Is Australia Failing Threatened Marine Species?
Despite that Australia is considered an ecologically important land with incredible biodiversity, relatively few studies have evaluated whether the country’s protected area networks are actually hitting the targets set by the Convention on Biological Diversity, a multilateral sustainable development treaty. The few studies that exist suggest targets are not being met. According to the Convention, 17% of terrestrial land and 10% of marine areas are to be protected by the year 2020 to prevent further decline of threatened species. This study attempted to establish range boundaries for the sawfish, the most threatened cartilaginous fish, and determine whether or not it is being adequately protected by Australia’s marine protected area network. This is the first study to examine the protection levels of any marine species. The lack of research in this area is partly due to the difficulty of evaluating these species’ ranges.
Four of the five species of sawfish are known to exist in Northern Australia. Certain sawfish species are born and live in freshwater before migrating to the ocean, so a protected area network that includes both marine and inland reserves is necessary to protect this species at all stages of its life cycle. Fishing areas also pose a threat because sawfish’s toothed snouts can easily get caught in fishing lines. Therefore, it’s important that protected areas offer good connectivity with low-use waterways. Prior to this study, sawfish range in Australian waters had only been roughly mapped. As such, this study involved determining the extent of occurrence (EOO), or the minimum area which a species occupies, and the area of occupancy (AOO), or the smallest area that a species inhabits most of the time, for all four species of Australian sawfish. To do this, the researchers used a mixture of private and public species location records, sawfish habitat preference information, and spatial data of Australian bioregions.
The researchers found that Australia’s networks protected less than 21% of all four species’ marine ranges. Given the 10% marine protection target, this qualifies as “adequate protection.” However, Australia’s protected area networks failed to meet the terrestrial range protection target (17%) for sawfishes residing in inland waters. The percentage of protected inland ranges for each species was between 1.55% and 15.15% for AOO estimates and between 13.34% and 16.74% for EOO estimates. The majority (40.5%) of sawfish range protection was in protected areas that also allow for sustainable development. Notable ranges for sawfish appear to be in the Great Barrier Reef and Kakadu National Park, however these areas lacked connectivity to nearby protected areas.
Importantly, the study helped identify one area–the Kimberley Commonwealth Marine Reserve–that provides one species of sawfish the most marine protection. The area has been identified as a “hotspot” for all sawfish species because increasing the number of protected areas that surround the Kimberley Reserve would expand the sawfish’s protected range. This is an important designation, as there are recent plans to develop natural gas reserves in this area.
Studies like this one provide potential methods for evaluating species conservation effectiveness in situations where little information about the species’ distribution is known. Considering the rapid rate of biodiversity loss and the number of species for which minimal data is available, this type of innovative thinking is essential to protecting the earth’s biodiversity before it is too late.