Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea
Изучены постэмбриональный рост, некоторые особенности биологии и размеры тела морской свиньи. Средняя длина тела новорожденных — 72,5 см; период рождений растянут не менее чем с апреля по август. Максимальная продолжительность жизни — не менее 20 лет, возраст достижения половой зрелости — 3–4 года,...
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nasplib_isofts_kiev_ua-123456789-32862025-02-09T22:19:50Z Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea Рост и размеры тела морской свиньи, Phocoena phocoena (Cetacea, Phocoenidae), в Азовском и Черном морях Gol'din, P. E. Морфология Изучены постэмбриональный рост, некоторые особенности биологии и размеры тела морской свиньи. Средняя длина тела новорожденных — 72,5 см; период рождений растянут не менее чем с апреля по август. Максимальная продолжительность жизни — не менее 20 лет, возраст достижения половой зрелости — 3–4 года, физической зрелости — 6–12 лет. Длина тела взрослых самцов и самок в Азовском море в среднем составляет соответственно 132–135 и 143–145 см, в Черном море — 122–124 и 132–134 см. Вопрос о правомерности выделения отдельных периодов роста в постнатальном онтогенезе остается открытым. Целесообразно выделять два периода замедляющегося роста. Впервые обнаружены факты, подтверждающие существование обособленных популяций в Азовском и Черном морях: взрослые азовские особи крупнее черноморских на 10–12 см. В течение последнего столетия произошло некоторое уменьшение размеров особей. Морские свиньи изученного региона явля¬ются в наши дни самыми мелкими представителями вида P. phocoena. Postnatal growth, some aspects of life history, and body size of harbour porpoise were studied. The mean body length of neonates is 72.5 cm; the calving sea¬son lasts at least from April to August. The maximum life span is at least 20 years; the age at attain¬ment of sexual maturity is 3–4 years, of physical maturity — 6–12 years. The mean body length of adult males and females is 132–135 cm and 143–145 cm respectively in the Sea of Azov, 122–124 cm and 132– 134 cm in the Black Sea. The question still remains of the existence of two growth stages in postnatal ontogenesis of harbour porpoises. It seems reasonable to distinguish two stages, each with decreasing growth rate. The first evidences are found for the existence of separate populations in the Sea of Azov and the Black Sea: adult specimens from the Sea of Azov are larger than those from the Black Sea in 10–12 cm. During the 20th century body size of the animals has somewhat reduced. The harbour porpoises in the studied region are at present the smallest representatives of P. phocoena species. 2004 Article Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea / P. E. Gol'din // Вестн. зоологии. — 2004. — Т. 38, № 4. — С. 59-73. — англ. 0084-5604 https://nasplib.isofts.kiev.ua/handle/123456789/3286 591.4:599.536(262.54)+(262.5) en application/pdf Інститут зоології ім. І. І. Шмальгаузена НАН України |
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Морфология Морфология Gol'din, P. E. Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea |
| description |
Изучены постэмбриональный рост, некоторые особенности биологии и размеры тела морской свиньи. Средняя длина тела новорожденных — 72,5 см; период рождений растянут не менее чем с апреля по август. Максимальная продолжительность жизни — не менее 20 лет, возраст достижения половой зрелости — 3–4 года, физической зрелости — 6–12 лет. Длина тела взрослых самцов и самок в Азовском море в среднем составляет соответственно 132–135 и 143–145 см, в Черном море — 122–124 и 132–134 см. Вопрос о правомерности выделения отдельных периодов роста в постнатальном онтогенезе остается открытым. Целесообразно выделять два периода замедляющегося роста. Впервые обнаружены факты, подтверждающие существование обособленных популяций в Азовском и Черном морях: взрослые азовские особи крупнее черноморских на 10–12 см. В течение последнего столетия произошло некоторое уменьшение размеров особей. Морские свиньи изученного региона явля¬ются в наши дни самыми мелкими представителями вида P. phocoena. |
| format |
Article |
| author |
Gol'din, P. E. |
| author_facet |
Gol'din, P. E. |
| author_sort |
Gol'din, P. E. |
| title |
Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea |
| title_short |
Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea |
| title_full |
Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea |
| title_fullStr |
Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea |
| title_full_unstemmed |
Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea |
| title_sort |
growth and body size of the harbour porpoise, phocoena phocoena (cetacea, phocoenidae), in the sea of azov and the black sea |
| publisher |
Інститут зоології ім. І. І. Шмальгаузена НАН України |
| publishDate |
2004 |
| topic_facet |
Морфология |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/3286 |
| citation_txt |
Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea of Azov and the Black Sea / P. E. Gol'din // Вестн. зоологии. — 2004. — Т. 38, № 4. — С. 59-73. — англ. |
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2025-12-01T08:59:36Z |
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| fulltext |
UDC 591.4:599.536(262.54)+(262.5)
GROWTH AND BODY SIZE OF THE HARBOUR PORPOISE,
PHOCOENA PHOCOENA (CETACEA, PHOCOENIDAE),
IN THE SEA OF AZOV AND THE BLACK SEA
P. E. Gol’din
V. I. Vernadsky Taurida National University,
4 Vernadsky av., Simferopol, AR Crimea, 95007 Ukraine
E-mail: oblako@home.cris.net
Accepted 31 October 2003
Growth and Body Size of the Harbour Porpoise, Phocoena phocoena (Cetacea, Phocoenidae), in the Sea
of Azov and the Black Sea. Gol’din P. E. — Postnatal growth, some aspects of life history, and body
size of harbour porpoise were studied. The mean body length of neonates is 72.5 cm; the calving sea-
son lasts at least from April to August. The maximum life span is at least 20 years; the age at attain-
ment of sexual maturity is 3–4 years, of physical maturity — 6–12 years. The mean body length of
adult males and females is 132–135 cm and 143–145 cm respectively in the Sea of Azov, 122–124 cm
and 132– 134 cm in the Black Sea. The question still remains of the existence of two growth stages in
postnatal ontogenesis of harbour porpoises. It seems reasonable to distinguish two stages, each with
decreasing growth rate. The first evidences are found for the existence of separate populations in the
Sea of Azov and the Black Sea: adult specimens from the Sea of Azov are larger than those from the
Black Sea in 10–12 cm. During the 20th century body size of the animals has somewhat reduced. The
harbour porpoises in the studied region are at present the smallest representatives of P. phocoena species.
Ke y wo r d s: harbour porpoise, age, growth, Sea of Azov, Black Sea.
