WeFish

How a marine park is threatening abalone

Here is a scientific report looking at the Maria Island reserve in Tasmania, they tried to show that an increase number of lobsters resulted in a decrease number of the sea urchin showing a healthier ecosystem, but what they also found was that there was a huge decrease in the abalone numbers as well, to the point that they are now worried about its numbers. This shows that while removing fishing will see an increased numbers of the targeted species, and let’s face it we don’t need a report to tell us that, but it will also have an effect on the prey of the targeted species, some species may benefit while others will suffer. It just happens that most of the species that have been shown to be in serious danger are the very prey of the species we target, and if they disappear then no matter how many lines they draw on the map it will be all over.


“Changes within the remote Maria Island MPA(the largest) relative to references sites have increased in the abundance of lobster and susceptible fish (Latridopsis frosteri), increase in the mean size of rock lobster and a decrease in the abundance of prey species such as urchins and abalone

At Maria Island there was also a 30% decline in the abundance of common urchins within the reserve, which may be the first Tasmanian evidence of  cascading ecosystem effect related to protection from fishing, Abalone numbers were also observed to decline sharply in the period sampled. This change was interesting in that one possible explanation was an inverse relationship between predators (lobsters) and the prey (abalone). If shown to be correct this finding is likely to have significant consequences for the integrated, ecosystem based management of these two “species.

http://www.imas.utas.edu.au/__data/assets/pdf_file/0005/68576/FRDC_Final_Report.pdf