1976 



20- 

 16- 

 12- 

 8 - 

 4 - 



On 



i i i i i 1 1 I i [ I I I I I I l I I I I I I I I I I I I I I I I I I I I I I I I I 

 15 18 21 24 27 30 3 6 9 12 15 18 21 24 27 30 



-APRiL- 



24- 



20- 

 16- 

 12- 

 8- 



1977 



Q i 1 1 1 n 1 1 1 1 1 1 ! 1 1 



a 



-i 



21 24 27 30 3 6 9 12 15 18 21 24 27 30 

 -APRIL i MAY 1 



1978 rfl 



L ■..Jill II III— 



24 

 20 

 16 



12 

 8 



4 



15 18 21 24 27 30 3 6 9 12 15 18 21 24 27 30 

 | APRIL 1 MAY 1 



Figure 4. — Comparison among years (1976-78) of observer effort (Iota! hours of 

 watch/hour) expended from 15 April to 30 May. The schedule for 1976 and 1977 

 called for rotating single observers every 4 h, whereas the 1978 schedule called 

 for two teams of two observers each (four total) to rotate every 3 h. Percent of 

 total survey hours watched were: 1976 = 37.0%; 1977 = 35.8%; 1978 = 86.7%. 



Cape Lisburne-Point Hope 



Counts of bowhead whales were made 6-16 May 1977 at 

 Cape Lisburne, Alaska. This was a feasibility study which 

 resulted in 54 bowhead whales counted during 72 h of watch. 

 Based upon results of the 1977 study, a full scale counting 

 study was conducted 2 April-7 June 1978 (Rugh and Cubbage 

 1980). Results of that study indicated that: 1) Spring migration 

 of bowhead whales past Cape Lisburne commenced during the 

 latter half of April; 2) bowheads generally pass Cape Lisburne 

 on a northeasterly course; 3) bowheads usually require 3-5 d to 

 traverse the corridor from Cape Lisburne to Point Barrow; 4) 

 our counting camps at Point Barrow were established before 

 whales passed Cape Lisburne; and 5) few if any whales moved 



past Point Barrow beyond 1 June. These results, and those 

 from aerial surveys, indicated that the 1978 counts made at 

 Point Barrow probably can be used to estimate abundance. 



Counts of bowhead whales were made at Point Hope from 

 18 April to 28 May 1977. A total of 185 bowhead whales was 

 observed during 546 h of watch. Two waves of movement 

 apparently occurred that year, the first during late April and 

 early May and the second during the latter half of May. 



Aerial Surveys for Bowhead and White Whales 



Approximately 75,000 km of tracklines were flown during 

 96 flights over the 1975-77 study period. For ease of analysis 

 and reporting, these surveys have been chronologically and 

 geographically ordered into 16 sets (Appendix I). Survey re- 

 sults are reported by month; no surveys were flown during 

 November-February. 



Statistics presented in figure captions associated with aerial 

 surveys are total number of whales counted, mean group size, 

 and standard deviation of group size. Whale counts from the 

 air were used as a relative indicator of how many whales 

 were present in any given area. Group size described the 

 number of whales observed in "close association" which 

 were counted at any one moment. When more whales sur- 

 faced, they were tallied as new sightings. Thus, mean group 

 size is downward biased since only a subset of the total group 

 was visible near the surface at any given time. 



March and April 



1976 



From 15 to 21 March 1976, four surveys were flown in the 

 vicinity of St. Lawrence Island. South of St. Lawrence Island 



Bering Sea 



I I I | I I I | I I I | I | I | I I I | if4-|-i+if H i | i I i | i I l 



172 



[66 



Figure 5. — Aerial survey tracklines flown in (he northern Bering Sea on 15, 18, 

 19, and 21 March 1976. No bowheads were observed. Dots depict the presence of 

 white whales: a total of 39 were counted with a mean group size of 2.8 and a 

 standard deviation (SD) of 2.3. Note: tracklines are not continuous because 

 effort was periodically broken in time; plots were drawn by computer and thus 

 reflect the actual route taken by the aircraft. 