Ðîñò è ðàçìåðû òåëà ìîðñêîé ñâèíüè, Phocoena phocoena (Cetacea, Phocoenidae), â Àçîâñêîì è
×åðíîì ìîðÿõ. Ãîëüäèí Ï. Å. — Èçó÷åíû ïîñòýìáðèîíàëüíûé ðîñò, íåêîòîðûå îñîáåííîñòè
áèîëîãèè è ðàçìåðû òåëà ìîðñêîé ñâèíüè. Ñðåäíÿÿ äëèíà òåëà íîâîðîæäåííûõ — 72,5 ñì;
ïåðèîä ðîæäåíèé ðàñòÿíóò íå ìåíåå ÷åì ñ àïðåëÿ ïî àâãóñò. Ìàêñèìàëüíàÿ ïðîäîëæèòåëüíîñòü
æèçíè — íå ìåíåå 20 ëåò, âîçðàñò äîñòèæåíèÿ ïîëîâîé çðåëîñòè — 3–4 ãîäà, ôèçè÷åñêîé çðå-
ëîñòè — 6–12 ëåò. Äëèíà òåëà âçðîñëûõ ñàìöîâ è ñàìîê â Àçîâñêîì ìîðå â ñðåäíåì ñîñòàâëÿåò
ñîîòâåòñòâåííî 132–135 è 143–145 ñì, â ×åðíîì ìîðå — 122–124 è 132–134 ñì. Âîïðîñ î
ïðàâîìåðíîñòè âûäåëåíèÿ îòäåëüíûõ ïåðèîäîâ ðîñòà â ïîñòíàòàëüíîì îíòîãåíåçå îñòàåòñÿ
îòêðûòûì. Öåëåñîîáðàçíî âûäåëÿòü äâà ïåðèîäà çàìåäëÿþùåãîñÿ ðîñòà. Âïåðâûå îáíàðóæåíû
ôàêòû, ïîäòâåðæäàþùèå ñóùåñòâîâàíèå îáîñîáëåííûõ ïîïóëÿöèé â Àçîâñêîì è ×åðíîì ìîðÿõ:
âçðîñëûå àçîâñêèå îñîáè êðóïíåå ÷åðíîìîðñêèõ íà 10–12 ñì.  òå÷åíèå ïîñëåäíåãî ñòîëåòèÿ
ïðîèçîøëî íåêîòîðîå óìåíüøåíèå ðàçìåðîâ îñîáåé. Ìîðñêèå ñâèíüè èçó÷åííîãî ðåãèîíà ÿâëÿ-
þòñÿ â íàøè äíè ñàìûìè ìåëêèìè ïðåäñòàâèòåëÿìè âèäà P. phocoena.
Êëþ÷åâûå ñ ëîâ à: ìîðñêàÿ ñâèíüÿ, ðîñò, âîçðàñò, Àçîâñêîå ìîðå, ×åðíîå ìîðå.
Introduction
Harbour porpoise Phocoena phocoena (Linnaeus, 1758) inhabits temperate waters of the Northern
Hemisphere. An isolated fragment of its distribution range is located in the Sea of Azov, the Black, Marmara
and Aegean Seas. The harbour porpoise in these waters is distinguished as a separate subspecies — P. p. relicta
Abel, 1905 (local names — azovka, mutur). During the 20th century the abundance of these subspecies has
substantially decreased due to prolonged take. Now P. p. relicta is included into the Red Data Books of several
Black Sea countries (conservation status of Category I in Ukraine) and into the European Red List. Many
aspects of life history of harbour porpoise in the Black Sea and adjacent waters still remain unstudied or were
studied only in 1930–1950s (Zalkin, 1938, 1940; Barabash-Nikiforov, 1940; Kleinenberg, 1956; Tomilin,
1957 etc.) — the fact that impedes the estimation of current population status. At the same time, the
comparative studies of harbour porpoises biology in different world regions are essential for understanding of
some specific characters of cetaceans as a whole.
Vestnik zoologii, 38(4): 59–73, 2004
© P. E. Gol'din, 2004
The objectives of this study are to find the regularities of growth in body length of harbour porpoise in
the Sea of Azov and the Black Sea, and to discover its regional peculiarities. Also, some aspects of life history
were specified.
Material and methods
The material for this study was obtained from 217 harbour porpoises: 127 from the Sea of Azov and 90
from the Black Sea, found dead at the coastline or by-caught during the fisheries operations in 1996–2003.
The papers were examined concerning the recent findings in the waters off the northern (Tanabe et al., 1997)
and north-eastern (Karacam et al., 1990) coast of Turkey, Aegean Sea, Caucasus (Glazov, Lyamin, 2000) —
that is, the studies in which the age of animals was determined. Also, some records of porpoise findings dur-
ing the last years were examined (Krivokhizhin, Birkun, 1999; A. A. Anastasov, A. A. Birkun, Jr., A. Frantzis,
D. M. Glazov, S. V. Krivokhizhin, V. V. Pavlov, V. M. Sabodash, A. Tonay, personal communications). The
data from 89 specimens were collected in 1997–1999 based on BREMA Laboratory (Simferopol), among
them 85 specimens in the frames of BLASDOL Project (general data on the sample were reported in BLAS-
DOL, 1999). Material from 7 specimens was collected by N. V. Frolova in 1996–1999; data on their age,
sex and body size were reported in Gol’din and Frolova (2003). The rest of the material was collected by the
author in 1999–2003 based on Department of Zoology, V. I. Vernadsky Taurida National University.
The material was collected all year round; however, 85% of findings were made during four months,
from May to August.
In 210 specimens total body length was measured point to point from the tip of rostrum to the notch
of flukes. Sex was determined in 196 specimens, age in 208 specimens. The age was determined by counting
growth layer groups (GLGs) in dentine according to the standard techniques (Bj/orge et al., 1995; Klevezal’,
1988; Perrin, Myrick, 1980), with the use of thin longitudinal sections of decalcified teeth stained by Erhlich’s
or Mayer’s haematoxylin. The age of animals found in spring and early summer, in which the boundary layer
in dentine has not been deposited yet but the intermediate growth layer has already completely formed, was
estimated as equal to the number of GLGs including the one being formed. For example, the age of speci-
mens who died in summer and had been born the previous summer was estimated as one year, even if the
first boundary layer has not been deposited yet. Such a procedure allowed to examine the growth process
more adequately. The neonates were regarded as specimens having unhealed umbilical scar, non-erupted
teeth and inflated lungs (similarly to Lockyer, 1995). For the statistical calculations two longest full-term
embryos were included in neonate category. The age of all the calves found in June — September and not
considered as neonates was estimated as 0.1 year. The age of specimens younger than 8 years found in
October — March was estimated as n + 0,5 years, where n is the number of completed GLGs in dentine.
The age of 18 specimens (mostly neonates) was determined from the body, skull and teeth size. The age of
3 specimens was determined from the GLGs number in mandible using the author’s own technique (Gol’din,
2003). In 5 specimens the age was not determined but the status of sexual maturity was stated.
