20235. JAMES F. FISH, JAMES L. SUMICH, and GEORGE L. … · 2010. 1. 14. · Tomilin, A. G. 1957. Kitoobraznye. ZverI S SR I prIlezhashchlkh stran (Cetacea. Mammals of the SSR and

..

natural food of thi s species of whale. Our captive 's habit of sweep in g a few centimeters o ff the smooth tank bot­tom does not deny the probability that weeping a soft or irregular bottom at sea could get mud o n the sweeper's back (cf. Fay in Pike, 1962, p. 823) , especia lly if the prey is actually benthic .

Cetological litera ture is fu ll of poor­ly supported conjecture, and we hesi­tate to add more. Although we have learned a number of things from th e captive Gigi , there i sti ll much un ­known . For one thing, her jetting water in pulses from a particular re­stri cted part of her mout h seems to im ply, perhaps, a specia l act ivity of the to ngue. Furthermore, we do not understand the mechanics of the hy­draulics tha t bri ng the food-beari ng water into the mouth . This is no mys­tery in whales that swim along with the mout h wide open , but it is not so obvious in a whale which swim along rather slowly with only a narrow slit open , as did our Eschrichrius . Here it seems necessa ry to increa e the volume of the mout h to cause useful inflow of water . We are handicapped by our Imperfec t u nde rstanding of the func­tions of th e muscul ar to ngue. W . E . Evans (pers. comm.) has told us that G igi's to ngue once pressed his hand pai nfull y hard a gainst he r pal ate . Such pressure migh t serve to push the gular region downward , enl a rging the mouth cavit y, a nd this idea fit with the ob­servatIOns of Donahoo and Ray of the m igrating to ngue-bulge visible from beneath .

Thus we su ppose, from the assorted eviden ce, the fo ll owing concatenation of events In fee ding: First the wha le ro lls over fa r enough so that the cheek is about pa ra llel wi th the bottom, and th e lip is opened as the tongue. press­ing against the palate, pushes the gular regi on away so that it expands, pro­ducing an inflow which brin gs in th e epibenthic food . Then the to ngue relaxes and the gular musculature tightens , reduci ng the size of the mouth cavit y and expelli ng water ; th e food is trapped in the baleen

fringes. We do not k now exactl y what happe ns next ; perhap a s light re­newed suction of water removes the food from the ba leen fringes , and swall owin g presumably fo ll ows.

LITERATURE CITED Andrews, R. C. 19 14. Mo nograp hs of th e

Pacific cetacea . I. The Cal ifornia gray whale (RlllIchulllecles glallcl/S Cope). Mem . Am . Mus. al. Hi I. ( ew SerIes) 1::':'7-:'87.

Gilmore , R. M. 1961. Th e ,tory of the gray whale, :'nd ed . PrI vately publtshed , San Diego, 17 p.

Howell , A . 8., and L. M. Huey . 1930. Food of the gray and other whales . J . M ammal. 11 :3:'1-3:':' .

Kasuya, T., a nd D. W . Ri ce . 1970. Notes on baleen plates and on arrangement of

parasitic barnacles o f gray whale . Sci. Rep. Wh a les Res . Insl. 22:39-43.

Nemoto, T . 1959. Food of baleen whales with re fere nce to whale movements. Sci . Rep . Wh ale Res . l nsl. 14: 149-290 .

Pike, G. C. 196:'. Migration and feeding of the gray whale (Eschnchlllis gdJboslIs). J . Fish . Res. Boa rd Can. 19:8 15 -838.

Rice, D . W ., and A . A. Wolm a n. 1971. The life history a nd ecology f th e gray whale (£.Ichnchlius r obuS/ lIn . Am. Soc. M ammal., Spec. Publ. o. 3, 14:' p. , 18 tables, 38 text figs.

