Horning M.,Oregon State University |
Mellish J.-A.E.,Alaska SeaLife Center |
Mellish J.-A.E.,University of Alaska Fairbanks
PLoS ONE | Year: 2012
The endangered western stock of the Steller sea lion (Eumetopias jubatus) - the largest of the eared seals - has declined by 80% from population levels encountered four decades ago. Current overall trends from the Gulf of Alaska to the Aleutian Islands appear neutral with strong regional heterogeneities. A published inferential model has been used to hypothesize a continuous decline in natality and depressed juvenile survival during the height of the decline in the mid-late 1980's, followed by the recent recovery of juvenile survival to pre-decline rates. However, these hypotheses have not been tested by direct means, and causes underlying past and present population trajectories remain unresolved and controversial. We determined post-weaning juvenile survival and causes of mortality using data received post-mortem via satellite from telemetry transmitters implanted into 36 juvenile Steller sea lions from 2005 through 2011. Data show high post-weaning mortality by predation in the eastern Gulf of Alaska region. To evaluate the impact of such high levels of predation, we developed a conceptual framework to integrate density dependent with density independent effects on vital rates and population trajectories. Our data and model do not support the hypothesized recent recovery of juvenile survival rates and reduced natality. Instead, our data demonstrate continued low juvenile survival in the Prince William Sound and Kenai Fjords region of the Gulf of Alaska. Our results on contemporary predation rates combined with the density dependent conceptual framework suggest predation on juvenile sea lions as the largest impediment to recovery of the species in the eastern Gulf of Alaska region. The framework also highlights the necessity for demographic models based on age-structured census data to incorporate the differential impact of predation on multiple vital rates. © 2012 Horning, Mellish. Source
Maniscalco J.M.,Alaska SeaLife Center
PLoS ONE | Year: 2014
Steller sea lions were listed as endangered following a collapse of the western distinct population beginning in the late 1970s. Low juvenile survival has been implicated as a factor in the decline. I conducted a multistate mark-recapture analysis to estimate juvenile survival in an area of the western population where sea lions are showing signs of recovery. Survival for males and females was 80% between 3 weeks and 1 year of age. Approximately 20% of juveniles continued to be nursed by their mothers between ages 1 and 2 and 10% between ages 2 and 3. Survival for juveniles that suckled beyond 1 year was 88.2% and 89.9% to ages 2 and 3, respectively. In contrast, survival for individuals weaned by age 1 was 40.6% for males and 64.2% for females between ages 1 and 2. Birth mass positively influenced survival for juveniles weaned at age 1 but had little effect on individuals continuing to suckle. Cumulative survival to age 4 was double that estimated during the population decline in this region. Evidence suggests that western Steller sea lions utilize a somewhat different maternal strategy than those in the eastern distinct population. Western adult females generally invest more in their pups during the first year but wean offspring by age 1 more often. This results in better survival to age 1, but greater mortality between ages 1 and 3 compared to the eastern population. Different maternal strategies may reflect density dependent pressures of populations at opposite levels of abundance. © 2014 John M. Maniscalco. Source
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase II | Award Amount: 750.00K | Year: 2011
Wildlife Computers presents a remote release device for use with marine mammal data-logging tags proposed with three variations to suit cetaceans and large and small pinnipeds. The device uses innovative approaches such as ElectRelease epoxy for the releasing mechanism and an Argos-based signaling system. Preliminary testing of device components are reviewed in summary from Phase I efforts. Outlined plans for prototype production and bench, field, and animal tests are described in detail as focus of this Phase II technical proposal. Production and bench tests are intended to test not only design features but numerous production materials to keep device light, strong and ocean-worthy. Bench and field tests will simulate real-world environment interactions the release devices may be exposed to in addition to testing signaling ranges and release-reliability. Animal tests are proposed for northern fur seals and Steller sea lions with oversight by research affiliate Dr. Russel Andrews. A Phase II Option will explore production of the cetacean device and its testing on short-finned pilot whales.
Agency: NSF | Branch: Continuing grant | Program: | Phase: INSTRUMENTAT & INSTRUMENT DEVP | Award Amount: 367.15K | Year: 2016
An award is made to the Alaska SeaLife Center (Seward, AK) to develop a miniaturized, implantable, life-long vital rate monitor for warm-bodied marine animals. This study will provide one postdoctoral researcher and a technical research associate the opportunity to participate in the multi-disciplinary integration of science and technology, and the application of technological innovation to promoting innovative biological research. Through a custom education and outreach package, the development efforts and linkages between technological innovation and biological research will be brought to a broad public audience including potential users of the new instrument, other scientists, public people of all ages, as well as grades 6-12 school children. The outreach package will enhance an existing, standards conforming STEM curriculum, downloadable from a project-specific website. Through addition of a geo-referenced data and information portal to this website (under development via separate funding, to go live in 2016), in combination with regionally available resources (distributed classroom activities kits) and remotely accessible training opportunities, modern science and technology learning opportunities will be brought to under-served rural classrooms in Alaska.
The purpose of the Life History Transmitter (LHX tag) is to determine survival, causes and locations of mortality of host animals. In female hosts, LHX tags also determine the age at birth of their first pup and the number of pups born over their life. Oceans comprise the majority of the Earths biosphere, and marine ecosystems are faced with potentially dramatic changes driven by natural and human factors, including use of natural resources and climate change. Many linkages between causes of changes, and effects in complex marine ecosystems, specially those involving top level consumers as well as their predators and prey, remain poorly understood, largely due to a lack of feasible ways to observe many marine species that spend most of their life at sea or under water. To overcome this difficulty, a new monitoring device was developed under previous IDBR funding that enables the collection of predation, survival and female reproductive data by a single instrument, no matter where the host might move to, feed, breed, and die. Building on the success of this new telemetry device that provided the first direct at-sea determination of predation rates on a large marine predator from satellite-linked transmissions initiated only after the death of the host, this project will improve the capabilities and enable the production of the Life History Transmitter, for collaborative studies on many top level species of interest and concern. This will enable researchers from a broad community of potential users to conceive and apply new experimental designs to provide a major surge in our understanding of marine ecosystems, food chain linkages, as well as consumer driven and resource driven effects within the many unresolved knowledge gaps.
Agency: NSF | Branch: Standard Grant | Program: | Phase: ARCTIC NATURAL SCIENCES | Award Amount: 324.79K | Year: 2013
This award will support program office and synergistic activities to conclude an integrated, multidisciplinary research program in the eastern Bering Sea, funded through a partnership between the National Science Foundation and the North Pacific Research Board (NPRB). Underway since 2007, the Bering Sea Project has involved dozens of individual research projects and more than 100 investigators, all working toward the goal of improving our understanding of how this highly productive (and economically critical) marine ecosystem may respond to climate change, particularly as mediated through changes in seasonal ice cover. This award seeks to maximize the return on NSF?s and NPRB?s investment during the final two years of the program, through several key activities deemed most critical to capturing and communicating the programs scientific accomplishments. The project would provide funds for 1) publication of thematic special issues of the scientific journal Deep-Sea Research II, 2) travel for members of the Bering Sea Project Science Advisory Board (SAB) to one in-person meeting in Arlington, Virginia and a scientific meeting (the 2014 Alaska Marine Science Symposium), and 3) travel and meeting expenses associated with a capstone open science meeting in 2014. From the start, the Bering Sea Project has incorporated a diverse suite of communication, outreach, and education activities to convey the scientific discoveries of the program to stakeholders, teachers, students, and the public. Funding would support print and electronic publication of short headlines scientific synopses, a longer Bering Sea Project magazine, and a programmatic lessons learned article.