Off the Maine Coast, Puffins Reveal Secrets of Atlantic Herring and the Ocean

Atlantic herring are vital to coastal ecosystems on the East Coast as prey for a wide variety of marine wildlife. This month, the New England Fishery Management Council will decide how to protect herring in coastal waters from intensive industrial fishing, and how to change the way that catch limits are calculated for this critical fish. The Pew Charitable Trusts recommends that the council vote to protect waters out to 50 miles from shore and set catch limits that reflect herring’s value to the ecosystem. This article is part of a series to raise awareness about the importance of herring.

Derrick Jackson/Courtesy of Steve Kress

Zoologist, wildlife manager, and environmental educator Steve Kress is a keen observer of New England’s marine ecosystem, which he studies as director of the Audubon Society’s Project Puffin. The behaviors and population fluctuations of these and other seabirds in the region tell scientists a lot about ocean health. Kress’ project has helped puffins return to some of the uninhabited islands in the Gulf of Maine to nest. The Pew Charitable Trusts spoke with Kress to discuss why forage fish, and especially Atlantic herring, matter to puffins.

Q: How did you come to study seabirds?

A: I was initially attracted to them when I visited nesting colonies in the Bay of Fundy in the late 1960s. In 1969, when I was teaching at Hog Island Audubon Camp in Maine, I discovered that puffins once nested on nearby islands but had been gone for nearly 100 years. I set out to try to restore the colony on Eastern Egg Rock Island, and eventually birds started breeding there in response to what Audubon was doing. It was the first puffin colony ever restored. Now about 1,300 pairs of puffins nest on five islands off the Maine coast.

Q: What do you monitor about the puffins recolonizing these islands?

A: We weigh and measure chicks, band birds, and, over the long term, record return rates and how long they live. In the 1980s, we started watching the food that seabirds bring back to their chicks and now have over 30 years of data on what species feed their chicks. We have one of the longest and largest data sets out there on this.

Q: Describe a typical summer day for a researcher on an island colonized by puffins.

A: From dawn to dusk, a research assistant will try to track the number and kind of fish that puffin parents are delivering to a particular chick. When the chicks are past three weeks old, we do something called grubbing—stretching down under these huge boulders to pull the chick out of the nest. A grubber might have half of their body under the boulder, and someone else has to help pull them out from the hole. When we succeed, we pull up this fluffy, very adorable puffin chick—proof that this restoration is working—then we weigh and measure to determine its health, and band it.

Q: Why are herring important to puffins?

A: Many kinds of birds depend upon herring because they’re high in fat, with two to three times the calories of other prey fish. Just one beak full of herring could make a meal for a chick. It’s also the right shape to slip down the throat of a chick without work or stress, so parents can raise their young faster and fledge heavier chicks than with other fish. Fledging weight is important: Heavier chicks have a better chance of surviving at sea than lighter-weight chicks.

Q: What do seabirds reveal about the state of ocean fish?

A: Seabirds are good indicators of fish population because most of their diet is made up of fish, and in the summer they almost always eat small fish, which they also feed to their chicks. Seabirds need a lot of fish—it can take over 2,000 fish to feed a single puffin chick during the weeks before they fledge. Once they leave the nest, puffin chicks must survive on their own, and their return rates are indicators of how much food is in the water around the islands. We also track changes in breeding, and when birds lay their eggs.  While puffins only lay one egg per year, other species such as terns can lay many eggs; that number increases with good food supplies.

Courtesy of Steve Kress

Q: And what do seabirds convey about the ocean ecosystem?

A: We’re seeing changes in the timing of breeding and declines in chick weight. Coupled with the fact that herring numbers are falling, this suggests that puffins have difficulty raising chicks on alternative foods. We’re also noting that when there is insufficient food, some puffins do not nest. This is because they lay unusually large eggs—equal to about 15 percent of the female’s body weight—and producing those requires a lot of energy on the part of the mother. A scarcity of eggs suggests that the puffins aren’t getting enough to eat. While Maine’s puffins are still thriving, elsewhere, such as in southern Iceland, the number of pairs occupying burrows is declining. It is clear that seabirds are sensitive measures of what’s going on in the ecosystem around them.

Q: How can the New England Fishery Management Council improve policies on Atlantic herring?

A: Under the current approach, with catch limits set every three years and a constant level of fishing allowed in each of those years, there is a 50-50 chance of overfishing in the third year of each period. So there is a high risk of taking too many herring. The council has evaluated its management strategy, including hosting workshops that my colleagues participated in and taking public comment. The council must move toward a better, ecologically based approach—one that ensures enough fish in the water for wildlife and for a sustainable herring fishery. The rules should be informed by solid science. For instance, if puffins and terns are bringing back few herring for their chicks, acoustic surveys find very low herring numbers, and the fish are underweight for their age, that’s a strong signal to reduce fishing pressure so more can survive to reproduce.

Q: What would a restored or revived Gulf of Maine look like?

A: A restored, healthy Gulf of Maine would have more forage fish in it. Forage fish nurture not just seabirds but other species, from predatory fish to whales. More forage fish would mean more life in the Gulf of Maine. The temperature and chemistry of oceans are changing, and this is challenging seabirds at the ecosystem level. Protecting forage fish is a win for people and ocean wildlife.

Jud Crawford