Fishery Harvest and Population Dynamics of Red Drum (Sciaenops Ocellatus) from Florida Bay and Adjacent Waters

Author： Tilmant James T. Rutherford Edward S. Thue Edith B.

Publisher： University of Miami - Rosenstiel School of Marine and Atmospheric Science

ISSN： 0007-4977

Source： Bulletin of Marine Science, Vol.44, Iss.1, 1989-01, pp. : 126-138

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Abstract

A fisheries harvest monitoring program has provided catch and effort data on the harvest of red drum from Florida Bay since 1958. Length data are available since 1974. Red Drum were sought by less than 7% of the fishermen in the late 1950's, but increased to nearly 40% of the fishermen during 1986. Red drum also comprised approximately 15% of the annual total reported harvest of commercial guide fishermen. The annual estimated total harvest from Florida Bay declined from 28,500 fish in 1973 to less than 17,500 fish in 1978, but then increased dramatically to a peak of 51,000 fish in 1984. Although fishing effort has continued to increase since 1984, total reported catch of red drum has seriously declined. The red drum fishery is largely comprised of newly recruited fish. Prior to a 18-inch minimum size limit imposed in September 1985, 51% of the annual harvest were l-year-old fish, 38% were 2-year-olds, and less than 12% were 3 years or older. Proportional age distribution within any given year has varied with annual recruitment to the fishery. A virtual population assessment suggests that the park's fishable population of red drum declined from around 120,000 fish in 1974 to a low of90,000 in 1977, but then increased to over 180,000 by 1980. During 1985, an estimated 41% of the available population was harvested. Recent declines within the red drum population are not likely due to fishermen harvest unless such harvest has impacted offshore breeding stocks. Data are not available on the rate of escapement and offshore stock abundance. Assuming constant annual natural mortality and offshore migration rate, estimated instantaneous rates of total annual fishing mortality (F) have ranged from 1.1 to 1.9. Increased recruitment to the fishery followed high rainfall years (r = 0.814, N = 10), suggesting improved recruitment and/or survival of early stage juveniles during periods of increased upland runoff.