7

PREFACE

The first International Symposium on the Biology papers were read by title and are included either in of the Seal was held at the University of Guelph, On­ full or abstract form in this volume. The 139 particip­ tario, Canada from 13 to 17 August 1972. The sym­ ants represented 16 countries, permitting scientific posium developed from discussions originating in Dub­ interchange of a truly international nature. lin in 1969 at the meeting of the Marine Mammals In his opening address, V. B. Scheffer suggested that Committee of the International Council for the Ex­ a dream was becoming a reality with a meeting of ploration of the Sea (ICES). The culmination of such a large group of pinniped biologists. This he felt three years’ organization resulted in the first interna­ was very relevant at a time when the relationship of tional meeting, and this volume. The president of ICES marine mammals and man was being closely examined Professor W. Cieglewicz, offered admirable support as on biological, political and ethical grounds. well as honouring the participants by attending the The scientific session commenced with a seven paper symposium. section on evolution chaired by E. D. Mitchell which The programme committee was composed of experts showed the origins and subsequent development of representing the major international sponsors. W. N. this amphibious group of higher vertebrates. Many of Bonner, Head, Seals Research Division, Institute for the arguments for particular evolutionary trends are Marine Environmental Research (IMER), represented speculative in nature and different interpretations can ICES; A. W. Mansfield, Director, Arctic Biological be attached to the same fossil material. Readers of this Station, Fisheries Research Board of Canada (FRB) volume should be aware of such differences when read­ represented the International Commission for North­ ing the papers in this section. The twelve papers of west Atlantic Fisheries (ICNAF); and K. S. Norris, S. H. Ridgway’s section on functional anatomy illus­ Director, Marine Mammal Council Executive Com­ trated the fundamental structure of the seal, as well mittee, represented the International Biological Pro­ as its associated control mechanisms. R. J. Schusterman gram (IBP). The Food and Agriculture Organization followed this theme by introducing ten papers on be­ of the United Nations (FAO) also offered its support haviour. He established a major focus on social or­ to the programme and ICNAF has contributed to the ganization and communication and their association financing of this volume. with the functional anatomy of the pinnipeds. D. E. Sponsors of national origin were the Fisheries Re­ Sergeant chaired the population dynamics section of search Board of Canada (FRB), the National Re­ seven papers, covering the modelling of populations search Council of Canada (NRCC), the Canadian and method of analysis of seal populations around the National Sportsmen’s Show (CNSS), the World Wild­ world. In the fifth section, J. R. Geraci, by means of life Fund (Canada) (WWF), and the University of papers and a panel discussion dealt with the care and Guelph. management of captive pinnipeds. W. N. Bonner co­ In his preliminary remarks Professor Ronald intro­ ordinated a presentation in the broad area of ecology, duced the representatives of these groups; namely J. R. and was able to bring together studies on environmen­ Weir, Chairman, Fisheries Research Board of Canada; tal factors and their associated behavioural and gene­ S. Bata, International Director and J. S. McCormack, tic control systems. The physiology section was chaired Director, World Wildlife Fund (Canada); and R. T. by H. T. Andersen, his introductory remarks forming D. Birchall, President, Canadian National Sportsmen’s the initial paper of the section. The other six papers Show and a Director of WWF (Canada). of his section emphasized the underwater responses of W. C. Winegard, President of the University of seals. The final and general section, chaired by J. E. Guelph, welcomed participants to the symposium and King, offered a broad coverage of several of the more commented particularly on how pleased he was to interesting areas in various disciplines. welcome representatives from so many countries. Later, A. W. Mansfield acted as rapporteur for the entire at a banquet sponsored by the Department of the En­ programme, and his report stressed the need for con­ vironment, Canada, he offered an invitation to the tinued cooperation by all biologists so that they might group to return in 1975 for a Second International understand seals and their importance to environmen­ Seal Symposium. tal studies. Altogether 62 papers were presented. A further 14 This volume includes with one exception, those pa- 8 K. Ronald pers either presented, read by title, or abstracted, but mammals of the world’ by D. W. Rice and V. B. the continuing discussion on the biology of the seals Scheffer (U.S. Fish and Wildlife Service, Washing­ led to one further paper that is included here. Some ton, 1968) has been used as the standard reference on of the discussion was formal and, where recordable, is nomenclature. included here, but by far the greater part of discussion The work of the chairmen of each of the seven sec­ was informal and hence must remain as extremely tions of this volume is especially recognized. As well, valuable, but merely mental recollections of the par­ the convenor wishes to thank the programme com­ ticipants in the symposium. mittee for their ability to support a somewhat unortho­ The symposium achieved its purpose of bringing dox procedural system, and particularly the sponsors together scientists interested in the Pinnipedia and it ICES, ICNAF, IBP, CNSS, FRB, NRCC, WWF (Ca­ offered leads into the international examination of nada), FAO, and the University of Guelph for their marine mammals. valuable financial assistance. The editors with little apology recognized that they The convenor is most grateful to Mr. H. Tambs- have not reached a completely uniform format in this Lyche, General Secretary of ICES, for his advice and volume since they have allowed use of both English encouragement from the embryonic stages of the sym­ and metric systems of measurement and both English posium to the publication of the proceedings; he also and North American word usage for the sake of har­ recognizes the considerable amount of expert help pro­ mony. The main editorial structure has been the con­ vided by A. W. Mansfield in co-editing this volume. sistency of usage throughout a particular paper. Finally, the effort put into both the symposium and Attempts have also been made to attain a fairly this volume by Mrs. Ginny Bandesen has been beyond uniform taxonomy for the species, but where there has measure, but I hope that she will accept the results of been any doubt caution has not overridden clarity. As the symposium recorded here as tangible proof of her in other mammalian groups, the systematics of the most valuable contribution. To the members of the Pinnipedia are still open to much interpretation. The Dean of the College of Biological Science’s office, the references are cited according to an Annotated Biblio- university support staff and our host Dr. W. C. Wine- praphy on the Pinnipedia*. The ‘List of the marine gard, I express on behalf of the participants and my­ self, our sincerest thanks. * Ronald, K., L. M. Hanly and P. J. Healey, College of Bio­ K . Ronald, logical Science, University of Guelph, Ontario, Canada. Convenor

