Subject: Abstracts of recent m.m.publications from CJZ (fwd)

Mike Williamson (pita@www1.wheelock.edu)
Mon, 11 Oct 1999 09:19:15 -0400 (EDT)

Date: Sat, 9 Oct 1999 11:59:23 -1000
From: "Robin W. Baird" <rwbaird@is.dal.ca>
To: MARMAM@UVVM.UVIC.CA
Subject: Abstracts of recent m.m.publications from CJZ

------
Abstracts from six recent publications from the Canadian Journal of
Zoology which deal with marine mammals follow. All abstracts from this
journal are available over the web, and the CJZ web site can be
accessed (along with the web sites of 60 other journals which publish
marine mammal articles) from:=20

http://is.dal.ca/~whitelab/sh/jwebalph.htm


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Multiple visits of individual humpback whales (Megaptera novaeangliae)
between the Hawaiian and Japanese winter grounds

Dan R. Salden, Louis M. Herman, Manami Yamaguchi, and Fumihiko Sato

1999. Canadian Journal of Zoology 77:504-508.=20

Abstract: We document through photographic identifications three
humpback whale (Megaptera novaeangliae) winter ground interchanges
between Hawai'i and Japan. Two of these whales, identified as male by
their behavioral roles, made multiple interchanges across years; i.e.,
they were initially seen in Hawai'i, were later observed in Japan, and
subsequently, returned to Hawai'i. The third whale was seen in only 2
different years, once in Japan and then in Hawai'i. Prior to this
report, there has been only one published report of a Hawai'i-Japan
interchange and only eight between Hawai'i and Mexico. None of these
involved multiple interchanges. The current findings demonstrate that
individual whales may be highly flexible in their annual choice of
widely separated winter destinations and suggest that these wanderers
may be mainly males. The occurrence of wanderers provides a mechanism
for increasing genetic variability in the breeding populations and
also suggests a mechanism for noted song similarities across different
North Pacific winter grounds.

---------------------------

Age and growth estimates of bowhead whales (Balaena mysticetus) via
aspartic acid racemization

John C. George, Jeffrey Bada, Judith Zeh, Laura Scott, Stephen E.
Brown, Todd O'Hara, and Robert Suydam

1999. Canadian Journal of Zoology 77:571-580.

Abstract: A total of 48 eye globes were collected and analyzed to
estimate ages of bowhead whales using the aspartic acid racemization
technique. In this technique, age is estimated based on intrinsic
changes in the D and L enantiomeric isomeric forms of aspartic acid in
the eye lens nucleus. Age estimates were successful for 42 animals.
Racemization rate (kAsp) for aspartic acid was based on data from
earlier studies of humans and fin whales; the estimate used was 1.18
10-3/year. The D/L ratio at birth ((D/L)0) was estimated using animals
less than or equal to 2 years of age (n =3D 8), since variability in the
D/L measurements is large enough that differences among ages in this
range are unmeasurable. The (D/L)0 estimate was 0.0285. Variance of
the age estimates was obtained using the delta method. Based on these
data, growth appears faster for females than males, and age at sexual
maturity (age at length 12-13 m for males and 13-13.5 m for females)
occurs at around 25 years of age. Growth slows markedly for both sexes
at roughly 40-50 years of age. Four individuals (all males) exceed 100
years of age. Standard error  increased with estimated age, but the
age estimates had lower coefficients of variation for older animals.
Recoveries of traditional whale-hunting tools from five recently
harvested whales also suggest life-spans in excess of 100 years of age
in some cases.

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Inshore and offshore bottlenose dolphin (Tursiops truncatus)
communities distinguished by association patterns near Grand Bahama
Island, Bahamas

Kelly A. Rossbach and Denise L. Herzing

1999. Canadian Journal of Zoology 77:581-592.

Abstract: Little is known about the behavior of offshore dolphin
populations. Our purpose was to distinguish and describe stable social
groups of bottlenose dolphins (Tursiops truncatus) between inshore and
offshore West End, Grand Bahama Island (26=B042'N, 79=B000'W).
Photoidentification was conducted from May to September, 1994 to 1996.
A simple ratio index described association patterns between dolphins.
Multidimensional scaling of association indices (n =3D 1711 dolphin
pairs) distinguished two dolphin communities consisting of 28 dolphins
(19 of known sex) found inshore and 15 dolphins (12 of known sex)
found greater than or equal to 27 km offshore. Eight of the 15
offshore dolphins were opportunistically photographed in the same
region between 1986 and 1990. The two communities were found at
different water depths (Mann-Whitney U test, p < 0.01), over distinct
bottom types (Kruskal-Wallis test, p < 0.01), and used different
bottom-foraging strategies. Long-term site fidelity of up to 10 years
and repeated dolphin associations of up to 8 years occurred greater
than or equal to 27 km from shore. Dolphins sighted greater than or
equal to 15 times averaged 48 associates (SD =3D 11, n =3D 28). A
dolphin's closest associate was of the same gender 74% of the time.
This study is the first to report long-term site fidelity and
association patterns of bottlenose dolphins found far from shore.=20

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Assimilation efficiency of prey in the Hawaiian monk seal (Monachus
schauinslandi)

