Commissioner Mary Griffin of the Massachusetts Department of Fish and Game and CRWA scientist Elisabeth Cianciola release shad larvae into the Charles.
In spring the U.S. Fish and Wildlife Service grabs adult American shad from the Merrimack River for spawning in tanks at its fish hatcheries in North Attleboro, MA and Nashua, NH. Last week, a Fish and Wildlife truck arrived at Charles River in Waltham with a huge tank filled with a few hundred thousand week-old larvae, each about half the size of a penciled eyebrow.
Shad are the largest member of the herring family and can grow to maybe eight pounds. Present in huge numbers in east-coast rivers, they were easy targets as they swam upstream from the sea to spawn, and they were crucial food fish for native Americans and then early European settlers.
But their range narrowed as dams were built, and like other local fish they were hit further by overfishing, pollution and loss of habitat. A decade ago shad were just about gone from the Charles and the Merrimack.
Both rivers had been painstakingly cleaned up, however. They offered fishways in their lower reaches. And effective technology for propagating shad fry was in hand, as shown by successful restocking programs in Chesapeake Bay and the Delaware River.
So the Fish and Wildlife Service joined with the Massachusetts Department of Fish and Game to begin bringing shad back in 2008. The partners now work with the Charles River Watershed Association (CRWA) to stock up the river with two or three million larvae annually.
This year, they were pleased to find that in a sample of adult shad in the Charles, most came from the restocking program.
“I’m really happy to return this part of the Charles River to wildlife,” CRWA executive director Robert Zimmerman told the small crowd gathered on the river bank just before the release. Nicely written up in a Boston Globe story, the event was a festive occasion, especially for the sunfish who soon lined the shallows for their best lunch of the summer.
In graduate school I took a course in science and society from the Russian-born nuclear physicist Lew Kowarski, a large elderly man who walked slowly with a cane and tolerated no fools gladly. Kowarski was best known for his 1940 escape from occupied France with most of the world’s supply of heavy water. He and his colleagues in the lab of Frédéric Joliot-Curie had already made key discoveries in uranium fission, and he told us that he had probably contributed about 1% of the research that led to the atomic bomb.
Kowarski also once remarked wryly on the metaphysical speculation that as physicists looked ever deeper for sub-atomic particles, they were creating the particles by looking for them.
I’ve been pondering his remark from time to time ever since.
It came up again last Friday as I sat on the soggy banks of the Stop River, a tributary of the Charles, in Medfield. I was with a team of Charles River Watershed Association volunteers, gathering microinvertebrates from the river bed. The day was gorgeous, the mosquitoes were a cloud. One of our compatriots would slowly trudge up and present a net. We would painstakingly scrape off the contents, seeking barely visible bugs among mud and weed and other river debris. We found worms, scuds, mayflies, clams, dragonflies, diving beetles and others not known to me, all plunked in alcohol for later careful identification and counting.
Most of these guys were truly tiny and we could only spot them as they moved around. The more we looked, the more we found—and it began to feel like we could keep finding them indefinitely.
That reminded me once more of Kowarski’s comment.
It also brought up a related and well-known concept drawn more from psychology than physics or metaphysics: So often we find what we expect, and sometimes that’s more about our expectations than our findings.
I also wished that I had found out more back then about Kowarski, whose claims to fame included building the first reactors in Canada and France, and the ability to play the piano with hands crossed behind his back. You can read more of his remarkable story in this 1969 Institute of Physics interview. His life was full of surprises.