250 



Abstract. -Juvenile ( 128-244 mm 

 fork length) pink snapper, Pristi- 

 pomoides filamentosus, were caught by 

 hook and line from 60-90 m depths off- 

 shore of Kaneohe Bay. windward Oahu, 

 Hawaii, during February-August 1994. 

 About one-half of the 180 specimens 

 were intercepted by scuba divers 15- 

 18 m below the sea surface and indi- 

 vidually "bagged" live before they were 

 retrieved for the remaining distance to 

 the surface. The other half were re- 

 trieved directly by fishing line to the 

 surface ("unbagged"l; these latter fish 

 thus remained at a continual risk of 

 prey loss from regurgitation while they 

 were stressed by the full extent of pres- 

 sure change. The retained stomach con- 

 tents of bagged and unbagged fish were 

 compared on the basis of volume and 

 type of food and on the size of individual 

 prey items. Bagged samples of juvenile 

 snapper on average retained a 1 16^ 

 (95% CI=70-157%) greater volume of 

 prey than unbagged snapper; bagged 

 snapper also had more types and 

 greater maximum body sizes of prey 

 than did unbagged fish. These results 

 are discussed in terms of designing 

 quantitative diet studies for juvenile 

 snapper and other deep-water physo- 

 clistous fishes. 



Barotrauma-associated regurgitation 

 of food: implications for diet studies 

 of Hawaiian pink snapper, 

 Pristipomoides filamentosus 

 (family Lutjanidae) 



Edward E. DeMartini 

 Frank A. Parrish 

 Denise M. Ellis 



Honolulu Laboratory, Southwest Fisheries Science Center 



National Marine Fisheries Service, NOAA 



2570 Dole Street, Honolulu, Hawaii 96822-2396 



Manuscript accepted 1 November 1995 

 Fishery Bulletin 94:250-256 ( 19961 



The diet and feeding habits of deep- 

 water physoclistous fishes are usu- 

 ally described by using fish collected 

 with gears (hook and line, set lines, 

 trawls, nets, traps) that subject 

 specimens to the stress of large re- 

 ductions in ambient pressure (baro- 

 trauma) as they are retrieved. Nu- 

 merous studies have derived esti- 

 mates of stomach fullness, prey con- 

 sumption or daily ration, and gas- 

 tric evacuation rates (reviewed by 

 Bromley, 1994) based on collections 

 that include or exclude specimens 

 with empty stomachs. Often over- 

 looked is the distinction between 

 naturally occurring empty stom- 

 achs and stomachs that have par- 

 tially or totally everted their con- 

 tents as a result of swimbladder 

 expansion during gear retrieval or 

 other procedures of capture (Kohler 

 and Fitzgerald, 1969; Daan, 1973; 

 Durbin et al., 1983; Rice, 1988; 

 Hislopetal., 1991). 



The Hawaiian pink snapper or 

 "opakapaka" (Pristipomoides fila- 

 mentosus) represents a major por- 

 tion of the deep-slope (150-300 m) 

 bottomfishery in Hawaii (Haight et 

 al., 1993a). Juveniles inhabit a shal- 

 lower (60-90 m), relatively narrow 

 depth zone on insular shelves 

 (Parrish, 1989; Ellis and DeMartini, 



1995; Moffitt and Parrish 1 ) but, 

 nonetheless, experience barotrauma 

 during conventional collection proce- 

 dures (Parrish and Moffitt, 1993). 

 Juveniles are discontinuously dis- 

 tributed, and localized patches of 

 occupied habitat have recently per- 

 sisted for at least five consecutive 

 years ( 1989-93; Parrish et al. 2 ). One 

 hypothesis for the persistence of 

 these patches of juveniles is the lo- 

 calized distribution of prey, which 

 in turn might reflect static sub- 

 strate characteristics or recurrent 

 patterns of near-bottom water 

 movements. Testing such hypoth- 

 eses requires describing the diet of 

 juveniles as well as the distribution 

 and availability of prey organisms. 



1 Moffitt, R. B., and F. A. Parrish. 1995. 

 Habitat use and life history of juvenile 

 Hawaiian pink snapper, Pristipomoides 

 filamentosus. Honolulu Lab., Southwest 

 Fish. Sci. Cent., Natl. Mar. Fish. Serv., 

 NOAA, 2570 Dole St.. Honolulu, HI 96822- 

 2396. Unpubl. manuscript. 



2 Parrish, F. A., E. E. DeMartini, and D. M. 

 Ellis. 1995. Effects of physiography and 

 coastal discharge on the longshore distri- 

 bution of juveniles of the snapper Prist: 

 pomoides filamentosus in the Hawaiian 

 Archipelago. Honolulu Lab., Southwest 

 Fish. Sci. Cent., Natl. Mar. Fish. Serv., 

 NOAA, 2570 Dole St., Honolulu, HI 96822- 

 2396. LInpubl. manuscript. 



