Results of Stocking Blacknose Crappie in Four Florida Lakes

Stocking of game fish into lakes with healthy fish populations has produced varied results that include no population increase, slight improvement in angler harvest of adult fish, and increased numbers of young, or juvenile, fish in the lake. To determine the effectiveness of stocking, scientists must be able to identify the stocked fish. Previously, black crappie stocked in Florida were either unmarked, fin-clipped, or injected with micro-wire tags (a tiny, thin, magnetically charged wire placed into cheek area). Fin-clipping proved ineffective for long-term use, and micro-wire tagging was too harmful to the fish. For these reasons, biologists studying stocking effectiveness used blacknose crappie because it could be easily identified by natural markings.

Blacknose crappie, which are black crappie that have a black stripe running from the top fin to the tip of the nose, were first described in Ohio in 1957. A later study reported that blacknose crappie had been found in 13 states, including Florida. Today, the only known naturally occurring Florida population of these fish is found in Lake Seminole near the Florida, Georgia, and Alabama borders. However, the Tennessee Wildlife and Resources Agency made blacknose crappie available to Florida's Fish and Wildlife Research Institute (FWRI) for a three-year stocking period. During this time, FWRI focused on determining if existing crappie populations could be improved by stocking blacknose crappie.

Researchers selected four lakes for stocking blacknose crappie in Florida:

• Starke Lake, a 200-acre lake in Orange County
• Watertown Lake, a 50-acre lake in Columbia County
• Bear Lake, a 110-acre lake in Santa Rosa County
• Tarpon Lake, a 2500-acre lake in Pinellas County

Starke Lake was the only lake to be stocked more than one year. It received 34,000 blacknose crappie in 1998 (1,025 fish/acre) and 45,500 in 1999 (1,370 fish/acre). In Bear Lake, scientists stocked 345 fish/acre, and they stocked 2,570 fish/acre in Watertown Lake in 1999. In 2000, biologists stocked 15 fish/acre in Lake Tarpon.

Scientists sampled crappie populations in Watertown and Bear lakes for three years after stocking. The blacknose crappie appeared to survive, grow well, and should have been ready to enter the sport fishery during the third year. Unfortunately, flocks of cormorants, large fish-eating birds, moved in and made these lakes their home. Studies in other states found that large numbers of cormorants in small lakes can harm sport fish populations. Cormorants at both Florida lakes often totaled more than two birds per acre, which is well above what is considered a high density of cormorants. Biologists believe this may be one reason why the sport fisheries there never materialized.

About 60,000 blacknose crappie were scheduled for stocking in Lake Tarpon in 2000. These fish were weak and very thin before getting to the lake, which may indicate that they were held in the hatchery pond too long. Over 400 crappie were collected in two years of extensive sampling on Lake Tarpon, but only one was a blacknose crappie. Because there was no way to determine the rates of mortality in the stocked blacknose crappie, researchers were unable to reach any conclusions regarding the success of the Lake Tarpon stocking.

The first year Starke Lake was stocked, the fish were large, healthy, and in excellent condition. Two years after these fish were stocked, blacknose crappie composed 20% of the angler harvest as determined by a creel survey (an on-lake survey of anglers conducted by FWRI biologists). The second year Starke Lake was stocked, the fish were smaller, in poor condition, and the amount of mortality at stocking was unknown. Two years after this stocking, blacknose crappie composed only 7% of the angler harvest. It appeared that researchers could get an improvement in fishing for only one year per stocking event-and then only if the fish were in good condition.

In summary, a total of 142,650 blacknose crappie were stocked in four Florida lakes over three years. The effects of cormorants and stocking poor-quality fish prevented scientists from determining the success of the stocking program on three lakes. When researchers were able to stock large, healthy fish that were not exposed to bird predation, the results were promising: blacknose crappie composed 20% of the harvest two years after stocking. It appears that stocking crappie into a lake that already contained crappie could briefly improve the fishery under the right conditions.