The first visual count of fish was undertaken at Nequasset Fish Ladder from April 13-June 3, 2012. Information below may assist other community groups interested in establishing a volunteer based visual count.
The counting methodology was defined and approved by Gary Nelson of Massachusetts Division of Fisheries, author of “A Guide to Statistical Sampling for the Estimation of River Herring Run Size Using Visual Counts”. Eliminating three hours on either side of low tide and limited to daylight hours, an average of 5 counting periods were defined for each day, and volunteers were asked to count two 10 minute slots during each 2 hour counting period, with as large a separation between the slots as possible.
|Dates||April 16-June 2, 2012|
|Harvest||1,111 bushel; 133,320 fish|
|Fish over the dam, actual||2,766|
|Fish over the dam, extrapolated||29,916|
|Estimated Total Run||164,000|
|# of volunteers||73|
|# of group tours||0|
Volunteers signed up to count 141 out of 240 periods (58%) during the 6 week spring migration. Volunteers were recruited through KELT email and local media; we had several headlining stories in local newspapers including Wiscasset Newspaper and Times Record.
Sign up took place online through a GoogleDoc accessed through the KELT website, this worked VERY well. Project Manager, Alicia Heyburn maintained the GoogleDoc and nightly checked to see if there were gaps sending email confirmations and soliciting more help if needed. 73 individual counters registered, and one individual counted 18 times (another 17, another 15).
A summer intern from Bates College offered three training sessions for volunteers and managed the data, compiling raw data into an Excel spreadsheet and running the statistical analysis to determine the size of the run.
Data analysis of the 2012 count data using Gary Nelson’s VisuCount program estimated the run at 29,916. The estimated ratio of fish passed/fish harvested is 18.3%. Based on the studies done in the 70’s and 80’s, Department of Marine Resources works toward 235 fish returning per surface acre with 35 passing and 200 harvested making their “sustainable” target ratio 17.5%.
2012 harvest was 1,111 bushels (at 120 fish per bushel = 133,320 fish).
Water Testing: Bev Johnson, Bates College Geologist, undertook a study on the biogeochemical cycling of nitrogen and phosphorus in Nequasset Lake on a monthly (biweekly initially) basis April – November. She hypothesizes that there will be an increase in DIN concentrations and an increase in nitrogen isotope composition of the NO3-, NH4+, seston, and zooplankton with the arrival of alewives (marine derived nutrients). The goal is to evaluate the relative importance of alewives to the input/export of nutrients to Nequasset Lake. Volunteer Pat Lewis held samples in her home freezer for collection.
Why count? To properly manage the important alewife run for long term sustainability, data is needed on how many fish attempt to access the spawning grounds of Nequasset Lake.
NO FISHING! The area immediately above and below the dam is posted “no fishing” by the state and the alewife fishing rights are awarded to the town and subsequently to a harvester. Please respect this law.