The status of sexual maturity in males was determined from general size and weight of testes and epi-
didymides, diameter of seminiferous tubules, active spermatogenesis, in some cases — from size and weight
of pelvic bones; in females — from presence of corpora lutea or corpora albicantia on the ovaries, pregnan-
cy or lactation. The data on sexual maturity in specimens examined in the frames of BLASDOL Project are
cited after study by À. À. Birkun, Jr. (BLASDOL, 1999).
Mean age at sexual maturity (ASM) in males in the Sea of Azov was calculated using the formula by
DeMaster (1978): ASM = x • [M(x) – M(x–1)], where x is the age, Ì(õ) is the frequency of occurrence
of sexually mature specimens at given age.
The status of physical maturity was determined on ankylosis of epiphyses in vertebra bodies in the tho-
racic and lumbar departments. For this purpose, the vertebrae of 47 specimens from the Sea of Azov and 3
specimens from the Black Sea were examined.
The mean values for specimens considered as physically mature were calculated by two methods.
According to the first method, the values were calculated for all the specimens aged 8 years and more.
According to the second one, after Read and Tolley (1997), the calculations were made for all the specimens
aged 7 years and more, plus all the specimens the size of which exceeded the asymptotic size predicted by
Gompertz formula.
The growth curves were calculated using von Bertalanffy, Gompertz, Richards, logistic and power
growth formulae, as well as models including several von Bertalanffy, Gompertz and power formulae. The
calculations for males from the Sea of Azov were made excluding the maximum value of body length
(152 cm); however, this value was taken into account while estimating the goodness of model fit. In the cal-
culations for the specimens from the Black Sea the value of the neonate body length was taken as 72.5 cm.
Statistical values were calculated with the use of standard methods. 95% confidence intervals for the
mean values are indicated in the text in parentheses.
Results and discussion
Compo s i t i o n a nd s t r u c t u r e o f s amp l e. The sample contains specimens
at the age 0 to 13 years from the Black Sea and 0 to 20 years from the Sea of Azov.
60 P. E. Gol'din
The characteristics of the age, sex and size structure of samples containing animals with
different causes of death were discussed in a special study on harbour porpoises from
Ukrainian waters. The author considers the use of such samples in life history studies
of harbour porpoise to be rational and useful (Gol’din, in press).
L i f e s p an. In this sample 95% of specimens from the Black Sea were at the age
of 11 or younger, from the Sea of Azov — 12 or younger. The oldest female was 20
years old (2001, near Osoviny, Crimea, the Sea of Azov); the oldest male was 14 years
old (2000, Tarkhan Cape, Crimea, the Sea of Azov). Thus, the life span of harbour
porpoise in the Sea of Azov and the Black Sea is comparable with the values reported
from the North Atlantic: the maximum known age of 24 years (Lockyer, 1995), the
average life span — about 8–10 years.
Growth in body length
The bod y l e n g t h of neonates in our sample falls in the range 58–83 cm, the
mean is 72.6 ± 4.0 cm (here and ff. p < 0,05, except where otherwise indicated), and
the maximum length of full-term embryo is 83 cm. The coefficient of variation is
10.8%. Sexual and regional differences in the neonatal body length were not found.
Zalkin (1940), examining the animals directly taken in fisheries, wrote that the mini-
mum length of neonates was 82 cm, the maximum length of embryos was 85 cm, and
the size of fetuses in May, before the peak of birth, was 62–84 cm (mean — 73 cm).
Sabodash and Nazarov (1998) reported the length of 75–82 cm in neonates from the
Sea of Azov. Tanabe et al. (1997) reported finding a female 59.5 cm long at the north-
ern coast of Turkey. A. Tonay (personal communication) has found a male 74 cm long
at the north-western coast of Turkey. Krivokhizhin and Birkun (1999) recorded find-
ing animals in length categories more than 70 cm in the Black Sea. Glazov and Lyamin
(2000) reported finding a male 52 cm long and female 60 cm long at the coast of
Caucasus.
Lockyer (1995) pointed out that the length at birth in harbour porpoises in the
North Atlantic (Phocoena phocoena phocoena (Linnaeus, 1758) was about 65–70 cm,
and the range of the neonate size was 60–80 cm.
According to a formula by Mikhalev (1970), the neonatal length of 72.5 cm cor-
responds to definitive female length of 160 cm. This agrees with the current data on the
size of porpoises in the North Atlantic (Lockyer, 1995; Lockyer, Kinze, 2003; Read,
Tolley, 1997).
Thus, the mean size of porpoise neonates in the Black Sea and the Sea of Azov
does not seem to exceed the value obtained in this study.
The earliest finding of a neonate was recorded on May, 12 (2002, near Balaklava,
Sevastopol), the latest one — on August, 5 (1999, Solyanoye, Crimea, the Sea of Azov).
However, in early June calves were found with umbilicus healed, erupted teeth with
postnatal dentine deposited, and body length up to 107 cm. This is the evidence of an
earlier birth period, i. e. not later than April. According to Zalkin (1940), the calving
season falls to late April — early July. However, according to my data, this term is even
more extended: at least from mid-April to early August. The peak of neonate findings
in the southern part of the Sea of Azov falls to early July.
Th e c h a r a c t e r i s t i c s o f g r ow t h. Growth formulae and stages. The linear
growth rate is maximum during the first year of life, especially the first months. At the
Crimean coast of the Sea of Azov, in the sample for present study, in June the calves with
body length of 88–107 cm were found, in July and August — 96–109 cm. It follows that
some specimens reach the minimum size of yearlings at the age of approximately two months.
Besides, there are records of smaller specimens found in autumn, winter and early
spring. A female 70 cm long was found in October 2002 at the Crimean coast of the
Black Sea (Black Sea..., 2003); a female 92.5 cm long was recorded in spring of 1993
61Growth and Body Size of the Harbour Porpoise…
in the waters off Turkey (Tanabe et al., 1997). At the southern coast of the Sea of Azov
the author of this paper found two specimens: 87 cm long (June 17, 2000) and about
90 cm long (July 2, 2002); their age was determined as about 0.5–1 year as indicated
by the skull and teeth size, skeleton ossification, and postnatal dentine depositions.
Presumably, it can be explained by the unusual pattern of growth in small neonates, or
extraordinarily low growth rate of these specimens. It is also probable that these ani-
mals were born in autumn, later than usual.
