[MARMAM] New publication: New Urban Habitat for Endangered Humpback Whales: San Francisco Bay
Dear MARMAM community, On behalf of my co-authors, we are pleased to share our recent paper in Aquatic Conservation. Markowitz, T. M., Keener, W., Webber, M. A., Payne, A. R., Lane, R. S., Fahlbusch, J. A., & Calambokidis, J. (2024). New urban habitat for endangered humpback whales: San Francisco Bay. Aquatic Conservation: Marine and Freshwater Ecosystems, 34(3), e4107. The open access article is available at: https://doi.org/10.1002/aqc.4107 Abstract: As populations of large whales recover from whaling, species that forage and breed in coastal waters, including the humpback whale (Megaptera novaeangliae), increasingly overlap with human activities. This represents a potential hazard in locations worldwide subject to intensive vessel traffic, including New York, Panama City and Brisbane. Historically, humpback whales were not considered part of San Francisco Bay's fauna, except for a few ‘lost’ whales that wandered into the estuary. An unprecedented influx of humpback whales into highly urbanized San Francisco Bay began in 2016. Research efforts in 2016–2018 from vessels and shore resulted in 496 photo-identification records plus 319 visual sightings. Sixty-one individuals were photo-identified, of which 80% (n = 49) used the bay on multiple days (range = 2 to 39), and 34% (n = 21) were resighted in successive years. Whales photographed in San Francisco Bay were found to belong to distinct population segments listed as endangered and threatened under the U.S. Endangered Species Act. Whales moved in and out of the bay seasonally (April–November). Habitat use patterns indicated movements farther into San Francisco Bay correlated positively with high tides. Humpback whales were visually observed lunge feeding on northern anchovy (Engraulis mordax) at the surface. Analysis of dive patterns by three tagged whales confirmed subsurface feeding when surface feeding was not apparent. The use of San Francisco Bay and adjacent waters by recovering populations of humpback whales exacerbates the potential for collisions with vessels, entanglement in fishing gear, and harassment by recreational vessels. The most pressing conservation concern is the risk of ship strikes, observed where humpback whales occur near active seaports. Bill Keener Research Biologist Cetacean Conservation Biology keen...@tmmc.org<http://www.marinemammalcenter.org/> | C: 415.297.6139 | MarineMammalCenter.org<http://www.marinemammalcenter.org/> The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA 94965 ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Fish Feeding and Rapid Foraging Behavior Switching by Gray Whales in California
Dear MARMAM community, On behalf of my co-authors, we are pleased to share our recent paper in Aquatic Mammals: Marc A. Webber, William Keener, Tim M. Markowitz, David Chamberlin, Darrin Allen, Rebekah S. Lane, Josephine M. Slaathaug, Pilar N. Rodriguez, Kathi George, and Julia E. O’Hern. (2024). Fish feeding and rapid foraging behavior switching by gray whales (Eschrichtius robustus) in California. Aquatic Mammals, 2024, 50(2), 132-151. The open access article is linked at: https://doi.org/10.1578/AM.50.2.2024.132, and a video clip is also available as supplemental material at: https://vimeo.com/918015758 Abstract: Gray whales (Eschrichtius robustus) evolved to suction feed on benthic invertebrates and typically do not consume adult fish. Yet, these whales are flexible foragers, occasionally skim feeding on planktonic invertebrates and rarely lunge feeding on fish, the latter according to anecdotal accounts. We documented the unusual phenomenon of multiple gray whales predating dense schools of anchovy over a sustained period (22 days) in June 2022 at Pacifica, California, in the Gulf of the Farallones. Analysis of 11,265 photos and 11 video clips (totaling 4 min 16 s) for behavior and whale identification resulted in a total of 165 foraging events by six identified gray whales. Attribution of foraging behavior to the most active individuals was achieved by matching left pectoral fins, visible during lateralized feeding behavior. Whales rolled onto their right sides in 96% of near-surface side-swimming bouts. Another behavior, first photographed here, was dynamic surface lunge feeding by one gray whale. Five gray whales interspersed fish feeding with benthic suction feeding evidenced by sediment streaming: prey type switching was executed rapidly, in less than 1 minute in several instances, the shortest intervals reported for a baleen whale. Similar results were obtained for foraging behavior switching (continuous side-swimming or intermit- tent lunging) in pursuit of fish. Four photo-identified Pacifica whales were sighted in San Francisco Bay/Gulf of the Farallones, one of which was also matched to the Pacific Coast Feeding Group. Such local and regional connections warrant efforts to determine whether gray whales use this area as a migratory stopover site or for summer foraging, or both. Our observations confirm gray whale behavioral plasticity and opportunistic exploitation of food resources in mid-latitudes, which may enhance their resilience to climate change. Bill Keener Research Biologist Cetacean Conservation Biology keen...@tmmc.org<http://www.marinemammalcenter.org/> | C: 415.297.6139 | MarineMammalCenter.org<http://www.marinemammalcenter.org/> The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA 94965 ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] Request for information on harbor porpoise behavior