Tom ilin , A . G. 1957. Kitoobraznye. ZverI S SR I prIlezhashchlkh stra n (Ce tacea. Mammals of th e SSR and adjacent coun­trIes.) 9. 756 p. (E ngl. tran I. Smithson. I nsl. , 1967 , 9, 7 17 p .J

Zimushko, Y. Y., a nd S. A. Lenskaya . 1970. o pita nil se rogo klta (£.Ichnchlllls glb­IwsLII Erx.) na mestakh nagula (Feedlllg of the gray whale {£.Ichnchlllls glbbo.luS Erx .} at foraging grounds). EkologJya AI-..ad. auk S SR 1{3} ::'6-35. (Engl. transl. , Consulta nt Bureau, Ple num Publ. Corp ., 1971, Ekologlya 1(3 )::'05-:'I:'.J

MFR Paper 1053. From Marine Fisheries Review, Vol . 36, No . 4, April 1974. Copies of this paper, in limited numbers, are available from 083 , Technical Information Division , Environmental Science Information Center, NOAA , Washington , DC 20235.

MFR PAPER 1054

Sounds Produced by the Gray Whale, Eschrichtius robustus

JAM ES F. FISH, JAMES L. SUMICH , and GEORGE L. LINGLE

ABSTRACT

Ullderwarer sOllllds produced by a yOllllg capril'e gray whale are d esc ribed . A "mewllic-HJlIlldillg pllised signal ," consisri ll g of 8 ro 14 pulses ill bursrs lasrillg lip ro 2 sec was rhe /lI osr com//101l \'ocali ::,a rio ll . Orh er soullds illcluded a lo w­freq uellcy "gro\\'I" or " m oall, " similar ro a sou lid recorded from gray whales £II

sea ; a shorr, broadballd. "grullrlik e" sOlllld; a lo w-pirched "blo whole rumble",' alld a 10llg "mera llic-soulldillg pulse rmill " rlwr m erged illro a lo w-frequency "groan." The SOli lids cOllld 1I 0 r be correlar ed wirh specific beh(/\'iors. A Iso de­scribed are "clic ks" recorded ill rhe presence of rh e whale whell she was rerumed ro sea alld similar "clicks" recorded from gray whales ill Wicka ll inllish Bay , VOllco u\ 'er Islalld, Callada.

This report desc ribes a variety of sounds recorded from Gigi, a young gray wha le, Eschric h rius ro bll.l·rUS, whi le she was in ca pti vit y a t Sea World , a ma rine park in Sa n Di ego, C a li f., and sounds reco rded in th e

38

vici nit y of th e whale when she was re turned to th e ocean nea rl y a yea r later . A lso described a re th e sounds recorded in the presence of gray wha les in Wic ka ninni sh Bay, Van­couver l ~a nd,Ca nad a.

Table 1.- Summary of previously published data on gray wha le sounds .

Dura tIon Frequency Reference Signal type (sec) (Hz)

Eberhardt & Evan s, 1962

" Croaker-like g runts "

" Low-frequency rumbles "

40-700

40-700

Pa inter , 1963

' Wen z, 1964

Ra smu ssen & Head , 1965

2Gal es , 1966

Hubbs, 1966

Asa-Do rian & Perk ins , 1967

Cumm ings et al ., 1968

Poul t er , 1968

" Pulses " " Low-pitched

grunting "

" Clicks "

No sounds

" Clicks "

No sounds

" Echolocat io n­like pulses "

" Variable whistles "

" Moans " " U nderwater

blo w " " Bubble -typ e

sounds " " Knoc ks "

" Croak- like grunts "

" Rumbl es" " Cri es "

" Grunting " " Rasping " " Pulses " " Chirps " " Bong " " Clicks "

<200->3.000

<200->3.000

70-3,000

1.5 20-200 Approx. l 15-175

0 .7 15-305

to 350

1 to several

2-5

to 12.000

1,2 Bot h re fe rences show data on sou nds reco rd ed by Asa-Dorlan i n 1955.

Vocalizati ons h ave been reco rd ed from mi grati ng gray w ha les off th e sou the rn Ca li forn ia coast (W enz. 1964. and Gales . 1966. bot h re po rtin g on record ings m ade by P . V . A sa- Dori an in 1955 ; Asa-Dorian and Pe rkin s. 1967 ; C um mings. T h ompson. a nd Cook. 1968) and from gray wh a les in th e lagoons of Baja Califo rni a. Mexico . whe re the wh a les breed (Eberha rdt and Eva ns . 1962: P ain ter. 1963 : Poulter. 1968). U nsuccessful att empts to o btain sounds fro m gray wha les off southe rn Ca li fo rni a and in th e lagoo n have been m ade by Ras musse n and H ead ( 1965) and by Hu bbs ( 1966). T he publi shed data on gray wha le sounds a re sum marized here in T a ble I .

