Photos of the Long Island Sound

Research & Monitoring

Status & Trends

LISS Ecosystem Targets and Supporting Indicators

Herring Runs at Streams with Upstream Planned Fishway Projects

( Click labels in legend to hide data and adjust scale )
Alewife – Fish Counter
Queach Brook Mill Brook Greeneville Fishlift (Shetucket River)
2002 10,048 2,288
2003   4,198    335
2004   2,385    318
2005   1,790    586
2006     3,113   9,131 2,681
2007     1,250       142 2,422
2008     2,684       797    535
2009     3,477           9    190
2010   50,668   1,239    156
2011     4,476   9,080    248
2012        610 17,057    267
2013        563   9,137    713
2014     1,395   1,543    787
2015        538      134    502
2016     1,514      406 1,456
2017     3,308   8,522    735
2018        738   6,989 1,653
2019 385 11,232 699
– indicates no counting done.
Shad – Fish Counter
Greeneville Fishlift (Shetucket River)
2002 3,056
2003 4,573
2004 1,993
2005 1,750
2006 1,981
2007 2,453
2008 1,966
2009 2,168
2010 2,461
2011    992
2012 3,132
2013 3,800
2014 2,248
2015  1,919
2016  2,669
2017  1,910
2018  1,216


River herring is a collective term for the Alewife, Alosa pseudoharengus, and Blueback herring, Alosa aestivalis, two anadromous fish species that are related to the American Shad. Anadromous fish migrate from the ocean to rivers to spawn.  The coastal range of the Alewife extends from northeastern Newfoundland to South Carolina, while that of the Blueback Herring extends from Nova Scotia to Florida. Both species undertake upriver spawning migrations during spring.  The American Shad, Alosa sapidissima, is the largest of the herring family, and is a favorite Connecticut River sportfish. It also undertakes upriver spawning migration during spring. The historic range of American Shad was from the St. Lawrence River to Florida. Shad are still distributed throughout their historic range but shad are most abundant in east coast rivers between Connecticut and North Carolina.


River herring and shad are important to our freshwater, marine and estuarine ecosystems because adult herring and their young provide food for a variety of predators including freshwater gamefish, marine gamefish, osprey, bald eagle, harbor seals, porpoise, egrets, kingfishers, and river otter. Historically, river herring runs into Connecticut rivers and streams numbered into the millions; however, runs have been declining steadily in recent decades. To help restore river herring populations and other anadromous fish, CTDEEP has built fishways at dams, removed dams, and widened culverts to allow fish to bypass barriers to find habitat upstream to spawn.


This group of streams has one fishway where fish are counted.  The amount of available habitat upstream of the fishway is expected to increase due to future fish passage projects (e.g. there are upstream dams that will have fishways in the future).  Because of this, the number of fish returning in the future will likely increase regardless of survival at sea.  These numbers can be used as an index of how restoration is progressing for each watershed over time.

These Alewife counts were mixed in 2018: Greeneville was up slightly, Mill Brook was down slightly, and Queach Brook was down significantly.  This kind of ‘mixed signals’ has been typical of Alewife runs in Connecticut in recent years.  It is believed that all runs are depressed since the mid-1980s and these ups and downs are relatively minor fluctuations in the respect to the Big Picture, perhaps reflecting the fact that in some years a few more fish by chance slip past nets in the ocean than those destined for another stream, yet this trend could be reversed the following year.

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