Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Midwest Region, December 23, 2012
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Eggs being gently squeezed from an anesthetized female lake trout.
Eggs being gently squeezed from an anesthetized female lake trout. - Photo Credit: Crystal LeGault-Anderson, USFWS
Eyed lake trout eggs being carefully packed for shipment.
Eyed lake trout eggs being carefully packed for shipment. - Photo Credit: James Anderson, USFWS
Mechanical egg picker sorting
Mechanical egg picker sorting "good" and "bad" eyed lake trout eggs. - Photo Credit: USFWS

Sullivan Creek National Fish Hatchery ships eyed lake trout eggs to other federal, state, tribal, and research facilities every November and December. This year Sullivan Creek has shipped over 5.6 million eggs in total with eggs transferred to: Jordan River National Fish Hatchery, Iron River National Fish Hatchery, Pendills Creek National Fish Hatchery, Dale Hollow National Fish Hatchery, Marquette State Fish Hatchery (Michigan Department of Natural Resources), Les Voigt State Fish Hatchery (Wisconsin Department of Natural Resources), and the Upper Midwest Environmental Science Center (UMESC) for the purposes of lake trout restoration of the Great Lakes, recreational fisheries in reservoirs, and research. Sullivan Creek NFH is one of very few lake trout brood fish stations in the U.S. Fish and Wildlife Service for the entire country.

The whole egg process begins with spawning season, which usually starts by the middle of September and runs until the middle of November each year. The adult lake trout are anesthetized so the eggs and milt can be collected and mixed together for fertilization. This allows the staff to handle the adults without harming them, and the fish will come out of the anesthetic and “wake up” in about twenty minutes after the process is complete.

Once the eggs are fertilized, disinfected with iodine, and water hardened which means to pull enough water inside their shells for the eggs to become “hard,” they are measured and counted into vertical stack incubators. The eggs will slowly develop inside the incubators for one to two months depending on how cold the water temperatures are, and will become “eyed eggs” where you can see the little fish eyes through the outer shells of the eggs. At this point, the eggs are “shocked”  or bounced fairly hard to get the “bad” eggs – ones that did not fertilize – to turn opaque white when the yolk is broken inside the egg. This process does not harm the good eggs at all.

The next step is to run all the eyed eggs through mechanical egg pickers which have a light sensitive photo-eye. The pickers shoot a ray of light through each egg, and if the light goes through the egg, it is a good egg and goes in one bucket. If the light cannot go through the egg, it is a bad egg and goes into a different bucket. We run all our eggs through two mechanical pickers, and hand pick them with tweezers or suction bulbs at least once. The good eyed eggs are again measured and put back in their incubators until shipments can be set up.
Eyed eggs are carefully packed into Styrofoam coolers and either shipped via FedEx, UPS, or transferred between facilities by hatchery staff. The little fish inside the eggs are looking at you the entire time.  That is a lot of eyes!

Contact Info: Crystal LeGault-Anderson, 906/437-5231, crystal_legaultanderson@fws.gov
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