Forage Fish and Salmon Survey
August 16 - September 26

August 19: Finding our groove

We're finding our groove for sampling. The first few stations are always a bit slow, as we relearn how to deploy gear and settle in our individual roles.

So far we have finished five oceanography and surface trawling stations and saw very different things. Over the deepest water (500m depth), the trawl captured mostly immature chum salmon (right), which have spent 2-3 years in the ocean.

Once we moved into shallower water (<125m depth), we found mostly age-0 (born this year) walleye pollock and Pacific cod (below).

Lots of jellyfish

The acoustics tell us that below 35m depth, the water is filled with jellyfish. Filled. In 2008, we had learned that you don't want to trawl that mass for too long.

When we finally do trawl to collect jellyfish for lengths and species composition, we will fish the net for just five minutes. We may still get several hundred pounds of jellyfish, which may take an hour or more to process.

Different patterns

The patterns in walleye pollock, Pacific cod, and jellyfish are different than we had expected to find based on our 2008 and 2009 observations. Since it's only day two, what other surprises are in store?

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August 17: Heading out and sampling

After a stop at a local store to buy essentials for 20 days at sea, the five members of the science party who didn't receive their luggage are resigned but laughing about it –- they'll probably look like some sort of team in their matching Dutch Harbor gear.

Right: This freighter was docked ahead of the Dyson. Each of the cargo containers on its deck are 40ft long by 10ft high by 8ft wide. A quick count found that the containers were stacked 7 high, 13 wide, and 16 long -– and they weren't done loading yet! Even the 209ft Dyson felt small next to this hulk.

We're heading for our first station located six hours north in 500m of water. A bit of time for everyone to get their "sea legs" before we start the survey isn't a bad idea. The forecast suggests that although we'll sail into 10ft seas tonight, the weather should grow progressively nicer as the week goes on.

Sampling for water properties and zooplankton

The science starts with oceanographic sampling at 0630. At each station (see the station map from August 12), we use a CTD unit (Conductivity-Temperature-Depth) to measure properties of the water from near-bottom to the surface. The CTD is also equipped with water collection bottles (Niskin bottles) that can be triggered to close at specific depths. Various mesh nets (Bongo, Pairovet, and Juday) will be pulled through the water to obtain samples of zooplankton. See more pictures of a CTD in action and learn more about why we use it to sample ocean water.

Surface trawling to learn about fish

After the oceanography is completed, we will tow a net at the surface (a "surface trawl") to collect fish and jellyfish at each station. The trawl is ~55 m wide and ~20-25 m high. When this net is fished at the surface, the vessel adjusts its speed, the crew adjusts the length of the wire going from the vessel to the net, and floats are placed on the top of the net opening to keep the trawl fishing at the surface. Surface trawling is how we'll get information on salmon species, particularly juveniles, and forage fish.

Acoustics: finding fish the high-tech way

Between stations, we use acoustics to map forage fish distribution. Acoustic units are like high-tech fish finders. A pulse of sound is sent into the water and is reflected by anything that is different than the water -- this allows us to see fish, jellyfish, squid, and zooplankton. Left: How fish and zooplankton appear through the acoustic equipment. See larger image

Air, like in the swimbladders of some fish, reflects a lot of sound energy because it is very different than water. On the other hand, squid bodies are more similar to water and don't reflect as much sound energy. The acoustics sends out sound pulses at a rate of one per second, giving us a very detailed look at the water column as we pass over it.

The trawl is fished below the surface (a "midwater trawl") to identify interesting things -- like a school of fish deep in the water -- that we see on the acoustics. From this we get species composition and, by repeatedly sampling things we see on the acoustics, can start to associate patterns on the acoustics with different organisms. We use the same net for midwater trawling as we do for surface trawling, but remove the floats and adjust the fishing to keep it below the surface.

Phew! Enough explanation – let's get the gear in the water!

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August 16: Welcome to Dutch Harbor!

I made it into Dutch Harbor today. As we approached, there were murmurs among the (primarily seasoned) passengers that you couldn't see high enough up Mt. Ballyhoo, a local measure of visibility, for the plane to land. Would we land or head back to Anchorage or Cold Bay? A break in the fog allowed us to touch down, and as I walked off the plane into 50 F, rain, and wind I was reminded that at that moment Seattle was likely 90 F and sunny. Welcome to Dutch Harbor.

By the end of the night, I knew that most of the science party had arrived and some (I among them) even had their luggage! The second half of the question, "Will I make it into Dutch?" invariably is "… and will my luggage make it?" You have to pack knowing that there is a possibility that your bags may not arrive before the research vessel leaves the dock -- and remember that there are only a few places where you can replace your missing items before you set sail. How's that for a reality check?

Despite all the possible pitfalls in getting here, and the weather, I always feel energized when I get to Dutch. It's ruggedly beautiful, rich in history, and hardworking. Because it's so unlike where many people live, arriving in Dutch can be like a wake-up call that something, maybe something big, is about to happen. Tomorrow that something big is boarding the Oscar Dyson and starting to get set up.

Gear, food ... and hopefully luggage

Under ideal circumstances, getting our gear aboard the ship would simply involve a phone call, but here, it involved five scientists climbing around on piles of gear looking for containers with our labels. Left: looking for the gear.

Earlier surveys had deposited gear in the same place and our gear was near the bottom of the pile. Fishing trawls, small nets, coolers, tubs, bins, bottles, rain gear all came aboard, and by dinner tonight the labs looked like labs.

This afternoon the food arrived -- boxes of potatoes, cases of apples, crates of eggs, huge bags of onions, frozen slabs of meat, jumbo packs of ketchup. Once we sail, I'll ask the Chief Steward just how much food it takes to feed 39 people for a trip like this.

Many scientists don't yet have their luggage. More flights will arrive before we sail; everyone is hopeful that their bags will be on the next flight, so are waiting until the last minute to break down and buy sweatpants and t-shirts at the few stores on the island. Tomorrow may be a frantic shopping spree before the lines are thrown and we head to the first station.

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August 12: Survey overview

2010 will be the third year in which acoustics and midwater trawling for forage fish (e.g. age-0 walleye pollock, capelin, herring) will be combined with normal BASIS operations (surface trawling for juvenile salmon, oceanography) as part of the Bering Sea Project.

The combination of acoustics, midwater trawling, surface trawling, and oceanography is a powerful one because it provides multiple perspectives on the fish community and its underlying habitat.

A closer look at pollock in 2010

This year we will also conduct a special, high-resolution survey of age-0 pollock. In 2008 (a "cold" year in terms of water temperature), age-0 pollock were found in the middle of the survey area, but in 2009 (a "colder" year) they were found in deeper water.

Knowing that 2010 is the "coldest" year since 2008, our goal is to understand what factors influence the distribution of young pollock and how this may affect their survival. Read more about why we do acoustic surveys, and learn more about how the Bering Sea has changed for pollock since 2008. This blog will track the adventures of the Oscar Dyson -– stay tuned for the science party's arrival in Dutch Harbor, AK.

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• Bering Sea Home
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