By the end of the first year of life, the body length of males in the Sea of Azov
reaches 104–125 cm (mean is 111.8 ± 2.9 cm), of females — 105–122 cm (mean is
113.9 ± 4.2 cm). Among the animals of undetermined sex the minimum length is
101 cm. The body length of males in the Black Sea reaches 98–117 cm (mean is
108.6 ± 3.2 cm), of females — 103–118 cm (mean is 109.4 ± 6.2 cm). No significant
sexual differences are found. Any differences in mean values during April–August are
not observed. Some differences in body length between the specimens from the Sea of
Azov and the Black Sea are observed but remain insignificant. In the Sea of Azov males
reach the minimum size recorded for physically mature specimens, in the Black Sea
they approach it.
During the second year of life the growth rates in animals in the Sea of Azov and
the Black Sea (especially females) are different. In the Sea of Azov males reach the
length of 118–126 cm (mean is 122.2 ± 3.1 cm), females — 128–145 cm (mean is
133.7 ± 11.1 cm). There was also found an animal 109 cm long of undetermined sex.
In the body length of animals in the Sea of Azov sexual differences are exhibited. In
the Black Sea males reach the length of 109–125.5 cm (mean is 116.4 ± 4.4 cm),
females — 110–132 cm (mean is 118.4 ± 7.3 cm).
During the third year of life almost all the males and Azov females reach the min-
imum length of physically mature specimens. The females from the Black Sea are the
most slowly growing group; their mean length is only 122.7 ± 3.7 cm. Later the growth
gradually ceases in all sexual and regional groups. The variability of the body length
remains high enough. For instance, the body lengths of 3-year-old males in the Sea of
Azov vary in the range of 115–137 cm (CV = 7.5%), and in an animal 115 cm long
the synarthrosis of epiphyses in thoracic and lumbar vertebrae was already in progress.
The best results in describing the postnatal growth with one growth curve were
obtained when fitting von Bertalanffy formula as follows:
Lt = L (1 – be–kt),
or Gompertz formula as follows:
,
where t is age in years, L is body length in cm, b and k are constants, L is asymp-
totic length in cm.
In general, the growth models suggesting two stages of growth describe the process
of growth somewhat better than the corresponding models suggesting only one stage.
This is especially true for the first year of life (tabl. 1, fig. 1). However, the differences
between the coefficients of determination r2 for models with one and two growth stages
are not significant for all groups. The best method for describing growth with several
stages is to apply the models including two von Bertalanffy or two Gompertz equations
with different coefficients. In males from the Sea of Azov the best formula for the first
stage was calculated for animals aged 0–1.5 years, for the second stage — 2 years and
more. The intersection point for the two curves is at the age of 1.4 year. In females
from the Sea of Azov the best formula for the first stage was calculated for animals aged
0–1.5 years, for the second stage — 1 year and more. The intersection point for the
two curves is at the age of 1 year. In males from the Black Sea the best formula for the
first stage was calculated for animals aged 0–2 years, for the second stage — 2.5 years
and more. The intersection point for the two curves is at the age of 2 years. A two-
stage model fitting for females from the Black Sea has failed.
kt
be
t
eLL
−
−
∞
⋅=
62 P. E. Gol'din
8
8
8t
Thus, the question remains of the existence of two growth stages in postnatal onto-
genesis of harbour porpoise. However, as an operational hypothesis it seems reasonable
to distinguish two stages, each with decreasing growth rate. The secondary growth spurt
marking the shift of stages falls to different ages in the samples of different origin.
It is remarkable that Gaskin and Blair (1977) found similar growth regularities in
harbour porpoise from the Bay of Fundy but came to the opposite conclusion, i. e. that
in practice it was better not to distinguish the two stages. However, they worked with
a sample where the ratio of neonates was very low.
The two-stage growth models suggest that in the animals from the Sea of Azov the
growth curve attains the asymptotic length of the first stage at the age of 3–6 months,
63Growth and Body Size of the Harbour Porpoise…
Ta b l e 1. Parameters of growth equations for linear growth of harbour porpoise, their standard errors (SE),
residual sum of squares (Sresid) and the coefficients of determination (r2)
Ò à á ëèö à 1. Êîýôôèöèåíòû óðàâíåíèé ëèíåéíîãî ðîñòà ìîðñêîé ñâèíüè, èõ ñòàíäàðòíûå îøèáêè (SE),
îñòàòî÷íûå ñóììû êâàäðàòîâ (Sresid) è êîýôôèöèåíòû äåòåðìèíàöèè (r2)
* Sresid was calculated for the specimens aged less than 1 year (Sresid ðàññ÷èòàíà äëÿ îñîáåé âîçðàñòîì
ìåíåå îäíîãî ãîäà).
Ma l e s (the Sea of Azov) (n = 53)
von Bertalanffy 132.1 ± 2.2 0.3915 ± 0.0241 0.9130 ± 0.1462 4360.6 0.8031
von Bertalanffy — the first
growth stage
112.4 ± 1.9 0.3948 ± 0.0275 11.8162 ± 2.8329 1040.0 0.8953
von Bertalanffy — the second
growth stage
132.2 ± 1.7 0.7109 ± 1.4102 1.1178 ± 0.9667 1096.8 0.8953
Gompertz 131.9 ± 2.2 0.4936 ± 0.0393 1.0583 ± 0.1609 4374.5 0.8022
Gompertz — the first growth
stage
112.4 ± 1.9 0.5022 ± 0.0454 13.5842 ± 3.0422 1040.0 0.8953
Gompertz — the second growth
stage
132.2 ± 1.7 0.7790 ± 1.5678 1.1440 ± 0.9787 1096.6 0.8953
Fema l e s (the Sea of Azov) (n = 45)
von Bertalanffy 144.7 ± 1.6 0.4468 ± 0.0187 0.7651 ± 0.0837 2074.4 0.9194
von Bertalanffy — the first
growth stage
115.1 ± 1.9 0.3442 ± 0.0239 5.5132 ± 1.9251 117.8* 0.9345
von Bertalanffy — the second
growth stage
144.4 ± 1.6 0.5051 ± 0.1283 0.8719 ± 0.2389 1569.1 0.9345
Gompertz 144.4 ± 1.5 0.5877 ± 0.0333 0.9127 ± 0.0953 2064.8 0.9198
Gompertz — the first growth
stage
115.0 ± 1.9 0.4214 ± 0.0372 6.5530 ± 2.1657 75.7* 0.9361
Gompertz — the second growth
stage
144.4 ± 1.6 0.6017 ± 0.1628 0.9333 ± 0.2494 1571.0 0.9361
Ma l e s (the Black Sea) (n = 48)
von Bertalanffy 122.8 ± 0.9 0.4007 ± 0.0374 1.2064 ± 0.1335 1003.6 0.7926
von Bertalanffy — the first
growth stage
118.5 ± 4.2 0.3886 ± 0.0529 1.5311 ± 0.4351 651.3 0.7990
von Bertalanffy — the second
growth stage
123.1 ± 1.0 0.3969 ± 2.4589 1.1014 ± 2.2685 321.4 0.7990
Gompertz 122.7 ± 0.9 0.5049 ± 0.0622 1.3783 ± 0.1591 1018.7 0.7894
Gompertz — the first growth
stage
118.1 ± 3.8 0.4880 ± 0.0855 1.7613 ± 0.4437 651.3 0.7990
Gompertz — the second growth
stage
123.1 ± 1.0 0.4052 ± 2.5174 1.1052 ± 2.2801 321.4 0.7990
Fema l e s (the Black Sea) (n = 41)
von Bertalanffy 132.4 ± 1.5 0.4166 ± 0.0426 0.7102 ± 0.1052 1525.5 0.7745
Gompertz 132.1 ± 1.5 0.5154 ± 0.0694 0.8011 ± 0.1240 1573.2 0.7675
Formula L ± SE b ± SE k ± SE Sresid r2
8
64 P. E. Gol'din
Fig. 1. Growth curves for length at age of harbour porpoise in the Sea of Azov and the Black Sea calculated
using one and two Gompertz formulae. Age (in years) is displayed at X-axis, length (in cm) is displayed at
Y-axis: 1.1 — males, the Sea of Azov; 1.2 — females, the Sea of Azov; 1.3 — males, the Black Sea; 1.4 —
females, the Black Sea. One-stage growth curve. Two-stage growth curve.
