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
     *************************************************************
     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.
     *************************************************************
     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.
     *************************************************************
     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.
     *************************************************************
     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.
     *************************************************************
     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.
     *************************************************************
     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.