Estud. Oceanol. 12: 37-53 1993 ISSN CL 0O71-173X

EXTERNAL FEATURES OF THE DUSKY obscurus (GRAY, 1828) FROM PERUVIAN WATERS

CARACTERisTICAS EXTERNAS DEL DELFiN OSCURO Lagenorhynchus obscurus (GRAY, 1828) DE AGUAS PERUANAS

Koen Van Waerebeek

Centro Peruano de Estudios Cetol6gicos (CEPEC), Asociaci6n de Ecologfa y Conservaci6n, Casilla 1536, Lima 18, Peru

ABSTRACT

Individual, sexual and developmental variation is quantified in the external morphology and colouration of the Lagenorhynchus obscurus from Peruvian coastal waters. No significant difference in body length between sexes is found{p = 0.09) and, generally, little is present. However, males have a more anteriorly positioned genital slit and anus and their is more curved, has a broader base and a greater surface area than females Although the dorsal fin apparently serves as a secondary sexual character, the use of it for sexing free-ranging dusky is discouraged because of high overlap in values Relative growth in 25 body measurements is characterized for both sexes by multiplicative regression equations. The colouration pattern of the dorsal fin, flank patch, thoracic field, flipper stripe and possibly (x2, p = 008) the eye patch, are independent of maturity status. Flipper blaze and lower lip patch are less pigmented in juveniles than in adults No sexual dimorphism is found in the colour pattern The existence of a discrete "Fitzroy" colour form can not be confirmed from available data. Various cases of anomalous, piebald pigmentation are described, probably equivalent to so-called partial albinism Adult dusky dolphins from both SW and are 8-10 cm shorter than Peruvian specimens, supporting conclusions of separate populations from a recent skull variability study.

KEY WORDS: colouration, external morphology, dusky dolphin, population, Southeast Pacific.

RESUMEN

Se cuantifica la variaci6n individual, sexual y de desarrollo en la morfologia extern a y la coloraci6n del delfin oscuro Lagenorhynchus obscurus de aQuas costeras peruanas No se detecta diferencia significativa en longitud corporal (p = 0,09) y, en general, poco dimorfismo sexual esta presente La ranura genital y el ano se situ an mas anteriormente en log machos que en lag hembras Ademas, la aleta dorsal en log machos muestra una mayor inclinaci6n, tiene una base mas larga y una superficie mayor. Aunque, aparentemente, la aleta dorsal sirve como caracteristica sexual secundaria, no se recomienda usarlo para determinar el sexo de delfines oscuros en alIa mar por un alto nivel de sobreposici6n en valores Ecuaciones de regresi6n multiplicativa caracterizan el crecimiento relativo en 25 medidas corporales, en ambos sexos EI patr6n de coloraci6n de la aleta dorsal, mancha del flanco, mancha toracica, banda de la aleta pectoral y, posiblemente (x2, p = 0,08), la mancha del ojo son independientes del estado de madurez; la mancha pectoral y la mancha dellabio inferior en log juveniles se yen menos pigmentadas que en log adultos. La existencia de una forma discreta de coloraci6n Ilamada "Fitzroy" no se puede confirmar con log datos presentes Se describe una anomalia de la pigmentaci6n que probablemente es equivalente con albinismo parcial, conocido en otros mamfferos Los delfines oscuros adultos del suroeste de Africa y de Nueva Zelandia miden unos 8-10 cm menos que log especfmenes del Peru, confirmandose conclusiones que forman poblaciones separadas, basado en un estudio reciente de variabilidad cranial. 38 Estud. Oceanol. 12, 1993

INTRODUCTION

Particularities in the external features of whales In New Zealand and Argentina, sex (and identity) and dolphins can offer valuable insight in their gen- of free-ranging dusky dolphins have been deter- eral biology. Differences in colouration pattern, adult mined through live-capture and photo-identification size and body shape often indicate reproductive based on distinctive scars and nicks of the dorsal fin isolation, and have contributed to the definition of and unusual pigment patterns (WORSIG & WOR- populations or management units of exploited spe- SIG, 1978; WORSIG & JEFFERSON, 1990). Cap- cies (e.g. YONEKURA et al., 1980; EVANS et al., ture however is exceedingly unpractical while photo- 1982; BAIRD & STACEY, 1988; KASUYA et al., identification permitted researchers to recognize 1988; HEYNING & PERRIN, 1991; PERRIN, 1990; only 20%, or less, of individuals. Some visual marker PERRIN et al., 1991). External features, such as of sex and maturity that would permit real-time clas- sexual dimorphism, play an important role in the sification of specimens would obviously be much visual communication of gregarious cetaceans, and welcomed. they seem closely related to social interactions, es- Recently, large numbers of fresh dusky dolphins pecially mating behaviour (see reviews by WURSIG have become available for study in Peru as a result et al., 1990; JEFFERSON, 1990). Ecological and of high catch levels in coastal small-scale fisheries behavioural field studies are greatly enhanced if sex (READ et al., 1988; VAN WAEREBEEK & REYES, and some appreciation of age or maturity can be 1990, in press). In the present paper I quantify and deduced for individuals from visible clues. It is there- discuss the variation in external morphology and fore rather surprising that the external morphology colouration in Peruvian L. obscurus and offer a and colouration for only a few small cetaceans have preliminary comparison with from other ar- been studied in detail and with adequate sample eas. sizes. All six species of the dolphin genus Lagenorhynchus remain largely undocumented. External measurements are available for only MATERIAL AND METHODS four (sub)adult dusky dolphins Lagenorhynchus obscurus (GRAY, 1828; WATERHOUSE, 1838; Field procedures LAHILLE, 1901; GALLARDO, 1912) and for one neonate from New Zealand (ALLEN, 1977) and Most of the information presented herein I took these are of limited use, for it is unclear how they from dusky dolphins landed at Pucusana (120 30' S) were taken. WEBBER (1987) offered a body length- and Cerro Azul (13000' S), ports located 60 km and weight plot for 15 New Zealand dusky dolphins 140 km, respectively, south of Lima, Peru. Estimated (mean adult length = 172.6 cm, range 166-184 cm) post-mortem time of specimens ranged from a few and compared colour patterns qualitatively between hours to about 12 hours, exceptionally up to 18 L. obscurus and L. obliquidens. Original observa- hours. The close examination of a few live-caught tions on the colouration of L. obscurus were pub- animals helped to define natural patterns and avoid lished by GRAY (1828), WATERHOUSE (1838), recording post-mortem artifacts. Data collection was LAHILLE (1901) and GALLARDO (1912); important executed at all seasons in the period 1985-1990; comparative discussions are by KELLOGG (1941), many different herds, but apparently a single popu- BIERMAN & SLIJPER (1947, 1948) and FRASER lation, were sampled (VAN WAEREBEEK, 1992, (1966). MITCHELL (1970) in an excellent paper 1993). The long collecting period and sample size standarized colour pattern components. Descrip- ensured that most of the existing colour variation tions of colouration by GASKIN (1972), LEATHER- was documented. WOOD & REEVES (1983), and WEBBER and A series of 26 external measurements (Fig. 1), LEATHERWOOD (1990), presumably, were mostly recorded to the nearest 0.5 cm and modified from inspired by observations on New Zealand dolphins; standardized methods by NORRIS (1961), was ob- those authors conducted much research in that tained for 394 dusky dolphins (208 females, 186 area. DAWSON (1985) reported "considerable geo- males) of all sizes. However, standard length was graphic variation in colour pattern, and some pattern available for 693 dolphins. Ten axial and nine point- variation within local groups" in New Zealand. A to-point measurements of appendages were taken mere three photographs of SE Pacific dusky dol- with a semi-rigid metal tape (usually on the left side phins have been published (BINI, 1951; ANDRADE of the body), and seven girths were measured with & BAEZ, 1980; GUERRA et al., 1987) without any a flexible plastic tape. In a few cases, the fluke span discussion. had to be inferred from the width of a single fluke by Van Waerebeek. External Features of the dusky dolphin 39