The following have kindly acted as Discussion Care and Management Section Leaders of the different Sections and also assisted in J. R. Geraci the editing of the contributions: Department of Zoology, University of Guelph, Guelph, Ontario, Canada. Evolution Section Ecology Section E. D. Mitchell Arctic Biological Station, Fisheries Research Board W. N. Bonner of Canada, Ste. Anne de Bellevue, Quebec, Canada. Seals Research Division IMER, c/o Fisheries Labora­ tories, Lowestoft, Suffolk, England.

Functional Anatomy Section Physiology Section S. H. Ridgway H. T. Andersen School of Anatomy, University of Cambridge, Nutrition Institute, University of Oslo, Blindern, Cambridge, England. Oslo, Norway.

Behaviour Section General Session R. J. Schusterman J. E. King Department of Psychology, California State University Department of Zoology, University of New South Hayward, California 94542, U.S.A. Wales, Kensington, N.S.W., Australia.

Population Dynamics Section Summary D. E. Sergeant A. W. Mansfield (Rapporteur) Arctic Biological Station, Fisheries Research Board of Arctic Biological Station, Fisheries Research Board Canada, Ste. Anne de Bellevue, Quebec, Canada. of Canada, Ste. Anne de Bellevue, Quebec, Canada. 161

Rapp. P.-v. Réun. Cons. int. Explor. Mer, 169: 161-164. 1975.

CRANIOMETRIC FEATURES OF SEALS OF THE GENUS PUSA

Yu. K. T im o s h e n k o Northern Branch of PINRO, Arkhangelsk, Uritskogo 17, U.S.S.R.

