Group Reports 2017 Herring Count Numbers for North & South Rivers, MA
August 9, 2017
The following report was provided by the North South Rivers Watershed Alliance.
The North South Rivers Watershed Alliance of Massachusetts recruited and trained 87 citizen scientist volunteers this year to count river herring migrating into First Herring Brook in Scituate, Third Herring Brook in Norwell and Hanover, Herring Brook in Pembroke, and the South River in Marshfield. From April 1 to May June 14 volunteers spent over 154 hours in 10-minute intervals counting over 11,341 fish.
Counts at First Herring Brook in Scituate have been low for the past few years, despite flow being restored to the Old Oaken Bucket fish ladder in 2012. No herring were seen by volunteers this year. NSRWA is working closely with the Town of Scituate to continue to provide flows for herring and instream habitat however, and is working to expand potential habitat by improving access to the Reservoir.
Herring counts were conducted at three sites in the Third Herring Brook this year now that Tack Factory Dam has been removed. Volunteers counted at the usual location of River Street and Broadway, as well as at the Tack Factory site and Mill Pond site. Roughly 2,600 fish were seen at River/Broadway, the most seen ever. Volunteers also saw six fish pass the Tack Factory site, on April 12 and May 9. Because that site is now open river, fish passage may be sporadic and spread out. NSRWA is working on ways to detect passage more effectively at both Tack Factory and Mill Pond.
Herring Brook is certainly our most robust population, reaching 7,649 herring observed by counters (the second highest year, behind 2012’s 10,449 count). The first sighting at Herring Brook was April 11th, counts then peaked on April 18, and the final sighting was May 22. Herring Brook is the only location where substantial counts and the presence of a fish ladder allow a provisional population estimate to be made. This year the population of Herring Brook is estimated at 91,219 +/-12,197 based on volunteer counts. This is likely lower than the counts from the electronic counter on Herring Brook, possibly due to missed fish that passed before 7am or after 7pm, when volunteers are not counting.
Volunteers at the South River counted ~1000 total herring downstream of the Veterans Memorial Park fish ladder, beginning April 11th, peaking May 25, and concluding May 29. This was also the first year that fish passing the ladder were observed in double digits (57), likely due to the attention and care that the Town of Marshfield took to ensure adequate flow. The fish ladder is very sensitive to changes in flow and can be hard to manage.