WALLACE RESOURCE LIBRARY Module 05 Natural Resource Use

WALLACE RESOURCE LIBRARY Module 05 – Natural Resource Use and Sustainability D 01 – Identifying overfishing on Indonesian coral reefs

Reefs are threatened in a number of ways Pollution: Increased nutrients can lead to phase shifts, and can increase coral disease Overfishing: Removing fish above a sustainable level, removes key species from the reef Destructive fishing: techniques that destroy the reef structure as collateral damage Anthropogenic impacts Invasive species: Species introduced to an area can have devastating ecological impacts Coral mining: Destroys the physical structure of the reef and reduces coastal protection from reefs Tourism: Coastal development can cause pollution and sedimentation, while diver/anchor damage destroys reefs

Overfishing You can remove fish without significantly damaging the ecosystem The highest amount of fishing pressure a coral reef can cope with is called the MAXIMUM SUSTAINABLE YIELD (MSY) Fishing below this will allow stocks to continually recover, and the reef will remain stable Fishing above MSY is known as overfishing and will mean fish stocks decline until the system collapses

Fish fences are one of many ways fishermen remove fish from coral reefs (a gear type). It is funnel shaped, made of bamboo and netting, and the opening faces the shore. Many fish migrate between the shallow water and the reef – fish fences trap these migrating species as the tide goes out.

Tasks for this data set • You have catch data from fish fences around Kaledupa Island in the Wakatobi Marine National Park, Indonesia, in 2005 and 2011 • You need to use this data to see how catches have changed between 2005 and 2011, as well as how effort has also changed • This data will be used to estimate the level of sustainability of reef fisheries around Kaledupa

Research questions 1. How have catches from fish fences changed between 2005 and 2011 in the Wakatobi Marine National Park? 2. What does the data tell us about the sustainability of coral reef fisheries in the Wakatobi Marine National Park?

Summary conclusions 1. The data demonstrates an increase in fish fence effort, but a decrease in the catch per unit effort and an increase in the proportion of fish caught as juveniles. These changes were shown to be statistically significant using t-tests. 2. The change in fish catches demonstrated by fish fences around Kaledupa Island indicates a high level of overfishing/overexploitation. Removal rates are clearly higher than the rate of replenishment, and MSY has been severely exceeded.