Gigi h ad a lread y been in capti \ it ) at Sea World and h and -fed b) her tra iner for about 2 m onths before the lank recordin gs \ ere m ade . Al th ou gh

she seemed quite co nt ent in her un ­na tu ral surroundings . he r behav io r w as certa inl y not repre ent a ti ve o f a free-rangi ng gray whale of th e same age . H ence. the soun ds mayor may no t be simil a r to sou nds e mitted b) a young gray whale in its na tura l en­viron ment. A second proble m "" ith any tank recordi ng is th e effect of tank reso nance and rev e rbe rat io n on the ph ys ica l ch a racteris ti cs o f th e sounds. Certa in frequenc ies we re probabl y accentua ted in a mplitude and extended in tim e. N e\ e rth e le s. the data at least represe nt th e ge ne ra l

Ja mes F. Fish is with the Na \ al U ndersea Center , Sa n Di ego, CA 92132. Jame L. Sumi ch is with Grossmont College, EI Cajon, CA 92020. George L. Lingle is wi th SEACO. Inc. at the N a\ aJ U ndersea Center. San Diego. C A 92 132.

39

Pulses per burst

4-6 4-9 pulses per grunt

5-22

3-5

P"lse RepelltiOn

rate (per sec)

Appro.

10

10

3-7

5-18 8

33

Pulse Pea

80300

80300

100 11

1·15 400·80C

100

freq uenc) ra nge and \anet\ <1\ a young ca pt tve gra) \~hale <lund

em t SS l o n ~.

SOUNDS OF GIG I AT SEA WORLD

ound~ ""e re recorded illlultanc ou ~ l ) in \\ a ter and tn Jtr on d 2-tra k ta pe reco rd er ( her 42(0)t at cm/~ec. Th e h\ drl) phl)ne (\\ lIn) r i\.l -H 90- I. clmnneeted tl' ,ne ch n ne l of th e recorder. \\a u pende\! I m above the bOtll)1ll 0\ the clfcul f concrete tank (II m "tde rn deep) The Ir":lju..:nc\ r..: p' n <: 01 the unden\ a ter reLl rdl ng )- tern \10 ~ 0 H z Il) Ih I.. H L. :::J JB 1he nller phone. Cl nnected to thc other hannd \\ a 1L)\\ crcJ ,\\<:r the lip l f the tan

not mp b t~e

co "0

...J W > W ...J

W > >= .. ...J W 0::

...J W > W ...J

W > § W 0::

N

:I:

'"' ,.: u z w :::> 0-w If

0

· 10

· 30

8.0

6.0

4.0

2.0

0.09

Or (8)

- 10 (A)

co "0

...J

~ · 20 w ...J

W

~ -30 S w 0::

· 40 ,-

·50'--15 20 0 5 10

FREQUENCY. kHz FREQUENCY. kHz

@

~ .~ L :- ~ f

I

I- '.

I • t' · . r •

"f~ :

.. . : . - ~'I • • . ..... -... .. • _ •. - .. __ ,-.H~ * ~_ ' _ . "-~:. ..:-::: ~.:_.:~ "-"':,"- : ••

:i.-~_~~""":!~;:-.-?~O-~ p~. r:- ;~~~ :.~.:~. . 1 1 "'1

o 0 .25 0 .50 0.75 1.0 1.25 TIME . sec

(F)

(G

.... w G; ...J

~ W 0::

TIME 2 sec

TIME 2 soc

15

Figure 2 .- A . Spectral display 01 clicks recorded during re lease 01 Gig!. Spectrum analyzer set In Ptlek H"I nols. during preceding 9 sec . For A and B. data In .ach 01 250 IIIt er locati ons updated, but only In a posit spectra 01 tha alght Ind ividual clicks shown In E below. Spectrum analyzer set In Transient Capture ",,,de clicks . F and G . Bruel and KJaer level recordings 01 two dille rent repeti tion rate c lick trains.