FIG 1 External measurements taken of Peruvian dusky dolphins, including axial (nos. 1-10), girths (nos. 11-17) and point-to-point measurements (nos 18-26). Numbers in square brackets refer to equivalent variables of Norris (1961). (1) Standard lenght: tip of upper jaw to deepest part of (15) Girth, at posterior insertion of dorsal fin. notch between flukes. [1] (16) Girth, at level of anus. [23] (2) Length of gape: tip of upper jaw to angle of gape [3] (17) Girth, at midpoint between anus and deepest part of (3) Length, tip of upper jaw to center of eye. [2] notch between flukes. (4) Length, tip of upper jaw to posterior edge of blowhole (18) Length base of dorsal fin. [33] (5) Length, tip of upper jaw to external auditory meatus. (19) Height of dorsal fin: fin tip to base. [32] [5] (20) Maximum width of left flipper [31] (6) Length, tip of upper jaw to tip of dorsal fin. [11] (21) Width of left flipper base at insertion. (7) Length, tip of upper jaw to anterior insertion of flipper. (22) Anterior length left flipper, from anterior insertion to [10] tip. [29] (8) Length, tip of upper jaw to midpoint of umbilicus [12] (23) Posterior length left flipper, from axilla to tip. [30] (9) Length, tip of upper jaw to anterior border of genital (24) Length of fluke: from insertion to tip of left fluke slit. (25) Depth of fluke: shortest distance from notch to anterior (10) Length, tip of upper jaw to midpoint of anus. [14] border of fluke. [35] (11) Girth, at level of eyes. (26) Fluke span width of from tip to tip. [34] (12) Girth, at level of axilla. [21] (27) Number of visible teeth: upper left. (13) Girth, at midpoint between axilla and anterior insertion (28) Number of visible teeth: upper rigth. of dorsal fin (29) Number of visible teeth: lower left (14) Girth, at anterior insertion of dorsal fin. [22] (30) Number of visible teeth: lower right.

doubling this value. One of the girths (N° 17) was the best means available. Contrast and vividness of abandoned for not having been taken rigorously colours improved considerably after carcases were throughout the study. A dorsal fin contour (DFC) was doused for a few moments with running seawater. obtained for 119 sexually mature dolphins (51 fe- Because the colour pattern was bilateral symmetric- males, 68 males) and 67 immature specimens (22 al, only a single side (usually the left) was photogra- females, 45 males). Gonads were examined when- phed. Transparencies of 257 Peruvian dusky dol- ever available to determine maturity status. phins were of sufficient quality to be used in a When feasible, a colour pattern data form was comparative study. For reasons of space, data are filled out in situ. Colour transparencies (35 mm; 100 presented here in summarized form; the raw data set ASA) were taken by daylight of the freshest speci- is deposited at the Centro Peruano de Estudios mens only; unusual patterns were documented by Cetol6gicos (CEPEC), Pucusana, Peru.

Van Waerebeek. External Features of the dusky dolphin 41 fully applied by EVANS (1975) for the common dol- prominently black, covering (almost) entire phin Delphinus delphis, in which colour compo- length of gape; nents (fields) are scored for large series of speci- YELLOW FRINGE (YEL)1.: 1 = unmistakable brown- mens (N > 100) Despite the generally subtle, non-

Transparencies were viewed with daylight slide viewers and characters were scored independently by Laura Chavez (University of Hamburg, Germany) who had field experience with the study species and I. Diverging scores were re-evaluated and, in the absence of an immediate consensus, the character FIG. 3. Colour pattern of the dusky dolphin, slightly modi- fied from Mitchell (1970), with AF= abdominal field, DFB = was left blank for that specimen dorsal fin blaze, dfb = dorsal flank blaze, EYEP = eyepatch, Because of indications of observer drift over time FLAP = flank patch, FLiB = flipper blaze, FLiS = flipper in character state definition, scores recorded directly stripe, LLiP = lower lippatch, SF = spinal field, THO = on the field but not supported by photographic mate- thoracic field rial were not further considered, except for the "pro- minent" state (score 1) of characters YEL and FLIS which were deemed unequivocal. Differences DORSAL FIN BLAZE (DFB): 1 = a very conspi- among sex and maturity groups were tested with X2 cuous, whitish patch covering most of the dorsal contingency analyses. fin; 2 = muted but clearly present, mostly light grey; 3 = hardly or not visible; dorsal fin usually Other populations dark grey to blackish overall; Original data on adult body lengths and photogra- FLIPPER BLAZE (FLIB): 1 = flipper uniformly light phic material of L. obscurus from other regions grey, without contrasting trailing edge; 2 = flipper were generously supplied by several researchers light to dark grey with contrasting blackish trailing (see acknowledgements). Limited morphometric in- edge and flipper tip; 3 = dorsal surface of flipper formation for New Zealand dusky dolphins has been almost uniformly dark grey to black; presented by WEBBER (1987) in processed form. EYE PATCH (EYEP): 1 = hardly noticeable, or very Additional photographs were consulted in the litera- lightly coloured; 2 = prominent, dark grey to ture: WORSIG & WORSIG (1978), GASKIN (1982), black; BAKER (1983), LEATHERWOOD & REEVES FLANK PATCH (FLAP): 1 = white of flank patch and (1983), MINASIAN et al. (1984), HARRISON & abdominal field (AF) blend into each other; 2 = BRYDEN (1988); QUAYLE (1988); WORSIG et al. FLAP and AF separated by grey to blackish, (1989); WEBBER & LEATHERWOOD (1990) and ill-defined stripe of varying width; 3 = FLAP and WORSIG (1991). The characterization of geogra- AF separated by broad uninterrupted, blackish phic variation in colouration I offer here is prelimi- band; nary. A quantitative analysis was deemed premature THORACIC FIELD (THO): 1 = entirely white, conti- because of small and heterogeneous samples (e.g. nuous with abdominal field, extending above flip- live animals besides specimens of variable post- per and often even above eye; 2 = anterior part mortem time) and unverifiable identity of specimens of THO above flipper greyish, posterior part white photographed at sea (i.e. a single individual may and, laterally, gradually fusing with abdominal appear on different frames). field without a clear dividing line; 3 = entire THO light or dark grey, demarcation with abdominal field fairly sharp; LOWER LIP PATCH (LLlP): 1 = greyish, minimum 1Data exclusively based on direct field observations definition; 2 = dark grey, moderately defined, (data form). extending over two thirds of length of gape; 3 = 20ata partly based on direct field observations 42 Estud. Oceanol. 12, 1993

