NOAA Teacher at Sea
Aboard NOAA Ship Oscar Dyson
July 22 – August 9, 2013
Mission: Pollock Survey
Geographical Area of Cruise: Gulf of Alaska
Date: Thursday, July 25, 2013
Current Data From Today’s Cruise
Weather Data from the Bridge (at 6:00 am Alaska Daylight Time)
Sky Condition: Fog
Temperature: 12° C
Wind Speed: 11 knots
Barometric Pressure: 1017.5 mb
Sun and Moon Data
Sunrise: 5:51 am
Sunset: 10:40 pm
Moonrise: 10:57 pm (July 24, 2013)
Moonset: 10:37 am
Longitude: 148° 47.7′ W
The ship’s position now can be found by clicking:
Science and Technology Log
How can you determine the population size of species? You could count every member of the population. This would be the most accurate method, but what if the individuals in the population move around a lot? What if the population is enormous and requires too much time to count each individual? For example, krill is a small crustacean (usually between 1 and 6 cm long) that accounts for 400-500 million metric tons of biomass in the world’s oceans. Would you want to count all of the krill in the Gulf of Alaska?
Often, ocean populations of animals are just too large to count. Sampling, or collecting a manageable subset of the population and using the information gathered from it to make inferences about the entire population, is a technique that ocean scientists use. There are a variety of ways to sample.
One method is called mark and recapture. In this method, one catches individuals from the population, tags them, and releases them in a certain area. After a set amount of time, an attempt is made to recapture individuals. Data are compiled from the recaptures and the population is mathematically calculated. Tuna populations in some areas are monitored this way; fishermen are required to report any fish that are recaptured. (Photo courtesy of Western Fishboat Owners’ Association)
Another method is quadrat sampling. The organisms in a subset area (quadrat) are counted and then the overall population in the entire area is calculated. For example, in the picture below, one quadrat would be randomly selected and the organisms counted. From this count the overall population would be extrapolated. (Photo courtesy of BBC Bitesize Biology)
The sampling method used on the Oscar Dyson employs the use of a transect line. The picture below illustrates the use of a transect line. On various increments along the transect line, samples of populations are taken. Imagine the Oscar Dyson’s path on the sea as the measuring tape and the trawl net is the sampling square. (Photo courtesy of Census of Marine Life Organization)
The overall survey area of the pollock study this summer is the northern Gulf of Alaska between the shore and the continental break. Within this area transect lines were established. These are pathways that the Oscar Dyson will travel along and periodically take samples of the fish.
The current set of transects are 25 nautical miles apart and are parallel, but transects in other areas may be 2 or 5 nautical miles apart. One nautical mile is equal to 1/60 of a degree (or 1 minute ) of latitude. Transects that we are following now are located on the shelf and are perpendicular to the coastline. Transects in inlets and bays may run differently, perhaps even zigzag.
If fish are located through acoustics monitoring off the transect line, the ship might break transect (a mark is made on the map), circle around to the desirable position, and collect a sample by trawling. The population of pollock can then be mathematically calculated from counting the sample. After trawling, the ship will return to the break and continue along the transect line.
Most days, scientists hope that the Oscar Dyson will finish a transect line by nightfall and then the ship can be at the next transect by sunrise. This maximizes the time for detecting fish acoustically and trawling to collect samples.
Food is available in the galley. It is planned for and shopped for before the mission. Chief Steward, Ava, and Second Cook, Adam, do an excellent job preparing and executing delicious, healthy meals at set times during the day (Breakfast: 7 to 8 am, Lunch 11 am to noon, Dinner 5 to 6 pm). Since the staff on the ship are working around the clock, there is always food available (salad bar, cereal, yogurt, peanut butter and jelly sandwiches) if meal time is missed for sleeping. Below is a photo of the galley. (What are those neon yellow things on the bottom of the chair legs for, do you think?)
Water is needed for in several capacities on the ship. The staff on the ship needs potable water to drink and to cook with. Additionally, water is needed for washing dishes, bathing, flushing toilets and doing laundry.
To get clean drinking water, we pump the salt water from the ocean into a desalination unit (a distiller). The distilled water is then sent to a 10,000 gallon holding tank. When water is needed, it is pressurized so that it will move to the faucets, drinking fountains, showers, and so on.
Water is also needed on the ship in the lab and on the deck to clean up after the catch is hauled in and processed. The water used here is salt water and is pumped onto the boat directly from the ocean.
Half of the staff on the ship is working around the clock; the other half is resting. For the science staff, there are two shifts, a morning shift (4 am to 4 pm) and an evening shift (4 pm to 4 am). The shifts are staggered at these hours so that the evening shift will be able to share two meals with the rest of the staff (usually lunch and dinner). In most cases, two people share a stateroom: one works days and the other works nights. Because the quarters are close on a ship, this gives each person some time alone in the room to sleep, bathe, and take care of other personal needs. A stateroom consists of a bunk bed, a desk, two lockers, and a bathroom/shower. Below are some photos of the stateroom that I share with my roommate, Abby. (Note: Because rooms are small and space is shared, it is not advisable to bring a large purple suitcase that won’t fit inside one’s locker.)
There are two workout areas on the ship. One workout area has a treadmill, an elliptical machine, a bike, and a yoga mat; the other has a treadmill, a rowing machine, and some free weights. There are limited walking spaces on the ship, so these machines provide a way to stretch one’s legs, so to speak.
Etymology is the study of the origin of words. Many of the words in science originate from ancient languages such as Greek or Latin. For example, the word etymology comes to us from two Greek words: etymon meaning “the true sense of a word“ combined with logia meaning “doctrine, study.” Combining these two roots gives us “the study of the true sense of words,” which can be said to be the meaning of the word etymology.
Here are some root words I came across today all originating from Greek words:
zoo-from zoion meaning “animal”
phyto-from phyto meaning “plant”
plankton-from planktos meaning “drifting” or “wandering”
vorous-from vorous meaning “eating”
In the blogs thus far, I have discussed two species: walleye pollock and one of their prey, krill. Krill are classified as zooplankton, literally “animals that drift. ” Krill eat phytoplankton, or “animals that drift.” Pollock are considered to be zooplanktivorous, or “drifting animal eaters.” An award winning short video explaining The Secret Life of Plankton can be viewed by clicking on the link.