Seasonal frequency of ciguatoxic barracuda in southwest Puerto Rico.

Ciguatoxicity of barracuda (Sphyraena barracuda) head, viscera and flesh tissues has been determined in 219 specimens caught along the southwest coast of Puerto Rico from March 1985 through May 1987. Twenty-nine percent of these specimens were toxic. Monthly frequencies of ciguatoxic barracuda showed an apparent seasonal variability, with peak values (60-70% toxic fish) in the late winter-early spring (January-May) and fall (August-November). Minimal frequencies (0-10% toxic fish) were observed during June-July and December. The most frequently toxic tissues in poisonous animals were the viscera and head. Viscera tissue was the only toxic tissue found in 31% of the poisonous fish assayed, and this tissue was poisonous in all toxic fish. In no case was a poisonous specimen found to have toxic flesh alone. Marked temporal variation in frequency of ciguatoxicity suggests that ciguatera toxins, at least in their active form, are not accumulated in barracuda tissues for extended periods of time. Variability in barracuda ciguatoxicity may reflect fluctuations in the toxicity of smaller reef fish prey, seasonal fluctuations in toxic benthic dinoflagellates and/or changes in the ability of the barracuda to detoxify ingested poisons or their precursors.