nonn.n.1 DUL.ijt.iiiM; »ul. 01, i\\j. i. 



two whales. Coincidently we were recording low- 

 level, high-pitched whistles and squeals from a dis- 

 tant group of saddleback porpoises, Delphinus 

 delphis. It was obvious that changes in the loudness 

 of other low-frequency signals, as aurally monitored, 

 and in the level on the graphic recorder were cor- 

 related with the nearby Bryde whale's proximity to 

 the ship. 



Later the same day, another whale was sighted off 

 Pta. Conception in the Mulege area and tentatively 

 identified as either a sei or Bryde whale of about 

 12 m (Contact 3). We recorded 407 sounds from this 

 whale The sounds were essentially the same as those 

 recorded earlier from the Bryde whales of Con- 

 tact 2. After analyzing the sounds, Contact 3 was 

 identified as a Bryde whale Sounds of these 

 characteristics were not encountered again during 

 the cruise, nor were any other Bryde whales 

 seen. 



About 100 km northwest of Guaymas, a large 

 whale was sighted at a range of about 450 m (Con- 

 tact 4). A brisk wind and choppy seas prevented iden- 



tification, but one distinctly whalelike moaning 

 sound appeared in the accompanying noisy record- 

 ing. 



East of San Pedro Martir Island, we recorded 42 

 sounds from another whale (Contact 5) identified as 

 a finback, about 15 m in length. Three large finback 

 whales were sighted off the southern tip of Isla 

 Angel de la Guarda (Contact 6). All of the 376 moans 

 recorded from these whales occurred when the 

 animals were below the surface 



On 19 June, we sighted about 35 finback whales 

 outside the entrance of Puerto Refugio (Contacts 7, 

 8). They surfaced in series of 2 to 7 times, usually 

 in pairs or in trios. Their blows were accompanied 

 by smooth resonant sounds similar to that expected 

 from air rushing through a confined space Climax- 

 ing the final appearance in a series of surfacings, 

 the whales strongly arched their backs and appeared 

 to dive at a steep angle Some of the finbacks' dor- 

 sal fins were distorted. Large concentrations of 

 whales, porpoises, and sea lions occurred over an 

 area of at least 6 km around the ship where they 



1 



TIME IN SECONDS 



Figure 2.-Spectrograms of typical Bryde whale moans. The effective analyzing filter bandwidth was 3 Hz. 



362 



