Fall Spawning Activities
October - December
Fall, like spring, is one of Craig Brook National Fish Hatchery's busiest seasons. Through October, preparations for spawning top the to-do list. Visitors to the hatchery may observe hatchery personnel handling broodstock in October, or may notice that some of the large tanks have been divided into sections. During October, it is necessary to sort through all the age three, four, and five broodstock in order to determine which broodstock will spawn come November. All of the fish will be crowded into the middle of each tank, and two dividers will be used to split the tank into thirds. Each fish is examined to determine whether it is male, female or immature. Male and female fish are separated into the two outer sections of the tank; immatures are kept in the middle. This makes it easier to work during the actual spawning season. The dividers will be left in place until the end of November. Any fish that is mature, but not required for egg production, is released back to the wild; this allows these fish to spawn in the wild.
Some fish will spawn in late October, but the majority will spawn in November; this is fairly representative of natural spawning in the wild. Spawning occurs daily from the end of October until just before Thanksgiving. Fish are examined to determine their 'readiness' for that day's spawn. Females are spawned into plastic pans to collect their eggs, then the males are used to fertilize the eggs; one male for every pan of eggs. The eggs and sperm are combined, allowed to rest to ensure fertilization, rinsed, packed in a disinfecting solution for one hour, and then poured into individual incubation trays. Craig Brook National Fish Hatchery annually produces approximately five to six million eggs. Many of these are eventually transferred to other hatcheries, including nearly 1.5 million eggs to Green Lake National Fish Hatchery in Ellsworth, Maine for smolt and parr production.
Once the eggs are placed in their individual trays, they are undisturbed during their initial development. To reduce the chance of disease spread, the egg-rearing rooms are closed to the public. However, there are viewing windows available in the downstairs area of the main hatchery building where the public can observe the incubation stacks.
Following spawning, the oldest year class of broodstock are released back to the river where they were initially collected.