RESULTS AND DISCUSSION (GOULD, 1966) and L. obscurus is no exception. Growth is characterized by least-squares regression External size and shape equations of the form Y = b.xa, where Y is a particu- lar body measurement, X is total body length, a is the Individual variation growth coefficient and b is a constant (Table 2). Taking into account the robustness of t -tests and During ontogeny, body dimensions change either ANCOVAs (WONNACOTT & WONNACOTT, 1969), isometrically (a < 1) or allometrically with total length; none of the 29 variables for either sex showed unac- in the latter case the growth rate can taper off with ceptable departure from normality (Kolmogorov- increasing length (a < 1) or intensify (a > 1) (see also Smirnov, p> 0.01), bar the lower right tooth count for CLARKE & PALIZA, 1972; PERRIN, 1975). males. The latter, however, may be due to chance In L. obscurus, measurements of the anterior fluctuation because of the large number of t-tests body (snout to gape, eye, blowhole, ear and to performed. Two character pairs (E1 0 and E26) devi- flipper insertion), as well as the size of the flippers ated slightly from the required homogeneity of vari- and the length and depth of the flukes, follow a ance between sexes (0.01 < P < 0.05), but one or two pattern in which growth declines in intensity with pairs were expected to do so by chance at the 0.05 increasing total length (Fig. 4). The span of flukes level of significance. Statistics of individual variation and the base and height of the dorsal fin are charac- in external measurements and counts of visible teeth terized by a positive allometric growth. Development are presented for 220 sexually mature Peruvian in girths ranges from a diminishing growth at the dusky dolphins (126 females, 94 males) in Table 1. level of the eyes, and a roughly isometric expansion Considerable variation was observed in the size and at mid-body (from axillae to dorsal fin), to an in- shape of the dorsal fin (Fig. 2) as discussed in detail creased growth in the body posterior to the dorsal fin below. A keel on the caudal peduncle as in the (Fig. 4). Atlantic white-sided dolphin Lagenorhynchus acu- The growth rate (slope) is significantly different ius (e.g. LEATHERWOOD & REEVES, 1983) was between sexes in 12 of 24 variables (Table 2). The not present. type of growth allometry (positive or negative), how- ever, is equal in males and females, with the possi- Sexual dimorphism ble exception of girth at axillae (E12). Individual I found no statistically significant difference (t = variation is negligible in juveniles, but it is greatly 1.68; P = 0.09) in total body length between adult amplified in adult animals, a feature also found in oceanic dolphins of the genus Stenel/a (PERRIN, females and males. Alternatively, small but highly significant differences (p < 0.005; t-tests and ANCQ- 1975). VAs) were present in six body measurements, Variation in the dorsal fin namely: girth at anus, maximum width of flipper, base length of dorsal fin, depth of flukes (all greater Males have a broader-based dorsal fin than fe- in males), snout to vent and snout to anus (greater males (E18, t = 3.31, P > 0.002), but there is no in females). Some proportional dimorphism was ap- significant difference in fin height (E19, t = 0.34, P = parent also in the anterior and posterior length of the 0.74). Also, the tip of the dorsal fin is markedly less flipper and the length of the fluke, which were some- erect, so the fin is more hooked (F = 12.2; df 1, 118; what greater in males than in females (ANCQV A, P < 0,001) in mature males (mean elevation a = P < 0.05). The slightly greater absolute values for 49,6°, SE = 0,66°), than in females (mean a = 53,2°, maximum girth (E13, Table 1) and girth in front of the SE = 0,83°). In addition, the dorsal fin becomes more dorsal fin (E14) in females (t-tests, p < 0.05) are hooked with increasing body length (SL); a linear direct consequence of the bigger size of the females regression with sexes pooled of dorsal fin tip eleva- in the sample; indeed, corresponding F-statistics tion against standard body length (SL, in cm) yielded (ANCQVA) are not significant. All measurements the following highly significant correlation: were highly correlated with the body length covariate a = 69,7° - 0,097 (SL) (F = 20,6; df 1, 182; P < 0,0001). (ANCQVAs, p < 0.0005). Tooth counts, logically, showed no significant correlation (ANCQV As, 0.30 < P < 0,70). However, only 10.2% (r) of total variation was explained by the model. The large residua! variation is believed to represent measuring error caused by Developmental variation difficulties in determining the correct base line on the Developmental change in body proportions is a DFC sheets; with a more accurate method for meas- widespread phenomenon among uring fin angles, r is expected to improve. Nothing Van Waerebeek. E al Features of the dusky dolphin 43

1 WMW~WMN ~Vww~mm~wmmw~~w mmmNW U> M~V~VV~VVVMVVVW~WWV~V~~~~~WW~ 00000000000000000000000000000 ~ 00000000000000000000000000000 .t: U 0 M m ~OON~~Nv VM~MN~M~~~~MMOO~ ~ cn ~~NMVm~~OOmV~NVM~~~~~~NOOOOOO~O~~ 'E ~~~~~~NM~~N~~~~MN~OO~~~OM~N~~ 0 t: Q) 01 (/J vvoo~~oovvomoovOONmMNV~oooo~~~m~M~V cu z W « ~~~~O~N~OO~~MmO~~OmO~M~~NOOmmOOOO ...Jc: -l w OONNNM~VOOOMWOO~mWM~~~MNM~VNNNN ~ ~ ~~ ~~~ In -0 .- « ~ c:"'iU ~ :c ":: Ll) Ll) Ll) Ll) .Q.~ 0- w ai~~ Ll)mLl) cDMLl)II>.-NCD ~Ll) Uo OLl)OO'-VNmLl).-Ll)v.-NNOLl)~~.-MOOOOCDLl)mCDCDMM ~ NNNMM.-vm ~ ~MN MNM.-Ll)MMMM ~c:> z , , , , , , , , , , , , , , , , , , , , , , , , , , , , , « Ll)Ll)Ll)VOOLl)Ll)OVv.-Ll)mOOOOLl)CDmOLl)OLl)Ll)OCDCDLl)Ll) 1n0) :J '(3 [l: ~.-NlI>aiNNNN~oomNCD~mOOOLl)~.- OM .- m'- N '-aiNw6VNNNNN N.- U.- .- .-

~~ ~o O)u II II VMVM~~N~V~~omOO~MMMMNNm~v~~~ro z mrororo~~ro~~~roro~rororororororororo~roro~~~~ ~> 0)0 roo+-' E ~

u~c: ,- ~m~m~oo ~OON~ MWNMW~~M~~~~OO~~ > M~~~~M~~~MM~~~W~OOOO~~~~~WWWWW~ CUu 00000000000000000000000000000 ~O) u

~ .9l.cuCU"::

