About the Island - Middleton Island Marine Biological Station

The Setting

A Strategic Location for Marine Science

Middleton Island comprises about 2,200 acres, excluding the supra-tidal lands resulting from the 1964 earthquake. The island lies smack in the middle of the main east-to-west flowing currents in the Gulf of Alaska—the Alaska Stream and Alaska Coastal Current.

Well-separated from the coast and low-lying itself, the island is little influenced by such factors as orogenic weather (mediated by coastal mountains), variable freshwater inputs (rainfall/glacial runoff) or other processes operating in a near-coastal environment.

Being situated only a short distance from the steeply sloping edge of the continental shelf, Middleton presents seabirds the option of foraging in either or both of two distinct ecological zones: neritic (continental shelf) and pelagic (deep ocean) marine habitats.

Quick Facts

Location: 60 miles offshore in north-central Gulf of Alaska

Size: 2,200+ acres

Summer Population: ~12 researchers

Winter Population: 2 FAA caretakers

What Makes Middleton Special

Islands have mystique, but Middleton is unique

To the biologist, all islands are appealing, but some are more amenable than others to research. Middleton Island offers several distinct advantages:

A Logistical Paradox

Though uncommonly isolated and remote, Middleton is highly accessible. With the ample and well-maintained airstrip constructed by the Air Force in the 1950s, a trip to Middleton entails just a 1-hour flight from Anchorage via air taxi.

Truly Oceanic

Middleton Island lies in the middle of the main east-to-west flowing currents in the Gulf of Alaska. Well-separated from the coast, the island is little influenced by near-coastal environmental processes.

Two Oceanic Domains

Being situated near the continental shelf edge, Middleton presents seabirds the option of foraging in both neritic (continental shelf) and pelagic (deep ocean) marine habitats.

Connected but Remote

Thanks to FAA infrastructure, researchers have telephone and internet access. The station has steady AC power supply—amenities unexpected in a remote Alaska field site.

Historic Significance

The island lies within the area affected by the Exxon-Valdez oil spill, serving as a useful control site for evaluating spill effects and responses within Prince William Sound.

Seismic Activity

The 1964 Alaska Earthquake raised the island nearly 4 meters, exposing previously submerged seafloor and creating dramatic changes in bird populations—a natural experiment in progress.

Geology & History

From Seafloor to Research Station

Geological History

Geologically speaking, Middleton Island is thought to be less than 5,000 years old. It comprises the exposed portion of a continental shelf area subject to continuous tectonic uplift. In 1964, the great Alaska Earthquake raised the island nearly 4 meters in the span of a few minutes, exposing previously submerged seafloor at the perimeter and greatly expanding the island's area.

Cultural History

Oral history documents seasonal use of Middleton by Chugach and Eyak Native peoples, while the first permanent inhabitants were probably settlers engaged in the fox-farming industry in the late 1890s through the 1920s. During WWII, the U.S. Coast Guard built a small communications station on the island, the first of successive U.S. Government operations including the Civil Aeronautics Administration, U.S. Air Force, Federal Aviation Administration, and various wildlife and land management agencies.

Biological History

Driven partly by changes wrought by the earthquake and partly by large-scale oceanographic factors, bird populations on Middleton are more dynamic than possibly anywhere else in Alaska. The island hosts substantial numbers of kittiwakes, cormorants, gulls, murres and puffins, but no species is stable—huge fluctuations, both up and down, have occurred since regular monitoring began in the 1970s.

Frequently Asked

Questions & Answers

Who owns Middleton Island?

Most of the acreage on the island is owned by Chugach Alaska Corporation, one of 13 Alaska Native regional corporations in the state. The Federal Aviation Administration retains some 200 acres in support of radar installations for weather and air traffic monitoring. The privately owned biological station (182 acres) is the other substantial inholding.

Why have wildlife populations on Middleton fluctuated so much?

Since the 1964 Alaska earthquake, former sea cliffs have eroded and vegetation is steadily advancing. This process affects nesting habitat availability. The "first cause" of volatility is thought to be changes in food supply, triggered partly by the earthquake but also reflecting natural and human-induced trends. A marked increase in predators, notably bald eagles, has compounded these effects.

How's the weather on Middleton?

Many summer days are cool and cloudy (temperatures in the low 50s F), or wet and windy, but balmy days in the 60s (F) can also be expected. In winter it can get quite cold and breezy—winds of 60-80 mph and higher are not uncommon, but the island's maritime setting moderates temperatures and keeps snow accumulation to a minimum.

Do any mammals live on Middleton?

There are no naturally occurring land mammals. However, domestic rabbits were released in the 1950s, and feral bunnies are now ubiquitous. Their numbers decline greatly in winter but rebound quickly in spring. Sea mammals include seals, sea lions, occasional sea otters, and several species of whales.