50
60
70
80
90
100
110
120
130
140
150
160
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
50
60
70
80
90
100
110
120
130
140
150
160
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1.1
1.2
65Growth and Body Size of the Harbour Porpoise…
Ðèñ. 1. Êðèâûå ëèíåéíîãî ðîñòà ìîðñêîé ñâèíüè â Àçîâñêîì è ×åðíîì ìîðÿõ, âûðàæåííûå îäíèì è
äâóìÿ óðàâíåíèÿìè Ãîìïåðòöà. Ïî îñè àáñöèññ — âîçðàñò (ãîä), ïî îñè îðäèíàò — äëèíà òåëà (ñì).
1.1 — ñàìöû, Àçîâñêîå ìîðå; 1.2 — ñàìêè, Àçîâñêîå ìîðå; 1.3 — ñàìöû, ×åðíîå ìîðå; 1.4 — ñàìêè,
×åðíîå ìîðå. Êðèâàÿ, ñîîòâåòñòâóþùàÿ îäíîé ñòàäèè ðîñòà. Êðèâàÿ, ñîîòâåòñòâóþùàÿ äâóì
ñòàäèÿì ðîñòà.
50
60
70
80
90
100
110
120
130
140
150
160
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
50
60
70
80
90
100
110
120
130
140
150
160
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1.4
1.3
and then the growth interrupts for 0.5–1 year. There are no direct evidences for this
phenomenon but it is implicated by the growth rates of the calves. In such a case the
interruption of growth immediately follows the weaning. This hypothesis is confirmed
by a poor-stained line, which is often layered in dentine in the middle of GLG of the
first year and divides the secondary growth layers of contrasting dentine structure.
À. Galatius (personal communication) suggested that the interruption of growth
between the two stages could be caused by difficulties in foraging after weaning and by
the infestation of parasites entering the organism with prey. Yet there can be another
explanation: the accelerated perinatal linear growth can be associated with the forming
of the hydrodynamic body parameters necessary for active movement and food search.
During this period other processes of growth and development are delayed, and the
ossification rate is slow. After the weaning the equilibrium is re-established; the body
weight grows, the facial bones fuse with skull, the bodies and arches of vertebrae fuse,
the metacarpal bones ossify. Thus, the growth strategy “switches” to other processes.
The hypothesis about the several-staged postnatal growth in toothed whales was
first experimentally grounded by Kasuya (1972) in a study of striped dolphin Stenella
coeruleoalba (Meyen, 1833), and then by Perrin et al. (1976) in a study of spotted dol-
phin Stenella attenuata (Gray, 1846). Different hypotheses were suggested for the
growth stage pattern in Phocoena phocoena. Benke et al. (1998) believe that the change
of growth stages occurs in the beginning of the first year of life; Galatius (personal com-
munication) — at the age between 1 and 2 years; Gaskin and Blair (1977) — between
3 and 4 years (i. e. just before or during attaining the sexual maturity); and Van Utrecht
(1978) — at the age of 4–5 years (i. e. in mature specimens, and only in males).
Furthermore, in many reports (Lockyer, 1995; Read, Tolley, 1997; Lockyer et al.,
2003; Lockyer, Kinze, 2003) the growth of harbour porpoise is described by one for-
mula, without distinguishing any stages.
Comparative analysis of the data concerning the growth of the North Atlantic har-
bour porpoise does not allow to make any definite conclusions about the age when the
interruption and the secondary spurt of growth could occur. The diagrams show that in
females from the Bay of Fundy the growth interruption can occur at age between 2 and
3 years, while in males it is not evident at all (Read, Tolley, 1997); in the waters off
Denmark the interruption in males can occur at the age between 1 and 3 years, in
females — between 2 and 3 years (Lockyer, Kinze, 2003); in males from Greenland
waters — before 2 years, in females — between 2 and 3 years (Lockyer et al., 2003); in
the waters off Britain and Germany the interruption is not evident (Lockyer, 1995;
Benke et al., 1998).
In any of the studies of large samples the growth spurt after attaining the sexual
maturity was not observed.
The difficulty in distinguishing growth stages in harbour porpoise can be explained
by small body size, early age of attaining the sexual maturity, high variability in the body
size in the age groups, and variability between different populations. Besides, there are
no good criteria for age determination within the accuracy better than 1 year. The only
conclusion that can be made is that there are at the most two growth stages in postna-
tal ontogenesis; the shift in the growth stages, if it takes place, occurs before attaining
sexual maturity, as in other delphinids and phocoenids (the list of references see in
Ferrero, Walker, 1999); the growth interruption can be associated with weaning.
A g e a t a t t a i nmen t o f s e x u a l ma t u r i t y. Bod y s i z e o f s e x u a l l y
ma t u r e s p e c imen s. The mean age at attainment of sexual maturity in males from
the Sea of Azov calculated by DeMaster formula was 3.25 years. Among the females
from the Sea of Azov all specimens at the age of 3.5 years and more were sexually
mature. In the animals from the Black Sea the mean age at attainment of sexual matu-
rity also seems to be about 3–4 years (BLASDOL, 1999).
