PERRIN ET AL.: STOMACH CONTENTS OF PORPOISE AND YELLOWFIN TUNA 



Stromateidae 



Although some young stromateoids are often 

 associated with floating objects, adults have 

 large depth ranges. Cubiceps cariiiatus has been 

 taken in a midwater trawl station in large num- 

 bers. Stromateoids appeared irregularly in the 

 stomachs of both species of porpoise. 



Melamphaidae 



Melanipiiaes and Scopelagadiis adults nor- 

 mally remain below 100 to 200 m) Ebeling. 1962; 

 Ebeling and Weed, 1963). Melamphaid otoliths 

 were found occasionally in large numbers in 

 S. lo)igirostris stomachs and rarely (cf. Appen- 

 dix 1) in those of S. attenuata. 



Bregmacerotidae 



Although Bregmaceros is known to occur 

 bathypelagically and is captured in midwater 

 trawls, it also can be found at the surface at 

 night (Fitch and Brownell, 1968). It occurred 

 regularly in low frequencies in both species of 

 porpoises; larger numbers were found in one 

 associated group of four porpoise (S. longiros- 

 tris). 



Gempylidae, Trachipteridae 



Species of both these families have been found 

 both in surface waters and at depth. A trachip- 

 terid otolith was found in the gut of one S. lon- 

 girostris. Gempylid remains were found in two 

 spinner porpoise stomachs, and in one S. atten- 

 uata from the far-west sampling area (Appendix 

 1). 



Paraiepididae, Bathylagidae, Scopelosauridae, 

 Evermannellidae, Opisthoproctidae 



Adult members of these families are not 

 normally found near the surface. Most museum 

 specimens have been caught in midwater trawls. 

 A few otoliths from species in these families 

 were regularly found in the stomachs of S. 

 longirostris. Two specimens of S. attenuata 

 caught in the far-west sampling location (Ap- 

 pendix 1) also contained otoliths from these 



families, including the only records of scopelo- 

 saurids and opisthoproctids. Otoliths from many 

 myctophids and melamphaids were also found 

 in these specimens. The overall pattern closely 

 parallels that seen for spinner porpoise nor- 

 mally (e.g.. Appendix 2). This indicates that 

 spotted porpoise are capable of shifting to a 

 mesopelagic feeding pattern, although epipe- 

 lagic feeding appears to be typical. The cause of 

 the shift is unknown. 



Shomura and Hida (1965) reported that the 

 stomach of a Hawaiian spotted porpoise con- 

 tained fish of the families Paraiepididae, Alepi- 

 sauridae, Gempylidae, Bramidae, and Myctophi- 

 dae, as well as squids (the major component), 

 nemeitean worms, and crab larvae. The fish com- 

 ponent was similar to that for the two western- 

 most specimens of eastern Pacific S. attenuata 

 discussed above. 



Depth Distributions of Squids 



No discrete depth sampling of squids has 

 been carried out in the area where the animals 

 were collected. Some information, however, is 

 available on the depth distributions of some of 

 the families concerned from other areas. 



Ommastrephidae 



The most abundant squids found in the stom- 

 achs were probably Dosidicus gigas and Sym- 

 plectoteuthia sp. Clarke (1966) reported that 

 D. gigas and species of Symplectoteuthis mi- 

 grate to the surface at night. Dosidicus gigas 

 and Symplectoteuthis oualaniensis have been 

 taken in the area by dip net at the surface under 

 lights at night (unpublished data). In this area, 

 the ommastrephids are the most abundant 

 epipelagic squids. 



Enoploteuthidae 



The enoploteuthid squid Abraliopsis afftnis 

 occurred next in abundance to the ommastre- 

 phids. It is a mesopelagic species. Gibbs and 

 Roper (1972) stated that enoploteuthids under- 

 go diurnal vertical migrations. It appears that 

 this species may move into or is resident within 

 the diving ranges of the two species of porpoise. 



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