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To determine if protogynous species are, as a result of fishing, more likely to suffer reproductive failure than are gonochoristic species, we modeled the production of fertilized eggs in simulated populations of graysby Epinephelus cruentatus. Additionally, we examined the effect of various compensatory mechanisms on maintaining fertilized-egg production despite increasing fishing mortality. These mechanisms included accelerated maturation, accelerated transition to malehood, accelerated growth, and combinations thereof. Protogynous stocks may be far more vulnerable to fishing than are comparable gonochoristic stocks. Stocks exhibiting uncompcnsated protogyny lost reproductive capacity as fishing mortality increased and failed reproductively (egg production less than 1% of that under natural mortality alone) at a lower fishing mortality rate than did gonochoristic stocks. Compensation through conservation of the numerical sex ratio somewhat reduced the impact of protogyny, and compensation through conservation of the cohort male biomass: fecundity ratio erased all effects of protogyny. All the modeled stocks incurred a drastic reduction in reproductive capacity even at moderate levels of fishing mortality. Delaying harvest of a cohort not only provides increased yield per recruit but also reduces the loss of reproductive capacity caused by fishing.

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We evaluated the effect on yield per recruit of mortality from catch and release of fish smaller than a legal minimum length. Catch‐and‐release mortality reduces the potential effectiveness of minimum size limits for increasing yield per recruit by an amount that depends on the fishing mortality coefficient, the minimum size limit, and the probability that undersized fish survive if released. For a given probability of survival, catch‐and‐release mortality has its greatest influence when fishing mortality and the minimum size limit are large, because these factors determine the number of undersized fish that are caught and released. As the survival probability declines, minimum size limits become less effective for increasing yield per recruit because greater numbers of undersized fish die and cannot contribute to future catches. With low survival probabilities, minimum size limits may actually reduce yield per recruit. We calculated yield per recruit for red snapper (Lutjanus campechanus) in the Gulf of Mexico for minimum size limit ranging from 254 to 635 mm total length, survival probabilities ranging from 0.20 to 1.00, and several natural (M) and fishing mortality coefficients. A recently implemented 330‐mm minimum size limit is predicted to increase yield per recruit as long as the survival probability exceeds 50% if M = 0.25; the survival probability must exceed 60% if M = 0.35.

Opaque rings on cross-sectioned otoliths from speckled hind Epinephelus drummondhayi and snowy grouper E. niveatus, taken off North Carolina and South Carolina, were determined to be annuli. Annulus formation occurred primarily between April and June for speckled hind, and from May through July for snowy grouper. The length-weight relationship for speckled hind was W = 1.1 x 10-SL s.07s and for the snowy grouper was W = 7.0 x 10-SL 2.•55, where W = weight in kilograms and L = total length in millimeters. Back-calculated mean lengths (mm) of speckled hind from ages 1 to 15 were 186, 317, 408, 475, 528, 572, 613,645, 678, 709, 739, 774, 804, 839, and 861. For snowy grouper ages 1 to 17, they were 210, 328, 403, 462, 514, 562, 605, 647, 686, 721, 762, 798, 832, 874, 900, 924, and 958. The maximum age of both species was at least 25 years. The von Bertalanffy growth equations for speckled hind and snowy grouper (t = age in years) are Lt = 967{1 -exp[-0.13(t + 1.01)]} and L, = 1,255{1exp[-0.074(t + 1.92)]}. Instantaneous annual mortality rates for speckled hind, determined from catch curves, increased from 0.26 to 0.40 in the headboat fishery between 1975 and 1979, and fluctuated between 0.23 and 0.32 in the commercial hook-and-line fishery. Snowy grouper mortality increased from 0.19 to 0.57 in the headboat fishery between 1972 and 1978, but remained stable at 0.24 to 0.25 in the commercial fishery from 1977 to 1979. Yield-per-recruit models for both species indicated that the headboat and commercial fisheries are harvesting between 60% and 80% of the maximum available yield per recruit.

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