-IWE2 0)..:: cn z OW~WOM~V~Mwm~ovWOMM~VMW~M~W~~ W < m~~~~~NW~~~M~NMNmmO~M~ONWmmWW oo-u -l w WNNNM~vWMMWO~~mWN~~~MNM~VNNNN ~ ~ ~~ ~~~ «~>. ~ ~ I-:J'E ~ "':J w cu... u. E cu .:2:-~ w It) It) It) It) It) MQ) 1t)1(jr--:a> ~~~ It) It) ro~ (9 ~ cD OVQ)~It)N~Q)MVIt)~NNO~MM~M~~VIt)It)WIt)NM :JO) z X... NNNMM~VQ)~~~~~~~~MN~~MNM~It)MMMM O)cu « In ~ [t: w~oom~~~~~oo~~~~6~6~~~m~~6~6~~~~~ "NN "M~ "N " "0 "a> "" ""NN vNNNN - ~ ~ N W~~Q)~Q) MM~ Oa> ~ Oc: N 0 0 Wa> Q) It)N ~N ~ ~ In .-cu "'> C::J :J,- 00) Uc.. .1::- W~~OOONOMM~~OOM~~~~w~~~~mowoooo "'CU 0,- z NOOOmmOmmmN~~~~NOmOOOOmomoooooooo 0'" ~~~~ ~ ~~~~~~~ ~~~~ ~ ...C: uO) c:U cuE ~o E-= u - c: III =2 In :3 ~ ~ c: QI ~QI "'U c: III c: I;:: a. Qla. o:?:- C:c: - a. a.a. .c:-- .- ~ I;:: I;:: m = QI a..- 4:: OJ 4:: .c: O).Q a. t 0 - - U! - U! - 10= QI .- QI OJ Eo ~ QI.': m m ~ c: - m 10= - - ~ - .: ~ QI c:U!U!2 ~~ OI;::°.Doo WW~~ :J - I;::.~:J c: 0 0 "C ro .c: ~:E a. a. QI QI In :5 0 - ~ .~ m U! QI .c: "C"C 0 U! - QI :5 OJ QI QI a. a. ~ ~ cu ~ QI ~ mQl= -~U!mt- U! ~:2a.~ c: ~~ ~~oo ~, > U! a..D - ~ - .- "C .c: 0:> ~, ~ ~ ~ ~ - - 0) E c: c: QI = OJ c: c: :J - "C > .9- c: ~ 10= ~ c: .c: .c: .c: .c: c: a. QI 0 ~ ~ a. E QI m >- - m 0 .- QI m >- >< E o - c: OJ E 10= QI - - m - - - - -OJQI.DQI"CIO=:J>oQlm ~.c:mc:o --50-a.QIQIQIQI "E 0 0 0 0 0 0 0 0 - ro ro :J c: 2 ro ~ - :J 0 5 ": .c: 0 U! 2 2 2 2 ro W m ------E .- .c: E .c: .: QI - .c: c: QI -.J "C :J .c: .c: ._>< .c: .c: .c: QI OJ ._>< - QI - OJ - ~ -0 -0 -0 -0 '------c: :J :J :J :J :J :J :J :J 0 - - - - - U!.- "C - U! c: a. 0) m 0 0 0 0 0 0 0 0 c: .: .: m .: .: .: m QI m .- c: 0 QI QI :J ~ ~ ~ ~ « x 2c:c:c:c:c:c:c:c:w~~~~~~~I~~<~~o~2222 W W W W W W W W W W ...... ~ ..O.-NM"3"LO(cCX>o)O.-NM"3"LO(c E E E E ~NM"3"LO~~CX>o)~'-'-'-'-'-'-'-'-NNNNNNN:J:J:J:J ~ wwwwwwwwwwwwwwwwwwwwwwwwwzzzz

Van Waerebeek. External Features of the dusky dolphin 45

TABLE 2 Growth pattern external measurements (VAR, see Table 1) in function of total body length (X) in Lagenorhynchus obscurus of Peru. Least-squares regression power equations and coefficient of determination (~) are indicated for females and males separately. All equations have highly significant slopes (ANVOVAs, covariate p < 0.0002). Significance level of sexual dimorphism in slope is indicated (ns = not significant). Growth equations not significantly different (95% C.I.) from the linear model are marked by L.

FEMALES MALES Dimorphism Var Equation Y= r2 Equation Y= r2 p

E2 0.27 XO84 93.4 0.16 XO93 92.6 < 0.005 E3 0.36 XO81 93.7 0.26 XO88 92.8 < 0.01 E4 0.23 XO92 94.4 0.16 XO99 (L) 94.5 < 0.05 E5 0.51 XO78 93.6 0.45 XO81 91.1 ns E6 0.77 XO96 98.9 0.68 XO98 (L) 98.6 < 0.05 E7 0.58 XO82 96.8 0.41 XO89 96.1 < 0.005 E8 0.71 XO92 99.1 0.64 XO94 98.8 ns E9 0.77 XO97 99.0 0.74XO95 98.9 ns E10 0.68 X1.01 99.7 0.70 X100 (L) 99.4 ns E11 1.44 XO.73 95.1 1.37Xo.75 97.3 ns E12 0.51 X1.01 (L) 85.0 0.64 XO97 96.5 < 0.05 E13 0.52 X102 (L) 96.7 0.63 XO98 (L) 96.7 ns E14 0.52 X102 (L) 95.5 0.61 XO99 (L) 96.8 ns E15 0.24 X113 94.0 0.41 X103 (L) 95.0 < 0.005 E16 0.19 X110 95.1 0.24 X107 95.6 ns E18 0.12 X104 93.3 0.11 X107 93.6 ns E19 0.09 X103 (L) 93.2 0.05 X113 93.0 < 0.01 E20 0.077 XO94 95.9 0.10 XO88 95.7 < 0.005 E21 0.14 XO85 95.6 0.094 XO.92 95.3 < 0.005 E22 0.32 XO89 96.4 0.27 XO.92 96.2 ns E23 0.20 XO.91 95.7 0.17 XO.95 93.8 ns E24 0.31 XO.88 94.9 0.19 XO97 (L) 94.5 < 0.005 E25 0.19 XO79 93.0 0.13 XO88 93.0 < 0.005 E26 0.12 X114 96.6 0.13 X113 94.6 ns

Dusky dolphins from southwestern Africa, with a ences, Peruvian and Chilean dusky dolphins prob- mean adult length of 179.9 cm (SD = 718 cm, N = ably form a single SE Pacific population (VAN 20, sexes pooled) and a maximum recorded length WAEREBEEK, 1992, 1993). A greater sample from of 1905 cm (N = 58) (P.B. BEST, South African Chile is needed to permit a definitive conclusion. Museum, unpubl. data), are comparable in size (t = Little can be said about L. obscurus from Argentina, 0.29, P = 0.77) to mature animals from New Zealand due to an almost total lack of data. Body lengths of which average 179.1 cm (SD = 8.97 cm, N = 12) and two females of unknown maturity have been publish- attain a maximum length of 195.5 cm (data provided ed: one 162.5 cm and the other 165.5 cm (WATER- by A.N. BAKER, National Museum of New Zealand HOUSE, 1838; LAHILLE, 1901). The standard body and P.J.H. VAN BREE, Zoological Museum, Univer- length of a specimen discussed by GALLARDO sity of Amsterdam). SW African and New Zealand (1912) probably was 175.5 cm (GALLARDO's dusky dolphins each are noticeably smaller than "100%"), and not 183 cm ("maximum length, their Peruvian counterparts (t-tests, p < 0.0001); 104,6%") as interpreted by KELLOGG (1941). mean and maximum lengths differ some 8-10 cm. This further supports conclusions from cranial vari- Colouration ation analysis that these groups constitute separate Variation within the Peruvian population populations, and possibly even valid subspecies. Despite a few (statistically) significant cranial differ- Individual variation in colouration is extensive

