RESULTS 



Migration Peaks and 

 Offshore IVIovements 



The picture of migration peaks ob- 

 tained from the aerial surveys agrees 

 with the summaries of Hubbs (1459) 

 and Gilmore (1960). The earliest 

 animals were seen in the third week 

 of December and the latest during 

 late May. The largest numbers of 

 animals were seen during the first and 

 second weeks of January and the sec- 

 ond and fourth weeks of March. Be- 

 cause the amount of aerial survey 

 effort varied from month to month, 

 indices of apparent abundance were 

 computed for data in blocks of a 

 month by dividing both the number 

 of aerial observations and the number 

 of individuals seen by the amount of 

 survey effort during that time period. 

 These indices (Figure 4) also clearly 

 indicate the periods of greatest abun- 

 dance off San Diego as January and 

 March. 



During both legs of the migration 

 many whales were sighted far offshore. 

 (Figure 5) presumably taking what 

 has been called the "inter-island leg" 

 (Gilmore. 1969). For instance, with- 

 in the 64 km wide band between lat. 

 32°I5'N and 32°55'N. southern mi- 

 grating gray whales were encountered 

 during 4.7 percent of the flights in 

 the first 80 km from shore. 5.0 percent 

 of the flights in the second 80 km. 

 and 1 percent of the flights over the 

 next 48 km. Similarly on the northern 

 migration, grays were sighted 6.4. 

 9.2, and 3.3 percent respectively of 

 the times the three zones were sur- 

 veyed. These findings support the con- 

 tentions of Rice (1965) and Rice and 

 Wolman (197 1) that at least since 

 1965 a rather high percentage of the 

 whales have passed offshore, out of 

 sight of Point Loma. 



Though most of the animals taking 

 the offshore route apparently strike 

 for the coast shortly after they pass 

 bv the southernmost of the Channel 



5.0- 



4.0 



3.0 



2.0 



1.0 



5.38 



2.36 



TOTAL DBS. 

 1" TOTAL FLT. HRS. 



2.20 



1.50 



.38 



.02 



OCT NOV DEC JAN FEB MAR APR IMAY JUN OCT NOV DEC JAN FEB MAR APR MAY JUN 



Figure 4. — Indices of apparent abundance (Ij) ol gray whales (rom aerial surveys. 1969-72. 



34° 



33 Figure 5. — Aerial survey 

 gray whale sightings, 

 1969-72. 



32° 



1?0° 



119° 



118° 



117° 



Islands, some do pass offshore toward 

 Guadalupe Island. Gilmore (1955) re- 

 ported Hubbs' sighting of three 

 mothers with calves outside Guadalupe 

 in February of 1950. In February 

 1972. I located two gray whales on 

 the outside of Guadalupe near the 

 southwest tip. A third animal, too 

 close to the cliffs to permit close ex- 

 amination, was also believed to be a 

 gray. The two verified sightings were 

 both adult animals 1 1 or more meters 

 in length. 



Cow-Calf Groups 



As was noted earlier, the routes 

 taken by females with calves during 

 the spring migration have been un- 

 known. 



Twenty-three northward migrating 

 groups containing mothers with calves 

 were observed during the aerial sur- 

 veys (Figure 6). The earliest was 

 sighted 18 February, the latest on 18 

 May. Although the majority of those 

 sightings were well inshore, this may 



47 