(0

20

©

0

· 10

'" "0

.J ~ · 20 ...J

w > f= · 30 .. ...J W 0::

·40

' 501 -0

~, :I:i tv

~

5 10 FREQUENCY . kHz

• '----oj

2 msec

15

de lor a g·sec sampl e 01 clicks (about 200 clicks) . B. Spect ru m 01 ambient e direction, every 0.0125 sec. Analyzing bandwidth 120 Hz . C. Over lapping

SpC'_trogram 01 a typical c lick train . E. Osci llosc ope photographs 01 typical

20

...

to record th e commentary of the tra iner in the tank with the wh ale. The 3-hr recording ess ion began a bout I hour before a feeding period and las ted until the water leve l. which initi a ll y was about I m a bove the whale's bac k. was too low to ma ke useful underwate r recordin gs.

Spectrograph ic analyses were made in the laboratory with a "Vibralyzer" (Kay E lectr ic Company) to determine freq uency v. t ime. and a real-time spectrum a nalyzer (Spectral Dynam­ics SD 330) connected to an X-V re­corder (H ewlett Packard 7035 B) to portray the relati ve amplitude vs. freq uency. T he wavefo rms were mo ni­tored with ei ther th e spectrum an­alyzer in the Scope Time mode or an external oscilloscope. All of the sounds described below were recorded from the hydrop ho ne output.

The whale was very inacti ve a nd emitted no sounds until the water was lowered enough fo r the traine r to stand in the tank a nd touch her back . N one of the sounds could be consist­ently associated with a pa rticul a r behavIOr. However. o ne type. a "me­talhc-soundlllg pul sed signa l. " wa emitted nearly every time the tra iner tapped the wha le ligh tly on the back .

A low-frequency "growl" or "moan ." Similar to one type of sound reco rded from gray whales off San Diego. Calif.. by Cummings et al. ( 1968). 'v\as produced t'v\ice during the re­cording session The principal energy of thiS signal recorded fro m the cap­tive animal was in a ba nd fr om 100 to 200 Hz. 'v\ith a seconda ry peak around 15kHz (Figure IA). Th e duration of the sound was just over I sec. There was no o bvio us moveme nt of the blowholes or ex pul ion of air associated 'v\ith thi vocali zati on .

The most commo n sound was the "metall ic-sounding pulsed s ignal " which consisted of 8 to 14 pu lse in bursts las ting up to 2 sec (Figure I B) . The pul es had sharp fr onts (fa t rise times ) with energy extending fro m below 100 H z to over 10 kH z. a nd several resonant peaks. the trongest being a t 1.4 kHz. This sound occurred

a often as Ave tim e a minute. even when not in cit ed by the tra ine r . Onl y occasiona ll y did it a ppea r to be co r­re la ted with exha la ti o n a nd move­ment of the blowh o les.

T hree ti mes durin g th e reco rdin g sessio n. a sho rt (0 .2 sec). broad ba nd . "gruntlike" sound (Fi gure IC) was em it ted. with out movement of th e blowholes . Its peak energy was cen­tered a t 200-400 H z a nd 1.6 kH z.

F igure 10 shows the unde rwate r sounds of an e.xh a la ti o n fo ll owed by a low-pitched . " blowho le rumble ." T his combi nation occu rred several ti mes.

Twice. a lo ng "me talli c-soun d ing pu lse train " wi th a repetitio n rate of about 14 pulses/sec merged into a long. low-freq uency "groan" after about 1.5 sec ( igure I E). xcept for the much fas te r pul se re petition ra te. th e Ar t part o f th is voca liza tion was simil a r to the sound hown in Figure lB .

Numerous other sou nd produced by Gi gi duri ng the 3-hr recording se sion essentiall y were variatio ns of o ne o f th e Ave types di scussed above .