Van Waerebeek. External Features of the dusky dolphin 47 ceptionally (8 of 208, 3.8%) the white of both fields (Chubut, Argentina) also greatly vary in degree of blend clearly into each other. The frequency of FLAP melanisation, possibly even more so than in Peru variants had no relation to either sex (X2 = 1.42; df 2; (see WORSIG & WORSIG, 1978; 64,66). In a heav- P = 0.49) or maturity (X2 = 2.39; df 2; P = 0.30) of the ily melanised phenotype, upper and lower lip dolphins. patches and the eye patch are strikingly black; a THORACIC FIELD-. The most common form of conspicuous flipper stripe forms a broad, continuous thoracic field in present sample (111 of 190,58.4%) black band that fuses with an equally dark flipper. was pigmented overall and therefore clearly differen- The dorsal fin is almost entirely black and a yel- tiated from the ventral field; in ten animals (5.3%) the lowishbrown hue of varying intensity may line the thoracic field appeared mostly white, while 69 speci- borders of the white fields along the body In a light-col- mens (36.3%) were intermediately coloured. The oured phenotype, the flipper, flipper stripe, eye patch intensity of pigmentation was independent of matu- and lip patches are so faintly pigmented as to appear rity (X2 = 0.70; df2; P = 0.70) and sex (X2 = 4.37; df almost absent (e.g. GALLARDO, 1912; WORSIG & 2; P = 0.11). WORSIG, 1978). Limited photographic material sug- LOWERLIP PA TCH-. Of 167 dusky dolphins ex- gests that the frequency of occurrence of these pheno- amined, 22 (13.2%) showed a lower lip patch (LLIP) types may be group-specific; moreover most specimens with minimal pigmentation; 93 (55.7%) had a moder- seem to be intergrades between the two extreme types. ately pigmented and 52 (31.1 %) a heavily pigmented In live animals the anterior portion of the dorsal LLiP. Sexual dimorphism was absent (X2 = 2.88; df flank blaze (dfb) is visible anterodorsally some dis- 2; P = 0.24), but juveniles had a less pigmented tance beyond the dorsal fin. Due to quick post-mor- lower lip than adults (x2 = 13.37; df 2; P = 0.0013). tem fading this trait was rarely obvious in the Peru- YELLOW FRINGE-. A brown-yellowish lateral vian specimens. fringe (YEL) was clearly visible in 33 of 190 (17.4%) dolphins. A first x2 test classified this trait as inde- Fitzroy form pendent of sex and maturity, but statistical values A femaledusky dolphin harpooned from the Bea- were lost and could not be re-calculated since the gle in Bahia San Jose (Argentina), was described by data set was unaccessible at time of writing. WATERHOUSE (1838) as Delphinus fitzroyi, sub- FLIPPER STRIPE-. The presence of a prominent sequently referred to the genus Lagenorhynchus eye to flipper stripe was fairly infrequent, namely in by FLOWER (1885). After more than a century of 36 of 224 (or 16.1%) of individuals examined. The confusion (reviewed by HERSHKOVITZ, 1966) L. frequency of occurrence was independent of sex (X2 = 3.06; df 1; P = 0.08) and maturity (X2 = 0; df 1, fitzroyi was still considered a separate species by P = 1.00, with Yates' correction). for instance NISHIWAKI & NORRIS (1966). Other authors including KELLOGG (1941), yANEZ (1948) and FRASER (1966) justly synonimized it with L. Geographic variation obscurus. More recently it has been regarded by some authors as a separate "Fitzroy" colour form of Variants of colour fields in New Zealand dusky the dusky dolphin (WATSON, 1981; LICHTER & dolphins, evaluated from photographic material of HOOPER, 1984; MINASIAN etal.1984; CARDENAS mostly live animals, were not qualitatively different et al., 1986). For reasons of clarity I reproduce here from these found in Peruvian specimens. As indi- (my comments in square brackets) the original descrip- cated earlier, no quantitative analysis was possible, tion of the colour pattem by WATERHOUSE (1838): but the form with an entirely white thoracic patch (THO = 1), relatively rare in Peru (5.3%), may be the "Upper parts of the body black, under parts pure more common form in New Zealand. DAWSON white, the two blended into each other by gray: (1985), discussing the latter, referred to the thoracic extremity of snout a ring round the eye [EYEP = patch as "a blaze of white extending from the snout, 2], the edge of the under lip, and the tail fin, black above the eye, and along the flank to join the white [LLIP = 3]; dorsal [DFB = 3] and pectoral fins of the belly", coinciding with our THO = 1 definition. [FLIB = 3] dark gray; a mark extends from the Several L. obscurus specimens from New Zealand angle of the mouth to the pectoral fin [FLIS = 1]; presented a (to Peruvian standards) unusually small above which, the white runs through the eye and and delicate flank patch. A comparison of coloura- is blended into grey over the eye; two broad tion with SW African dusky dolphins also revealed deep-gray bands are extended in an oblique no obvious deviations from the pattern seen in Peru- manner along each side of the body, running vian animals, but further research is necessary. from the back downwards and backwards [FLAP Dusky dolphins from the Peninsula Valdez area = 1 or 2]". 48 Estud. Oceanol. 12, 1993

The description and the accompanying litho- not of an infectious nature, since the affected skin graph made by Captain Fitzory "after an excellent surface was smooth and apparently healthy. The coloured drawing, when fresh killed" indicates that phenotypic condition is highly reminiscent and prob- the Fitzroy specimen is similar to the heavily melan- ably equivalent to piebaldness (Dr. P.JH. VAN ised colour type, as referred to above, from photo- BREE, in liff. 19 May 1992), a genetic melanisation graphs presented by WURSIG & WURSIG (1978). defect well-known in humans and domestic animals, The reported colouration of the Fitzroy specimen is also referred to as "Weiszscheckung" or "partial albi- aberrant in that "the white runs throught the eye" and nism" (SUNDFOR, 1939; HOEDE, 1940; COOKE, in the unusual, indistinct shape of the flank patch 1952; COMINGS & ODLAND, 1966; HUL TEN et al. (see WATERHOUSE, 1838: plate 10). The 1987). Probability considerations suggest consan- was either an anomalous case of the melanised form guinity for two affected animals (one a severe case) or, despite claims by WATERHOUSE (op. cit.), has landed the same day at the Pucusana wharf (Table not been accurately depicted. The flank patch of the 3). Differential frequencies of this dominantly inher- GALLARDO (1912, Fig. 1) specimen was also fairly ited trait perhaps could help delineate local breeding unusual, so perhaps this patch is more variable in groups, however for large-scale population discrimi- Argentinian than in Peruvian L. obscurus. If in an nation (e.g. Peru versus SW Africa) it is probably adequate sample from Argentina, the melanised useless. Indeed, its occurrence in humans of various form would prove to be a discrete phenotype, it could races and widely separated areas suggest that it can be referred to as the "Fitzroy form"; if not, and in the arise, apart from direct inheritance, by new mutation meantime, this name should be reserved for histori- (see SUNDFOR, 1939). Whether piebaldness is cal reviews only. identical with Chidiak-Higashi syndrome, previously reported from a (RIDGWAY, 1976, quoted in MATKIN & LEATHERWOOD, 1986, Anomalous pigmentation Fig. 3.3) is still unclear. In any case, the partial Five Peruvian dusky dolphins and one specimen skin melanisation and the normal pigmentation from SW Africa showed anomalous piebald pigmen- of the eyes clearly distinguishes it from albinism tation in the form of irregular white flecks of blotches (see HOE DE, 1940; HAIN & LEATHERWOOD, superposed on the normal pattern (Table 3). White 1982). patches on (black) skin have been associated with In the genus Lagenorhynchus aberrant pigmen- Candida spp. infections in captive SW African dusky tation, but not piebald ness, has otherwise been de- dolphins (FOTHERGill & JOGESSAR, 1986), but scribed solely from L. ob/;qu;dens (BROWN & the abnormalities reported here were presumably NORRIS, 1956; BROWNELL, 1965; BLACK, 1989

