DeVRIES and CHITTENDEN: SPAWNING TO MORTALITY OF SILVER SEATROUT 



General 



The production of several spawned groups 

 over a broad time period in each annual spawn- 

 ing season is extremely important to the popula- 

 tion dynamics of C. nothus. This species is short- 

 lived and appears little more than an annual crop 

 whose abundance could fluctuate greatly from 

 year to year. However, the multiple-spawned 

 group structure would buffer against population 

 instability just as a multiple year class structure 

 buffers population size in longer lived species. 

 The multiple-spawned group feature may aver- 

 age over a longer period each year the effects of 

 environmental variation on spawning success, 

 may dampen fluctuations in annual spawning 

 success associated with environmental extremes, 

 and may stabilize population sizes. Similarly, 

 the effects of fishing would be averaged over a 

 greater number of spawned groups in 1 yr, so 

 that the multiple-spawned group structure 

 might minimize the possibility of recruitment 

 overfishing. In that event, stock assessments 

 based on dynamic pool models and growth over- 

 fishing would be more valid. 



Many features of the population dynamics of 



C. nothus — short life span, high mortality rate, 

 and rapid turnover of biomass — are similar to 

 those in the Atlantic croaker, Micropogonias un- 

 dulatus, of the Carolinean Province (White and 

 Chittenden 1977; Chittenden 1977). This sup- 

 ports the suggestion (Chittenden and McEachran 

 1976; Chittenden 1977) that the abundant species 

 of the white and brown shrimp communities in 

 the gulf have evolved towards a common pattern 

 of population dynamics. Because of their similar 

 population dynamics, the implications of Chit- 

 tenden's (1977) simulations on croaker could 

 serve as a first approximation of the effects of 

 harvesting C. nothus, so that this species also 

 should have a great biological capacity to resist 

 growth overfishing. 



ACKNOWLEDGMENTS 



We are much indebted to the Texas Parks and 

 Wildlife Department, and particularly the crew 

 of the RV Western Gulf(T. Cody, K. Rice, Capt. 



D. Perez, and D. Majorando), for allowing the 

 senior author to participate in cruises aboard the 

 RV Western Gulf and for all their cooperation 

 and assistance. P. Shlossman and Captains H. 

 Forrester, J. Forrester, and M. Forrester also 

 assisted greatly with field collections. J. Merri- 



ner, R. Noble, K. Strawn, and T. Bright reviewed 

 the manuscript and made many very helpful 

 suggestions. Financial support was provided, in 

 part, by the Texas Agricultural Experiment 

 Station and by the Texas A&M University Sea 

 Grant College Program, supported by the 

 NOAA Office of Sea Grant, U.S. Department of 

 Commerce. 



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