"Nick, how does a hatchery count the fish it stocks?"
In Wyoming there are ten fish hatcheries, which stock over 5 million fish in 450 waters statewide every year! The number that is stocked into each lake can range from 100-250,000 fish therefore, counting each individual stocking can be very easy or somewhat complicated. Here are a few cases that show how we count:
Small stocking: Sheridan fairgrounds pond for example, was stocked in 2017 with 100 fall rainbow trout. For this stocking we could easily count our 100 fish on to a fish distribution tank.
Medium stocking: Jim Bridger Pond in south central Wyoming was stocked with 3,000 fall rainbow trout in 2017. In this case it would take a long time to count the fish on the distribution tank, so we would take a small sample of fish to determine how many fish there are in one pound. To collect these samples we take a net full of fish, weigh that net load and count the number of fish in that sample. This is repeated a number of times until we have an average for the group of fish. Using that average we can figure how many pounds of fish to load into our tank and ultimately release for you to enjoy.
Large stocking: When Pathfinder reservoir in central Wyoming was stocked with 86,000 fall rainbow trout in 2017, a sample count was done to determine how many pounds of fish would be needed to stock 86,000 fish. At 4,000 pounds per truck, multiple truck loads are needed to fill such a large request. The trucks which are equipped with scales, weighed the poundage of fish being loaded. A running count was kept over the two week period for every truck load that left, until the goal was met.
After every individual stocking trip, the number of fish stocked is entered into a statewide database to help Game and Fish fish managers know which lakes have been stocked and how many fish are still needed to complete the stocking requests for the year.