Procedure 



Whale counters were usually sta- 

 tioned at Point Loma, where each 

 counted for five hours daily, either 

 fronn 7 a, m. to noon, or from noon 

 to 5 p. m. These periods cover the 10 

 daylight hours of midwinter at the 

 latitude of San Diego, 32°45'N. Five 

 hours are about the limit of endurance 

 of one counter; a longer period pro- 

 duces observational fatigue. 



Each counter was equipped with a 

 logbook, a pair of binoculars, and a 

 watch. Each time a whale, or group 

 of whales was sighted, the time, num- 

 ber of whales, and visibility were 

 recorded. 



Identifying characters of the gray 

 whales, of use to the watchers, are 

 the length of 30 to 45 feet, color dark 

 gray or nearly black, blotched with 

 white marks of roughly circular or 

 irregular outline up to a foot in diam- 

 eter, absence of dorsal fin which is 

 replaced by a low, thick ridge followed 

 by a series of 8 to 12 small sharp 

 knuckles and a convex rostrum. The 

 dorsal ridge and series of knuckles 

 are the most characteristic and easily 

 observed diagnostic feature of the gray 

 whale. The flukes are often thrown 

 conspicuously in the air on a "sound- 

 ing" dive. Although of characteristic 

 shape with small tips and prominent 

 rear curve, the smallish flukes are 

 not always seen clearly. 



Extrapolations 



In virtually all wildlife censuses, 

 some individuals escape detection and 

 are not counted. In estimating the 

 whale population, the writer has added 

 corrections for whales which passed 

 (1) during bad weather in daytime with 

 poor or no visibility, (2) at night, and 

 (3) beyond sight of land. 



Extrapolations for poor visibility . -- 

 Daytime bad -weather extrapolation 

 was based on three points: (1) degree 

 of visibility; (2) abundance of whales, 

 i. e., intensity of migration at the 

 time; and (3) density of fog (when 



reduced visibility was caused by fog) 

 because fog was assumed to slow the 

 rate of travel. 



When visibility was not zero, and 

 some whales were seen close to shore, 

 extrapolation was based directly and 

 entirely upon the estimated degree of 

 reduced visibility. For example, if the 

 haze settled so heavily that visibility 

 was lowered to 1,000 yards, or 25 

 percent of normal, and 10 whales were 

 seen, the number estimated to have 

 passed unseen was 30, or a total of 40. 



When rain or fog reduced visibility 

 to zero, the nearest period of clear 

 visibility was taken as a basis for 

 extrapolation. For example, if visi- 

 bility was completely blanked out by 

 fog in morning (7 a, m. to noon) and 

 the afternoon hours (noon to 5 p. m.) 

 were clear, and 25 whales were seen, 

 the extrapolation value for the morn- 

 ing was 25. Or, if there had been three 

 days of heavy fog with visibility zero, 

 the past previous day of good visibility 

 was taken as a basis for extrapolation. 

 If 50 whales had been seen on that day, 

 the extrapolated value for each of the 

 three foggy days would be 50, 



Persistent foggy weather was be- 

 lieved to slow down travel of whales. 

 If three foggy days occurred in a row, 

 the extrapolation was weighted down- 

 ward by 40 percent; the extrapolation 

 was further reduced if the fog con- 

 tinued. (Here the writer freely admits 

 the possibility of fairly serious error.) 



Extrapolation for night migration. -- 

 Gray whales are known to migrate at 

 night. They are seen occasionally from 

 boats, though the speed of night travel 

 has never been learned. Nevertheless, 

 suppositions which lead the writer to 

 conclude that gray whales slow down 

 considerably at night are as follows: 



Whales presumably have occa- 

 sional rest periods. As whales were 

 not seen sleeping in daytime, they 

 must do so, if at all, at night. 



If dependence is upon vision (in 

 air) for close navigation of the 

 shore, and light of sun or moon is 



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