Oshoro maru's IPY research cruise in 2007
Heidi Herter's journal entries, July 23–30, 2007
- Setting off
- Groundfish moving north
- Ocean chemistry
- Measuring primary production
- Salmon on the high seas
- Inventory of Bering Sea animals
- IPY symposium in Nome
The Arctic Yukon Kuskokwim Sustainable Salmon Initiative (AYKSSI) encourages outreach programs to facilitate education about natural resources for coastal communities in western Alaska. I was recently given the opportunity to travel with the Oshoro maru, a research vessel from Japan's Hokkaido University, from Dutch Harbor to Nome, Alaska.
I live in Nome and work as the UAF Marine Advisory Program agent for the Bering Strait region. My role is to provide technical assistance and educational opportunities for coastal communities through fisheries and marine-related activities. The Marine Advisory Program is comprised of agents and specialists in 12 hub communities across Alaska. Public outreach and education on marine issues is the main focus of our program. We work on issues regarding commercial fisheries, coastal community development, aquaculture, marine mammals, conservation, marine recreation and tourism and business development as well as seafood quality, technology and marketing. Our goal is to facilitate connections among marine resource user groups and to help Alaskans wisely use, conserve, and enjoy Alaska's marine and coastal resources.
The purpose of this cruise is to study the effects of climate change in the Bering and Chukchi Seas as part of the International Polar Year 2007–2009. Thank you to the University of Washington and Kawerak Inc., whose AYKSSI grants funded my participation on this project. These stories are from my travels with the Oshoro maru…
Heidi prepares to board the Oshoro maru in Dutch Harbor.
July 24, 2007. The Oshoro Maru left Dutch Harbor at 1000 this morning. Unalaska/Dutch Harbor is an extremely beautiful place of steep green mountains and islands, but it is also highly industrial with thousands of people busily processing fish and crab. There are 67 people on board the ship, including scientists, graduate and undergraduate students, and crew. Most people are from Japan's Hokkaido University but there are also a few research scientists from the University of Washington, Woods Hole Oceanographic Institute in Massachusetts, the Korean Polar Research Institute, and the Alaska branch of NOAA Fisheries, located in Seattle. Over the next 11 days we will be journeying back to Nome, where I live. Along the way we will be stopping at many stations to sample the water and the animals living there and collect information on how they are coping with warming ocean temperatures. My job on the ship is to take part in different projects and convey information to people who are curious about what kind of climate change research is happening in western Alaska and why.
There are many different projects going on aboard this vessel. The first is a project studying juvenile salmon on the high seas—which everyone loves to help with because the fish all have to be caught with rod and reel! Both the pink salmon and the chum that we caught were shiny silver and black. The two species looked very similar without the bright colors and markings that we see on spawning salmon in the rivers. Dr. Kate Myers from the University of Washington showed us how to identify each species by the markings on the tail, also called the caudal fin. Chum had silver striped bars on the tail. There was no silver on the tails of pink salmon but they had distinct spots on the tail instead.
Some people on the ship work the night shift so that we are collecting samples around-the-clock. Last night we reached a sampling station at 2 a.m. Salmon were swarming around us. These salmon were positively phototactic, meaning that they were attracted to the light of the boat. The main goal of juvenile salmon is to eat as much as possible; that's why they opt to leave the rivers where they were born and enter the ocean where food is more abundant. Juvenile salmon are visual feeders so they visited our ship looking for something good to eat. They found it, but unfortunately for them the food was attached to our lines! The fishing poles lashed around the deck bounced constantly with the news of yet another catch! Data regarding the length and sex of each fish were written down in a notebook. The fish and each of its organs were weighed using an old-fashioned hand-held Japanese balance. I was told that this type of balance is preferred because all of the boat's rocking can make electronic balances read inaccurately. The scientists and students will look at data collected during a 1997 cruise of this area and determine whether warming ocean temperatures seem to be changing any of these measurements.
I'll try to describe all of the projects in detail as the cruise goes on!
