Tag: Rockfish

NOAA Teacher at Sea
Patty McGinnis
Aboard R/V Ocean Starr
May 20 – 29, 2013

Mission: Juvenile Rockfish Survey
Geographical Area of Cruise: Pescadero, California
Date: Tuesday, May 28, 2013

Weather Data from the Bridge
Latitude: 37 16.941 ° N
Longitude: 123 07.440° W
Air Temperature: 14 Celsius
Wind Speed: 25 knots
Wind Direction: NE
Surface Water Temperature: 12.8 Celsius
Weather conditions: foggy

Science and Technology Log

I’ve come to realize that each trawl is a whole new adventure; although Chief Scientist Keith Sakuma has the historical data to predict what might be found at each station, he is occasionally surprised at the treasures that are yielded by the ocean’s pelagic zone. The majority of our trawls are conducted at 30 meters below the surface. The area that falls between the surface and 200 meters below the surface is known as the epipelagic zone. The next zone, the mesopelagic, is the area that lies 200 meters to 1,000 meters below the surface. Last night our first trawl of the night was a deep water trawl. Although described in the Project Instructions, this was our first opportunity to conduct a deep water trawl. Keith was taking advantage of the fact that the captain wanted to unwind one of the trawl winch cables so that it could be carefully rewound onto the spool.

During the deep water trawl, the net was dragged for 15 minutes at a depth of 300 meters, rather than the traditional 15 minutes at 30 meters. In addition to a large number of adult hake, we pulled up a long-finned dragonfish. Like many fish that live in the deep ocean, the dragonfish has an organ on its head that produces a bioluminescent light. This light is used by some species to attract prey and can also serve to help the fish see its surroundings. Tonight we found another type of deep dwelling fish; the stoplight loosejaw fish, so named for its large jaw. Its red spot is capable of producing red light to help it navigate. We also pulled in several King of the salmon specimens. The King of the salmon is not a real salmon, but is a type of ribbon fish. It has a very flat, ribbon-shaped body and a long dorsal fin that runs down the entire body. Deep water fish like the stoplight loosejaw and King of the salmon tend to get pretty banged up in the trawl.

Lindsey good-naturedly dissected out a handful of otoliths (ear bones) from the adult hakes so that I could have a memento of my NOAA Teacher at Sea voyage. I anticipate using the otoliths to create a lab activity for the middle school science classroom. The hake lengths were then measured on a special board and a small piece of tissue was cut from five of them to be frozen and analyzed later.

We conducted five additional trawls at 30 meters. Prior to and during each haul one of us does a mammal watch. This consists of listening and watching for mammals that may appear alongside the ship during the trawl. Should we encounter any marine mammals, the protocol is to stop the trawl immediately to avoid injuring any mammals. As of today, we have yet to be accompanied by any marine mammals during our trawls.

One of the surprises of the night was a catch of northern anchovies. I was surprised at their size; rather than the small fish I had envisioned, these fish were solid, robust, and at least 6 inches in length. Keith was pleased with the number of anchovies we hauled in given that very few or none were obtained the last two years. As he explained, the anchovy population tends to go through boom and bust cycles and have been down for the last several years. We also pulled up a North Pacific spiny dogfish, a shark named for its sharp dorsal spines.

Other hauls yielded large amounts of juvenile rockfish and market squid. I have a great fondness for the squid, which I dissect annually with my students each spring. The small market squid we pull up, some barely an inch in length, pale in comparison to the adult squid which I use in my classroom. There is, however, no mistaking the miniature squid for anything else, so strong is their resemblance to their full-grown relatives that make their way from California’s pelagic waters to my classroom in Eagleville, Pennsylvania.

Krill, of course, are well-represented in the hauls as well. The abundance of the tiny crustacean makes it easy to envision the humpback whale straining out mouthfuls of krill as they make their annual trek to Alaska each spring.

