The spring herring count takes place annually at the Ipswich Mills Dam fish ladder to track trends in the population. The results have shown consistently low numbers of river herring returning to the Ipswich River on their annual spawning migration. Barriers to migration, leading to loss of access to historic spawning ponds have greatly reduced the population compared to adjacent rivers such as the Parker and Essex Rivers.
This year’s count took place from April 1st to June 6th, 2026. Over this time period, 62 volunteers performed a total of 278 individual, ten minute counts using a method designed by the Mass. Division of Marine Fisheries in order to produce a statistically reliable run size estimate. There was good coverage from day to day and the viewing conditions were relatively clear, with less turbulence than can sometimes happen due to high springtime flows. Despite all this only a total of 2 herring were seen among all the counts, making this year’s the lowest ever! We shared the data with the Mass. Division of Marine Fisheries and based on the counting effort and visual count, they calculated a total run size estimate of 21 +/-48 river herring. For comparison, the run size last year was 317 and the average over the last 15 years has been around 500. By contrast, the count at the Parker River for the 2026 season was 32,788!
Another aspect of the herring count has been the addition of a video monitoring system to work alongside the volunteer herring count. The camera records continuously throughout the season and the footage was saved as individual, 30 minute clips for later analysis. Reviewing all that footage is very tedious, so a research group at the Woodwell Climate Research Center and MIT Sea Grant developed a machine learning program specifically designed to identify and count migrating river herring for all fish ladder video monitoring systems like this and others around the region. We are currently awaiting the results and look forward to the reporting on this in the future. Upon checking a few random bits of footage, I noticed a couple of times when small groups of herring were going upstream in the fish ladder during the evening hours, around 8-10 pm, outside of the hours when volunteers count, so we are hopeful there will be more like this!