388 



Fishery Bulletin 100(2) 



Large fast-swimming fish recorded from A. ferox stom- 

 achs include chub mackerel iScomber japonicus) 35 cm 

 long iKubota and Uyeno, 1970) and a pink salmon (On- 

 corhynchus gorbuscha) reported by Balanov and Radchen- 

 ko (1998). However, salmons (O. gorbuscha, O. nerka, and 

 O. keta) found with slash marks attributed to lancetfish 

 likely indicate that lancetfish also prey on these fast- 

 swimming fish (Radchenko and Semenchenko, 1996). 



The jaw structure and large teeth of lancetfish allow 

 these fish to hunt for relatively large animals. However, 

 large epi- and mesopelagic fishes, inhabiting the same or 

 bordering niches with lancetfishes are able to evade at- 

 tack, as a rule, because of their swimming speeds. The 

 elongate (anguilliform) body of lancetfishes and their fiab- 

 by and watery muscles suggest an inability to swim for a 

 long time with a high cruising speed in order to chase prey. 

 This species has no developed deep red muscles, a char- 

 acteristic feature of fishes able to cruise at high speeds 

 (Sharp and Pirages. 1978, He and Wardle, 1988). The mus- 

 cle tissue of the lancetfish consists mainly of white mus- 

 cles that are responsible for short-term bursts of motion 

 (Sharp and Pirages, 1978; Schmidt-Nielsen. 1979); and 

 its body form allows it to make short impetuous rushing 

 movements, characteristic of many predatory fishes with 

 anguilliform bodies (Trichiuridae, some of the Gempyli- 

 dae, Muraenidae, A;K)^op/t'rH,s pharao. etc.). The high dor- 

 sal fin of A. ferox and the large area of the caudal fin are 

 additional signs of the high maneuverability of this spe- 

 cies for swimming and hunting at short distances. 



Yellowfin tuna, unlike lancetfish, are constantly active 

 and swim in a rather fast motion, as has been demonstrat- 

 ed by numerous day-long (or several days long) telemetric 

 tracking experiments (Carey and Olson, 1982; Cayre and 

 Chabanne, 1986; Holland, et al., 1990; Cayre, 1991; Mar- 

 sac and Cayre, 1998). To maintain hydrostatic equilibri- 

 um, small yellowfin tuna swim within the range of 1.3-1.5 

 body lengths per second (Brill''), which in the case of the 

 tuna found in the lancetfish stomach corresponds to a rate 

 of 48-55 cm/s. Rarely the does the speed decrease to 14-22 

 cm/s (Cayre and Chabanne. 1986. Holland et al., 1990. 

 Brill et al., 1996, Marsac'). 



Needless to say, it is not easy for a rather slow-swim- 

 ming lancetfish to catch a fast-swimming tuna. In our 

 opinion, the only way for the lancetfish to catch the tuna 

 was to rush suddenly and to catch the prey with its large 

 saber-like teeth. Ambush-rushing type of hunting is rath- 

 er widespread among predatory fishes. Perhaps it prevails 

 over other types of prey capture because it is efficient 

 and requires less energetic expense than would an active 

 chase of an escaping victim. In the pelagic environment 

 it is hardly possible to use ambush tactics owing to the 

 character of the pelagic environment, i.e. the absence of 

 natural shelters. Therefore for those fish unable to use 



•^ Brill. R. W. 1997. Personal commun. Honolulu Laboratory, 

 Southwest Fisheries Science Center, National Marine Fisheries 

 Sei-vice. 2.570 Dole St., Honolulu, HI 96822-2396. 



" Marsac, F 1997. Personal commun. Unite de Recherche n° 

 109 (THETIS) Centre IRD BP 172 97492 Ste Clotilde Cede.x La 

 Reunion, France. 



high-speed cruise swimming, the method of hunting may 

 be that of lying motionless or slowly sneaking up on the 

 prey and then making a violent rush to catch the prey. For 

 the lancetfish in our study, we suggest that the tuna swam 

 by the motionless or slowly swimming lancetfish at a dis- 

 tance appropriate for a rush but also close enough, so that 

 the tuna was unable to react to or evade the attack. 



Obvious lateral damage of the tuna's body may indicate 

 that the lancetfish attacked the tuna in the vertical posi- 

 tion either from the belly or from the back. Similar forag- 

 ing behavior has been suggested for Anotopterus pharao, 

 another aulopiform fish that resembles Alepisaurus in 

 physical shape and structure, habitat, and diet (Balanov 

 and Radchenko, 1998). 



Several of our colleagues suggested that the tuna may 

 have been dead when the lancetfish seized it. Starvation, 

 or if the tunas was a discard from a fishing vessel, and oth- 

 er reasons were given as the cause of mortality. However, 

 in the area of the longline set by the research cruise, and 

 in the general vicinity of the survey, no commercial long- 

 line or tuna purse-seine vessels were spotted. We believe 

 that the lancetfish made a successful natural attempt to 

 seize a large, fast swimming food item. If indeed this was 

 the case, the finding is new and expands our knowledge 

 of lancetfish biology. It also indicates the efficiency of am- 

 bush-rushing type of hunting and the ability of a species 

 unable to cruise at high speeds to catch rather large fast- 

 swimming fishes. 



Acknowledgments 



We express our acknowledgements to V. F. Demidov, N. 

 N. Kukharev, Ch. N. Nigmatullin, M. A. Pinchukov, L. K. 

 Pshenichnov, E. A. Roshchin, and S. I. Usachev for useful 

 discussions during the preparation of the note. We also 

 wish to offer our sincere thanks to B. Collette, R. Brill, and 

 F. Marsac for valuable unpublished information. We offer 

 deep thanks to B. Collette for revision of the manuscript 

 and correction of the English text. Lastly, we thank two 

 anonymous reviewers for their suggestions, which helped 

 to improve this note. 



Literature cited 



Balanov, A. A., and V. I. Radchenko. 



1998. New data on the feeding and feeding behavior of dog- 

 gertooth Anotupterus pharao. Vopr Ikhtiol., .38(4):492- 

 498. 

 Brill. R.. B. Block, C. Boggs. K. Bigelow, E. Freund, and 

 D. Marcinek. 



1996. Horizontal and vertical movement of adult yellowfin 

 tuna near the Hawaiian Islands observed by acoustic telem- 

 etry: proceedins of the 47th annual tuna conferenece (A. 

 Jackson. R. Rasmussen, and N. Bartoo, eds. ), p. 21. South- 

 west Fisheries Science Center, National Marine Fisheries 

 Sei'vice. La JoUa, CA. 

 Carey, F G., and R. J. Olson. 



1982. Sonic tracking experiments with tunas. ICCAT Coll. 

 Vol. Sci. Pap., 27:4.58-466. 