Since identifying and counting the majority of all the organisms for each trawl would be too labor intensive, we concentrate on a subsample. Keith then extrapolates the data from the subsample to obtain an estimation of what the total haul contained. Depending on what is present in the haul, we generally identify a subsample of 1,000 or 5,000 millilitres. Difficult sorts such as one that consists primarily of krill and small shrimp, may be restricted to 1,000 millilitres, whereas easier sorts may be up to 5,000 millimeters. Regardless, the total volume of the trawl is always recorded, as is the total volume of krill. Keith bags some of the catch for later use, carefully labeling each bag with the haul number, cruise number, and species identification code. Up to 30 specimens of each important species are also measured and recorded. In the morning, it will fall to Don Pearson to transfer the data from the data sheets to the computer. These numbers are then cross-checked the following evening to ensure that the data is accurate. The result: the groundfish stock assessments NOAA produces are as accurate as possible, an important factor for fisheries management.

As busy as the night shift is, the day shift keeps busy with important work, too. Don conducts CTDs throughout the day, while Jamie filters phytoplankton from water samples that the CTD captures.

As I am sleeping the ship periodically conducts transects over the ocean floor. These transects are conducted in areas where upwelling tends to occur. Upwelling is caused when a predominantly northwest wind pushes water offshore. Water rises up from below the surface to replace the water that was pushed away. In doing so, nutrients from the ocean bottom are transported from the sea floor to the water column. These nutrients serve to promote the growth and reproduction of phytoplankton, which is the basis of all ocean food chains. Upwelling areas therefore attract fish, birds, and marine mammals. While the ship is running transects, a computer in the lab is continually monitoring evidence of sea life at different frequencies. The picture below shows four graphs that monitor for krill, invertebrates, and fish. Fisheries biologist Don Pearson explained that it takes a practiced eye to spot patterns in the data. These patterns should correspond with the birds and mammals that Sophie spots on deck as seeing lots of organisms on the computer means lots of food for the birds and mammals. As much as I’ve enjoyed the night shift, part of me wishes that I had been able to have spent more time on the lookout deck with Sophie.

All of this takes an enormous amount of preparation. Keith, Don, Amber, and oceanographer Ken Baltz spent the better part of a day setting up the equipment which will be used over a six-week span. This includes the trawling net which has been built to a specific length, opening and mesh size. The use of a standardized net is important because it enables the scientists to compare catches throughout the years. Other equipment includes an array of computers, the CTD, and miscellaneous equipment needed to sort through catches.

Personal Log

It is interesting getting used to life on ship; this small community consists of 17 crew and 8 scientists (including myself). This vessel, in addition to being equipped with the necessary science equipment, houses its inhabitants in “staterooms.” I have been partnered with Kaia, a reflective wildlife biologist whose company I thoroughly enjoy.

I have taken note that you can set your clock by the four meals served each day. Our ship’s steward, Crystal, and her assistant Liz, never fail to amaze me with the diverse menus that they faithfully create for us each day. The mess, or the room where we eat, has snacks and sodas available at all times of the day and night. Crystal also keeps a refrigerator stocked with leftovers that are available for anyone to access at any time. If that wasn’t enough, there is an entire freezer which houses nothing but a variety of ice cream bars (which the night shift enjoys on a regular basis). The mess is a popular place to hang out between meals. Two large televisions are constantly on; I’ve noticed that sci-fi movies (especially B-rated ones) and old war movies seem to be the favored among the crew.

Yesterday I had an opportunity to do my laundry using one of the ship’s two washing machines. When I first came on board I asked Keith about fresh water on the ship. He explained to me that as long as the ship is moving that it is able to make fresh water through a desalination process. Since the Ocean Starr is in constant movement other than when the CTD is being employed, having fresh water has not been an issue. Regardless, taking the type of long showers favored by many of my students is something I did not indulge in.

As I write this the ship rocks gently from side to side. I think of how quickly I have adapted to my new surroundings and to the companionship of my new friends. As Keith had promised, after three days of working the night shift my body has adjusted and has acclimated to the routine. My time here is drawing short, however…three days from now I’ll be back in my classroom sharing stories and photos with my students.

Did You Know?

Commercial fisherman use a big spotlight to attract market squid?

Here is a list of some of the fish I have seen this week:  barracudina, northern lampfish, blue lanternfish, Pacific hake, pallid eelpout, yellowtail rockfish, shortbelly rockfish, cowcod, blue rockfish, boccacio, lingcod, cabezon, Irish lord, wolf-eel, medusafish, Pacific sanddab, speckled sanddab, rex sole, Dover sole, and many more