PacSci Perspectives

Math, Fish & The Bering Sea

by | Apr 20, 2016

For marine biologist Dr. Kirstin Holsman, math is as essential as nets, boats, and waterproof boots. Every few years, come May, Holsman joins a team of scientists aboard a small vessel on an annual survey of the Bering Sea, dropping nets at more than 370 sites to observe which fish are at which locations, how many, how big—and even what’s in fish stomachs.

What do you do, and why do you do it?

I’m a marine biologist who works on fish and climate change in Alaska to provide scientific advice for fisheries management. There’s a lot of change in Alaska because of warming and changes to Arctic sea ice. We want to know: What are the long- and short-term impacts to fisheries in the region?

My background is in field biology, and at the heart of that is math. The world is governed by this invisible scaffolding; math is the language we use to describe that. It’s almost like a quantitative clairvoyance. People who work in natural science or physics feel like the world is always in flux. It’s always changing, but there’s a pattern to the change. It’s like looking at cars on the freeway. There’s an order to the movement. If you can see the pattern, you can see the future.

You can’t see fish in the ocean, so you have to use creative ways to measure them. Math helps us to see what’s going on and discern the pattern from the noise. We look at how patterns change over time. What are they going to be next year? What are they going to be in 100 years?

It’s a combination of statistical and mathematical modeling, sort of like a video game. We build mathematical models and run different scenarios. What would happen if we turn up the temperature two degrees? We build food-web models: if this fish eats this smaller fish or this crab how does the ecosystem change? What will it eat next year given a certain water temperature?

What’s the single most important thing people should know about your field?

I got into marine biology because I love the natural world and connection to ocean. I got into fisheries because most fishermen have that deep connection to the ocean. They’re relying on it for their livelihood. Although there’s a perception that fisheries are damaging, they don’t have to be – it’s actually one of the last industries that relies entirely on a healthy functioning ocean.

Look at the salmon fisheries in Alaska. When I went up into Alaska salmon camps as a college student, it was apparent to me how much the human communities there depend on the salmon coming back every year just as the bears and eagles do. If you look at the salmon industry, which is important commercially, that legacy has led to protection of river and lake systems—stewardship that’s also important for cultural reasons.

There are also examples of that not happening. Wild Atlantic salmon on the East Coast are commercially extinct because large changes to the river systems really hurt that ecosystem. Look at Washington state. We put dams in 100 years ago in well over half the watershed to make clean hydropower, but we didn’t know salmon returned to very specific spots in the river, and damming eliminated spawning habitat for Columbia river chinook. Pollution from road runoff in the Puget Sound region has also caused declines in salmon.

What do your mathematical models say about the impact of climate change on the ecosystem in the Bering Sea?

Fish that like cold water are likely going to decrease: maybe Pacific cod, Walleye pollock, snow crab. How far can we push our adaptive management to reduce impacts? If we lessen harvest, does that counter climate change? Warm water fish will probably take their place, fish like Arrowtooth flounder. People don’t know it because it’s not a good fish to eat. The flesh turns to mush when you freeze it. It is a voracious predator of fish like pollock. There will be winners and losers under climate change.

What is it about your field of science that excites you?

1. Being able to go out into the field and be in nature. 2. The people I work with who are incredibly creative, motivated by deep interest in the natural world and dependence on the natural world. 3. The mathematical models and statistics—a fun puzzle.

Why did you get into this field of science?

I grew up boating in the San Juans. Dad is an architect, so I was drawn to math. At 20, I was invited to sail back from Hawaii with a boyfriend at the time. That changed my trajectory…being in the middle of weather and storms…and the animals we encountered…jellyfish with sails on them, seabirds that almost never go to shore. I came back intrigued by the oceans, how volatile and energized they were and how much life is in them. I wanted to provide science to protect that natural environment and had a feeling people were the solution to that. The strongest stewardship of the ocean is by people who depend on it. It’s finding the sweet spot between using a marine environment but not hurting it.

What was your first science experiment?

An engineering experiment to build a bridge across an expanse and put a bucket in the middle. Also, designing a container to keep an egg from breaking after you launched it off a building.

Who is your favorite scientist and why. Has anyone else influenced you to this career?

I’ve always been a fan of Rachel Carson (author of Silent Spring )and her descriptions of the natural world. Jane Goodall is a groundbreaking ecologist who is able to communicate her work.