INTRODUCTION seal skulls were measured at the Institute of Zoology, Despite the efforts of a number of investigators, the USSR Academy of Sciences and at the Museum of craniometric features of the Baikal seal (Pusa sibirica Zoology, Moscow State University. To eliminate the Gmelin), ringed seal (Pusa hispida Schreber) and effect of age variations the skulls used for measure­ Caspian seal (Pusa caspica Gmelin) are still not clear­ ments were those from animals aged 10 years and ly understood. The limitation common to earlier stu­ above. The age was deduced from layers of dentine dies is that they were based on inadequate material and cement in the teeth by the now universally adopt­ that failed to take into account the variability with age ed procedure discovered by Laws (1953). For the and sex, and were in most cases restricted to structural Baikal seal, data were available from the measure­ characters. This hampered the approach to an objec­ ments of 157 skulls belonging to similarly aged animals tive estimation of the craniological similarities or dis­ published by Pastukhov (1969). similarities of the three species. Measurements were made mostly according to the On the basis of several characteristic features of the procedure proposed by Chapskii (1963). The follow­ skull (shape of nasal bones, extent of nasal-inter­ ing measurements were taken: 1. condylobasal length; maxillary junction, and orbit size) Nordquist (1899) 2. length of cranium from the optic foramen to con­ and later Ognev (1935) suggested that the Baikal seal dyles; 3. zygomatic width; 4. mastoid width; 5. width was taxonomically closer to the Caspian seal than to of cranium above mastoid processes; 6. height of skull the ringed seal. This problem was investigated by from tympanic bullae; 7. rostral width at canines; 8. Chapskii (1955) who, on the basis of structural char­ least interorbital width; 9. width of occipital condyles; acters, arrived at the conclusion that there was greater 10. length of palate from anterior margin of inter­ similarity between the skull structure of the Baikal and maxillary bones; 11. width of facial part of skull at ringed seals than between the Baikal and Caspian posterior margin of last molar; 12. least width of pal­ seals. However, Iablokov (1966) has analysed the ate in region of posterior nostrils; 13. maximum length variability of morphological characters in the seals of of nasal bones; 14. greatest width of nasal bones at the genus Pusa, including those of the skull and points anterior margin; 15. length of tympanic bulla; 16. out the similar nature of variability in the Baikal and width of tympanic bulla; 17. length of upper post­ Caspian seals. Comparison of the relative values of canine row; 18. height of lower jaw posterior to mo­ craniometric characters led Pastukhov (1969) to be­ lars. The diagram of measurements is shown in Figure lieve that the Baikal seal was closer to the Caspian 130. Measurements were processed by commonly used than to the ringed seal. However it should be noted statistical methods. Standard deviation was determined that in considering the Caspian and ringed seals, from the formula Pastukhov used indices obtained by earlier investiga­ t = (M x - M y) l v'(m2x + m2y). tors (Smirnov and Chapskii, 1932; Chapskii, 1970) from the measuring of a small number of skulls from seals the se and age of which were unknown. RESULTS The analysis of data (Tables 13, 14) shows diffe­ MATERIALS AND METHODS rences in the absolute skull measurement values of the The present author collected 93 Caspian seal skulls Baikal, Caspian and ringed seals, the three species on the sealing grounds in 1965-68 and 44 ringed seal differing from one another to a variable degree. The skulls were made available for study bv Y. I. Nazaren­ most prominent differences were found between the ko and V. A. Potelov of the Northern Branch of Baikal and the Caspian seals. In 17 out of 18 skull PINRO. A further 17 Caspian seal and 11 ringed measurements the differences were highly significant

it 162 Yu. K. Timoshenko

A B

t o

GO

C D Figure 130. Measurements of skulls of the genus Pusa (Baikal seal skull, reproduced from Pastukhov, 1969). A - dorsal view; B - ventral view; C - back view; D - lower jaw ; side view.