July 25, 2007. Species ranges are moving increasingly northward as the climate warms here in western Alaska. Every animal has an optimal temperature range because of its ability to keep itself warm or cool, and to find preferred foods. In Alaska, the water along the northern “too cold” edge of the Bering Sea is warming rapidly, creating new habitat for many species to move into. When animals move into new areas on their own it is called a species range expansion. If humans have accidentally or purposefully brought animals into a new area where they do not belong, it is called an introduced species. One introduced species in Alaska is the Louisiana crayfish which has recently been found in small numbers in the Kenai River. An invasive species may refer to either type of introduction of an animal to a new ecosystem. Both range expansions and species introductions can seriously affect an ecosystem if the new species changes predator-prey dynamics or is able to out-compete naturally occurring animals for food or space. These occurrences are becoming more common in Alaska as our warming climate creates new habitat where species from southern areas can survive.
A graduate student from Japan's Hokkaido University launches the bongo net.
NOAA fisheries scientists Morgan, Kevin and Colleen are studying changes in the distribution of pollock. Pollock are highly adaptable and are found from the open ocean of the Bering Sea to eel grass beds in Puget Sound, Washington. Young pollock larvae and juveniles are captured using a METHOT or mid-water trawl, which involves a large net moving through and collecting animals from the middle layers of the ocean. Species ranges may also change if there are changes in the distribution of their food. The NOAA scientists sample the water column with bongo-net tows for the presence of pollock food like euphausids (krill), amphipods (beach fleas), pteropods (tiny “winged” snails), and copepods. On each METHOT or bongo-net tow, a flow-meter is attached to measure the volume of water that the net passes through. By counting the number of fish or prey animals caught and knowing the sampled volume of water, we can estimate the density of larval or juvenile fish found in this part of the ocean. The mesh of the METHOT net is very fine and can catch pollock as small as 0.5–1.5 inches in length (12–30 mm). NOAA scientists have been catching these young pollock in the same locations within the southern Bering Sea for 20 years. This is referred to as a 20-year timeseries. Long-standing data sets like this one are very valuable when studying climate change. The older data can be used as a baseline for newer data to be compared against when looking for changes in fish distributions.
Groundfish like pollock are expanding their ranges to the north and are becoming a more common catch aboard fishing boats in the northern Bering Sea. It is difficult to say whether pollock are expanding their reproductive ranges or if adults are simply expanding their feeding ranges to the north. Morgan will be going on another research cruise later in the summer to look for pollock larvae and juveniles in the Chukchi Sea. Recently hatched pollock larvae are basically swimming eyeballs with tails. Larvae are meant to disperse, or move, from the areas where they hatched on tides and currents. The tail on a larval pollock makes it quite a good swimmer and able to control at least its vertical position in the water column. If pollock larvae are found farther north than expected it does not necessarily mean that a reproductive range expansion has occurred. Larvae have different strategies of dispersal and some travel farther than others. Pollock larvae in surface waters may travel up to about 60 miles (100 km) away from their place of hatching. In this way, it is possible for pollock larvae to travel into water that is too cold for them to actually survive. If juvenile pollock are caught in the Chukchi Sea, that is a better indication that the species range is expanding to the north.
July 29, 2007. Prae and Deanna are studying radioactive elements in the Bering Sea, including radium and thorium, which naturally occur everywhere. Prae is working on her Ph.D. in chemistry at Woods Hole Oceanographic Institution in Massachusetts. Deanna is a summer intern who recently graduated with a B.S. in Biology. Whenever the ship reaches a station, these science students collect surface water in huge barrels and filter it to concentrate radium. Radium naturally occurs in very small quantities in the ocean so about 60 gallons of water must be filtered to find detectable traces.
Most elements occur in a few forms, each with a different number of electrons. Each different version of an element is called an isotope and some isotopes are more stable than others. Usually the most stable isotope will be the most abundant. Radium has four isotopes, with 223, 224, 226 and 228 electrons. Radium isotopes experience decay, which is the process of losing electrons and/or protons until a particle becomes a more stable element, ultimately converting radium to lead. The half-life of any isotope is the amount of time necessary for exactly half of the available particles to decay and become more stable particles. Prae is most interested in radium 223 and 224 because they are unstable and have relatively short half lives of about 11 and 4 days, respectively.
