Counting Herring in the Ipswich River
February 26th, 2013 | by Ryan
If you follow ocean fisheries related news in New England, you know about herring and their decline. But how are herring connected to the Ipswich River? Well, there are actually two classes of herring: Atlantic herring that live exclusively in the ocean and river herring (including Blueback herring and alewife) that swim up rivers to spawn in late spring. In 1600, river herring or alewife existed in the Ipswich River in the millions. Early dams blocked access to the river and by 1840 other migratory fish like Atlantic salmon, Shad and Sturgeon disappeared from the Ipswich, while river herring have barely held on with only a few hundred returning to spawn each year.
Besides dams, historic herring spawning lakes, such as Wenham Lake, have been transformed into water supply reservoirs; and chronic low-flow and no-flow periods caused by water supply withdrawals have all contributed to the decline of river herring. Also, large ocean trawlers targeting Atlantic herring unintentionally take river herring as bycatch. Stocks of river herring have declined more than 95% along the Atlantic coast and many states now have moratoriums on their harvesting. The National Marine Fisheries Service declared river herring a species of concern in 2006.
Since 1999, the Ipswich River Watershed Association has conducted an annual herring count to document the state of the river herring population and raise awareness of the importance of this species. The herring count takes place at the fish ladder on the Ipswich Mills/Sylvania Dam. A counting board is placed in the water at the top of the ladder to increase visibility in the naturally dark water of the Ipswich River. Volunteers perform ten minute counts during daylight hours to see if any fish are entering the river. The goals of the program are to document the status of the River herring population returning to the Ipswich River and to contribute to a better understanding of the current health of the fishery across the region.
The fish count usually takes place from April 1st to mid-June. Volunteers sign up for ten minute counts between 7am and 7pm. By using short count times throughout the day, we make it easy for people to participate while having enough coverage to determine a reliable estimate of how many herring might actually be entering the river for the entire season.
This program is one of the longest running fish counts in the state. In 2012, over 50 volunteers performed a total of 365 individual counts. That is over 60 hours of watching! Since it is impossible to watch the river every minute of the day, the Massachusetts Division of Marine Fisheries has created statistical software to estimate the total run size for the entire season. For 2012 we observed 55 herring from March 25th to June 2nd and the statistical estimate was about 750 river herring returning to spawn. The most herring counted in one year was 133 in 2008. By contrast, the fewest we counted were in 2007 and 2010 when only 15 were observed. Runs sizes in neighboring rivers are much better by comparison; the Mystic River Watershed Association conducted their first annual herring count in 2012 with a staggering population estimate of nearly 200,000 fish! The nearby Parker River also fares better with counts of 2000 fish not uncommon. These may sound like impressive numbers, but they are dwarfed by historical figures in the millions. In the 1970’s, for example, the Parker River had run sizes of nearly 40,000 fish!
We would like to encourage as many people as possible to help us with our herring count this year. The more coverage we have, the more fish we are likely to see and the more accurate our run size estimates. This will greatly aid restoration efforts to restore healthy fisheries. Our annual training will be held on March 19th from 7-9pm at Ipswich River Watershed Association Headquarters, 143 County Rd. Please visit our website: www.ipswichriver.org to learn more about river herring and our restoration work or follow us on Facebook: facebook.com/ipswichriver to find out how you can help.
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