The survey crew did our first sampling on May 23^rd- a beautiful day to be on the lake. We measured temperature and dissolved oxygen from the top on the lake to the bottom of the lake to characterize the lake environment. We then took water samples to measure nutrients and chlorophyll-a from almost every meter in depth. We also captured a sample of zooplankton.

Chlorophyll-a is a pigment found in algae cells, so we use the amount of chlorophyll-a as a proxy measure of the amount of algae in the lake (a much more difficult thing to measure because the algae are so small). By the way, you might also hear us refer to “Phytoplankton” – the name means “plants that float around” – these plants are the tiny algae that we measure indirectly using the chlorophyll-a amount. Often when there are many algae in the water the water may appear green and the water clarity drops (an algal bloom!).

This year the alewife run started on May 24th – later than most runs in the region because the fish migrate upstream cue on temperature – and the Presumpscot River, originating in Lake Sebago, is colder than most. Fish are still continuing to come in to spawn, but we’ve also started to see some spawners heading back out to sea. To date (7 June), 8559 fish have been counted directly. We will use a statistical method to calculate the total number of fish at the end of the run.