Wimmer Tonya

No Thumbnail Available
Last Name
Wimmer
First Name
Tonya
ORCID

Filters

2012 - 2016 3
3
3
Reset filters

Settings

Search Results

Now showing 1 - 3 of 3
  • Article
    Assessment of management to mitigate anthropogenic effects on large whales
    (John Wiley & Sons, 2012-10-01) van der Hoop, Julie ; Moore, Michael J. ; Barco, Susan G. ; Cole, Timothy V. N. ; Daoust, Pierre-Yves ; Henry, Allison G. ; McAlpine, Donald F. ; McLellan, William A. ; Wimmer, Tonya ; Solow, Andrew R.
    United States and Canadian governments have responded to legal requirements to reduce human-induced whale mortality via vessel strikes and entanglement in fishing gear by implementing a suite of regulatory actions. We analyzed the spatial and temporal patterns of mortality of large whales in the Northwest Atlantic (23.5°N to 48.0°N), 1970 through 2009, in the context of management changes. We used a multinomial logistic model fitted by maximum likelihood to detect trends in cause-specific mortalities with time. We compared the number of human-caused mortalities with U.S. federally established levels of potential biological removal (i.e., species-specific sustainable human-caused mortality). From 1970 through 2009, 1762 mortalities (all known) and serious injuries (likely fatal) involved 8 species of large whales. We determined cause of death for 43% of all mortalities; of those, 67% (502) resulted from human interactions. Entanglement in fishing gear was the primary cause of death across all species (n= 323), followed by natural causes (n= 248) and vessel strikes (n= 171). Established sustainable levels of mortality were consistently exceeded in 2 species by up to 650%. Probabilities of entanglement and vessel-strike mortality increased significantly from 1990 through 2009. There was no significant change in the local intensity of all or vessel-strike mortalities before and after 2003, the year after which numerous mitigation efforts were enacted. So far, regulatory efforts have not reduced the lethal effects of human activities to large whales on a population-range basis, although we do not exclude the possibility of success of targeted measures for specific local habitats that were not within the resolution of our analyses. It is unclear how shortfalls in management design or compliance relate to our findings. Analyses such as the one we conducted are crucial in critically evaluating wildlife-management decisions. The results of these analyses can provide managers with direction for modifying regulated measures and can be applied globally to mortality-driven conservation issues.
  • Article
    Erratum to “Vessel strikes to large whales before and after the 2008 Ship Strike Rule”
    (John WIley & Sons, 2016-06-15) van der Hoop, Julie ; Vanderlaan, Angelia S. M. ; Cole, Timothy V. N. ; Henry, Allison G. ; Hall, Lanni ; Mase-Guthrie, Blair ; Wimmer, Tonya ; Moore, Michael J.
  • Article
    Vessel strikes to large whales before and after the 2008 Ship Strike Rule
    (John WIley & Sons, 2014-05-01) van der Hoop, Julie ; Vanderlaan, Angelia S. M. ; Cole, Timothy V. N. ; Henry, Allison G. ; Hall, Lanni ; Mase-Guthrie, Blair ; Wimmer, Tonya ; Moore, Michael J.
    To determine effectiveness of Seasonal Management Areas (SMAs), introduced in 2008 on the U.S. East Coast to reduce lethal vessel strikes to North Atlantic right whales, we analyzed observed large whale mortality events from 1990–2012 in the geographic region of the “Ship Strike Rule” to identify changes in frequency, spatial distribution, and spatiotemporal interaction since implementation. Though not directly coincident with SMA implementation, right whale vessel-strike mortalities significantly declined from 2.0 (2000–2006) to 0.33 per year (2007–2012). Large whale vessel-strike mortalities have decreased inside active SMAs, and increased outside inactive SMAs. We detected no significant spatiotemporal interaction in the 4-year pre- or post-Rule periods, although a longer time series is needed to detect these changes. As designed, SMAs encompass only 36% of historical right whale vessel-strike mortalities, and 32% are outside managed space but within managed timeframes. We suggest increasing spatial coverage to improve the Rule's effectiveness.