Abstract. — Squirrelfish of the 

 genus Myripristis are valued in 

 small-scale fisheries throughout 

 much of the tropics. The life his- 

 tory and species biology of most of 

 these soldierfishes is poorly known. 

 For the brick soldierfish, M. amae- 

 na, in Hawaii and Johnston Atoll, 

 we found that sexual maturity for 

 both sexes was reached between 

 145 and 160 mm standard length 

 at about six years of age — a large 

 fraction of the apparent maximum 

 size and lifespan. Fecundity was 

 relatively low and increased as the 

 fifth power of body weight. Spawn- 

 ing peaked from about early April 

 to early May, and a secondary peak 

 occurred in September. Myripristis 

 amaena is a nocturnal predator, 

 feeding mostly on meroplankton. 

 especially brachyuran crab mega- 

 lops, hermit crab larvae, and 

 shrimps, but also taking a variety 

 of benthic prey. In pristine fish 

 communities, holocentrids were 

 abundant, quantitatively impor- 

 tant (often dominant) reef preda- 

 tors and prey. Myripristis amaena 

 (and probably other common and 

 important soldierfish) seems to be 

 relatively long lived (at least 14 

 years), slow growing, and late ma- 

 turing. The populations suffer con- 

 siderable natural predation and 

 depend mainly on the largest and 

 oldest fish for reproduction. Heavy, 

 unregulated fishing of these 

 soldierfish, especially at prerepro- 

 ductive size, may severely reduce 

 populations. 



Reproductive and trophic ecology 

 of the soldierfish Myripristis 

 amaena in tropical fisheries 



Anderson J. Dee 



PO Box 1 154 



Hayward. Wisconsin 54843 



James D. Parrish* 



National Biological Survey, Hawaii Cooperative Fishery Research Unit 

 2538 The Mall. University of Hawaii, Honolulu, Hawaii 96822 



Manuscript accepted 30 December 1993. 

 Fishery Bulletin 92:516-530 ( 1994). 



516 



Soldierfish, Myripristinae, of the 

 squirrelfish family, Holocentridae, 

 occur widely throughout the trop- 

 ics (Greenfield, 1965, 1968, 1974). 

 They are typically abundant and 

 are an important component of com- 

 mercial, recreational, and subsis- 

 tence fisheries in much of the 

 world's tropics. Throughout most of 

 the central and western Pacific 

 Ocean, the brick soldierfish, Myri- 

 pristis amaena (Castlenau), is an 

 important member of this group 

 (Greenfield, 1968). It contributes 

 significantly to fish communities 

 and to fishery catches in shallow 

 reef and rocky habitats. It is par- 

 ticularly important in the recre- 

 ational fishery at Johnston Atoll 

 (JA), where it is typically the spe- 

 cies caught in greatest abundance 

 (Irons et al. 1 ). It is also common in 

 catches throughout the Hawaiian 

 archipelago. 



Relatively little quantitative in- 

 formation has been published about 

 the life history and biology of spe- 

 cies of the genus Myripristis, and 

 very little is available about M. 

 amaena in particular. Data about 

 diets are available for only a few 

 species of Myripristis; for most of 

 these, sample sizes are small (e.g. 

 14 specimens for M. amaena; 

 Hobson, 1974). Results on age and 

 growth from our studies of the JA 

 population of M. amaena have been 



reported (Dee and Radtke, 1989). 

 There have been no thorough pub- 

 lished studies of the reproduction of 

 M. amaena or closely related spe- 

 cies. Because of the wide distribu- 

 tion, considerable abundance, and 

 substantial fishery importance of 

 M. amaena, we undertook to de- 

 scribe more fully its food require- 

 ments and trophic position in the 

 community and to quantify the re- 

 productive characteristics that af- 

 fect the dynamics of its populations. 

 The parameters we determined may 

 also provide reasonable first ap- 

 proximations for similar Myripristis 

 species that are less well studied. 

 The results will contribute to an 

 informed approach to management 

 of species that are now typically un- 

 managed and probably overfished 

 in most localities with even moder- 

 ately dense human populations. 



The JA population of M. amaena 

 was the major focus of this study for 

 several reasons. Many biological 

 and ecological characteristics of M. 

 amaena (e.g. size, morphology, hab- 

 its, habitat used, fishery value) 

 seem to be representative of a num- 



To whom correspondence should be sent. 

 Irons, D. K.. R K. Kosaki, and J D. 

 Parrish. 1990. Johnston Atoll resource sur- 

 vey. Final report of Phase Six 1 21 July 

 1989-20 July 1990). Project rep. to U.S. 

 Armv Engineer Distsrict, Honolulu. HI, 

 150 p. 



