Part 3 Life of a Rainbow Trout
In Part 1 and Part 2 of Life of a Rainbow Trout, you learned about the transition of Rainbow Trout eggs into fry. You will now learn about the next stages of development of Arizona’s stocked Rainbow Trout at Sterling Springs Hatchery.
Following the swim-up of the fry, small pinches of a very small, but highly nutritious food are dropped into the trough. We use a small sifter to tap the feed onto the surface of the water until all the fish are feeding at the surface. After a while small, single taps of the sifter turns into several taps an hour. These small taps can continue for 6 to 8 hours a day. We then increase the amount of feedings every other hour or as often as needed.
Once the fish are feeding well, fecal material begins to accumulate in the troughs. The rearing units must be cleaned daily. We take special care to remove all of the fecal material, as well as ,all deformed, dead, and dying fish. We also count the moralities on a daily basis to keep track of how many fish remain in the trough. This is important because we need to adjust the amount we feed based on the number of fish in the trough.
The fry remain in the troughs for about 6 weeks. Around this time, the fry have grown and there are so many fish, they are too dense to remain in the small troughs. At this point, we transferred them to larger tanks inside our hatchery building. Before we transfer the fish to their larger homes, we count and weigh them in buckets.
This process ensures we do not overcrowd their new tanks. We are very careful as we move the fish to reduce any stress the transfer can cause. We count and weight the fish in small numbers with lots of water in our buckets. This can be a tedious process but it is very important to reduce stress caused by overcrowding in buckets.
Once the fish have been moved into the larger tanks, we constantly monitor the oxygen levels in the water. We also adjust the amount of incoming fresh water to keep a constant depth in each tank. All of these actions insure that our fish are healthy, happy, and feeding well. At this point, we are also increasing the feed size to a larger grain. The fish happily gobble up the larger food about 4 times a day as the feed is broadcast over the tank.
After three to four weeks in the larger inside tanks, the fish are bigger and becoming really crowded in their tanks. It is now time for us to move them to an even larger raceway outside. We fill the outside raceway with water from a natural spring. We also place a cover over the raceway to keep birds and other predators from making a meal of our Rainbow Trout. Next, we place shade screens over portions of the raceways to provide cover and protection from the sun. Lastly, we place oxygen stones throughout the raceways to ensure there is enough oxygen in the water for all the fish.
Once again, we determine the number of fish, their size, and their weight using buckets. We then carry the buckets outside as quickly as possible. We then gently dumped the fish into the outside raceways. It takes us all day to move multiple buckets of 3 to 5 pounds of fish. It is important to carry small loads of fish in the buckets to ensure we do not stress the fish.
Once the fish are in their new homes, they stay there for a couple of months. After a few months, they have grown to approximately 3 inches. Once they reach the target size, we transfer them to an even larger hatchery, Page Springs Hatchery. During moving day we take another count and measure the fish to get an average size. We then place the fish into the awaiting hatchery truck that is going to take them to their new home!
Stayed tuned for the final part of our series Life of a Rainbow Trout where you will see the finals steps Rainbow Trout go through before they are stocked out for you to catch!