Dams, Sand Supply Reduction + Habitat Recovery

March 8, 2024

Illustration of the fish Alewife. Alosa pseudoharengus. (Courtesy of NOAA Great Lakes Environmental Research Laboratory, CC BY-SA 2.0 DEED, via Flickr).

Dammed but Not Doomed – Hakai Magazine

As dams come down on the Skutik River, the once-demonized alewife—a fish beloved by the Passamaquoddy—gets a second chance at life.

Heroic fish tales tend to focus on species with a certain je ne sais quoi: the leaping salmon, the globetrotting tuna, the mammoth marlin towering above its captor as it dangles from a scale. Not so much the modest alewife, flashing in the sunlight as a teenager stands on a riverbank in northern Maine and threatens to stuff it down the back of their friend’s shirt.

But on a mild day in mid-May, alewife—one of two closely related species referred to collectively as river herring—are the undeniable center of attention. On the banks of the Pennamaquan River, students from schools at the nearby Passamaquoddy Nation communities of Motahkomikuk (Indian Township) and Sipayik (Pleasant Point), Maine, gather in groups for Alewife Day. Some wade into the water downriver from a dam to scoop migrating alewives from the churning rapids with long-handled nets, while on the bank, other students, alternating between quiet concentration and enthusiastic retching, divide the fish into buckets so a visiting scientist can teach them how to collect biological information. As he shows the students how to scrape scales from the alewives’ bodies, the scientist apologizes for making them gag. “That’s okay, we signed up for this,” a student replies.

From a vantage point on the dam just upriver, Ralph Dana, with Sipayik’s environmental department, surveys the action. Dana, who often ends his sentences with an upward lilt, as if his enthusiasm is carrying his words skyward, says he likes coming here because it’s so similar to the much larger river at the heart of Passamaquoddy territory: the Skutik, or St. Croix, one river to the north. “It really is a scale model of our river,” he says. Like the Pennamaquan, the Skutik has dams; it has fishways, watery ramps that help fish swim around obstacles; and it has alewife, which, as Dana has spent the morning telling students, are in trouble.

Every spring, runs of alewife (siqonomeq in Passamaquoddy)—a slender, shoebox-length fish suited to charging against the current—navigate from the Atlantic Ocean to the freshwater habitats where they spawn, traveling up rivers and streams across northeastern North America. The Skutik, which begins at a group of lakes puddled along the Maine–New Brunswick border and runs 185 kilometers along the international boundary to Passamaquoddy Bay, plays a particularly important role in this migration: the river once supported what was the largest run of alewife in Maine, and potentially on the continent, a coursing silver line connecting the fresh water and the sea, some 80-million-fish strong.

For the Passamaquoddy, a nation of approximately 3,500 people whose territory straddles the Canada–United States border, the abundance of alewife in the Skutik River supported a way of life stretching back millennia. (Archaeological work in the territory has found alewife bones in charcoal pits dating back 4,000 years.) But over centuries, the Passamaquoddy were forced off their territory, even as dams blocked the passage of alewife upstream. At one point, barriers threatened to wipe alewife out from the river altogether.

After years of effort led by the Passamaquoddy, alewife are now poised to recover. Last summer, work began on the most significant step yet: removal of the Milltown Dam, the first barrier fish encounter when migrating upstream. That work is expected to be completed in 2024.

Yet, the removal of this dam, which was built in the 1880s, is only one step in a much longer journey toward restoring alewife, and their habitat, across the Passamaquoddy Nation’s territory—a journey that has united scientists, Indigenous communities, and officials from occasionally squabbling countries on both sides of the border. Such a restoration would benefit the whole ecosystem—everything from whales to eagles to salmon eat alewives—as well as industries like lobster fishing, but it’s also inseparable from the nourishment of the communities surrounding it. And if there’s a fish who could carry this responsibility, it’s the unassuming alewife; to the Passamaquoddy, this fish feeds all…


More on Dams and Sand Supply Reduction + Habitat Recovery

Mekong River (by Dominique Bergeron CC BY-NC-ND 2.0 via Flickr).

China’s Mekong dams turn Thai fishing villages into ‘ghost towns’- Context

From February to April each year, Kam Thon spends most of her days knee-deep in the waters of the Mekong River by her village in northern Thailand, gathering river weed to sell and cook at home. Kam Thon and other women who live by the Mekong have been collecting river weed, or khai, for decades, but their harvest has fallen since China built nearly a dozen dams upstream. The dams have altered the flow of water and block much of the sediment that is vital for khai and rice cultivation, researchers say…

Fishing Boats in the Old Hammamat - Tunisia (by Ghassan Tabet CC BY-NC 2.0 via Flickr).

Why are Tunisia’s beaches disappearing and what does it mean for the country? – Reuters

Rising sea levels are causing Tunisia’s beaches to gradually disappear. This is making life hard for the country’s tourism and fishing industries.

The Maghreb – made up of Morocco, Tunisia, Algeria and Libya – is more affected by coastal erosion than any region outside South Asia, the World Bank found in a 2021 study. Among these countries, Tunisia has had the highest erosion rates in the last three decades, averaging almost 70cm a year, it found…

Sand dunes in Kernel - Sydney, Australia (by Bea Pierce CC BY-NC 2.0 via Flickr).

Grains of Sand: Too Much and Never Enough – EOS Magazine

Sand is a foundational element of our cities, our homes, our landscapes and seascapes. How we will interact with the material in the future, however, is less certain…

“The use of sand is now faced with two major challenges,” said Xiaoyang Zhong, a doctoral student in environmental science at Leiden University in the Netherlands. “One is that it has caused enormous consequences in the environment,” he explained. “The second challenge is that easily usable sand resources are running out in many regions…”

Mekong Basin (by Shannon1, CC BY-SA 4.0 via Wikimedia Commons).

Starving the Mekong – Reuters

Lives are remade as dams built by China upstream deprive the Mekong River Delta of precious sediment

Standing on the bank of the Mekong River, Tran Van Cung can see his rice farm wash away before his very eyes. The paddy’s edge is crumbling into the delta.

Just 15 years ago, Southeast Asia’s longest river carried some 143 million tonnes of sediment – as heavy as about 430 Empire State Buildings – through to the Mekong River Delta every year, dumping nutrients along riverbanks essential to keeping tens of thousands of farms like Cung’s intact and productive…

Daytona Beach, 20022 (by Jim Allen CC BY-NC-ND 2.0 via Fliickr)

Florida beaches were already running low on sand. Then Ian and Nicole hit – the Washington Post

“I think we’re starting to discover that, despite our best efforts and wanting to throw as much money at this as possible, it has become very difficult to keep these beaches as wide as we would like to keep them,” Robert S. Young, a geology professor at Western Carolina University and director of the Program for Developed Shorelines… “We simply don’t have the capacity to hold all of these beaches in place.”

Plaża w Benalmadenie na Costa del Sol (Photo: Beata77, CC BY-SA 4.0 via Wikimedia)

Half of the beaches on the Costa del Sol are at serious risk of sand loss – SUR

The loss of sand is a “serious risk” for half of the beaches in Malaga province, while another 40% are at “moderate risk” and 5% at slight risk, according to a report on the Strategy for the Protection of the Malaga Coast which the Secretary of State for the Environment, Hugo Morán, presented to mayors and councilors in Malaga on Tuesday morning…

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