lockingtoni for locomotion and buoyancy in the 

 open ocean is compared with that of another 

 pelagic centrolophid, Schedophilus meduso- 

 phagus Cocco. 



Materials and Methods 



One /. lockingtoni was captured during an 

 open-water skin and scuba diving operation con- 

 ducted from the RV Nautilus in the San Pedro 

 Channel (lat. 33°30'N, long. 118°30'W) off south- 

 ern California on 24 October 1974. The fish was 

 approached by a scuba diver at a depth of 1 1 m as it 

 swam slowly beneath a scyphozoan medusa (ten- 

 tatively identified as a member of the family 

 Pelagiidae) approximately 30 cm in bell diameter. 

 The specimen was captured in a 1-liter jar, placed 

 in a container filled with aerated seawater aboard 

 the ship and transported to the laboratory at 

 California State University, Fullerton, where it 

 was placed in a 95-liter Instant Ocean 1 Tank. Ap- 

 proximately 6 h lapsed between time of capture 

 and placement of the fish in the laboratory tank. 

 Sea temperature at the depth of capture was 15°C 

 and the temperature of the seawater in the tank 

 when the fish was introduced was 13°C. Tempera- 

 ture of the seawater in the tank during the 

 maintenance period ranged from 8.8°C to 22.2°C (x 

 ± 1 SD = 14.9 ± 2.2°C) and the salinity from 

 35.0%« to 37.5%« (35.7 ± 2.3%o). 



The fish began feeding regularly on 7 November 

 1974 and was fed daily (except for 8 days, irregu- 

 larly spaced, when feeding was not possible) by 

 hand with measured amounts of frozen brine 

 shrimp (90% water content). The fish took the food 

 at the surface so that it was possible to keep an 

 accurate record of the amount of food it ingested. 

 The daily diet of frozen brine shrimp ranged in 

 weight from 1.2 to 8 g (0.4 -1.4 g dry wt/100 g live 

 wt fish). The feeding rate was based on the amount 

 the fish would consume immediately. Weight and 

 standard length (SL) of the specimen were re- 

 corded on 7 November and at irregular intervals 

 throughout the maintenance period by removing 

 the fish in a tray from the tank and placing it on a 

 platform balance beside a metric rule. The weigh- 

 ing and measuring procedure required that the 

 fish be out of water a maximum of 15 s. The con- 

 version of food into fish flesh was obtained by di- 



1 Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



viding the food intake (dry wt) by the gain in 

 weight of the fish (wet wt) (Hastings and Dickie 

 1972). 



Locomotor behavior was recorded from periodic 

 observations and from analysis of an 8-mm cine 

 film made of the fish swimming in the tank. 



Buoyancy of the specimen was measured im- 

 mediately after its death (7 April 1975) by weigh- 

 ing it in air and in water of known temperature 

 and salinity. Results were expressed as the per- 

 cent of the weight in air that the fish weighed in 

 seawater. 



After the buoyancy determination the specimen 

 was frozen and later thawed for lipid analysis. 

 Total lipids of the spine, skull, viscera, and flesh 

 (all other tissues) were extracted with 

 chloroform-methanol (2:1, vol/vol) and expressed 

 for each of the four body parts as the percent of 

 total body lipid and as the percent of dry weight of 

 that body part. 



Results 



The specimen of /. lockingtoni became con- 

 ditioned within 1 wk of capture to take food di- 

 rectly from the hand. Chunks of frozen brine 

 shrimp offered at the surface were quickly ap- 

 proached and usually taken in a single bite. 

 Throughout the maintenance period, the fish occa- 

 sionally swam upside down, apparently a normal 

 mode of swimming, and sometimes fed in this posi- 

 tion. The fish also bit at other available objects in 

 the tank, including human fingers at feeding time, 

 grasping them and then rolling and twisting its 

 body as if to tear free the objects. Vision appeared 

 to be the primary sense used in locating food. 



The specimen measured 105 mm SL at the time 

 of capture. On 7 November, when the fish began to 

 feed regularly and the record of food intake and 

 growth was begun, the fish weighed 30.6 g and was 

 115 mm SL (Table 1). The specimen lived 165 days, 

 until 7 April 1975, when the temperature of the 

 tank increased unexpectedly to 26°C apparently 

 causing death. At death, the fish weighed 54.5 g 

 (78.1% increase over its 7 November weight) and 

 had grown to 168 mm SL (46.1% increase). Its 

 weight peaked on 5 February at 64.6 g then de- 

 clined to the final value. 



During the 151-day period (7 November-7 Ap- 

 ril), 65.7 g (dry wt) of frozen brine shrimp were 

 ingested by the fish (Table 1). Based on this intake 

 and the weight gain recorded (23.9 g wet wt), the 

 overall conversion factor was 2.7. For the 90-day 



454 



