Pond Boss Forums MANAGING AN EXISTING POND Corrective stocking Stocking of Fingerlings

Corrective stocking can involve stocking of fingerling fish into an existing fishery. A recent study at Texas Parks and Wildlife (J. of Fisheries Management 2006) looked at prerelease habituation as a way of improving the post stocking survival of fingerling LMB (1.2"-2.0"). Prerelease habituation is defined as allowing fish to become accustomed to their new environment before release.

The study found that in ponds, habituation for 60 minutes before release significantly reduced predation of the fingerling bass. The study found that if fingerlings were released directly into complex habitat, prerelease habituation did not greatly affect the amount of predation during the first 24 hours. Complex Habitat was defined as having or containing 250 stems per square meter.

The study was performed in 0.5 ac ponds and EACH TEST LASTED JUST 24 HRS. To test the effects of habituation, researchers constructed predator exclusion cages (2’diaX4’tall cylinders) using netting (1/8",3mm) with a floatation ring on top. The cage bottom was open with a lead line sewn around the lower edge to hold it onto the bottom so fish could not escape. The LMB fingerlings to be tested were MARKED and held in each cage for 60 min before release, whereas control, unmarked, fingerlings were directly released into the pond remotely away from structure. Structurally complex habitat consisted of a cluster of 6 ft tall Fraser fir trees and bamboo stalks encompassing 100 sq ft. Test fingerlings were released directly into the dense habitat. At the end of each 24 hr test, the pond was seined and then drained.

Survival of fingerlings after 24 hrs into an open pond ranged from 13% -25% whereas survival of fingerlings with habituation or complex habitat ranged from 17% -38%. Dense habitat provided some refugia for fingerlings in the first 24 hrs and reduced predator efficiency. Further research should focus on: 1. what habitat types and the density are best for reducing predation and 2. what would the survival rate of fingerlings be after a longer study period, such as 1 to 6 months.