SOUNDS RECORDED DU RI NG RELEASE OF GIGI

Unfo rtun ate ly . we did not record again in the presence of G igi unt il she was re leased o n 13 Ma rch 1972. T he recordi ng and a nalysis system used fo r these data was th e same as used a t Sea Wo rld . Sho rt ly a ft er G igi was lowered in to the wa ter from th e barge that ca rri ed he r out to sea. lo ng trai ns of "clicks" we re hea rd . A lthough a t the time th ere was no way to determine if th ese sounds. which were unlike any reco rded fro m Gigi a t Sea W orld. actuall y came fro m th e whale o r fr om a nother un -een bio logica l source in th e area. we

now bel ieve they were emi tted by G igi. T he c li c k were nea rl y identical to th e click we have recentl y recorded in the presence of gray whales in Wick­aninni sh Bay. Vancouver Island. Can­ada.

4 2

The cl ic k reco rded in the presence o f Gi gi are hown in F igure 2. T heir princ ipa l ene rgy occupied a band fr o m about 2 to 6 kHz. cente red a t 3 ,4 to 4 .0 kH z. C lick durati o n was I to 2 m ec. Eight minutes a nd 15 sec a ft e r th e wh ale ent e red the water most boa t in th e area shut down the ir engines fo r our reco rdin g. The Ar t bu rs t of 29 clicks was recorded 6 ec la ter . T hree minute a nd 49 sec late r the boa ts sta rt ed their engines a nd we had to terminate our Anal recordin g of Gig i. Durin g th e 3 min a nd 55 ec of qui e t- hip conditi o ns we recorded 1.304 cl ic ks . Th e number of c li c ks per burst (o r tra in ) va ri ed fro m I to 833 and th e click repetiti o n ra te fro m 9.S to 36 .0/ ec . The lo nge t c li c k tra in . cont ainin g 833 cli c ks a t a n average repetiti on ra te of 19/ ec. began about I m in afte r th e boa ts had shut do~ n th ei r e ngine. Altho ugh the a mplitude of th e signal va ri ed wi th time. we could not correla te signal leve l with th e loca ti o n of Gi gi because the a ni mal was not een du r­ing the enti re tim e of the recordin g.

SOUNDS RECORDED FROM GRAY WHALES OFF VANCOUVER ISLAND

The sy te m u ed to record sound in the pre ence o f gray whal es in Wi c ka ninni sh Bay o n the we t coast o f Va ncouve r Island . Canada . co n­sis ted of a casse tte recorder (So ny Model T C- 12 6) a nd a po rtabl e unde r­water li stening set (Inte rOcean Mode l 90 A Bi o -Acustik l. Th e useable fre ­quency range o f the system was 100 Hz to 10 kHz. T he hydropho ne ar­ra nge ment shown in Fi gure 3 res ul ted in good qualit y reco rdi ngs wi th the small boat system.

Si nce 1967. a ma ny as seven gray wha les have been ighted a t o ne tim e in W icka ninni h Bay . However . all of the recordi ngs de cri bed he re we re fr om in gle whales or pairs. A t 1725 hr o n 10 A ugust 1973. seve ral c lick tra ins we re recorded fro m a s ingle feeding gra y whale in 10 m of water. 1.200 m from sho re . Very littl e w ind

and calm seas made recording condi­tions ideal. The first clicks. shown in Figure 4F. began I mi n after the whale started a 3-min-35-sec-long dive , at a distance of 50 to 70 m from the hydrophone. Additional click trains (Figure -+G) occurred simultaneously with the first exhalation after the dive. Twenty sec later. noise from an unseen boat began and continued for 95 sec. A third click train was emit­ted 50 sec after the boat noises cea ed and 50 sec prior to the next blow. By then. the whale was 80 to 100 m from the hydrophone and the received leve l of the clicks was 5 to 7 dB lower than the level of the clicks recorded when the whale was half that distance from the hydrophone .

On 18 August 1973 , the click train shown in Figure 4H was recorded from a single feeding gray whale at 0900 hr. The whale was about 600 m from shore in -+ m of water. The sur­face was calm with about a 1m swell. At the time the click train was emitted , the whale was 100 to 150 m from the hydrophone . Twenty min later a sin­gle harbor porpoise , Ph oeoena pho­eoenC/, was observed in the area.

