Subject: abstracts - Aquatic Mammals, vol 25 (2), 1999 (fwd)
Mike Williamson (pita@www1.wheelock.edu)
Tue, 3 Aug 1999 18:10:36 -0400 (EDT)
---------- Forwarded message ----------
Date: Tue, 3 Aug 1999 15:55:34 -0400
From: Dagmar Fertl <Dagmar.Fertl@mms.gov>
To: marmamed@uvic.ca, ECS-all@mailbase.ac.uk
Subject: abstracts - Aquatic Mammals, vol 25 (2), 1999
Dear Marmam and ECS-mailbase subscribers,
The following are abstracts/summaries for articles appearing in the
most recent issue of Aquatic Mammals. Aquatic Mammals is a benefit of
membership with the European Association for Aquatic Mammals. Please
do not request reprints from me or the Marmam editors; I have provided
addresses for authors to whom reprint requests should be directed.
Thank you for letting me know you appreciate postings of recent
publications, most especially Aquatic Mammals.
I'd like to thank Dr. Paul Nachtigall for doing such a great job with
Aquatic Mammals while he was editor, and for supporting posting of the
abstracts for the articles.
Please direct future correspondence and manuscripts to the new editor:
Dr. Jeanette Thomas
Laboratory of Sensory Biology
Western Illinois University Regional Center
3561 60th Street
Moline, IL 61265, USA
email: Jeanette_Thomas@ccmail.wiu.edu
Sincerely,
Dagmar Fertl
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Ritter, F.* and B. Brederlau. 1999. Behavioural observations of
dense beaked whales (Mesoplodon densirostris) off La Gomera, Canary
Islands (1995-1997). Aquatic Mammals 25(2): 55-61.
*M.E.E.R. e.V., Weichselstr. 20, 10247 Berlin, Germany
Dense beaked whales (Mesoplodon densirostris) were sighted 24 times
during 1 September 1995 through 31 August 1997 off La Gomera, Canary
Islands. Sightings occurred year round. Group size was estimated to
range from 2 to 9 individuals (mean 3.44, SD=2.07, n=23). Of the seven
sightings for which such information was recorded, mean depth was 320
m (SD=270 m), and mean distance from shore was 4.39 km (SD=1.85 km).
Adult males and calves were both observed during many encounters. The
reaction of the animals to the observation vessel avried from
avoidance to approach. During two encounters swimmers were able to
approach the whales underwater.
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Mobley, Jr., J.R.*, G.B. Bauer, and L.M. Herman. 1999. Changes over a
ten-year interval in the distribution and relative abundance of
humpback whales (Megaptera novaeangliae) wintering in Hawaiian waters.
Aquatic Mammals 25(2): 63-72.
*Social Sciences, University of Hawaii-West Oahu, 96-129 Ala Ike,
Pearl City, HI 96782, USA
Aerial surveys of the wintering population of humpback whales
(Megaptera novaeangliae) were performed during the 1990 season
(Jan-Apr) in the waters adjoining the major Hawaiian Islands using
methods consistent with those used in earlier surveys (1977-80).
Analysis of these data showed significant increases in both calves and
total whales across the intervening period of ten years. Comparisons
of numbers of whales and calves seen on peak flight dates across the
five years (1977-80 and 1990) showed significant differences, with
numbers of whales and numbers of calves for 1990 revealing the
greatest departures from expected frequency. Comparisons of overall
encounter rates for both calves (calves/km) and total whales
(whales/km) showed signifcant differences across years, with 1990
rates significantly higher than for all previous years. When
encounter rates for total whales were compared across years within
each of the five major regions (Big Island, Four Island, Penguin Bank,
Oahu, and Kauai/Niihau regions), there was a general trend of greater
increases moving northwest through the island chain. Together these
data suggest that the wintering population may be 'spilling over' from
previously preferred habitat (Four Island and Penguin Bank regions)
and offer supportive evidence that this endangered population may be
recovering.
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Johnson, C.M.* and K. Moewe. 1999. Pectoral fin preference during
contact in Commerson's dolphins (Cephalorhynchus commersonii).
Aquatic Mammals 25(2): 73-77.