(p < 0-001). The absolute values of most skull between the Baikal and Caspian seals. In measure­ measurements were found to be higher in the Baikal ments such as condylobasal length, zygomatic width, than in the Caspian seal, the exceptions being the height of cranium, rostral width, palate length, least length of cranium, interorbital width, greatest width width in the region of posterior nostrils, length of nasal of facial part and width of nasal bones (in females bones, length of upper postcanines and height of lower only). jaw posterior to tooth row, the Baikal seal was found Comparison of the Baikal and ringed seals also to have greater values than the ringed seal, while the showed differences in all skull measurements; however values of other measurements were higher in the the degree of difference was usually less than that ringed seal than in the Baikal seal. Craniometric features of seals of the genus Pusa 163

Table 13. Skull measurements in female Caspian, Baikal and ringed seals

Caspian seal Baikal seal Ringed seal Measure­ ment «i M x ± m1 CTl n2 M 2 ± m2 ct2 *3 M, ± m3 0-3 *1 - 2 *1-3 12-3

1 23 175-1 ±0-56 2-68 84 181-0 ±0-57 5-2 25 169-0 ±0-93 4-65 _ 7-37 + 5-64 + 11-00 2 25 77-0 ± 0-38 1-90 84 70-1 ±0-42 3-7 24 74-7 ± 0-41 2-01 + 12-10 + 4-18 _ 7-93 3 24 93-6 ± 0-50 2-45 84 111-5 ±0-34 3-1 24 102-3 ± 0-64 3-13 - 29-83 _ 10-74 + 12-77 4 26 89-6 ± 0-53 2-70 84 96-7 ± 0-34 3-1 25 100-7 ± 0-75 3-75 _ 11-26 - 12-06 _ 4-87 5 24 76-6 ± 0-33 1-62 84 81-7 ±0-23 2-2 25 84-4 ± 0-45 2-25 - 12-75 13-92 _ 5-40 6 26 58-6 ± 0-33 1-68 84 65-8 ±0-19 1-8 25 64-1 ± 0-44 2-20 —18-95 - 10-00 + 3-54 7 23 24-8 ± 0-21 1-01 84 26-4 ± 0-14 1-3 25 25-4 ± 0-35 1-75 — 6-40 _ 1-46 + 2-63 8 26 5-6 ±0-14 0-71 84 3-5 ± 0-05 0-5 25 5-4 ±0-21 1-05 + 14-0 + 0-80 _ 9-04 9 24 49-7 ± 0-60 2-94 84 53-0 ± 0-27 2-3 25 54-4 ± 0-36 1-80 — 5-0 — 6-71 _ 3-07 10 22 76-9 ± 0-55 2-58 84 79-5 ± 0-40 3-7 24 70-1 ±0-68 3-33 - 3-82 + 7-72 + 11-89 11 21 38-9 ± 0-32 1-47 84 37-9 ± 0-20 1-8 24 40-9 ± 0-56 2-74 + 2-63 — 3-12 — 5-08 12 20 25-1 ±0-23 1-03 84 26-9 ±0-19 1-8 24 25-8 ± 0-44 2-15 - 6-0 — 1-42 + 2-50 13 21 39-9 ± 0-69 3-16 84 46-9 ± 0-34 3-0 16 39-0 ± 1-19 4-76 — 9-09 + 0-65 + 6-42 14 21 10-7 ±0-14 0-64 84 9-8 ±0-13 1-2 13 11-9 ±0-20 0-72 + 4-74 — 5-00 _ 8-75 15 26 27-9 ± 0-28 1-43 84 30-8 ± 0-20 1-8 25 35-6 ± 0-51 2-55 - 8-53 —13-27 _ 8-72 16 26 28-0 ± 0-20 1-02 84 33-4 ± 0-14 1-3 24 35-9 ± 0-40 1-96 - 22-50 _ 19-75 _ 5-95 17 25 38-4 ± 0-26 1-30 84 39-7 ± 0-18 1-7 18 35-1 ±0-41 1-74 — 4-06 + 6-87 + 10-22 18 26 16-3 ± 0-24 1-22 84 17-5 ±0-11 1-0 21 16-3 ± 0-22 1-01 - 4-61 0 + 4-80

Table 14. Skull measurements in male Caspian, Baikal and ringed seals

Caspian seal Baikal seal Ringed seal Measure­ ment "i ± m1 o-i «2 ± m2 «3 M8 ± m3 *1—2 *1-3 *2-3

