Success and Failure of Macroscopic Gonad Analysis in Two Protogynous Hermaphrodites (black sea bass, Serranidae; red porgy, Sparidae)

Thursday, September 12, 2013: 1:40 PM
Pope (Statehouse Convention Center)
Nikolai Klibansky , Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC
Frederick S. Scharf , Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC
We found simple macroscopic gonad analysis to be a powerful tool in distinguishing sex, reproductive activity, spawning capability, and ripeness in black sea bass (Centropristis striata; n=1240) and red porgy (Pagrus pagrus; n=982), often producing the same results as more complex and expensive microscopic methods; estimates of key reproductive parameters dependent on these distinctions like sex-change ogives, spawning season duration, spawning fraction, and batch number were similar or equal between methods.  Apparent seasonal spawning activity was also similar whether estimated from macroscopic, microscopic, or mean gonadosomatic index data.  However, macroscopically distinguishing maturity in inactive females often did not match microscopic data; maturity ogives, dependent on these data, were significantly different between methods for black sea bass (red porgy could not be tested). While we were able to macroscopically identify signs of sex transition in very advanced specimens, early signs were only evident microscopically.  Despite widespread use of both macro- and microscopic methods in fisheries science, comparisons between them are scarce. Certainly much more detail is visible with a microscope, but we show that several population-scale parameters important to fisheries management can be estimated equally well with the naked eye.  For large surveys and long-term research programs in particular, determining when microscopy is and is not needed can greatly improve efficiency and reduce costs without compromising data quality.