Gone Fishin’ Recent Posts
April 04, 2013
Largemouth Love: New Hatchery Rearing Strategies Prep Bass For Real World - 1
It's not exactly champagne and Barry White, but the strategies employed by the Florida Fish and Wildlife Conservation Commission have certainly proven effective at putting largemouth bass in the mood. They call the objective "out-of-season" spawning and a new agency study on the recent round of fingerlings released into various Florida waterways between late March and early April seeks to validate the effort.
Since 2007, the Bass Conservation Center – the state's main fish hatchery in Webster – has manipulated light and temperature to trick bass into thinking the cool season has given way to the baby-makin' days of spring. The process starts with moving brood stock females to spawning raceways in June. After simulated winter conditions, increasing daylight and water temperature has the fish ready to go by October – well ahead of the usual February-March spawning period. Hatchery biologists introduce males to the raceways, add spawning mats and collect fertilized eggs about a week later.
Seven days after hatching, the bass larvae head to outdoor nursery ponds where they're raised to the Phase 2 ("Advanced") size of 4 inches in time for spring stocking. Out-of-season spawning yields a considerably larger fingerling, which has a key advantage over naturally-spawned counterparts of 1 ½ inches.
"At this size, the Phase 2 fingerlings are totally piscivorous (fish eating)," said Center Director Rick Stout. "We're trying to release these when the major forage species – threadfin shad – are spawning. The Phase 2 fingerlings are old enough to forage on the juvenile shad and stay with them throughout the summer."
With FWC studies showing hatchery fish more likely to wander away from cover than wild fry, the Center has started introducing predators into hatchery ponds to condition Phase 2 fingerlings for their new home. Half of the Phase 2 fingerlings receive natural forage at the hatchery and when they're released, they're on their own. The other half receive feed pellets at the hatchery before being released inside a 1-acre block net stocked with natural forage. These fingerlings get five days to acclimate to natural habitat, identify predators and learn to eat natural forage while kept mostly safe from predation.
Coded wire cheek tags with microchips (different cheek for each group) identify hatchery fish collected in future seine net sampling. Center staff will monitor lakes stocked with Phase 2 fingerlings for about two years to determine the effectiveness of the block net strategy, along with overall survival of these larger hatchery fish.
"This out-of-season spawning allows us to double-crop our largemouth so we can produce twice as many bass in a year as we could under conventional techniques (of only spring spawning)," Stout said. "Also, this allows us to stock a 4-inch fish when the forage is available. This can yield significant growth and survival of stocked fish."