At each station, Prae filters the radium out of the surface water in her barrels and looks at the concentration of radium 223 and radium 224. Radium in the ocean is originally from land-based freshwater runoff or decays from Uranium found on the ocean floor. They expect a higher concentration of radium to be found near the Bering Sea shelf, rather than in the open ocean, where we are closer to the sources of radium. As we move farther away from radium sources, they expect radium 223 to be more abundant than radium 224 due to its longer half life. By measuring radium 223 and 224, Prae and Deanna get an idea of how surface water flows in the Bering Sea, including information on where the surface water masses probably came from and how long it took them to get to our stations.
Deanna is also collecting water samples from the CTD (see description in next section) and looking for thorium 234. Unlike radium, thorium easily sticks to other particles, like carbon or nitrogen, and the extra weight pulls thorium from the surface into deeper waters. Since thorium readily attaches itself to carbon and sinks below the surface, Prae and Deanna have to collect water samples from different depths using the CTD.
Prae and Deanna measure the ratio of thorium 234 to carbon in each sample. As depth increases, more thorium and less carbon is found. With these ratios, Prae can calculate the rate and amount of carbon falling from the surface to the ocean floor at every station. In nutrient-rich areas of the ocean, primary productivity is high. Measuring carbon throughout the water column can be a good indicator of primary productivity because the main source of carbon in the water column is dead phytoplankton. Areas with high levels of primary productivity can sometimes be carbon sinks. Carbon sinks may actually help to slow ocean warming processes by using up more of the available carbon dioxide in the atmosphere.
July 26, 2007. Many of the scientists on board the Oshoro maru are interested in sampling the water column using the CTD, which is made up of a set of 12 tubes called Niskin bottles and a computer. The CTD collects water as well as information about Conductivity (which can be converted to salinity), Temperature and Depth throughout the water column. The CTD is carefully dropped into the water with all Niskin bottles open until it reaches the desired depth. Some CTDs can go down deeper than 1.5 miles (3000 meters)! On the way up, the computer triggers each Niskin bottle to close at a specific time, taking samples from different layers of water all the way back to the surface.
These water samples may be used for many purposes. Besides looking at radioactive particles, scientists may also be interested in comparing the levels of other elements like oxygen, nitrogen, phosphorus and carbon that can describe how productive the ocean is at each layer. Primary productivity is measured by the amount of photosynthesis occurring, which is the process of converting sunlight into energy for growth and reproduction in plants. Phytoplankton is the collective name for all of the small algae particles in the ocean, including diatoms which are the most common. Phytoplankton may also be collected by the CTD, but these algae will only occur in the presence of plenty of sunlight, carbon dioxide and the nutrients (i.e., nitrogen, phosphorus) necessary for photosynthesis. Because algae need all of these things to grow, phytoplankton are most abundant near the surface and in the springtime when the amount of sunlight is increasing each day and nutrients are plentiful.
Every animal is ultimately dependent on photosynthesis to make nutrients and the sun's energy available through the food web. Because the midnight sun allows for photosynthesis during both the day and night, polar waters like the Bering Sea produce more phytoplankton in the short Arctic summer than most other oceans produce in an entire year. In an experiment by the Korean Polar Research Institute, scientists are measuring productivity of water from different depths by leaving their samples out in the sun. A carefully measured amount of carbon is added to each sample to be taken up during photosynthesis. Some of the samples are in black bottles with the light blocked entirely, others are in mesh bottles with light partially blocked and others are in clear bottles which the sun can easily shine through. After some time, the amount of carbon remaining in each sample will be measured to determine the amount of photosynthesis that has occurred. Plants need carbon (or carbon dioxide) for photosynthesis. We depend on plants to use up some of the excess carbon dioxide created by human use of fossil fuels to slow the warming process and produce oxygen (a plant's waste product) for us to breath.