Gwen D. Goodman-Lowe, James R. Carpenter, and Shannon Atkinson

1999. Canadian Journal of Zoology 77: 653-660.

Abstract: Assimilation efficiency, digestive efficiency, metabolizable
energy, and nitrogen retention in three captive adult male Hawaiian
monk seals (Monachus schauinslandi) were measured with the
indigestible marker chromic oxide for four experimental diets: a
control diet of herring (Clupea harengus) and three test diets
consisting of flagtail (Kuhlia sandvicensis), squid (Loligo sp.), and
lobster (Panulirus marginatus), each of which was used in combination
with herring. The addition of all three test prey to herring decreased
the digestibility of gross energy by a mean of 3.58 =B1 3.89%.
Assimilation efficiency of gross energy was 96.1 =B1 4.0% for herring,
73.8 =B1 6.8% for flagtail, and 94.1 =B1 5.7% for squid, but could not be
determined for lobster. Digestive efficiency and metabolizable energy
of the diets examined were high (4602.2 =B1 247.1 and 4062.5 =B1 178.4
kcal/d, respectively; 1 kcal =3D 4.18 kJ) and were positively correlated
with the amount of gross energy ingested. Nitrogen retention was
highest for the squid-herring diet (33.2 =B1 1.2 g=B7d-1) followed by the
lobster-herring diet (11.5 =B1 3.3 g=B7d-1), the flagtail-herring diet
(6.0 =B1 0.0 g=B7d-1), and the herring (control) diet (-5.7 =B1 1.6 g=B7d=
-1).
This study indicates that prey which are both higher in protein and
lower in fat than herring provide greater metabolizable energy for
productive functions in Hawaiian monk seals.

----------------------

Individually distinctive pup vocalizations fail to prevent
allo-suckling in grey seals

Susanne McCulloch, Patrick P. Pomeroy, and Peter J.B. Slater

1999. Canadian Journal of Zoology 77:716-723

Abstract: In crowded aggregations that occur in breeding colonies,
female pinnipeds commonly become separated from their pups and may use
spatial, olfactory, or auditory cues to locate them. A system of
mutual recognition based on vocalizations is known for otariids.
Female phocids are known to use location and olfaction to help
identify pups, but evidence for vocal recognition is weak. During the
1997 breeding season on the Isle of May, Scotland, vocalizations were
recorded from grey seal, Halichoerus grypus, pups; playback
experiments were carried out; and nursing of nonfilial pups was
observed. Pup vocalizations were found to be both stereotyped and
individually distinctive, features normally associated with a system
of individual recognition. However, playback experiments revealed that
mothers did not respond more to vocalizations of their own pups than
to those of nonfilial pups. Furthermore, seventeen cases of
allo-suckling were observed during 68 h of observation on the colony.
High densities of animals and frequent separations present challenges
to identification of pups by their mothers.

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The development of diving behavior in juvenile Weddell seals: pushing
physiological limits in order to survive

Jennifer M. Burns

1999. Canadian Journal of Zoology 77:737-747.

Abstract: In juvenile phocids, the successful transition from nursing
to independent foraging is contingent upon the development of adequate
diving skills within the limited time between weaning and the
depletion of body reserves. Yet, because juvenile seals are unable to
remain submerged for as long as adults, owing to their smaller size,
higher metabolic rates, and lowered oxygen stores, their behavioral
options are likely constrained. To determine how such limitations
might influence foraging strategies, we studied the development of
diving behavior and physiology in Weddell seal (Leptonychotes
weddellii) juveniles, using a combination of time-depth recorders,
satellite-linked dive recorders, and morphological and physiological
measurements (mass and blood chemistry). Time-depth recorder data
indicated that the average depth, duration, and frequency of dives
made by pups increased rapidly in the period from birth through
weaning, but slowed soon thereafter. While preweaning increases in
these parameters were correlated with seal age, postweaning increases
in dive capacity were gradual and were probably the result of slower
changes in mass and body composition. In weaned pups and yearlings,
dive frequency and time underwater increased with age and (or) mass.
Despite their smaller size and lower absolute energy requirements, the
amount of time juveniles spent in the water was similar to that spent
by adults. However, because juveniles were unable to remain submerged
as long as adults and because most foraging dives were deep, juveniles
were unable to spend an equivalent amount of time at the foraging
depths. This difference was evident even though juveniles dove much
closer to their anaerobic threshold than did adults. These findings
support the hypothesis that the foraging efficiency of younger seals
is reduced relative to that of adults, owing to physiological and
morphological constraints on aerobic dive duration, and suggests that
low juvenile survival might result from behavioral constraints.=20









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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
Robin W. Baird, Ph.D.
Post-doctoral fellow, Biology Dept., Dalhousie University
Research Director, Pacific Whale Foundation, 101 N. Kihei Road,=20
   Kihei, HI 96753 USA.=20
Phone (808) 879-8860 (work), 879-7061 (home). Fax 879-2615
e-mail: rwbaird@is.dal.ca=20
http://is.dal.ca/~whitelab/rwb/robin.htm=20
http://www.pacificwhale.org/learn/index.html