Fishery harvest and population dynamic among spotted seatrout, Cynoscion nebulosus, in Florida Bay and adjacent waters

Rutherford, Edward; Tilmant, James; Thue, Edith; Schmidt, Thomas

Catch rates of spotted seatrout, one of the four most popular recreational gamefish in Everglades National Park, have been monitored nearly continuously since 1958; total harvest and effort data and commercial landings have been monitored since 1973, and lengths have been measured since 1974. Sport fishermen catch rates of Florida Bay spotted seatrout were higher from 1958 to 1967 than from 1973 to 1985 and reached a period of record low in 1973-1977. Commercial hook-and-line fishermen and sport fishermen together accounted for an average 84% of the total annual spotted seatrout catch from 1973 to 1979, with guide fishermen and commercial net fishermen accounting for an average 13% and 3% of the catch. During 1973-1976, total harvest declined from 130,000 to 59,000 fish, then increased to 74,000 fish in 1979 because of increased commercial harvest, and declined again in 1980 when bag limits of I 0 fish/person/day greatly restricted the commercial fishery and reduced recreational catch. Total annual effort was closely correlated with harvest (r2 0.950). Since 1980, total annual harvest has increased to early 1970 levels with increases in both recreational and guide fishermen harvest. Catch rates and length frequency distributions suggest different unit stocks of spotted sea trout in the Florida Bay area and the Gulf Coast area of the park. The reduction in spotted seatrout harvest in the Florida Bay area appeared due to reduction in fishing effort and to environmental factors. Current harvest levels (avg. I 00,000 fish/year) have moderate impact on the stock. Average fishing mortality rate for 197 3-1984 was 0.36 and ranged from 0.20 to 0.55. Between 13% and 28% of the total recruited stock in the florida Bay area were harvested annually from 1973 to 1984. Age of harvested spotted seatrout ranged from age 1-8 with ages 3-5 providing up to 70% of the catch. Estimated population size of spotted seatrout in the Florida Bay area ranged from 686,000 to 786,000 fish from 1974 to 1978 and then decreased slowly to 631,800 fish by 1984. Recruitment of age-l fish varied from 166,700 to 317,000 fish, peaking in 1976, 1977, and 1984 and being lowest in 1983. Catch rates were poorly correlated with rainfall and water levels in upland marshes. There was no relationship between estimated parent stock and recruitment or rainfall/upland water levels and recruitment.

Fishery harvest and population dynamic among spotted seatrout, Cynoscion nebulosus, in Florida Bay and adjacent waters

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