The herring are running and we've had some great news about herring numbers in the Achushnet and Mill rivers due to the recent fish passage projects – see the 'Latest News' section of the website for details. There's also exciting news from our neighboring New England states where some new fish ladders have been built.
There is much we don't know about what has caused the decline of river herring populations – but the effect of dams is quite clear. For example, in 2010 three researchers (Carolyn Hall, Adrian Jordaan, & Michael Frisk) published a paper in the journal Landscape Ecology titled, "The historic influence of dams on diadromous fish habitat with a focus on river herring and hydrologic longitudinal connectivity." They looked at the history of dam construction in Maine and showed that the dams, "...by 1850 had reduced accessible lake area to less than 5% of the virgin 892km² habitat and 20% of virgin stream habitat." I bet the overall story in the other states is similar.
It can take years to get a fish ladder built – the ladder on Poquetanuk Brook, Connecticut had been discussed since the 1970s and the one on the Presumpscot River in Maine since 1996. It is hard and frustrating work to apply for and secure funding from multiple sources, discuss and agree on the appropriate design, coordinate with dam owners, develop plans for operation and maintenance, and then monitor the structure to see if it is working as planned. Thank goodness for all the folks in RI, NH, CT and ME who have advocated for and are implementing these projects.
With monitoring and evaluation each new ladder gives us the opportunity to learn how to build better ones. I look forward to hearing updates on how many fish are passing and I hope that any 'lessons learned' can be applied to projects in Massachusetts. There is still a lot of work to be done!
Hallville Dam in Preston, CT – Poquetanuk Brook, Thames River Watershed
Cumberland Mills Dam in Westbrook, ME - Presumpscot River
Wiswall Dam in Durham, NH - Lamprey River
Abby Franklin - May 13, 2013