About 5 hr of recordings were made in the presence of the gray whales In Wickaninnish Bay and much additional monitoring was done without recordin g. Although at times nearly conti nuous very fai nt c l icki ng could be heard , only about 250 of the recorded clicks had good signal -to­noise ratios . The number of clicks per train varied from I to 96 with repeti­tion rates of 8 to 40/sec. The principal energy of these clicks occupied a band from abou t 2 to 6 kH z, centered at 3.5 to 4.0 kHz . The average click duration was a little under 2 msec.

DISCUSSION

We do not know how any of the sounds discussed in this paper were actually produced by the gray whales. The "metallic-sounding pulsed signal" produced by Gigi at Sea World sound­ed like air bubbles escaping from an area of high pressure through a con-

striction (similar to the sound of air' escaping from a scuba regulator un­derwater). Since this whale sound generally was not associated with ex­halation or blowhole movement, if it were, in fact, generated by escaping air, the air must have passed from one internal chamber to another. No bub­bles were observed comi ng from the mouth or blowholes .

Although the possibility exists that another species of marine mammal could have produced the clicks re­corded when Gigi was released off San Diego and the clicks recorded in the presence of gray whales in Wick­aninnish Bay. we think the evidence indicates that the clicks did come from the gray whales. The acoustic param­eters of the clicks recorded from the geographic areas are nearly identical. The only mari ne mammals, other than gray whales. observed in either recording area was the single Phoeoena phoeoena observed a hal f hour after the recording was made on 18 August 1973 in Wickaninnish Bay and a small group of Delphinus delphis , about 2 km away from the site of Gigi 's release a half hour before she was released. Phoeoena phoeoena ,

TAPE RECORDER

~AMPUFIEA

~ CORK FLOATS -......,

however , has not been observed off San Diego, and clicks of Delphinus have a much higher frequency content than described in this report. Also , the level of the clicks recorded in the presence of Gigi was too high for the sounds to have come from the Del­phinlls as the clicks appeared to origi­nate from a si ngle source rather than from a group of ani mals.

We have no evidence that the cl icks recorded in the presence of gray whales have an echolocation function , but if they do , their frequency range (2 to 6 kHz) probably would be too low for the sounds to be useful for locating small individual food organ­isms. However, they could be helpful for finding dense concentrations of organisms or for ranging off the bot­tom to feed or navigate. Despite four seasons of recordi ng in the presence of hundreds of migrating gray whales off San Diego, Naval Undersea C enter personnel have never recorded similar clicks from the whales. But , accord­ing to most authorities. gray whales do not feed on their long migrations (Rice and W olman, 1971). If the clicks were associated with feeding , we consequently should not expect to

- WIND SPAR BUOY /BICYCLE

/ INNER TUBE)

HYDROPHONE LINE / /60 FT LONG)

_- BRASS SW IVEL

8" DAMPING DISC--

/' 8-BAlL HYDROPHONE

~CORK FLOAT FOR NEUTRAL BUOYANCY

- -WEIGHT

Figure 3.-Hydrophone suspension system used to record underwater sounds in Wickaninnish Bay, Vancouver Island , Canada .

43

-I:L (Xl .., J ~ -20 ,-w -' w > ;::: ..: -' w

"" -40 ,-

-50 0

~o

~ ~O ~

> u ~ 4.0 ~ 0 w E 2.0

-' w > w -' w > ;::: ..: -' w

""

0~9

0

® ® . -,: ~ 1

Or

-10 (Xl

©

'C 'C

J ~ -20 w -'

J t ' ~ - 20 -'

w w > > ;::: -30 ..: -' w

"" -40

~ -30 IM~NI' -40

-50 u

5 10 15 20 5 10 15 20 0 5 10 15 FREQUENCY. kHz FREQUENCY, kHz FREQUENCY, kHz

@ ®

... - I!!" - .. t'" • i ~ I!'"~ ~~ti 'z ,

;:-

0.25 0.50 0.75 10 125 TIME. sec EM'

~

® 2 msec

® -' w > w -' w > ;::: j w

""