Dear MARMAM community, We are working on an international collaborative paper documenting harbor porpoise mating patterns globally. If you or your colleagues have photos, videos or other data on harbor porpoise aerial behavior or mating, please reach out us. Our goal is to document whether the conspicuous behavior that we described from San Francisco Bay in our 2018 paper (the male's rapid approach to the female's left side that often ends with the male becoming aerial) occurs in all harbor porpoise populations. Our results have shown that porpoise aerial behavior may be a sign of mating activity, and such observations could factor into decisions affecting potential breeding hotspots and the designation of marine protected areas. Our open access paper in Aquatic Mammals (https://doi.org/10.1578/AM.44.6.2018.620) is available here: 44_6_keener<https://www.aquaticmammalsjournal.org/index.php?option=com_hikashop=product=download_id=915>. At the World Marine Mammal Conference in Barcelona, we presented a poster inviting collaborators, available here: https://www.marinemammalcenter.org/assets/pdfs/vetsci-stranding/scientific-contributions/2019/Webber_et_al_2019_Porpoise_mating_behavior_WMMC_Poster.pdf All the best, Bill Keener (The Marine Mammal Center; keen...@tmmc.org) Marc Webber (The Marine Mammal Center; webb...@tmmc.org) Dara Orbach (Texas A University - Corpus Christi; dara.orb...@tamucc.edu) Bill Keener Research Associate Cetacean Field Research Program keen...@tmmc.org<http://www.marinemammalcenter.org/> | C: 415.297.6139 | MarineMammalCenter.org<http://www.marinemammalcenter.org/> The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA 94965 ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication on the sex life of harbor porpoises
Dear MARMAM community, On behalf of my co-authors, I’m pleased to announce the publication of our article: The Sex Life of Harbor Porpoises (Phocoena phocoena): Lateralized and Aerial Behavior William Keener, Marc A. Webber, Isidore D. Szczepaniak, Tim M. Markowitz and Dara N. Orbach. Aquatic Mammals, Vol 44, Issue 6, 2018. Abstract The Golden Gate Bridge in San Francisco Bay provides a non-invasive aerial platform where harbor porpoises (Phocoena phocoena) can be observed mating. We photographed 144 mating events over an eight-year period (2010 to 2018) occurring in all seasons. The mating habits of free-ranging male harbor porpoises are systematically described, a first for any member of the family Phocoenidae. The males’ rapid sexual approaches toward females were characterized by high energy and precision timing as males rushed to contact females surfacing to breathe. Males always attempted to copulate by positioning their ventral sides on the females’ left side. This extreme laterality in sexual approach has not been reported for any cetacean. Males approached females with force and speed that often resulted in male aerial behaviors (69% of mating attempts). These behaviors, observed exclusively in mating contexts, included leaps and splashes that counter the species’ reputation for inconspicuous behavior. Males also displayed their ventrum or penis toward females without attempting to copulate. The penis was visible in 60% of the 96 mating events for which the ventrum could be observed, with intromission confirmed in one event. Males always initiated mating and approached lone females in 62.5% of mating events. Calves accompanied females during 25% of mating events. Calves were temporarily separated from their mothers by the approaching males in approximately half of these events. Additional adults were observed in 12.5% of groups, although no male-male interactions were observed. Our findings on the unique mating pattern exhibited by male harbor porpoises validate some predictions made about their behavior based on their reproductive biology and anatomy. The data support the hypothesis that males compete primarily by sperm competition and not contest competition. The full article, is available at https://doi.org/10.1578/AM.44.6.2018.620 and is open access as part of a special issue of Aquatic Mammals in honor of Bernd Wursig. To see the video clips of mating behavior, go to the online supplemental material page: https://www.aquaticmammalsjournal.org/index.php?option=com_content=article=10=147 https://www.aquaticmammalsjournal.org/index.php?option=com_content=article=10=147 To request a PDF copy, please email me at bill.kee...@comcast.net mailto:bill.kee...@comcast.net Cheers, Bill Keener Golden Gate Cetacean Research Corte Madera, California, USA___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
