A new planning tool could help improve the effectiveness of efforts to rescue threatened and endangered species from the brink of extinction. Scientists have presented the approach in a new article in Frontiers in Ecology and the Environment.
The U.S. Endangered Species Act requires the development of recovery plans for species listed as threatened or endangered. While the goal of these plans is to help the species recover sufficiently so that then it can be removed from federal listing, their effectiveness has been sharply criticized by both politicians and scientists.
According to Alan Bolten and fellow researchers, "The lack of knowledge regarding the relative importance of threats that each species faces leads to long “shopping lists” of management-related interventions that ultimately contribute to the failure of recovery plans"
In an attempt to address this problem, the researchers developed a tool to compare the relative risk of different threats to a listed species based on estimates of their impact on population growth rates.
They tested the approach on the Northwest Atlantic population of the loggerhead sea turtle. However, the concept is applicable to any threatened or endangered species in which mortality data exists for multiple threats.
Working with the Loggerhead Recovery Team, the researchers listed in a matrix the threats that the species faces across its different life stages. They then estimated a likely range of annual mortality rates for each threat and adjusted the number based on the relative reproductive value of the life stage.
This process could help inform recovery efforts in a number of ways. First, the researchers were able to identify the most serious threats that warrant management intervention. For example, they found that bycatch from certain types of fisheries present the biggest threat to the turtles.
Also, for certain threats, the researchers were not able to estimate mortality because of a lack of data. This pinpoints critical knowledge gaps where future research is needed to better infrom species recovery work.
Finally, the transparency of the process and the user-friendly presentation of the results in a colorful matrix could help communicate the science underlying species recovery to the various stakeholders.
--by Rob Goldstein
Bolten, A., Crowder, L., Dodd, M., MacPherson, S., Musick, J., Schroeder, B., Witherington, B., Long, K., & Snover, M. (2010). Quantifying multiple threats to endangered species: an example from loggerhead sea turtles Frontiers in Ecology and the Environment DOI: 10.1890/090126