NOAA Teacher at Sea
Aboard NOAA Ship Henry B. Bigelow
September 4 – 20, 2012
- Mission: Autumn Bottom Trawl Survey with NOAA’s North East Fisheries Science Center
Geographical Area: Off the Coast of Cape Hatteras, North Carolina
Date: September 14th
Latitude: 35′ 10.67
Air Temperature: 23.40 (approx.74 °F)
Wind Speed: 2.17 kts
Wind Direction: Southwest
Surface Water Temperature:2 7.61 °C (approx. 82°F)
Weather conditions: Sunny and fair
Science and Technology Log
One of the things I was curious about was the deployment of these large instruments and the technology that supports it. One of the keys to the deployment of things like the BONGO nets, Continuous Depth Recorders (CTD’s) and the trawl net itself are winches. A winch spools the wire cable that is hooked to all of the instruments and allows them to move up, down and out into the water column. With some of the instruments, like the BONGO’S and CTD casts, a retractable A-Frame is used to lower the cable from the winch. You can see the A-Frame on the right and the winch on the left in the photo below. This winch in particular controls the deployment of the net and connects to two winches on the stern that roll out the net to open up the mouth. The wire is constantly monitored from the bridge on the screen below and is automatically adjusted to maintain equal tension on both sides.
Once the net is run out with the aid of the winches, it is constantly monitored for its shape during the tow with a number of different censors attached to the net. There is an autotrawl system that sets the depth of the trawl and the tension of the wires. A Global Positioning System (GPS) plots the position of the net for each trawl so that it can be associated with all organisms caught in the tow. At the end of the tow the winches reel back the cable and a crane brings the net with the catch over to the “checker” where the net is unloaded!
The fun part begins when the net opens and all the animals enter the checker. When all of the catch goes into the checker the scientists take a look at the catch, and remove anything too large to go up the conveyor belt. If a fish dominates the catch it will “run”. This means, as it goes down the conveyor belt it won’t be taken off and it will be weighed by the basketful and then a subsample will be taken for further analysis.
The fish are all divided up by species and electronically coded in the FSCS system to be measured. After they are measured, the system will prompt for further analysis for that particular species. If extra sampling of the fish is required, it is labeled with a printed sticker for the species with a unique barcode that can be scanned to retrieve its record in the database.
I thought I’d share some photos with you of some of the unique things we have seen so far fishing today. We are off the coast of Carolina and finishing up our Southern stations today into early morning!
Catch of the day! Thanks for reading!