1 34 182-1 ±0-76 4-43 73 190-4 ± 0-65 5-6 30 173-4 ± 1-1 6-02 — 8-3 + 6-54 + 13-28 2 34 78-9 ± 0-35 2-04 73 73-1 ±0-42 3-7 30 77-0 ± 0-58 3-18 + 10-54 + 2-79 - 5-49 3 33 98-7 ± 0-54 3-10 73 115-7 ± 0-40 3-5 30 105-2 ± 0-80 4-38 -25-37 - 6-70 + 11-66 4 33 93-4 ± 0-40 2-30 73 101-7 ±0-38 3-3 30 103-8 ± 0-52 2-85 -15-1 -16-00 - 3-28 5 33 78-4 ± 0-31 1-78 73 83-4 ± 0-29 2-5 30 86-3 ± 0-44 2-41 -11-90 -14-62 - 5-57 6 35 60-1 ±0-38 2-25 73 67-1 ±0-24 2-1 30 65-2 ± 0-52 2-85 -15-55 - 7-96 + 3-33 7 34 26-4 ±0-21 1-22 73 29-6 ±0-18 1-5 30 27-1 ±0-29 1-59 -11-43 - 2-00 + 7-35 8 29 5-9 ±0-15 0-81 73 4-3 ± 0-07 0-6 30 5-6 ±0-12 2-24 + 10-0 + 1-57 - 9-28 9 31 51-4 ±0-29 1-61 73 54-1 ±0-26 1-9 30 55-9 ± 0-68 3-72 - 6-92 - 6-08 - 2-46 10 33 79-1 ± 0-56 3-22 73 84-0 ± 0-55 4-8 30 73-2 ± 0-88 4-82 - 6-28 + 5-67 +10-48 11 31 41-1 ±0-28 1-56 73 39-7 ± 0-21 1-9 29 42-1 ±0-35 1-88 + 4-0 - 2-27 - 5-85 12 32 26-2 ± 0-28 1-58 73 28-0 ±0-16 1-8 30 26-3 ± 0-34 1-83 - 5-0 - 0-22 + 4-59 13 26 41-9 ±0-58 2-96 73 49-8 ± 0-41 3-5 23 40-3 ± 0-72 3-45 — 11-13 + 1-73 + 11-44 14 23 11-0 ± 019 0-91 73 11-3 ± 0-18 1-5 22 12-4 ±0-19 0-89 + 5-18 - 5-18 - 4-23 15 34 29-7 ± 0-26 1-52 73 31-8 ± 0-17 1-5 30 35-8 ± 0-34 1-86 - 6-77 -14-18 -10-52 16 35 28-8 ±0-17 1-00 73 34-5 ±0-17 1-5 30 36-9 ± 0-30 1-64 -23-75 -23-82 - 7-05 17 34 39-9 ± 0-24 1-40 73 41-1 ±0-20 1-8 29 35-5 ± 0-40 2-15 - 3-87 + 9-56 + 14-0 18 32 17-1 ±0-15 0-85 73 18-8 ±0-16 1-4 19 17-2 ± 0-42 1-83 - 7-73 - 0-22 + 3-55

The smallest differences were observed in compar­ ringed seals, than between the Caspian and Baikal ing the skull measurements of the Caspian and ringed seals. seals. In five measurements, interortibal width, length Sex differences in the craniometric characters of of nasal bones, rostral width, height of lower jaw the Baikal seal have been treated by Pastukhov posterior to molars and least width in the region of (1968), those of the ringed seal by Nazarenko (1968), posterior nostrils, the differences were not confirmed and some information on this problem in the Caspian statistically. The values of most skull measurements seal is given by Smirnov and Chapskii (1932) and were found to be higher in the ringed seal than in the Ognev (1935). As seen in Table 15 sexual dimor­ Caspian seal. phism of the skull is most pronounced in the Baikal Chapskii (1955) also indicated a greater similarity seal. The values of all skull measurements are higher between the structure of molars in the Caspian and in males than in females. In the Caspian seal there il 164 Yu. K. Timoshenko

