Abstract
One of the most robust metrics for assessing the effectiveness of protected areas is the temporal trend in the abundance of the species they are designed to protect. We surveyed coral-reef fish and living hard coral in and adjacent to a sanctuary zone (SZ: where all forms of fishing are prohibited) in the World Heritage-listed Ningaloo Marine Park during a 10-year period. There were generally more individuals and greater biomass of many fish taxa (especially emperors and parrotfish) in the SZ than the adjacent recreation zone (RZ: where recreational fishing is allowed) — so log response ratios of abundance were usually positive in each year. However, despite this, there was an overall decrease in both SZ and RZ in absolute abundance of some taxa by up to 22% per year, including taxa that are explicitly targeted (emperors) by fishers and taxa that are neither targeted nor frequently captured (most wrasses and butterflyfish). A concomitant decline in the abundance (measured as percentage cover) of living hard coral of 1–7% per year is a plausible explanation for the declining abundance of butterflyfish, but declines in emperors might be more plausibly due to fishing. Our study highlights that information on temporal trends in absolute abundance is needed to assess whether the goals of protected areas are being met: in our study, patterns in absolute abundance across ten years of surveys revealed trends that simple ratios of abundance did not.
Highlights
One of the most robust metrics for assessing the effectiveness of protected areas is the temporal trend in the abundance of the species they are designed to protect
There was no support for a difference in trends between sanctuary zone (SZ) and recreation zone (RZ) in densities of any family, so we considered the combined trends
Ten years of observations in and around the Mandu Sanctuary Zone revealed a consistent decline in abundance for multiple taxa in both the protected sanctuary zone (IUCN Category II), and an adjacent zone open to recreational fishing
Summary
One of the most robust metrics for assessing the effectiveness of protected areas is the temporal trend in the abundance of the species they are designed to protect. Management plans for protected areas frequently set goals that imply (or explicitly state) maintenance or restoration of abundances of species deemed especially worthy of protection (and occasionally to reduce abundances of species deemed unworthy) In the sea, this protection is most commonly implemented as marine parks. Abundance can be quantified in different ways, including counts of the number of individuals, counts of individuals per unit area (density), and biomass (a measure which is frequently used to estimate the abundance www.nature.com/scientificreports of fish). Each of these can yield different estimates of trend. We surveyed fish assemblages of shallow reefs in the majority of years from 2007–2016; we sought to determine whether our surveys yielded evidence of increasing or decreasing trends during that period, and if so, to quantify what the trend was, and if it varied between management zones designed to control fishing
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