Mentors: Everyone I work with these days is a constant inspiration. Early on I was influenced by Dr. Julia Parish, leader in the field of seabird ecology, and Dr. Mary Ruckelshaus, leader in marine conservation. Both are accomplished female scientists, strong women, and excellent mentors. My graduate advisor, Dr. David Armstrong, was also a strong inspiration and mentor for both scientific achievement and emotional intelligence.

Tell us about your greatest scientific achievement thus far:

Being able to pull together an amazing team of people to look at climate change in Alaska.

Give us a science fact not very many people know about:

The Bering Sea is twice the size of Texas and it produces roughly enough pollock catch each year to feed every person in the U.S. a five-ounce pollock dinner for an entire week.

What’s your favorite science fiction movie and why?

The Abyss, an ’80s movies set on the sea floor. Also really enjoyed Interstellar, a clever way of talking about communication across gravity.

What’s your favorite science/tech gadget?

We’d be hard pressed to live without satellites! But some of the most fun are acoustic tags you can put on fish, crabs, whales.  After tagging blue fin tuna, scientists discovered the fish were traveling across the Pacific and back.

What’s your workspace like, and why does it work for you?

My day-to-day office at NOAA has three monitors and a computer. I work with people close by, analyzing data.

For field work, I also fly on an airplane to Anchorage, then a propeller plane to Dutch Harbor and a boat out to the middle of the Bering Sea. Seeing the environment and the fish makes the numbers more real.

On the boat, usually there’s a crew of four or five scientists, a captain and three deckhands. You get up in the morning and set the net, then pull it up after 20 minutes. If the waves are rolling, everything’s sliding back and forth, the fish on the table are squirming and flopping around. We measure the halibut and return them to the water so they don’t die. For a small portion of the population, we remove the stomach and have the team count the fish inside or bring them back to the lab in Seattle to analyze. We do that four to five times a day, every day for three weeks.

There’s a method to the day. Collect fish. Write down the numbers. Repeat. There’s something therapeutic about that. You’re out in the world, observing it, not sheltered. It makes you feel very alive.

Your best tip or trick for managing everyday work and life.

Bottom line: You have to love what you do. It’s really hard for scientists to leave work at work. I love what I do and I could do it 24 hours a day and stay up all day and night doing it. I have to put it down and pick up being a mom, wife, friend and sister and put as much energy into that. It makes me more efficient at work. My daughter is 5 ½. She’s a little scientist.

Mac, Windows or Linux?

Mac. And lot of R and C+ programming packages.

Kirk, Picard, or Janeway?

Tina Fey. I like comedies.

Transporter, Time Machine or Cloak of Invisibility?

Time machine.

If someone gave me $1 million…

I’d leverage a long-term conservation goal. A project that could involve the public in science. Citizens, conservation, protecting land, understanding probability and uncertainty.

I once waited in line for…

Coffee, daily, 10 minutes ago…

First Computer

The first Apple notebook.

Current Phone

iPhone 6

Favorite App


Favorite Cause

Climate change and everything around that.

Most Important Technology of 2016

Smart phones in general and advances Google has made with meta-information to understand everything from traffic to all this info from individual users. The idea of the collective unconscious.

Most Important Technology of 2018

It’s going to be really important for us to see what’s happening environmentally. We have a couple satellites up collecting information on sea ice. Improving computer speed . . . quantum computers will be world-changing. So will electric vehicles – anything Tesla does will be huge.

Final words of advice:

It’s easy in this day and age to get a little discouraged when you’re doing a lot of work and it’s hard to know what your niche is going to be. As long as you follow what makes you happy and work with people that you like, it will all fall in place. In the end, you have to trust the people you work with. You can’t do it alone; you need a team.

Dr. Kirstin Holsman is a research scientist with the Alaska Fisheries Science Center (NOAA Fisheries). In collaboration with colleagues at NOAA and the University of Washington she’s developing methods to assess and manage the impact of climate change on fish and fisheries. You may have caught (ha!) Holsman’s fascinating discussion at Pacific Science Center’s Science Café: “Seafood 101: How Ecosystem Science Informs U.S. Fishery Management.”

Get a new perspective on math and life at  Math Moves!, on exhibition through May 1, 2016. Talk with local scientists about their cutting-edge research at our Science Cafés.

Photo of Dr. Kirstin Holsman at Skaftafell at the base of the Vatnajökull glacier in Iceland, 2013; photographer, Sean McDonald.