GROWTH AND PRODUCTION ESTIMATES FOR BIOMASS-DOMINANT FISHES ON A SOUTHERN CALIFORNIA ARTIFICIAL REEF

Somatic growth and somatic and gonadal production were estimated durin g May-November 1989 for six species, comprising most of the standing c rop biomass of the fishes on a shallow (10- to 15-m deep), 14-year-old , quarry rock reef (Torrey Pines Artificial Reef #2, TPAR), off La Jol la, California. Growth was estimated from weight-converted length incr ements of 142 Floy-tagged individuals at liberty for a median of 187 d ays. Egg production was estimated for females of three taxa (four spec ies) as the product of the weight of batch egg production and spawning frequency (the latter determined from histological evidence of day-ol d postovulatory follicles). Milt production was deduced from male to f emale ratios of gonad weights for reproductive fish. Somatic growth ra tes varied three- to fourfold among the six species and, in part, refl ected the distribution of maturity stages of intraspecific populations . On average, the per capita growth rates of taxa dominated by immatur e stages were faster than those dominated by large adults. Somatic pro duction varied more than somatic growth rates (by a factor of 15), bec ause of additional variations in standing stock biomass among populati ons. The somatic production of at least one species was underestimated as a result of a tag effect on growth. Weight-specific egg production varied only twofold among the three taxa examined, perhaps because fi shes with smaller batch egg productions compensated by spawning more f requently, and vice versa. Estimates of weight-specific milt productio n further diverged because of the influence of relative testis-to-ovar y weights that ranged from a small fraction to unity. Additional varia tion among taxa in total gonadal (egg plus milt) production was about one-half that of somatic production (a factor of eight). Besides repre senting interspecific differences in adult biomass, variations in gona dal production reflected intraspecific differences in the biomass cont ributions of the two sexes within the fraction of adults that were rep roductively active. Despite likely substantial underestimates of gamet ic materials, gonadal production ranged from a large fraction to a lar ge multiple of somatic production among the four species. Our observat ions suggest that the elaboration of tissue unrelated to yield is nont rivial and represents a major component of energy flow through the fis hes in this reef system and perhaps others.