Magnetic Island Marine Park Zones: Effects of Fishing Restrictions on Predatory Reef Fish Populations

Over the past several decades industrialized fishing practices have decimated fish stocks worldwide. Top-down trophic cascades have occurred within many marine ecosystems as top predators are removed. Numerous regions world wide are being designated as marine park “no-take” zones in order to aid in the recovery of these species and with the hope that surplus population will spillover into unprotected zones.. This study aimed to determine if there were significant differences in abundances of three major families of predatory reef fish (Serranidae, Lutjanidae, and Lethrinidae) between fringing reefs located in four bays of various zones around Magnetic Island, QLD. Data were collected by snorkeling over two 50m transects (width determined by turbidity) four times at each bay from April 19, 2015 to April 30, 2015 and recording any fish observed from the aforementioned families. One-way analyses of variance and Tukey’s Honest Significant Difference test determined that significant differences only occurred between Geoffrey Bay, a no-take zone, and Nelly Bay, a take zone that allows all fishing except trawling. Geoffrey Bay had significantly higher abundances of Lutjanids (F = 3.57; df = 3, 28; p = 0.026453) and fish overall (F = 3.52; df = 3, 28; p = 0.027817) when data for Lutjanus carponotatus was removed. A marginally significant difference was also found for populations of L. carponotatus alone (F = 2.56; df = 3, 28; p = 0.075029). While not significant, there were also definite trends in the no-take zones having the highest abundances while Nelly Bay always had the lowest or was tied for the lowest. Further studies are needed that improve upon this design, though, through timed swims looking at temporal variations in fish stocks between zones to determine if there is a more significant marine park zone effect. This paper was written for the Australia: Rainforest, Reef, and Cultural Ecology program