Plastic growth of the herbivorous reef fish Sparisoma viride:field evidence for a trade-off between growth and reproduction

Abstract

The growth of d~fferent life phases and social categories of the protogynous parrotfish Spansoma vinde was studied on a fringing reef on Bonaire (Netherlands Antilles) using mark-recapture procedures and by taklng repeated stereographic measurements of free-sw~mming fish W e ~g h tgrowth was best descnbed by the Putter/von Bertalanffy growth equatlon for all categories allowing companson of s p e c ~f ~c growth rates (d W/ Wdt) using analysis of covanance with W 'lJ as the covanate Growth was retarded by Peterson dlscs, but no effect of fin clips was detected Adjusted for s ~z e differences, growth of luven~les was fastest, followed by sexually lnactive termlnal phase (TP) males living In groups Init~al phase (IP) females and territor~al TP males (spawnlng daily) showed the lowest growth rates Growth rate of terntorial males was negat~vely correlated w ~t h thelr average spawnlng rate All adult categones showed seasonal varlatlons In growth the highest rates occurnng in the warmest season (August to October) A possible effect of depth on growth is confounded by differences In soclal and reproduct~ve status Growth of group TP males showed a weak positive correlation w ~t h t h e ~r condit~on Gross growth efficiencies were estimated by combining data on growth and body compos~tion with previously published data on food intake and assimilation Growth effic~ency is highest for p r o t e ~n , ranging from 50 6% of food intake for luven~les to 0 12% for terntonal males Corresponding values are 6 25 to 0 01 % for ash-free dry weight and 7 9 to 0 01 % for energy The high abundance of small, sexually inactive group TP males (early sex-changers) In our S wnde populat~on 1s related to their fast growth We suggest that these bachelors trade growth agalnst current reproduction and thereby enhance their chance to acquire the status of a territor~al male w ~t h h ~g h reproductive success Insight into intraspec~f~c vanation In growth improves the accuracy of trophodynam~c models and increases our understanding of complex life history patterns In fish