SURFACE FEEDING BY A JUVENILE GRAY 

 WHALE, ESCHRICHTWS ROBUSTUS 



Recently Ray and Schevill (1974) summarized in- 

 formation on the feeding habits and feeding be- 

 havior of Eschrichtius rohustus. The gray whale is 

 primarily a bottom feeder whose diet consists 

 mainly of six species of benthic gammaridean am- 

 phipods taken in the Bering and Chukchi Seas 

 during the summer months (Zimushko and 

 Lenskaya 1970; Rice and Wolman 1971). It is gen- 

 erally assumed that gray whales fast during mi- 

 gration and while at the breeding grounds along 

 the Mexican coast. Several reports, however, 

 suggest the possibility that feeding may occur oc- 

 casionally outside of the Arctic region and may 

 include a wide array of different food items, e.g., 

 smelt, anchovylike fish; planktonic crusta- 

 ceans — Euphausia and Pleuroncodes (Howell and 

 Huey 1930; Matthews 1932; Gilmore 1961; Bal- 

 comb in Ray and Schevill 1974). In addition to 

 these, reports of bits of woods, stones, tube worms, 

 shell, etc., including kelp fragments have been 

 reported in stomach contents of gray whales (Tom- 

 ilin 1957). However, most of these items are prob- 

 ably attributable to incidental swallowing. 



Herein we report observations made on a 

 juvenile gray whale,* ca. 6-m long, exhibiting un- 

 usual surface feeding behavior in a kelp, Macro- 

 cystis angustifolia, bed near Refugio Beach State 

 Park, 38 km west of Santa Barbara, Calif. Be- 

 tween 1 and 9 April 1976, four visits were made to 

 the area and a total of 8 h were spent detailing the 

 observed behavior. Throughout the study period 

 the whale's activities were confined to the exten- 

 sive kelp bed situated between Refugio Beach 

 State Park and Arroyo Hondo — a distance of 3.2 

 km. This feeding activity was restricted to the kelp 

 canopy and occurred in shallow water (<5-10 m 

 depth) and 50 to 200 m offshore. We last saw the 

 whale on 9 April 1976. Apparently it left the area 

 shortly thereafter as subsequent searches were 

 made on 16 and 18 April 1976. 



Description of Feeding Behavior 



When first sighted, the whale's head was pro- 

 truding a meter or more above the surface of the 



' On a number of occasions the whale laid nearly horizontal on 

 the surface of the water only a meter from our boat ( 7-m Boston 

 Whaler), thus we were able to make a reasonably accurate esti- 

 mate of it's overall length. Reference to trade names does not 

 imply endorsement by the National Marine Fisheries Service, 

 NOAA. 



water in the center of a dense kelp bed (Figure lA). 

 Shortly after surfacing snout first, its mouth 

 opened and a large volume of water and kelp 

 flowed into the oral cavity (Figure IB). Next the 

 jaws closed (Figure IC) and in the process a small 

 squirt of "excess" water issued from the most an- 

 terolateral margins of the mouth. Within mo- 

 ments entrapped water was forced out of the 

 mouth across the baleen plates through the lips in 

 a strong flush directed posterolaterally (Figure 

 ID). This sequence was repeated several times 

 before the whale submerged. Prior to submerging, 

 the head was raised at an angle approximately 60° 

 normal to the surface of the water. The body then 

 slid backwards through the kelp canopy with its 

 jaws slightly agape releasing the kelp present in 

 its mouth. Resurfacing generally occurred a short 

 distance away. There was little deviation from 

 this pattern during the entire observation period. 

 Visits were made at all hours of daylight during 

 which the intensity of the feeding behavior ap- 

 peared consistent. 



During a typical 27-min period when the whale 

 was exhibiting feeding behavior, we noted that it 

 emerged in the kelp, fed, submerged, and then 

 reemerged a total of 18 times. A single feeding- 

 submergence interval averaged 90 s, of which 56 s 

 were spent feeding and 34 s submerged. Fre- 

 quency of breaths during this period were recorded 

 for 11.5 min. The average time from inhalation to 

 exhalation was 48 s; the maximum was 70 s and 

 the minimum 20 s. The act of breathing (i.e., ex- 

 haling, then inhaling) at the surface averaged 2 s. 

 These data clearly demonstrate that the whale 

 was quite active in its behavior. 



At first impression the whale appeared to be 

 "biting and eating" the kelp, but on closer inspec- 

 tion the fronds and stipes of the kelp incurred little 

 if any damage. While there is no direct evidence 

 available from stomach analyses, we suggest 

 the whale's activities among the kelp were di- 

 rected to procuring quantities of the small kelp 

 mysid crustacean, Acanthomysis sculpta. Sam- 

 pling of the mysid fauna was accomplished using a 

 50-gal plastic trash can which was lowered into 

 the water at a horizontal angle from the boat in 

 such a fashion that the surface water down to 30 

 cm fiowed freely into the container. The mysids 

 were subsequently filtered out, counted and vol- 

 ume determinations made. A total of four repli- 

 cates provided a conservative estimate of 5 to 10 

 mysids/1 at the canopy surface. The size range for 

 individual mysids in our sample was 6 to 12 mm, 



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