100-kg sea lion had been fed 5 kg of surf smelt, 

 Hypomesus pretiosus, 3 h prior to being lavaged. 



Successful lavage required two procedures: 1) 

 restraint of the animal and 2) entubation, irriga- 

 tion, and suction. Restraint varied greatly depend- 

 ing on whether a pinniped or cetacean was to be 

 lavaged. Delphinids are generally easy to re- 

 strain. The procedure many investigators have 

 used with success utilizes a canvas sling and 

 U-shaped pipe frame to hold the animal (Ridgway 

 1972). Normally the use of a sling is sufficient 

 restraint, however A. B. Irvine (pers. commun.) 

 has also used a wooden step ladder covered with 

 closed cell foam padding and padded straps to re- 

 strain large or especially aggressive delphinids. 

 This latter procedure requires that the animal be 

 gently lowered onto the padded ladder and then 

 immobilized with the padded straps. Pinnipeds 

 are more difficult to restrain in the field than del- 

 phinids. Squeeze cages (Ridgway 1972) are gen- 

 erally effective, but are normally too cumbersome 

 and heavy to use at sea. During the lavage test in 

 San Diego, the squeeze cage was used with suc- 

 cess, though considerable care was taken to avoid 

 being severely bitten. Use of the padded wooden 

 ladder and straps as a restraining technique for 

 pinnipeds in the field appears reasonable but 

 needs testing. 



With the animal successfully restrained, we 

 proceeded with entubation after lubricating the 

 entubation tube with a jelly lubricant. The 

 plugged end of the tube was gently pushed down 

 the animal's esophagus. After completing the en- 

 tubation I waited a few moments to make sure the 

 animal was breathing normally. If the animal 

 gagged or abnormal respiration was evident, I 

 quickly but gently removed the tube. If respiration 

 was normal, I connected the content collection 

 chamber and irrigation solution hose and pumped 

 about 300 ml of warm water into the stomach. 

 Warm water was used to avoid thermal shock to 

 the stomach. I then opened the vacuum control 

 valve and applied suction to the stomach. As suc- 

 tion began to remove the stomach content slurry, 

 more irrigating solution was pumped into the 

 stomach. In this manner a 2- to 3-liter food sample 

 was collected in a period of about 5 min. When I 

 felt I had collected sufficient material for test pur- 

 poses, I shut off the suction, ceased pumping ir- 

 rigating solution, and gently removed the stomach 

 tube. The stomach contents were filtered from the 

 slurry using a small hand vacuum pump and then 

 preserved in 70% alcohol. 



Results 



Using the above procedure otoliths, muscle 

 myomeres, skeletal bones, and scales were col- 

 lected from all five marine mammals. The animals 

 tested were returned to their tanks unharmed and 

 were doing well several days later. 



Discussion 



Using the equipment described and associated 

 procedure it was possible to remove almost all of 

 the diluted stomach slurry by suction; and by 

 rotating the tube while suctioning, it was possible 

 to vacuum the rugae of the stomach in order to 

 collect otoliths and squid beaks which tend to ac- 

 cumulate in these folds. J. E. Fitch of the Califor- 

 nia Department of Fish and Game has used fish 

 otoliths as a means to identify prey species on a 

 routine basis. With experience it is possible to 

 correlate size of otoliths and approximate sizes 

 and weights of the intact fish. The Alaska De- 

 partment of Fish and Game is presently establish- 

 ing such an otolith reference collection, allowing 

 not only identification of otoliths but also estima- 

 tion of intact prey length and weight (L. F. Lowry 

 pers. commun.). 



The limiting factor in the use of this device ap- 

 pears to be the ability of the capture personnel to 

 restrain specimens. Pinnipeds over 150 kg are 

 probably too large to be effectively restrained 

 mechanically, and are therefore very difficult or 

 impossible to entubate. Cetaceans, perhaps as 

 large as 500 kg, can be effectively entubated and 

 lavaged since these animals are generally much 

 more easily restrained out of water than the pin- 

 nipedia. In addition, certain pinnipeds, e.g., Erig- 

 nathus barbatus,Phoca hispida,P.fasciata, feed to 

 a greater or lesser degree on soft-bodied crusta- 

 ceans, and these prey organisms would probably 

 be effectively destroyed by suction and passage 

 through the entubation tube (L. F. Lowry pers. 

 commun.). 



I have made no mention of the use of chemo- 

 restraining techniques because I feel that these 

 methods are still unsuited for general use in the 

 field, especially with cetaceans. With proper 

 supervision, they have proven effective for re- 

 straining captive pinnipeds. In August 1972, I 

 used a chemorestraining solution of Ketamine- 

 Atropine onZ. californianus in the field. Although 

 dosages were at the level recommended by marine 

 mammal research veterinarians, I found the drugs 



655 



