West Farms Rapids
The Daily Plant : Monday, October 23, 2006
Pop Goes The Herring?
From August through September, Parks & Recreation’s Natural Resources Group (NRG) staff, Wildlife Conservation Society (WCS) personnel and volunteers from Lehman College, Rocking the Boat and the community have kept their eyes peeled for “popping” on the Bronx River. Popping refers to the feeding behavior of juvenile alewife, which involves a leap out of the water to capture insects as they emerge. The characteristic flash of silver and small splash differentiates popping by these fish from other disturbances on the river.
Alewife, a species of river herring, were reintroduced to the Bronx River, at the Bronx Zoo, on March 21, 2006 from a stream in Connecticut, through a combined effort from NRG, the Connecticut Department of Environmental Protection’s Inland Fisheries Division, Lehman College, the Bronx River Alliance, WCS, and other community partners. After being released into the Bronx River, the transplanted alewife laid low, in deep portions of the river, biding their time until the waters warmed and they could begin spawning. This spawning began in April 2006, resulting in the first generation of Bronx River born alewife since the first dam was built on the river, more than 350 years ago. The adult fish then abandoned their thousands of fertilized eggs and migrated back to the Atlantic Ocean. The embryos eventually hatched into larvae and the larvae grew to become juveniles. At approximately 2” in length, the juveniles begin “popping” during feeding. The juvenile alewife use a variety of cues, including water temperature and day length, to recognize when they ought to follow in their parents’ fin-steps and return to the sea.
To determine whether the spawning was successful, and the juvenile alewives survived, popping surveys were conducted. Employees from NRG, WCS and volunteers counted the number of pops they observed at two locations in the Bronx River during one hour before dusk, three evenings a week from July 18 through the end of September. The evening of August 15 marked the first observed popping on the Bronx River. Observers measured the most activity on August 17, September 7 and September 20, and continued to witness popping until the conclusion of the survey on September 28. These observations confirmed the initial success of the alewife reintroduction project. If all goes as planned the young fish seen this year will return by 2011 as adults to spawn and continue the cycle.
Popping surveys have the advantage of not requiring physical contact that can stress and harm young fish - an obvious advantage over other monitoring techniques. In order to compare alewife activity over multiple seasons, popping surveys will continue for at least the duration of the reintroduction project. Reintroduction efforts will continue for at least the next four years, perhaps longer depending on its success and funding. The goal of the project is to produce a sustainable alewife population in the Bronx River.
QUOTATION FOR THE DAY
“Oh, somewhere in this favored land the sun is shining bright;
The band is playing somewhere, and somewhere hearts are light,
And somewhere men are laughing, and somewhere children shout;
But there is no joy in Mudville - mighty Casey has struck out.”
Ernest L. Thayer