Fisheries staff from DEC Region 8 conducted a survey of two tributaries to Lake Ontario, Sandy Creek and Oak Orchard Creek, as part of a strain evaluation of stocked Atlantic salmon. The purpose of the survey was to assess the survival and return of two different strains of Atlantic salmon stocked into Lake Ontario: one is the Lake Sebago strain that has been stocked since 2017, and the other is a low thiamine tolerant strain.

Atlantics are especially susceptible to low thiamine issues which stems from eating alewives, the primary forage fish of Lake Ontario trout and salmon. Alewife contain an enzyme called thiaminase which breaks down thiamine (Vitamin B1) in adult trout and salmon. When this occurs, the adults pass insufficient thiamine to their eggs, causing a condition called Early Mortality Syndrome which limits survival of newly hatched fish. Both strains of Atlantic salmon were raised at the USFWS Dwight D. Eisenhower National Fish Hatchery in Vermont. While in the hatchery, genetics are taken from the parents of both strains, so each fish subsequently caught from Lake Ontario will be able to be traced back to the original parentage strain.

During the survey, a total of 63 Atlantic salmon were caught with lengths ranging from 20 to 31 inches. Fish were caught using a boat electrofishing unit which sends an electrical current into the water and temporarily stuns the fish. Fish are then scooped up with a long-handled net and placed into a holding tank for recovery. Once recovered, a small portion of the adipose fin is clipped for genetic testing, scales are collected for aging and a length is measured. The fish is then released to continue its journey up the creek. The information gathered from the survey will help inform future stocking strategies to ensure optimal survival of Atlantic salmon stocked into Lake Ontario.

These efforts tie into the Lake Ontario Atlantic Salmon Fisheries Management Plan (PDF) which aims to improve the survival of stocked fish and increase the number of adult Atlantic salmon that return to tributaries to spawn.