PERRIN and HUNTER: ESCAPE BEHAVIOR OF PORPOISE 



Figure 7. — Typical "failure to 

 escape" episode. Moana (1) pa- 

 trols moving wall at beginning of 

 trial, then (2) takes up position 

 at apex of chamber and remains 

 there for most of trial, in vertical 

 attitude. As chamber nears clo- 

 sure Moana dives (3) , orients to- 

 ward opening (4) , and turns and 

 swims into moving wall (5), be- 

 coming entangled (6). 



%fe - 



-^*^ 



Figure 8. — Porpoise (Stevella 

 grnffmnni) in tuna purse seine 

 at beginning of set, when net is 

 at near-maximum diameter. An- 

 imals are circling and diving in 

 groups of a dozen or so individu- 

 als. 



Figure 9. — Porpoise in purse seine, after most of net has been taken aboard. 

 Animals are "rafting" in compact group, each maintaining approximately vertical 

 attitude, with blowhole exposed and dorsal fin submerged. Large fish underwater 

 in foreground are yellowfin tuna. 



59 