66 P. E. Gol'din
The maximum length in immature males recorded in the Sea of Azov was 137 cm,
in females — 145 cm. The mean and limit values for mature specimens from the Sea
of Azov are presented in table 2. In the Black Sea (BLASDOL, 1999; Gol’din, 2000)
the maximum length recorded in immature males was 126 cm, in females 132 cm; the
minimum length in mature males was 118 cm (specified data), in females 121.5 cm
(124 cm in a specimen having corpora albicantia).
In the sample of Tanabe et al. (1997) the length of sexually mature males was
112–121 cm, of females 129.5–138.5 cm.
Ag e a t a t t a i nmen t o f p h y s i c a l ma t u r i t y. The earliest case of attainment
of physical maturity, i. e. complete ankylosis in all vertebral column, was recorded in
a specimen at the age of 6 years (supposedly female). The rest of physically mature ani-
mals were at the age of 10 and 12 years. Partial epiphyseal ankylosis in all the verte-
brae was recorded, starting from the age of 5 years, in more than half animals at the
age of 7–8 years, and in all older specimens up to 12 years. The mean age at attaining
the physical maturity can be regarded as about 8 years, like in harbour porpoises in the
North Atlantic (Lockyer, 2003); however, further research is needed to verify this value,
in light of the last data (Galatius, Kinze, 2003).
According to the growth formulae used in this study, the asymptotic value of the
body length (with accuracy of 0.1 cm) is attained at the age of 6–10 years, and 99%
of asymptotic length is attained at the age of 3–4 years in males and 4–5 years in
females. Thus, the age when 99% asymptotic length is attained corresponds approxi-
mately to early partial ankylosis in all the vertebral column.
A s ymp t o t i c b od y s i z e o f a du l t s p e c imen s. Size characteristics of adults
(conditionally regarded as physically mature specimens — see “Material and Methods”)
calculated by two methods are presented in table 2. The length values of the two males
at the age of 10 and 12 years from the Sea of Azov are not included; their length could
not be determined exactly but did not exceed 120 cm.
The variability of the body length is rather high, as in other marine mammals
(Yablokov, 1965). The coefficient of the variation fluctuates between 3.1–6.9% in dif-
ferent samples, the limit values are recorded in the males from the Black Sea and the
Sea of Azov respectively.
S e x u a l d imo r ph i sm of the body length is exhibited in statistical values: mean,
minimum, and maximum size of adult specimens (see table 2). As in the other popu-
lations of harbour porpoise, females are larger than males. The differences of the mean
values, according to a number of estimation methods, average 9–11 cm in the Sea of
Azov, 10–11 cm in the Black Sea; all the differences are significant (t-test, p < 0.05 in
67Growth and Body Size of the Harbour Porpoise…
Ta b l e 2. Body length (cm) of sexually and physically mature harbour porpoises from the Black Sea and the
Sea of Azov: number of specimens (n), limit values (lim), mean values (x ¯̄) with standard deviations (sx)
Ò à á ëèö à 2. Äëèíà òåëà (ñì) ïîëîâîçðåëûõ è ôèçè÷åñêè çðåëûõ ìîðñêèõ ñâèíåé èç Àçîâñêîãî è ×åðíîãî
ìîðåé: îáúåì âûáîðêè (n), ïðåäåëüíûå çíà÷åíèÿ (lim), ñðåäíèå çíà÷åíèÿ (x ¯̄) è èõ ñðåäíåêâàäðàòè÷íûå
îòêëîíåíèÿ (sx)
The S e a o f A zo v
Sexually mature 21 115–152 132.0 8.6 26 130–160 143.5 7.1
Physically mature:
– at age of 8 years and more 10 117–152 134.5 9.3 13 135–160 143.1 5.6
– calculated after Read and Tolley (1997) 16 117–152 135.0 7.5 24 135–160 144.9 6.4
Th e B l a c k S e a
Physically mature:
– at age of 8 years and more 10 118–131.5 122.3 3.8 12 127–146 133.2 5.6
– calculated after Read and Tolley (1997) 21 118–131.5 123.9 3.5 18 127–146 133.6 5.2
Age/category
Male Female
n lim x ¯̄ sx n lim x ¯̄ sx
the Sea of Azov, p < 0.01 in the Black Sea). Similar differences are observed in the
studied sample between the maximum lengths of adult males and females in the Sea of
Azov (152 and 160 cm) and minimum lengths in the Black Sea (118 and 127 cm).
Hence it can be predicted that the specimens filling the “gaps” will be found in cate-
gories not matching these values: physically mature females with the length of 125–
130 cm in the Sea of Azov, males with the length up to 140 cm in the Black Sea.
The difference in the mean length of sexually mature specimens in the Sea of Azov
is 11.5 cm. Zalkin (1938), basing on material from both the Sea of Azov and the Black
Sea, indicated the difference as 7 cm.
Sexual differences are exhibited somewhat weaker than in the North Atlantic popu-
lations, where they average about 15 cm (Read, Tolley, 1997; Lockyer, Kinze, 2003 etc.).
Differences in body size in harbour porpoises
from the Sea of Azov and the Black Sea
Animals from the Sea of Azov are longer than those from the Black Sea. The dif-
ferences in the mean length of specimens at the age of 7 years and more average 11–
12 cm; they are strictly significant (p < 0.01 for males, p < 0.001 for females). The same
concerns the asymptotic values predicted by the growth formulae. Significant differ-
ences were also discovered in the values of the body length of all sexually mature ani-
mals. In females significant differences in the body length are exhibited since the age
of 3 years.
This phenomenon can be explained either by spatial segregation based on the body
size, or by the existence of a separate population group in the Sea of Azov.
Segregation in cetaceans is caused, as a rule, by age and sex factors (about the pos-
sibility of age segregation in harbour porpoise — see Cox et al., 1998); the body size
merely reflects these factors. However, no differences in age and sex structure were
found in the animals at the age of 1 year and more in the samples from Ukrainian
waters of the two seas (Gol’din, in press).
Harbour porpoise inhabits the Sea of Azov from spring to autumn. The majority
of animals migrate simultaneously with the autumn mass migration of anchovy through
the Kerch Strait to the Black Sea, where they spend winter. According to the local res-
idents’ reports, only in warm winters single specimens are observed in the southern part
of the Sea of Azov.
The peak of parturition of harbour porpoise falls to warm season (July–October
after the data of Zalkin, 1940), preceding the migration of the Azov animals to the
Black Sea, i. e. at the time of their geographical isolation. This fact supports a hypoth-
esis of the existence of a separate population in the Sea of Azov. Earlier harbour por-
poise in the region was considered to be a single herd migrating from the Black Sea to
the Sea of Azov and back in spring and autumn respectively (Kleinenberg, 1956).
Nowadays, however, there is no doubt that harbour porpoise is distributed throughout
all the area of the Black Sea in summer season.