TABLE 3 Known cases of piebald colouration in Lagenorhynchus obscurus

Number Locality Date Sex SL(cm) Description and source s.n Anc6n, Peru Sept. 85 ? white blotches on anterior body and lower lip; photograph by J.C. Reyes (CEPEC) s.n Pucusana, Aug. 86 ? ? white blotches on flukes and tail stock; pho- Peru tograph by J.C Reyes (CEPEC)

KVW1018 Pucusana, 25 Dec. 87 M 194.5 blotches on flank and thoracic patch, dorsal Peru flank blaze absent; photographs by author, skin sample KVW1288 Pucusana 2 Jun. 88 M 190.0 flecked pattern over most of body, super- Peru posed on normal pattern; photographs by author, skin sample KVW1313 Pucusana, 2 Jun. 88 F 196.0 flecked patches; photograph by author Peru SAM37754 Hout Bay, 7 Mar. 76 F 168.0 unpublished photograph courtesy of Dr. P.B. South Africa Best (South African Museum, ) Van Waerebeek. External Features of the dusky dolphin 49

CONCLUSIONS level and sample size (so-called 13error, see WON- NACOTT & WONNACOTT, 1990), may be fairly Although sexual dimorphism is statistically signifi- high. At any rate differences are subtle at best, and cant in several external measurements, only differ- one may safely state that, based on size, shape and ences in the position of the genital slit and anus and colouration, female and male dusky dolphins are the shape/size of the dorsal fin are of sufficient hard to distinguish from each other. This fact, toge- magnitude to manifest a biological function. The ther with equal length at (50%) sexual maturity for more forward positioned genital aperture and anus males and females (175 cm), huge testis size, and in male dusky dolphins are typical cetacean features apparent absence of wide-spread male antagonistic (e.g. SERGEANT, 1962b; SL/JPER, 1962; PERRIN, behaviour suggests a promiscuous mating system 1975; YONEKURA et al. 1980). The slightly greater with sperm competition in the dusky dolphin (VAN girth at the anus in males can be related to this. WAEREBEEK, 1992; VAN WAEREBEEK & READ, There is no vertical thickening of the caudal stock in press). behind the anus as for instance is seen in mature Of eight colour components tested, the flipper males of the eastern spinner dolphin Stenel/a longi- patch, lower lip patch and eye patch are substan- rostris orientalis (PERRIN, 1975; PERRIN et al. tially less pigmented in juveniles than in adults. Full 1991 ). pigmentation, at least in some elements of the colour The dorsal fin of the male is more strongly curved pattern, tends to be reached only at maturity, which and broader-based and has a substantially greater is in agreement with findings for other delphinids. surface area than that of the female. These dispari- WALKER et al. (1984, 1986) found muted expres- ties are accentuated with increasing body length. I sion of elements of the adult colour pattern in foe- propose that the dorsal fin, besides its hydrodynamic tuses and newborn calves of the Pacific white-sided function, serves as a secondary sexual character, a dolphin and intensification with age. PERRIN (1972) morphological signature of sexual maturity and, indi- noted a progressive obscuring of the dorsal cape in rectly, social status. In any case, the dorsal fin of L. the spinner dolphin. GWINN & PERRIN (197~) obscurus is more variable than either its flippers of through microscopic examination found some evi- flukes, which suggests that additional selective pres- dence of pigment aggregation with development, in sures are at work. The same argument probably the epidermis of gray and black areas of the com- goes for various other cetaceans, including killer mon dolphin. Yellowish-brown pigment is rare in whales, eastern spinner dolphins, Dall's cetaceans and has been reported only from the Phocoenoides dal/i (JEFFERSON, 1990; PERRIN , the Atlantic white-sided dolphin et al., 1991) and Pacific white-sided dolphins Lagenorhynchus acutus and some young speci- (BROWN & NORRIS, 1956). In adult spinner dol- mens of the killer whale (MITCHELL, 1970; GWINN phins and Dall's porpoises, males have a more ere.ct AND PERRIN, 1975; ELLIS, 1989). Thus the discov- dorsal fin than females (JEFFERSON, 1990; PER"::- ery of a yellow fringe in L. obscurus is not without RIN, 1990; PERRIN et al., 1979, 1991). The reverse importance. Although our current colouration record is true for the dusky dolphin and, possibly, the Pacific for the various populations is incomplete, there are white-sided dolphin Other Lagenorhynchus spp. indications that divergences may exist in relative should be checked to see whether this trait is idio- frequencies of colouration pattern variants. syncratic for the genus. Unfortunately, individual The striking differences in mean and asymptotic variation and overlap in dorsal fin size and shape are body length between Peruvian and both New Zea- too great to permit reliable sexing of free-ranging land and SW African dusky dolphins support the dusky dolphins. In killer whales, gender has been recognition of discrete populations (and possibly judged on the basis of ratio of dorsal fin height to even separate subspecies) based on craniometric basal length, although that method as well was and geographic considerations (VAN WAERE- thought not to be foolproof (MATKIN & LEATHER- BEEK, 1992, 1993). WOOD, 1986). No significant sexual dimorphism was found in the colouration of L. obscurus. However, it is per- ACKNOWLEDGEMENTS haps worth to warn here for undue definitive conclu- sions concerning (absence of) dimorphism where I owe special thanks to J.C. Reyes for his long- borderline values for p were found (e.g. eye patch term assistance in the field, and to Dr. P.J.H. van and measurements E8 and E24, with 0.05 P ~ 0.07) Bree and T. Luscombe for advice and logistical sup- since the probability that these characteristics are port. I extend my gratitude also to J. Alfaro, Dr. M.F. slightly dimorphic but were not detected at chosen a Van Bressem, L. Chavez, A.C. Lescrauwaet, Dr. 50 Estud. Oceanol. 12, 1993