*Dept of Cognitive Science, University of California-San Diego, La
Jolla, CA 92093-0515, USA
The Commerson's dolphin, Cephalorhynchus commersonii, is well
documented as having saw-toothed serrations on the leading edge of,
primarily, its left pectoral fin. However, the function of these
serrations, which apparently develope with sexual maturity and are
more often exclusively on the left in males than in females, had not
heretofore been explored. In this captive study of six mature
Commerson's dolphins - two males and four females - instantaneous scan
samples were taken once every ten seconds for 24 minutes per session
in 220 sessions (for 31,680 scans, 88 hours of observation). 'Pec
touches' - contact between the leading edge of one animal's flipper
and any part of the body of another animal - were observed in 946 of
these scans. 907 (96%) of these were performed by the two males. Of
these 907 observations, 853 (94%) involved the male's serrated left
pectoral fin. This preferential use of the left flipper was consistent
across their full range of partners (male or female) and regardless of
arousal state (i.e. involving genital or non-genital contact). These
results suggest that flipper serrations may, in part, serve to enhance
tactile stimulation during social contact and further, that this may
reflect a gender-specific adaptation.
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Carter, S.K.*, F.C.W. Rosas, A.B. Cooepr, adn A.C. Cordeiro-Duarte.
1999. Consumption rate, food preferences and transit time of captive
giant otters Pteronura brasiliensis: implications for the study of
wild populations. Aquatic Mammals 25(2): 79-90.
*Current address: Washington Cooperative Fish and Wildlife Research
Unit, School of Fisheries, Box 357980, University of Washington,
Seattle, WA 98195-7980, USA
Food consumption, food preferences and transit time of digesta were
determined in captive giant otters, Pteronura brasiliensis, at the
National Institute of Amazon Research (INPA), Manaus, Brazil. Food
consumption of an adult female was 0.097 kg^-1day^-1. Giant otters
showed significant and varied preferences for the single Siluriformes
(catfish) and various Characiformes species offered. The adult female
preferred Anostomidae and Hypophthalmus (catfish), followed by
Triportheus. Myleinae (pacu) were the least preferred, and other
species of Characiformes offered were intermediate between Triportheus
and Myleinae but not different from one another. The subadult male
preferred Psectrogaster, Potamorhina and Semaprochilodus, followed by
Hypophthalmus and finally Hemiodontidae. Within species, larger fish
are chosen significantly affected the percentage of times fish offered
were consumed completely (P<0.016). Overall, most fish were consumed
completely more often than siluroids (77.8% vs 38.6% of trials,
P<0.0001), but the percentage of times different characoids were
consumed completely varied (range 0-100%). Small fish (5-15 cm) are
more likely to be consumed completely than medium (15-25 cm) fish
(84.9% vs 80.2% of trials, P<0.02). Transit time of particulate
markers averaged 3.13 h. Captive preferences are compared to diets of
wild otters in the region (central Amazonia), and implications of
study results for determination of food habits in wild otters using
scat analysis are discussed.
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Maze, K.S.* and B. Wursig. 1999. Bottlenose dolphins of San Luis Pass,
Texas: Occurrence patterns, site fidelity, and habitat use. Aquatic
Mammals 25(2): 91-103.
*Present address: Unit C, 17th floor, 148 Qing Hui Rd., Dailiang Town,
Shunde City, Guandong Province 528300, People's Republic of China
Bottlenose dolphins (Tursiops truncatus) in the Galveston Bay Estuary,
Texas, have been studied continuously since 1990. Most of this
research has taken place in the 'Galveston Bay' area at the
northeastern end of Galveston Island. In September 1995 we began a
project to examine bottlenose dolphin occurrence patterns, habitat
use, site fidelity, and movements in the San Luis Pass area, a
relatively undisturbed area at the southwestern end of Galveston Bay
Estuary; and to compare findings to previous work in Galveston Bay,
approximately 48 km away. Eighty-three boat-based photo-identification
surveys were conducted during 12 months in 1995-1996, totaling 349.4 h
of effort, of which 94.3 were spent in direct observation of 102
dolphin groups. Seventy-one individuals were identified, including 37
'residents' (Bay) and 34 'transients' (Gulf). These individuals were
compared with 63 individuals identified in the study area in 1990.
Fourteen of 71 (19.7%) animals identified in 1995-1996 were present in
1990, suggesting that some dolphins exhibit long-term site fidelity to
the area. Dolphins identified in San Luis Pass were compared to
photographs taken during 1995 surveys of Galveston Bay. Three animals
were sighted in both study areas, indicating coastal movements between
sites do occur. The study area was divided into four sections based
upon habitat characteristics. Season and study area section were not
independent with regard to group sightings. During summer, animals
were most frequently sighted in a shallow bay furthest inland, whereas
during winter, they were most frequently sighted in the Gulf of
Mexico. This study suggested that the San Luis Pass area, devoid of
deep man-made channels and structures, is inadequate to support
dolphins during winter. This in contrast to Galveston Bay, where
groups have been sighted regularly in bays and channels year-round. We
suggest that food resources in Galveston Bay are present year-round
due to deeper water provided by the Houston and Galveston Ship
Channels, and that this habitat may therefore be more attractive to
dolphins than before human restructuring of the underwater
environment.