Obviously, the isolation of porpoises in the Sea of Azov and the Black Sea cannot
be total. Some animals migrate from the Sea of Azov through the Kerch Strait to the
Black Sea in summer. This is supported by the reports of local residents. E. g., in July
2000 small migrating groups were observed. The question of summer migrations from
the Black Sea to the Sea of Azov has not been studied at all. Winter distribution of ani-
mals from the Sea of Azov also requires further study. Finally, nothing is known about
how strictly individual specimens are associated with a certain local geographical area
in summer and whether they can migrate from one basin to another not annually.
Determination of the ranks of harbour porpoise groupings in the Sea of Azov and
the Black Sea requires further investigation, primarily genetic. However, irrespective of
the fact whether these groupings represent the true populations, it is obvious that dif-
68 P. E. Gol'din
ferent morphological or ecological “races” have formed in the two seas. Hence the
grouping of harbour porpoise in the Sea of Azov has to be regarded as a separate stock,
especially in regard to conservation and management policies.
The small body size of harbour porpoises from the Black Sea was reported recent-
ly by many researchers. According to the data by Krivokhizhin and Birkun (1999) and
the results of BLASDOL Project (BLASDOL, 1999), among several hundreds of por-
poises found at the Black Sea coast of the Crimea in 1989–1998, the maximum length
of females was 148 cm. Tanabe et al. (1997) recorded the maximum length of 130.5 cm
in males, 138 cm in females in the sample of 49 specimens. A. Tonay (personal com-
munication) recorded the maximum length of 140 cm in females in the sample con-
sisting of several dozens of animals studied in 1997–2003. Rosel et al. (2003) reported
finding a male 126 cm long and 13–14 years old.
At the same time, Karacam et al. (1990) observed specimens with the length up
to 160–166 cm in a small sample from the waters off the northern coast of Turkey, and
Rosel et al. (2003) reported a 157 cm female from the Aegean Sea. These data can also
be related to migrating specimens from the Sea of Azov. The body size of the porpois-
es noted in Karacam et al. (1990) as a whole corresponds to the measurements obtained
in this study for the specimens from the Sea of Azov.
Sabodash and Nazarov (1998) reported large porpoises from the Sea of Azov
(females up to 163–165 cm long, males up to 156 cm). Krivokhizhin and Birkun
(1999) reported findings animals up to 180 cm long; however, their data concerning
the largest specimens were obtained from volunteers; in 1994 a female 156 cm long was
found (S. V. Krivokhizhin, personal communication).
The sample studied by Glazov and Lyamin (2000) at the coast of Caucasus could
include specimens originated from both the Black Sea and the Sea of Azov. The max-
imum body length recorded was 150 cm in females, 147 cm in males.
Thus, the differences in body size of harbour porpoise from the two seas are con-
firmed by most studies.
The data on the body size of harbour porpoise in the first half of the 20th centu-
ry implicate that such differences could also exist in the past. Zalkin (1938), while
examining the material in the Sea of Azov and the Black Sea, reported the body length
in males up to 167 cm, in females up to 180 cm. At the same time, Barabash-Nikiforov
(1940) and Kleinenberg (1956), basing on the Black Sea material only, recorded the
maximum body length of 148 and 157 cm respectively; however, they dealt with much
smaller samples.
The differences in body size between the animals from the Sea of Azov and the
Black Sea can be explained from the ecological perspective. For many years the Sea of
Azov has been characterized by the highest fish productivity (7 times more than the
Black Sea (data by Moiseev, 1989) and high variety of prey species for harbour por-
poise (Zalkin, 1940). Besides, the shallowness of the sea facilitates the availability of
prey. The abundance and biomass of gobies has critically decreased during the last
30–40 years, but at present the population growth is observed (Demchenko, Mitiay,
2001). The anchovy abundance substantially decreased at the end of the 1980s
(Chashchin, 1997) but is gradually increasing in recent years (Animal life…, 2001).
Nowadays the productivity of fish species, which are prey for harbour porpoise, is rel-
atively high in the Sea of Azov (Animal life…, 2001); so in this respect the Sea of Azov
still can have advantage over the Black Sea.
The significant differences in the body length in the neighbouring regions indicate
high ecological plasticity of this characteristic.
The minimum lengths of adult males at the age of 8 years and older in the Black
Sea and the Sea of Azov remain the same: 117–118 cm. This value (the bottom limit
of size range) can be a more conservative index. It is remarkable that this value is the
69Growth and Body Size of the Harbour Porpoise…
same (117 and 118 cm) in the two dolphin species with body length close to that of
harbour porpoise from the Black Sea — Hector’s dolphin Cephalorhynchus hectori (Van
Beneden, 1881) (Slooten, 1991) and Commerson’s dolphin Cephalorhynchus commer-
sonii (Lacepede, 1804) (Lockyer et al., 1988). These seem to be the smallest body
lengths recorded in the adult cetaceans.
Changes in body size of specimens through the 20th century
On the basis of 1394 measurements of the body length, Zalkin (1938, 1940) con-
cluded that the mean lengths of sexually mature males and females were respectively
141.5 and 148.5 cm, the maximum lengths were 167 and 180 cm, and the minimum
length of pregnant females was 130–135 cm. Therefore, the values he got were signif-
icantly greater than those obtained in this study.
To explain this fact, one can resort to the following hypotheses. First, there are
certain differences in measurement techniques: in Zalkin’s study the total body length
was measured along the ventral side, while in this study it was measured point to point.
However, when a measured animal lies on its belly (like the one in the photo in Zalkin
(1938)), these measurements are just identical or, in any case, cannot differ so dramat-
ically. Second, V. I. Zalkin has examined a much greater sample than this one, so it
could be suggested than in an analogous sample one would obtain similar values. But,
as it was already noted above, none of the researchers in this field during the last 20
years has found an animal longer than 165–166 cm. Furthermore, in this study only
one male had the length more than 141.5 cm, which is the mean value reported by
V. I. Zalkin; two more specimens were recorded by Sabodash and Nazarov (1998) and
Glazov and Lyamin (2000) respectively. The only remaining hypothesis is that some
changes in the body size took place in the last decades.
There are numerous reports on the body size of harbour porpoises in different
regions of the North Atlantic during the twentieth century (Clausen, Andersen, 1988;
Read, Gaskin, 1990). During less than 20 years the asymptotic length of males has
reduced by 2 cm, of females — by 8 cm in the Bay of Fundy (Read, Gaskin, 1990)
(according to another study, by 3 and 5 cm respectively) (Read, Tolley, 1997) under
the pressure of an anthropogenic factor, namely the incidental by-catch.
