Jean Adams is a statistician with the U.S. Geological Survey-Great Lakes Science Center and the Great Lakes Fishery Commission, both in Ann Arbor, Michigan. She earned a master’s degree in statistics from the University of Wisconsin and spent two years with the Peace Corps in Papua New Guinea.
Spending eight days on Lake Ontario doing fieldwork gives statistician Jean Adams a better idea about the kind of statistical support her colleagues in the U.S. Geological Survey need. What follows is a record of one day on the trip.
I climb down from my bunk at 7 a.m. Bob, the biologist in charge, is already in the galley. This is his cruise. He’s been trawling for alewives in Lake Ontario every spring for 30 years. It’s his life’s work. Ted, the biological technician, is readying the equipment for the day. Ed, the captain, tells us the weather forecast: east winds 10–15 knots, waves 1–3 feet. Bob says, “We’ll start with the transect closest to port and work our way out. If the winds pick up, we’ll high tail it back to the dock.” Nods all around. Terry, the engineer, fires up the ship’s engine and runs some tests. Then Ed eases the Kaho away from the dock and sounds the horn. It’s 8 a.m. Saturday and we just woke up Olcott, New York.
We all work for the U.S. Geological Survey-Great Lakes Science Center, headquartered in Ann Arbor, Michigan. Bob is a research fisheries biologist and chief of the Lake Ontario Biological Station. I am the center statistician. We’ve been working together on the design of the annual alewife bottom trawl survey.
We’ll be at the first transect in half an hour. I put on my oilers (waterproof overalls), steel-toed boots, float coat, and knit cap, then step out of the warmth of the cabin and onto the back deck. I lean my back against the fish-sorting table and anchor my feet wide apart, watching the horizon slant left then right. I flip up the collar of my jacket and zip it to the top. The boat slows and turns. We’re getting close. The captain’s tinny voice comes over the intercom, “Ready to go, 55 meters, bottom trawl, warp of 600 feet, 10-minute tow.” The warp is the cable that connects the net to the boat. It takes 600 feet of line to get the net down 55 meters so that it’s on the bottom.
After invading the Great Lakes when the Erie Canal opened in 1825, alewives are now a major part of the food web in Lake Ontario. They recently shifted to deeper waters, and Bob wants to change the survey to better target them, so he invited me to participate in the survey and spend a few days onboard the USGS research vessel Kaho.
Bob and I throw the end of the net off the stern into the water. Terry operates the hydraulics that unreel the net. Bob and I stand aside, making sure we aren’t caught up in the net as it races across the back deck. The bottom trawl is made of green mesh, like a badminton net, with grapefruit-sized orange floats along the head rope and heavy chain along the foot rope to keep the net’s mouth open under water. The net floats on the surface of the water behind the boat. It’s shaped like a cone, maybe 30 yards long. Bob and I connect the trawl doors to the net cables; they make a horrible racket as they tumble down the side of the boat into the water. The trawl doors help hold the net on the bottom of the lake, with the mouth open wide, so it can catch fish. The winches groan as Terry lets out the warp. After a few minutes, Terry turns off the winches and shouts, “Net’s down! Brake on! Six hundred feet!” Silence. Ed keeps the boat at a steady speed of 2.5 knots.
The U.S. Geological Survey provides reliable scientific information to manage the nation’s resources, and the Great Lakes Science Center focuses on the living resources and their habitats in the Great Lakes basin ecosystem. It’s a great place for me to work, allowing me to apply my formal training in biology (BS) and statistics (MS) to real-world challenges.
After nine minutes, Ed lets us know, “One minute left in the tow, one minute.” A minute later, he starts the count: “Five, four, three, two, one, pull ’er up.” His voice is immediately drowned out by the winches reeling in the net and the snapping of the cable. After several minutes, the doors appear in the water, blurry and blue. They clamber up out of the water, the heavy chains racing into the pulleys. Terry continues reeling, slowly. “Net’s up!” Bob shouts, to let the captain know. The engine rumbles, the boat turns, and we’re off to the next site. Bob opens the cod end, easing the fish into a tub. We hover over the catch: oval, silver, shining alewives; oblong, gray-green rainbow smelt; boxy, dark-brown round gobies.
I am no expert in fish biology. I don’t need to be. As I work with Bob and other center scientists, I learn enough about their work to understand what sort of statistical support they need. The collaborations are rewarding, and the variety of projects is stimulating.
Bob and I dump the fish on the sorting table. Bob, Ted, and I stand astride counting fish. I lean forward against the table for balance, legs anchored wide. We write down the counts and weigh the buckets of fish. We double-check the data sheet. Has everything been counted and weighed? Good. Now we need to measure lengths. Bob measures alewives to the nearest millimeter and says the length aloud. I put a tick mark next to that number on the length frequency data sheet. The boat slows and turns; we’re getting close to our next site. We take a break from measuring to set the net. When we return, Bob continues to call out the lengths until he’s measured the entire sub-sample.
As a statistician, there is no better way for me to learn about my colleagues’ projects than to participate in their fieldwork. Inevitably, I see things in the field we never discussed in the office, things I never even thought to ask about, things that may have important statistical consequences. Going out in the field is one of my favorite parts of the job.
We hear Ed’s voice on the intercom, “One minute left in the tow, one minute.” Then he calls out, again, “Five, four, three, two, one, pull ’er up.” And so the day continues, site after site, tow after tow, and tub after tub of fish. The engine’s rumble and winches’ groan become a steady rhythm. I am part of that rhythm, part of the routine, part of the machine. By 5 p.m., we’re tied up at the dock again. Over dinner, I tell the guys it’s been good cruising with them. After dinner, I climb up in my bunk, utterly exhausted and thoroughly content. The next sounds I hear are Bob and Ed in the galley fixing breakfast and talking about the weather. Time to get up and do it again.
Leave a Reply