NOAA Teacher at Sea
Aboard R/V Hugh R. Sharp
June 6 – 21, 2017
Mission: Sea Scallop Survey
Geographic Area of Cruise: Northeast Atlantic Ocean
Date: June 7, 2017
Weather Data from the Bridge
Latitude: 41 30.90 N
Longitude: 69 18.76 W
Air Temp 14.1° Celsius ( 57.3° Fahrenheit)
Wind speed 4.7 Knots (5.4 mph)
Science and Technology Log
Due to the poor weather delay on the 6th, June 7th was our first day out for the crew I am working with. Our ship is divided into two crews so we can work our operations around the clock. The crew I am working with works from noon to midnight, while the other crew works midnight to noon. On the 7th, were able to drop the dredge and attempt to collect scallops to assess the health, size, and population of those organisms.
We work those hours mainly using the collection process of dredging the ocean floor for scallops, but along the way, several other bottom dwelling ocean creatures are caught in the dredge.
A crane operator with the help of two deck workers lowers the dredge into the water. Once the dredge is in place to go into the water the crane operator releases cable until the dredge reaches the ocean floor. Depth readouts are calculated beforehand to determine how deep the dredge will need to drop. With this information the dredge cable is let out at a 3.5:1 ratio, meaning for every meter of ocean depth we are in, 3.5 meter of cable is let out. With this ratio the dredge is dropped with an angle that keeps it flat to the ocean floor. The crane operator is also reading a line tension readout in the crane booth to determine when the dredge has hit the ocean floor. We are typically in 200–350 ft of water when these dredges occur. The dredge travels behind the boat for 15 minutes, and is then pulled in.
On the dredge is a sensor called the “Star-Oddi.” This sensor detects the pitch and roll to make sure it was lying flat on the bottom of the ocean. The Star-Oddi also collects temperature and depth information as the dredge is traveling. The sensor is taken out of the dredge once it is brought up so watch-chief can see if the dredge was functioning properly throughout the tow.
Once the dredge is hauled up, it is dumped onto a large metal table that the science crew stands around. Two of the Hugh R Sharp’s vessel technicians then scoop the collected haul to an awaiting science crew.
The science crew will then divide the haul into several different collection pails. The main objective of this crew is to collect scallops. Scallops collected are organized into different sizes. Fish are also collected and organized by a NOAA scientist who can properly identify the fish. At some of the dredge stations we collect numbers of crabs, waved whelks, and sea stars as well.
Once the haul is collected and sorted, our science team takes the haul into a lab station area. In the lab, several pieces of data are collected. If we are at a station where crabs and whelks are collected, then the number of those are recorded as well. Fish taken from the dredge are sorted by species, some species are weighed and measured for length. Some of the species of fish are measured and some are counted by NOAA scientists.
Also in this lab station, all of the collected scallops are measured for their shell height. A small sample of scallops are shucked (opened) to expose the meat and gonads, which are individually weighed and recorded. Once opened we also identify if a scallop is diseased, specifically looking for shell blisters, nematodes, Orange-nodules, or gray meats.
Also at this station, the gender of the scallop is identified. You can identify the gender by the color of the gonad. Males have a white gonad, while a female’s looks red or pink. Finally at this station, commensal organisms are checked for. A common relationship we have seen during this trip is that of the scallop and red hake. The red hake is a small fish that is believed to use the scallop shell as shelter while it is young. As they get older, red hake have been identified to be in the depression around the scallop, still trying to use the scallop for shelter, even though it can no longer fit inside.
After that has happened the shells are cleaned and given an ID number. These scallop shells are bagged up, to be further examined in NOAA labs by a scientist that specializes in scallop aging.
If you’d like to know how this process works, watch the video below. The watch-chief, Nicole Charriere, of the science crew members I work with, explains the process in this short clip.
(0:00) Nichole Charriere. I’m the watch chief on the day watch, so working with Terry. I’ve been working at the Northeast Fisheries Science Center for about 6 ½ years. When we’re out here on deck, basically, we put a small sensor on the dredge that helps monitor the pitch, the roll, and kind of whether the dredge is fishing right side up or upside down. And we offload that sensor after every tow, put a new one on, and that sensor will tell us basically how that dredge is fishing, because we always want the dredge to be in contact with the bottom, fishing for the entire 15 minutes if we can.
(0:45) The dredge is deployed 15 minutes for the bottom and then it comes back up and then the catch is dumped on the table. Then depending on how far away the next station is, sometimes we take out crabs and whelks, and we account for the amount of starfish that are in each tow because those are predators of scallops. So we want to make sure that we’re kind of tracking the amount of predation that’s in the area. And you usually find if you have sometimes a lot of starfish, a lot of crabs of certain sizes, you’ll find less starfish. I mean you’ll find less scallops.
(1:22) After the entire catch is sorted, we’re bringing it to the lab. We have scallops, we have scallops “clappers,” which are dead scallops that still have the hinge attached, and that’s important for us because we can track mortality. Once the hinge kind of goes away, the shell halves separate. Can’t really tell how recently it’s died. But while that hinge is intact, you can tell it’s basically dead recently. So you kind of get a decent idea of scallop mortality in that area like that.
(1:52) Scallop, scallop clappers, we kind of count fish, we kind of measure usually commercially important ones as well. Then we take scallop meat weights, so we open up the scallop– Terry’s been doing a lot of that too– open up the scallop, we kind of blot the meat weight so it’s like a dry meat weight, and we measure, we weigh the gonad as well, and that kind of tracks the health of the scallop.
(2:21) And then the rest of us are doing lengths of the scallop, and that’s so that we get a length frequency of the scallops that are in the area. Usually we’re looking for about… if you look at the graph it’s like a bell curve, so you kind of get an average, and then you get a few smaller scallops and a few larger scallops. And that’s pretty much it. We’re taking length frequencies and we’re looking at the health of the scallops.
From the time I woke up on Tuesday till about the time I went to bed that night, sea-sickness was getting the best of me. I listened to the advice of the experienced sailors on board, and kept working through the sickness. Even though I felt sick most of the day, and I just wanted the day to end at that point. However, I was rewarded by sticking it out, and not going to my room to lay down, by one of the most incredible sites I’ve ever seen. From about 4pm til about 8pm, many humpback whales were all around our boat. We had a little down time waiting to get to the next dredge spot, so I was watching the horizon just trying to get my sea-sickness in check. As I was sitting by the side of the boat, I saw a whale towards the bow of the ship. I got out my camera and was in the right place at the right time to get a video of it. It was one of the most amazing sites I’ve ever seen.
Video of a humpback whale diving near R/V Hugh R. Sharp
Did You Know?
The typical bleached white sand dollars that most people are accustomed to seeing as decorations are not the actual look of living sand dollars. In one of our dredge catches, we collected thousands of sand dollars, and only a couple were bleach white in color. Sand dollars are part of the echinoderm family. They move around on the ocean floor, and bury themselves in the sand. The sand dollars use the hairs (cillia) on their body to catch plankton and move it towards their mouth. The bleached white sand dollars that most people think of when they think of a sand dollar is just their exoskeleton remains.