Assuming that the data by Zalkin (1938) refer primarily to the animals from the
Sea of Azov, the changes of mean length in the 20th century (9.5 cm in mature males,
5 cm in mature females) seem to agree with the general trend of body size reducing in
harbour porpoise within its whole distribution range.
Comparison of body size in harbour porpoise in the Sea of Azov
and the Black Sea with animals from other geographical areas
Lockyer (2003) in the paper summarizing the results of recent studies in the North
Atlantic concluded that the asymptotic lengths of males in different populations were
141–149 cm, females — 153–163 cm. The maximum body lengths recorded were 167
cm in males, 189 cm in females (Lockyer, Kinze, 2003). The smallest mean lengths
were recorded in the adult specimens from Greenland waters, 141 and 154 cm respec-
tively (Lockyer et al., 2003); the lengths of animals from German waters of the North
Sea were close to them, 144 and 152 cm respectively (Benke et al., 1998). The mini-
mum length recorded in animals 8 years old and more was 126 cm in males, 135 cm
in females (Lockyer, Kinze, 2003). Harbour porpoises in the waters off the Southern
Europe and the Northern Africa were characterized by remarkably larger body size; the
maximum body length exceeded 2 m (Smeenk et al., 1992; Sequeira, 1996).
The mean values of the body length of the porpoises from the Sea of Azov and the
Black Sea are remarkably smaller (tabl. 2). The differences in the body length in com-
70 P. E. Gol'din
parison with that of the adult animals from the Bay of Fundy (North America) (Read,
Tolley, 1997) are highly significant for all the groups (p < 0.01 or p < 0.001). The dif-
ferences between the asymptotic body size values calculated from the growth formulae
are also highly significant. What is especially remarkable is the extremely small body
size of many adult males, which is less than 120 cm.
Harbour porpoises of the Sea of Azov and the Black Sea are obviously the small-
est representatives of the Ph. phocoena species nowadays. As for the body size, they are
similar to the smallest species of Phocoenidae family, vaquita Phocoena sinus Norris,
McFarland, 1958, in which the asymptotic length is 135 cm in males, 141 cm in
females (Hohn et al., 1996).
The differences in the mean size of specimens could also exist at the first half of
the 20th century, when the porpoises were larger both in the Atlantic and in the Black
Sea basin. In the material examined by Zalkin (1938), only 5 of 744 males and 24 of
650 females were longer than 160 cm, whereas in the material reported by Mo �hl-
Hansen (1954) that ratio was 11 of 225 males and 55 of 164 females. At that, the max-
imum lengths of the animals in both samples were 180 cm.
Thus, harbour porpoises from the Sea of Azov differ in the body size from those
from the Black Sea, and both populations differ from the North Atlantic ones, the ani-
mals from the Sea of Azov possessing the intermediate body size between the Black Sea
and Atlantic porpoises.
Perrin (1984) considered the emergence of dwarf forms in inner seas to be a gen-
eral tendency to variability in cetaceans and confirmed the idea with the examples of
the Black Sea and Mediterranean populations of two species: short-beaked common
dolphin Delphinus delphis Linnaeus, 1758, and bottlenose dolphin Tursiops truncatus
(Montagu, 1821). The causes of this phenomenon are unclear and require further inves-
tigation.
Conclusions
1. Investigations of the growth and life history of harbour porpoise in the Sea of
Azov and the Black Sea have shown that the mean body length of neonates is 72.5 cm,
like in harbour porpoises in the other regions. The calving season lasts at least from
April to August. The peak of neonates’ findings in the Sea of Azov falls to early July.
The greatest increment of body length occurs during the first months of life. The max-
imum life span is at least 20 years; the age at attainment of sexual maturity is 3–4 years,
of physical maturity — 6–12 years. 99% of the body length is possessed at 3–4 years
in males and 4–5 years in females. The mean body length of adult males and females
is 132–135 cm and 143–145 cm respectively in the Sea of Azov, 122–124 cm and
132–134 cm in the Black Sea. The body size is characterized by high variability. Adult
females are larger than males in 9–11 cm; sexual dimorphism is exhibited in statistical-
ly calculated values.
2. The question still remains of the existence of two growth stages in postnatal
ontogenesis of harbour porpoises. It seems reasonable to distinguish two stages, each
with decreasing growth rate. The shift of the stages takes place before attaining sexual
maturity. The age when the shift occurs depends on sex and stock. The growth inter-
ruption at the end of the first stage can be associated with weaning.
3. The results of the comparative analysis of the body size of the porpoises in the
Sea of Azov and the Black Sea demonstrate that adult specimens of both sexes from
the Sea of Azov are larger than those from the Black Sea in 10–12 cm on an average.
These are the first evidences for the existence of separate populations in the Sea of Azov
and the Black Sea. The Azov grouping of the harbour porpoise should be regarded as
a separate conservation and management stock.
71Growth and Body Size of the Harbour Porpoise…
4. The minimum length of adult males in both seas is 117–118 cm. This value, as
well as the minimum size in dolphins of genus Cephalorhynchus, is the smallest length
known in adult cetaceans.
5. During the 20th century the size of specimens somewhat reduced. This phe-
nomenon agrees with the general trend observed within all the distribution range of the
harbour porpoise.
6. The results obtained show that the harbour porpoises in the Sea of Azov and the
Black Sea are at present the smallest representatives of Ph. Phocoena species; as for the
body size, the animals from the Sea of Azov are intermediate between the Black Sea
and Atlantic porpoises.
The author sincerely thanks the staff of the Department of Zoology of V. I. Vernadsky Taurida National
University (Simferopol), BREMA Laboratory (Simferopol), and the Department of Pathological Anatomy of
the Crimean Republican Oncological Centre (Simferopol) for their assistance during various stages of this
study; D. V. Markov for many years of help in field expeditions; A. A. Anastasov, À. À. Birkun, Jr., E. V. De-
nisova, A. Frantzis, N. V. Frolova, D. M. Glazov, E. V. Godlevska, E. B. Gol’din, S. V. Krivokhizhin,
V. V. Pavlov, V. M. Sabodash, A. Tonay for the information about findings or measurements they have kindly
provided me with; H. Benke, S. G. Bushuev, A. Galatius, S. A. Gilevich, I. Hasselmayer, A. A. Hohn,
C. C. Kinze, G. A. Klevezal’, C. H. Lockyer, Yu. A. Mikhalev, À. J. Read, U. Siebert, M. V. Yurakhno for
their helpful recommendations and participation in the discussion of the results; À. Galatius, C. H. Lockyer
and C. C. Kinze who favoured me with manuscripts of their papers; M. V. Yurakhno for his valuable remarks
concerning the manuscript. This study was partially supported by the Award of President of Ukraine for the
Graduate Students and the Grant-in-Aid of the Society for Marine Mammalogy.
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