A.J. Read and to M. Chandler, L. Lehman and J.S. BROWNELL RL Jr. 1965. An anomalous color pat- McKinnon, who for varying periods helped with in a Pacific striped dolphin. Bulletin of the measuring dolphins. Photographic material and un- Southern California Academy of Sciences published data were courteously put at my disposi- 64(4): 242-3. tion by Dr. A.N. Baker, Dr. P.B. Best, Dr. P.J.H. van BROWNELL RL Jr. 1974. Small odontocetes of the Bree, Dr. S. Leatherwood, M. Webber and Dr. B. Antarctic. Antarctic Map Folio Series 18: 13- Wursig, to whom I extend my most sincere thanks. 19. Dr. W.F. Perrin, Dr. J.H. van Bree, and Dr. J.H. Stock CARDENAS JC, STUTZIN ME, OPORTO JA, CA- made valuable comments on an earlier version of BELLO C & D TORRES 1986. Manual de identi- the manuscript. Present study was supported by ficaci6n de los cetaceos chilenos. CODEFF, grants from the Whale and Dolphin Conservation Santiago, Chile, 102 pp. Society (WDCS) and the King Leopold III Fund for CLARKE R & 0 PALIZA 1972. Sperm whales of the Nature Research and Conservation. Additional fund- Southeast Pacific. Part III: Morphometry. Hvalra- ing was provided by IUCN/UNEP, BBC-Wildlife dets Skrifter 53. Det Norske Videnskap-Akade- Magazine, Consejo Nacional de Ciencia y Tec- mi I Oslo, 106 pp. nologia (CONCYTEC, Peru), and the Van Tien- COMINGS DE & GF ORLAND 1966. Partial albi- hoven Foundation. nism. Jama 195 (7): 519-523. COOKE JV 1952. Familial white skin spotting (Pie- baldness) ("Partial albinism") with white forelock. REFERENCES Journal of Pediatrics 41(1): 1-12. DAWSON S 1985. The New Zealand Whale and ALLEN JF 1977. Dolphin reproduction in oceanaria Dolphin Digest. Brick Row Publ. Co., Auckland, in Australasia and Indonesia. In Breeding Dol- 130 pp. phins, Present Status, Suggestions for the futu- ELLIS R 1989. Dolphins and porpoises. A.A. Knopf, re. SH Rigway & K Bernirschke (eds.). Rep. New York, 270 pp. MMC-76/07 to US Marine Commission, EVANS ME 1975. The biology of the common dol- pp.85-100. phin, Delphinus delphis, Linnaeus. Ph. D. the- ANDRADE H & P BAEZ 1980 Presencia del delfin sis, University of California. listado:Lagenorhynchus obscurus (GRAY, 1828) EVANS WE, THOMAS JA & DB KENT 1984 A en la costa de Valparaiso Noticiero Mensual del study of pilot whales (Globicephala ma- Museo Nacional de Historia Natural 288/289: 7-9. crorhynchus) in the southern California bight. BAIRD RW & PJ STACEY 1988 Variation in saddle Admin. Report LJ-84-380, NMFS/SWFC, La Jo- patch pigmentation in populations of killer wha- lla, California, 47 pp. les (Orcinus orca) from British Columbia, Alas- EVANS WE, Y ABLOKOV A V & AE BOWLES 1982. ka, and Washington State. Canadian Journal of Geographic variation in the color pattern of killer Zoology 66: 2582-85. whales. Reports of the International Whaling BAKER AN 1983. Whales and Dolphins of New Commission 32: 687-94. Zealand and Australia. Victoria University Press, EVANS WE, THOMAS JA & DB KENT 1984. A 133 pp. study of pilot whales (Globicephala ma- BIERMAN WH & EJ SLIJPER 1947. Remarks upon crorhynchus) in the southern California bight. the species of the genus Lagenorhynchus. Ko- Adm. Rep. LJ-84-380, NMFS/SWFC, La Jolla, ninklijke Nederlandse Akademie voor We- California: 1-47. tenschappen50: 1353-64 FLOWER W 1885. List of the British Mu- BIERMAN WH & EJ SLIJPER 1948. Remarks upon seum. Proceedings of the Zoological Society, the species of the genus Lagenorhynchus. Ko- London. ninklijke Nederlandse Akademie voor We- FOTHERGILL M & VB JOGESSAR 1986. Haemato- tenschappen 51 (1): 127-33. logical changes in two Lagenorhynchus obs- BINI G 1951. Osservazioni su alcuni mammiferi ma- curus treated with Ketoconazole. Aquatic Mam- rini sulle coste del Cile e del Peru. Boll. Pesca mals 12(3): 87-91. Piscicultura Idrobiol 6 (n.s.) 1: 79-93. FRASER FC 1966. Comments on the Delphinoidea. BLACK N 1989. Pacific white-sided dolphins in Mon- In Whales, Dolphins and Porpoises. KS Norris terey Bay. Whalewatcher 23(1): 5-8. (ed.). University of California Press, Los Ange- BROWN DH & KS NORRIS 1956. Observations of les, pp. 7-30. captive and wild cetaceans. Journal of Mamma- GALLARDO A 1912. EI delfin Lagenorhynchus logy 37(3): 311-26. fitzroyi (Waterhouse) Flower, capturado en Mar Van Waerebeek. External Features of the dusky dolphin 51

del Plata. Anales del Museo Nacional de His- Segregation of two forms of short-finned pilot toria Natural de Buenos Aires 23: 391-7. whales off the Pacific coast of Japan. Scientific GASKIN DE 1972 Whales, Dolphins and Seals: Reports of the Whales. Research Institute 39: With Special Reference to the New Zealand Re- 77-90. gion. Heinemann Educational Books, London KELLOGG R 1941 On the identity of the and Auckland, 200 pp. amblodon Field Museum of Natu- GASKIN DE 1982. The Ecology of Whales and Dol- ral History, Zoological Series 27: 293-311 + 7 phins Heinemann Educational Books, London, pis. 459 pp. LAHILLE F 1901 EI delfin de Fitzroy Lagenorhyn- GOULD SJ 1966. Allometry and size in ontogeny chus fitzroyi (Waterh.) Flow. Boletin de Agri- and phylogeny Biological Reviews 41: 587- cultura y Ganaderia 1(4): Buenos Aires: 3-6 640. [Not seen]. GRAY JE 1828. Spicilegia Zoologica - Or original LEATHERWOOD S & RR REEVES 1983. The Sie- figures and short systematic descriptions of new rra Club Handbook of Whales and Dolphins. Sie- and unfigured animals. London, pt. 1: 1-8. rra Club Books, San Francisco, 302 pp. GUERRA C, VAN WAEREBEEK K, PORTFLITT G LICHTER A & A HOOPER 1984 Guia para el reco- & G LUNA 1987. Presencia de cetaceos frente a nocimiento de cetaceos del Mar Argentino. Fun- la segunda region de Chile. Estudios Oceano- daci6n Vida Silvestre Argentina, 96 pp. 16gicos 6: 87-96 MATKIN CO & S LEATHERWOOD 1986. General GWINN S & WF PERRIN 1975 Distribution of mela- biology of the killer whale. Orcinus orca: a nin in the color pattern of Delphinus delphis synopsis of knowledge. In Behavioral Biology of (Cetacea; Delphinidae). Fishery Bulletin 73(2): Kiler Whales BC Kirkevold & JS Lockard (eds.). 439-44. Alan R. Liss, Inc., New York, pp. 35-68. HAIN JHW & S LEATHERWOOD 1982 Two sight- MINASIAN SM, BALCOMB III KC & L FOSTER ings of white pilot whales, Globicephala melae- 1984 The World's Whales. Smithsonian Institu- na, and summarized records of anomalously tion, 244 pp. white cetaceans.Journal of Mammalogy63(2): MITCHELL E 1970 Pigmentation pattern evolution 338-43. in delphinid cetaceans: an essay in adaptative HARRISON R & MM BRYDEN 1988. Whales, dol- coloration. Canadian Journal of Zoology 48(4): phins and porpoises. Facts on File Publications, 717-40. New York, 240 pp NISHIWAKI M & KS NORRIS 1966 A new genus, HERSHKOVITZ P 1966. Catalog of living whales. Peponocephala, for the odontocete cetacean Smithsonian Institution, Washington D.C.: 259 species Electra e/ectra. Scientific Reports of pp. the WhalesResearch Institute 20: 95-100 HEYNING JE & WF PERRIN 1991. Re-examination NORRIS KS (ed.) 1961 Standardized methods for of two forms of common dolphins (genus Delphi- measuring and recording data on the smaller nus) from the eastern North Pacific; evidence for cetaceans. The Committee on Marine Mammals, two species SWFC/NMFS Adm. Report. LJ-91- American Society of Mammalogists. Journal of 28, 37 pp Mammalogy 42(4): 471-76. HOE DE K 1940 Erbpathologie der menschlichen PERRIN WF 1972. Color patterns of spinner porpoi- Haut. In: Erbbiologie und Erbpathologie korperli- ses ( cf. longirostris) of the eastern cher Zustande und Funktionen. I. Von Julius Pacific and Hawaii, with comments on delphinid Springer, Berlin. pigmentation Fishery Bulletin of the and HULTEN MA, HONEYMAN MM, MAYNE AJ & MJ Wildlife Service US, 70: 983-1003 TARLOW 1987. Homozygosityin piebald trait. PERRIN WF 1975. Variation of spotted and spinner Journal of Medical 24: 568-71. porpoise (genus Stenella) in the eastern Pacific JEFFERSON TA 1990. Sexual dimorphism and de- and Hawaii. Bulletin Scripps Institute of Ocea- velopment of external features in Dall's porpoise nography 21: University of California Press, Phocoenoides dam. Fishery Bulletin 88: 119- Berkeley, 206 pp. 32. PERRIN WF 1990. Subspecies of Stenella longi- KASUYA T 1981. Identification manual of dolphins rostris (Mammalia: Cetacea: Delphinidae) Pro- and porpoises in the Japanese waters. Research ceedings of the Biological Society of Wash- Division, Japan Fisheries Agency: 41 pp. In Ja- ington 103(2): 453-463. panese. [Not seen]. PERRIN WF, AKIN PA & JV KASHIWADA 1991. KASUYA T, MIYASHITA T & F KASAMATSU 1988. Geographic variation in external morphology of 52 Estud. Oceanol. 12, 1993

