom. When traps are moving they don’t catch fish. They also cannot be used to reliably index the number of species seen on the videos.  Therefore, they can only be used to show what the habitat in the area looks like.

We deployed our first set of chevron traps at 10 & started hauling them back around 11:30. Once we started looking at the video, we knew that the traps were moving too much to be counted as samples and would ultimately be disregarded as data. The haul back was slightly dicey as well, with the boat blowing over one of the traps. Since the traps were of minimal use in these conditions and our next site for mapping was a few hours’ steam away, Zeb decided to not set any more traps. As the day has worn on, the weather has improved significantly, with seas down to 3 feet or less and winds dying down to less than 20 knots. The weather is forecast to continue improving for the next few days, so we should be able to set plenty of traps in the coming week.