I - .. I ®

-'

"& '0.1 w

CLICK TRAINS > CLICK TRAINS w -' w > ~~~1\M TIME ;:::

j 2 sec

TIME 2 sec

w

"" Jl'

TIME 2 sec

Figure 4.-A. Spectral dllplay 01 cllckl recorded In the pr .. ence 01 a gray whale In Wlckanlnnllh Bay . Spectrum analyzer let In Peak Hold mode lor a 6-lee lample 01 clicks (about 90 clicks). B. Spectrum 01 ambient noise during preceding 6 lee. For A and B , data In each 01 250 IIlIar locatlonl updatad , but only In a pOllllve direction, every 0.0125 lee. Analyzing bandwidth 120 Hz . C. Overlapping spectra 01 the eight Individual cllckl Ihown in E below. Spectrum analyzer lei In Tranllant Capture mode . D. Spectrogram 01 a typical click train . E. Oscilioicope photographl 01 Iyplcal cllckl F, G, and H. Bruel and KJaar laval racordlngl 01 lavaral click Iralnl . Note changing repetition rate ~~ ~

20

encount er th em in thi s a rea o f mi grat­ing wh ales. When th e cli c ks were recorded in Wicka ninni sh Bay , th e gray wha les we re feedin g. Wh y G igi emitt ed clicks wh en re leased is un ­known . In thi s case , the ir fun cti o n could have been ori enta ti o n since it is unlike ly th a t she was lookin g fo r food so soon a ft e r bein g pl aced in a new environme nt. The cli cks d i ­cussed he re a re o nl y sli ghtl y li ke those recorded by Asa- Do ri an in 1955 (see W enz, 1964). They a re no t simil a r to any o th er report ed gray whale sounds.

Ot he r recent ev idence fo r m ysti cetes produ cing cli c k-ty pe sounds has been repo rt ed by Beami sh a nd Mitc hell ( 197 1). T heir recordin gs in th e p re­ence of blue w hales included clicks with peak energy in a band fro m 2 I to 3 1 kH z .

ACKNOWLEDGMENTS

W e a re grateful to Wilburn G . ('" Bud ") Donahoo fo r hi s help a t Sea World duri ng the recordi ng sess io n ; to W ill ia m C. C ummin gs fo r hi s advice a nd assis ta nce in th e recordings of G igi a t sea , a nd to Willi am E . Eva ns and F ay Wolfso n fo r th e ir suggest io ns o n the ma nuscri p t.

This work was supported by the Nava l U ndersea C enter. Independent Research fund ing, a nd th e Office of Nava l Resea rch , O ceanic Bi o logy Branch, G rant No . N R 104-1 23.

LITERATURE CITED

Asa-Doria n , P . V., a nd P. J. Perkins. 1967. The co nt rovers ia l producti on of sound by the C a lifo rni a gray whale, Eschnchll l/s gibbos lis. Nor. H valfa ngst-Tid . ( o rwe­gian Whaling G azelle) 56: 74-77.

Beamish, P ., and E . Mitch ell. 197 1. Ult ra­sonic sounds recorded in the presence of a blu e whale , Ba /aenoplera /II I/SCLl/ LlS. Deep-Sea Res. 18:803-809.

Cummings, W . c. , P . O. Th ompson , a nd R . Cook . 1968. U nderwate r sounds of m i­gratin g gr ay wha les, Eschrichlills g/a l/c 1/s (Cope) . J . Acoust. Soc . Am. 44: 1278- 128 1.

Eberhardt , R. L. , and W . E . Evans . 1962. Soun d ac ti vity of th e California gray whale, EschrichliLls g /a l/ c lis. J . Aud . E ng. Soc . 10:324-328 .

Gales, R. S. 1966. Pickup, a na lys is , a nd Inte rpreta tion o f underwater acousti c data. In K . S. N orris (editor), Whales . do lphins, and porpoi es , p . 43 5-444 . Univ. Cali f. Press . Berke ley a nd Los Angeles.

H ubb's, c. 'L. 1966 . Comments. I II K . S. N orris (edito r), Wh ales, do lphins, and po rpOises, p . 444 . Uni v. Cali f. Press, Berke ley a nd Los Angele .

