Fish need calcium—so do trees. In eastern Maine, there’s not enough of it. After a century or more of acid rain, the calcium in our soils and in our waterways has been leached away. And, while the acid rain has abated significantly since President George H. W. Bush implemented major amendments to the Clean Air Act, the levels of calcium in our soils have not recovered. They will in time—decades from now natural weathering will replace the lost calcium in the soil. Rainwater, percolating through the ground, will then deliver it to streams and rivers where it will be available once again to fish.
Until that happens, however, terrestrial and aquatic life is diminished. If you happen upon a stream that has no water spiders skittering across its surface, no bugs and crawly things under its rocks, or no minnows darting back and forth, there’s a good chance there’s not enough calcium in the water. If you are an owner of a woodlot and notice that your trees are growing more slowly than they should, if their terminal buds or the outer edges of their leaves are dying—then there’s a good chance your soils are low in calcium.
The Downeast Salmon Federation is working to recover native species of diadromous fish—fish that live part of their lives in salt water and part in fresh. The organization was founded by hook and bullet clubs that came together in the 1980s to speak with a more powerful voice when the numbers of Atlantic salmon running up Maine rivers dropped off a cliff. The decline in salmon was so severe that the federal government listed the iconic fish as endangered in 2000. Since then, a tremendous amount of work has been done tackling—what appeared to be—the key reason for the fish’s decline: no or limited access to its freshwater spawning grounds. Dams have been removed, barriers bypassed, impassible culverts replaced with fish-friendly ones. These efforts were huge, and today many hundreds of acres of freshwater habitat are now accessible to salmon—yet salmon populations continue to decline. In recent years, less than 1000 adults a year have returned to Maine to spawn.
Clearly, there is another factor at play preventing recovery. In truth, there are probably many factors keeping salmon numbers low, but DSF believes that the next important factor to address is low calcium.
Fish need calcium for strong bones—but low calcium also results in high acidity and increased levels of toxic aluminum. Salmon, brook trout, and several other native species are extremely sensitive to acidity. The toxic aluminum released into water when calcium levels are low binds to a fish’s gills making it unable to transition from fresh to salt water.
Trees need calcium to build cell walls—trees deficient in calcium are unable to produce new leaves or needles, root tips, or woody growth. The impact of acid rain may be exacerbated on Maine’s commercial timberlands because logging—cutting down a tree and making a house with it--also removes calcium from the local ecosystem.
Conceptually, low calcium is easy to fix: add calcium. Calcium, in the form of agricultural lime, is cheap. The difficulty is you need hundreds of tons of it spread over a huge area. The only viable treatment method is by helicopter. Helicopters are not cheap. A helicopter assisted terrestrial liming project underway in Nova Scotia (video) is costing US$1,200 (after initial capital costs) to spread 10 tons/hectare in a sub-watershed of the West River.
Here’s where the win/win kicks in. Spreading calcium on forest lands benefits both timberlands and fish. DSF is in the initial stages of talking to landowners and raising funds to initiate a liming project in a salmon stream in eastern Maine. We also hope to add a third “win” to our project by engaging the Coast Guard or Army. Airlifting lime could provide helicopter crews with flight time and good practice carrying loads. And, not incidentally, would lower our helicopter costs.
As we see it, terrestrial liming would be an example of how recovering a near-extinct fish would benefit both the fish and the neighboring landowners. Everybody wins.