July 27, 2007. This cruise is affiliated with the Arctic Yukon Kuskokwim Sustainable Salmon Initiative (AYK SSI). Recently there has been a great deal of salmon research in western Alaska under this initiative. Wild salmon spawn along rivers and streams which are also prime land for building new human homes and infrastructure like dams for electricity. There are no longer any wild salmon left on the Atlantic Coast of the United States, and wild salmon populations on the Pacific Coast of the United States are in danger of loosing too much of their freshwater habitat. Alaska's salmon still have many healthy freshwater rivers to spawn in and most of our wild populations are doing very well. These populations are supplemented with many fish from hatcheries to make sure there are enough fish for harvesting by fishermen.
Salmon scientists have looked at the existing data from Alaska and the Pacific Northwest to determine research priorities for salmon in western Alaska. Data on juvenile salmon from the high seas is difficult and expensive to collect. Japanese graduate students on this ship are collecting as much data as possible on each salmon that we catch. In the past week, we have caught chum, pinks, coho and chinook salmon using fishing rods and Japanese longline gear. Once a gull also got tangled in our fishing line but we were able to set it free without any problem. Students measure the length and weight of each fish, and the gonads, or sex organs, stomach, and intestines. They collect blood samples to look at the hormones present in the developing fish, and part of the dorsal fin as a genetic sample. A few scales and the otoliths, small bones in the head of the fish that help with balance and orientation, are also collected from each specimen. Scales and otoliths have growth annuli, rings for every year that the fish is alive—like a tree trunk—which can be counted to reveal a fish's age. Scientists compare the size of a fish with its age to see how the environment has affected its growth. Warmer water will generally cause fish to grow faster. These data will be compared with measurements of Bering Strait salmon from the past and future to access the effects of a warming climate on salmon growth and development.
NOAA biologist Morgan Busby examines the catch from a METHOT tow.
July 30, 2007. More news from the Oshoro maru! Along the way we have been using mid-water trawls (METHOT) and bottom trawls to take a look at the different types of animals living in the Bering Sea. Many animals had no backbone, which we refer to as invertebrates. Some invertebrates that we find are sessile, meaning that they are stuck to the ocean floor, like anemones, feathery hydroids and sponges. These are all actually animals even though they look a bit like plants. One anemone that we found had many juveniles growing all around her base. We also scoop up many types of sea stars, some with 6 thick legs and also brittle stars and the beautiful basket star. Sometimes we catch fish including chum salmon, arrowtooth flounder, halibut, pollock, Pacific cod and snailfish (lumpsuckers). In one bottom trawl we caught an entire school of pollock, which was far too many fish. We also caught many young snow crabs. You can distinguish between male and female snow crab by the shape of their abdominal flap. Looking at the underside of the crab, the flap on the belly of a male is longer and narrower. The female must hold her eggs under this flap so hers is much larger and circular. In the mid-water trawl we caught some very young snow crab yesterday. Different stages of larvae, early zoeae and later megalopae were stuck in the tentacles of a lion's mane jellyfish. The zoeae looked very different from the adult crabs and had long spikes coming out of their heads. They were very small and we needed a microscope to get a good look at them. The megalopae were bigger, about the size of a pencil eraser, and looked like very tiny crabs. Also stuck to the jelly's tentacles were some very tiny tunicates which looked like tiny pink, purple and peach jelly beans covered in slime.
The International Polar Year research symposium in Nome.
August 3, 2007. Arrival in Nome! The ship actually arrived yesterday but we couldn't get into the port until this morning. Last night we passed by St. Lawrence Island. It looked very big but far away. The horizon, as far as you can see on the ocean, is about 60 nautical miles away. It feels good to be home but now we have to be land-sick for a few days getting used to a world that isn't constantly rocking.
August 4, 2007. Today we met up with the group of researchers who are about to board the Oshoro maru for the next leg of the journey up through the Chukchi Sea. Everyone took part in an International Polar Year Symposium to commemorate our journey and experiences. The topic for the symposium was “Marine Ecosystem Responses to Climate Change in the Bering and Chukchi Seas.” Presentations were given by scientists from Japan, Thailand, England, and the United States who told some of the stories that I've shared with you here.
I hope you've enjoyed reading about our travels and research!