the spinner dolphin Stene//a longirostris in the VAN WAEREBEEK K & JC REYES. In press. The eastern Pacific and implications for conserva- interaction of small cetaceans and Peruvian fish- tion. Fishery Bulletin, 89: 411-428. eries, catch statistics 1988-1989 and analysis of PERRIN WF & SB REILLY 1984. Reproductive pa- trends. In Mortality of Cetaceans in passive Fish- rameters of dolphins and small whales of the ing Nets and Traps, International Whaling Com- family Delphinidae. Reports of the Internatio- mission (Special Issue). nal Whaling Commission, Special Issue 6: WALKER WA, GOODRICH KR, LEATHERWOOD 97-133. S & RK STROUD 1984. Population biology and PERRIN WF, SLOAN PA & JR HENDERSON 1979. ecology of the Pacific white-sided dolphin, Lage- Taxonomic status of the "southwestern stocks" of norhynchus obliquidens, in the northeastern spinner dolphin Stenel/a longirostris and spotted Pacific. Part II: biology and geographical varia- dolphin S. attenuata Reports of the Internatio- tion. Adm. Report LJ-84-34C, NMFS/SWFC, La nal Whaling Commission 29: 175-184. Jolla, California, 39 pp. QUAYLE L 1988. Dolphins and Porpoises. Gallery WALKER WA, LEATHERWOOD S, GOODRICH Books, New York, 144 pp. KR, PERRIN WF & RK STROUD 1986. Geo- READ AJ, VAN WAEREBEEK K, REYES JC, graphical variation and biology of the Pacific whi- MCKINNON JS & LC LEHMAN 1988. The ex- te-side dolphin, Lagenorhynchus obliquidens, ploitation of small cetaceans in coastal Peru. in the north-eastern Pacific. In Research on Biological Conservation 46: 53-70. Dolphins. MM Bryden and Harrison (eds.). Ox- RIDGWAY SH 1976. Statement at Hearings before ford University Press, Oxford, pp 441-465. the Subcommittee on Fisheries and Wildlife and WATERHOUSE GR 1838. The Voyage of H.M.S. the Environment, U.S. House of Representatives Beagle during the years 1832-1836. Mammalia, Merchant Marine and Fisheries Committee, May part II. London, 96 pp. 4, 1976 [not seen]. WATSON L 1981. Whales of the World. Hutchinson SERGEANT DE 1962a. The biology of the pilot & Co., London, 302 pp. whale or pothead whale Globicepha/a melaena WEBBER M 1987. A comparison of dusky and Paci- (Traill) in Newfoundland waters. Bulletin Fishe- fic white-sided dolphins (Genus Lagenorhyn- ries ResearchBoard of Canada132: 1-84. chus): morphology and distribution. M.Sc. the- SERGEANT DE 1962b. On the external characters sis, San Francisco State University, 102 pp. of the blackfish or pilot whales (genus Globicep- WEBBER M & S LEATHERWOOD 1990. Dusky ha/a).Journal of Mammalogy 32(3): 395-413. dolphin, Lagenorhynchus obscurus. In Wha- SLlJPER EJ 1962. Whales: Basic books, 511 pp. les and dolphins. A.R. Martin (ed.). Salamander STSC, Inc. 1989. STATGRAPHICS [software]. Sta- Books, London, pp. 154-155. tistical Graphics System by Statistical Graphics WONNACOTT TH & RJ WONNACOTT 1969. Intro- Corporation, Rockville, USA. ductory Statistics. Fifth Edition 1990, John Wiley SUNDFOR H 1939. A pedigree of skin-spotting in & Sons, New York, 711 pp. man - 42 piebalds in a Norwegian family. Jour- WORSIG B 1991. Cooperative foraging strategies: nal of Heredity 30: 67-77. an essay on dolphins and us. Whalewatcher VAN WAEREBEEK K 1992. Population identity and 25(1): 3-6. general biology of the dusky dolphin Lage- WORSIG B & TA JEFFERSON 1990 Methods of norhynchus obscurus (Gray, 1828) in the photo-identification for small cetaceans. Re- Southeast Pacific. Ph.D. thesis, University of ports of the International Whaling Commis- Amsterdam. 160 pp. sion, Special Issue 12: 43-52. VAN WAEREBEEK K 1993. Geographic variation WORSIG B, KIECKHEFER TR, JEFFERSON TA and sexual dimorphism in the skull of the dusky 1990. Visual displays for communication in ceta- dolphin Lagenorhynchus obscurus (Gray, ceans. In Sensory Abilities of Cetaceans. J. Tho- 1828). Fishery Bulletin 91(4): 754-774. mas & R. Kastelein (eds.), Plenum Press, New VAN WAEREBEEK K & AJ READ. In press Repro- York, pp. 545-559. duction of dusky dolphins Lagenorhynchus WORSIG B & M WORSIG 1978. Day and night of the obscurus from coastal Peru. Journal of Mam- dolphin. Natural History 88(3): 60-67. malogy. WORSIG B, WORSIG M & F CIPRIANO 1989. Dol- VAN WAEREBEEK K & JC REYES. 1990. Catch of phins in different worlds. Oceanus 32(1): 71-75. small cetaceans at Pucusana port, central Peru, YANEZ P 1948. Vertebrados marinos chilenos I: during 1987. Biological Conservation 51 (1): mamiferos marinos. Revista de Biologia Mari- 15-22. na (Chile) 1 (2): 103-23. Van Waerebeek. External Features of the dusky dolphin 53

YONEKURA M, MATSUI S & T KASUYA 1980. On Scientific Reports of the Whales Research the external characters of Globicephala ma- Institute 32: 67-95 crorhynchus off Taiji, Pacific coast of Japan. ZAR JH 1974. Biostatistical Analysis. Second Ed. 1984. Prentice-Hall Inc., New Jersey, 718 pp.

~

FECHAACEPTACION: 15 noviembre 1993