Painte r , D. W ., 1I . 1963. Ambient no ise in a co asta l lagoon. J . Acou t. Soc. Am . 35 : 1458- 1459( L).

Po ulter , T. C. 1968. Voca li zatio n of the gray wha les in Laguna Ojo de Li ebre (Scammo n 's Lagoon) Baja a lifo rni a, Mex Ico. N o r H va lfa ngst-Tid . (N orwegia n Wh aling G azelle) 57:53-62.

Rasmussen. R. A., and . E. Head. 1965 The qu iet gray" hale (EH'hnchIlLls ~/I1L1CI/\). Deep-Sea Res. 12 :869- 77.

Rice, D. W., and A. A. Wolman Ill71 T he li fe h istory a nd ecolog) of the gra\ whale (Eschrichlllls robLlSIIIS) . Spec Pub!. 3, Am. Soc. M amma!., 142 p.

We nz, G. M . 1964. C urious nOises and the sonic envi ro nment in the ocean. I II W . N. Tavolga (ed itor), Manne bIO­acoustics, p. 10 1- 123. Pergamon Pre'>s.

ew York.

MFR Paper 1054. From Marin e Fisheries Review, Vol. 36, No. 4, April 1974. Copies of this paper, in limited nu mbers , are available from 0 83, Technical Information Division , Environmental Science Information Center NOAA , Washington , DC 20235. '

MFR PAPER 1055

Aerial Observations of Migrating Gray Whales, Eschrichtius robustus, off Southern California, 1969-72

J. S. LEATHERWOOD

ABSTRACT

Migra lin g gray lI 'hale,\ were obserl'ed frolll h elicopler and fi.\ed-II'ing aircI'I!/i

fro lll ce n lred Ca liforn ia sOll lh to Cedros alld Glladaillpe I.Ilands , Baja Calijim/ia,

M exico, lI 'i ,h 117 1' pri lllary sighling efforl off sOlllh('1'1/ California . Peak 1I1111/hers w ere obsen 'ed off 50 11 1171'1'11 California in Janllary fiJr Ihe ,\oulhward lIIigralion and in Marc h for 1171' northward lIligration. / ndil'idllals were ob.\e/'I'ed wilh Ihe

sa lli e relm iI'e freqllency 80-/60 k III offshore as I hey were lI 'i I hi n 80 k III of'

sh o re . Call's lI'i lh w / l'es 11'1'1'1' seen fro III Fehruary Ihrollgh May, prillllll'l/l illSh o re, and lended 10 be alone or wilh olher COli'S wilh ca/l'es. Y earling ,dllliel

w ere seen illSh ore frO Ill February Ih rollgh April and also lellded to he solifllry or wilh olh er yearlin gs. A I'erage speed of lIlovelllelll for lIorrhll 'ard lIligranll

lI 'as 2.8 klll /h o ll r. R eSlllls of aeria l slIn'eys cOlllpare jill'orahly willi pllhlished WlIIlIlari el III

Ih e lilll ing of m igral io n hased Oil shore alld ,Ihip sample,\ alld support Ihe I'li/lle

oIaerial surl'eys as ({ rool ill cefllceall populalioll sflIdies.

INTRODUCTION

Since sho rtl y afte r its popul a ti o n began to recover fro m a second nea r­exte rmina ti o n by man in the 1920's and 1930's (G ilm o re, 1955), the Cali ­fo rni a gray w hale, E.IChrichli ll s 1'0-bllSflIS, has been th e subject of more pu bli c interest a nd more scienti fic resea rch th an perhaps an) othe r pe­cies of la rge whale. Because of their

45

spectacu lar nature and proximity to shore along much of the route. the migrations of the species ha\e been rather ex hausti vel)- de cri bed by Scam­mon (187'+)' Hubb (1959). Gilmore (1960a and 1960b). Rice (\ 96 I), PI hoe (1962). Hubb and Hubbs (1967)' Adams (1968). and Rice and Wolman (1971). Ob~enations from hore ~ta­

tions (primaril) at Point Loma In