Table 15. Sexual dimorphism in skull measurements that the degree of sexual difference in skull measure­ of Caspian, Baikal and ringed seals ments of seals of the genus Pusa is a distinctive speci­ fic character. Caspian seal Baikal seal Ringed seal Measurement ------CONCLUSIONS tj- 9 t ø - 9 The craniometric characters of the seals discussed 1 + 7-40 10-84 + 3-05 in this paper are of some interest from the viewpoint 2 + 3-60 + 4-96 + 3-23 3 + 6-92 + 7-90 + 2-84 of the evolution of these species. The characters sug­ 4 + 5-79 + 9-90 + 3-40 gest a comparatively close phylogenetic relationship 5 + 1-76 + 4-34 + 2-85 of the Caspian and ringed seals. Pronounced cranio­ 6 + 3-08 + 4-18 + 1-62 metric differences between the Baikal seal, on the 7 + 5-37 + 14-17 + 3-77 8 + 1-60 + 9-10 + 0-83 one hand, and the Caspian and ringed seals on the 9 + 2-58 + 2-83 + 1-94 other hand seem to suggest long-term isolation of the 10 + 2-87 + 6-57 + 2-88 former species, which is consistent with the idea that 11 + 5-26 + 6-32 + 1-81 the Baikal seal is a relic of the tertiary fauna (Ognew, 12 + 3-08 + 3-77 + 1-09 13 + 2-20 + 5-25 + 0-93 1935; Chapskii, 1955; Kondakov, 1960; Pastukhov, 14 + 1-42 + 6-63 + 1-85 1969). 15 + 4-81 + 3-95 + 0-32 16 + 3-31 + 4-83 + 2-00 REFERENCES 17 + 4-26 + 5-04 + 0-63 18 + 2-61 -j- 6-45 + 1-70 Chapskii, K. K. 1955. [A contribution to the problem of the history of development of the Caspian and Baikal seals]. Tr. Average, all Zool. Inst. Akad. Nauk S.S.S.R., 17:200-16. measurements + 3-76 + 6-39 + 1-93 Iablokov, A. V. 1955. [Variability of mammals]. Moscow. Kondakov, N. N. 1960. [On the problem of the systematic status of the Baikal seal.] Mosk. O.-vo. ispyt. Prir., Otd. Biol., Biull., 65:120-21. are practically no differences between males and fem­ Laws, R. M. 1953. A new method of age determination in mam­ ales in width of cranium, width of nasal bones, and mals with special reference to the elephant seal (Mirounga interorbital width, but they are significantly different leonina). Falkland Isl. Depend. Surv., Sei. Rep., 2. (/>< 0-001) in condylobasal length, zygomatic width, Nazarenko, Y. I. 1968. [Sexual dimorphism of the ringed seal.] [Summ. Rep. Present, to 7th Meet. Sei. Counc. Probl. Biol. length of cranium, mastoid and rostral width, greatest Resourc. \Vhite Sea & Inland Waters of Karelia, Petroza­ width of facial part, length of tympanic bulla and vodsk.] length of upper postcanines. In other measurements Nordquist, O. 1899. Beitrag zur Kenntniss der isolierten Formen the differences are less significant. In the ringed seal der Ringelrobbe (Phoca foetida Fabr.). Fauna Fenn., 15, Art. 17. sexual dimorphism in skull measurements is not statis­ Ognev, S. I. 1935. [Animals of the U.S.S.R. and neighbouring tically significant. countries. 3. Carnivores and pinnipeds.] Moscow. Thus craniometric differences between males and Pastukhov, V. D. 1969. [Craniometric characteristics of the females are most pronounced in the Baikal seal and Baikal seal (Pusa sibirica Gmel.).] Zool. Zh., 48(5). Smirnov, V. A. & Chapskii, K. K. 1932. [A contribution to the least marked in the ringed seal, with the Caspian seal study of age markings on the skulls of genus Pusa.] [Leningrad occupying an intermediate position. This indicates Res. Inst. Ichthiol.], Tr., 13(2) : 133-46.