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Mazzuca, L., S. Atkinson*, B. Keating, and E. Nitta. 1999. Cetacean
mass strandings in the Hawaiian Archipelago, 1957-1998. Aquatic
Mammals 25(2): 105-114.
*Hawaii Institute of Marine Biology, University of Hawaii, P.O. Box
1346, Kaneohe, HI 96744, USA
Cetacean mass stranding data for the Hawaiian Archipelago, from 1957
through 1998, were analyzed to determine age (estimated from body
length), location, frequency, and seasonal distribution of stranding
occurrence. Using data collected from the National Marine Fisheries
Service Pacific Area Office and published news reports, 9 mass
stranding events, involving 4 species comprised of 96 animals, were
identified and analyzed. The stranded animals were predominately adult
odontocete whales. Ninety-five percent of the animals that came ashore
were alive at the time of the stranding. Human intervention occurred
in all of the live mass stranding events however, 81% of the animals
subsequently died. Short-finned pilot whales (Globicephala
macrorhynchus) stranded in the largest groups and experienced the
greatest number of stranding events (x=14 animals, 5 events); pygmy
killer whales (Feresa attenuata) stranded in two events, consisting of
2 and 4 animals each; and rough-toothed dolphins (Steno bredanensis)
stranded in one event in a group of 18 live animals. One pygmy sperm
whale (Kogia breviceps) event was a female stranding with a calf. The
greatest incidence of mass strandings occurred on the Island of Maui
during the month of June. Mass strandings occurred on all high
Hawaiian Islands, except Hawaii; none were reported on the islands, or
atolls north of Kauai. Two-thirds of the events occurred on the
leeward sides of the islands with similar bottom topography, coastal
configuration, and geomagnetic characteristics in all events.
*************************************************************
Reddy, M.L.*, S.E. Kaupp, H. Goforth, and S.H. Ridgway. 1999.
Reduction of suspended particulates by mussels and other organisms in
dolphin enclosures. Aquatic Mammals 25(2): 115-118.
*SPAWARSYSCEN D3503 49620 Beluga Rd, Rm 204, San Diego, CA 92152, USA
Water clarity inside bottlenose dolphin (Tursiops truncatus)
enclosures in San Diego Bay was greater than that outside the
enclosures, in spite of fecal and urinary input by the dolphins. We
investigated the possibility that this was due to common bay mussels,
Mytilus edulis, that had colonized on the netting inside the dolphin
enclosures. Using an estimated population of over 200,000 mussels and
a range of published pumping rates, we calculated that the volume of
water filtered by the mussels was equivalent to nearly 18.4 to 184
times the enclosure volume per day. The synergistic combination of
available substratum, nutrient mixing, and the rich, natural
microenvironment found in the dolphin enclosures enhanced the water
quality of the immediate local environment by reducing the amount of
particulate matter and algae in the water column. This resulted in
greater clarity inside the mussel-encrusted enclosures. Similar
substrata could be used by aquaculture operations for the treatment of
natural waters used to house a variety of organisms from abalone to
fin fish, either in small volume enclosures or in those with high
density populations. Furthermore, mussel-encrusted netting might be
employed to clear water overloaded with organic matter from sewage
overflow, river runoff, fish farms, feedlot effluents, and other
sources of organic pollution.
*************************************************************
Rodriguez-Lopez, M.A. and A.A. Mignucci-Giannoni. 1999. A stranded
pygmy killer whale (Feresa attenuata) in Puerto Rico. Aquatic Mammals
25(2): 119-1211.
Red Caribena de Varamientos-Caribbean Stranding Network and
Laboratorio de Mamiferos Marinos del Caribe, Departamento de Ciencias
y Technologia, Universidad Metropolitana, SUAGM, P.O. Box 361715 San
Juan, Puerto Rico 00936-1715, USA
no abstract provided.
This stranding event is the third record of pygmy killer whale for the
Caribbean and documentation of this species as part of the cetacean
biodiversity of Puerto Rico. Hematogram and blood chemistry values
are provided, as well as details from the necropsy, including stomach
contents.