Green, A.G.

Global assessment of the status of coral reef herbivorous fishes: evidence for fishing effects


On coral reefs, herbivorous fishes consume benthic primary producers and regulate competition between fleshy algae and reef-building corals. Many of these species are also important fishery targets, yet little is known about their global status. Using a large-scale synthesis of peer-reviewed and unpub- lished data, we examine variability in abundance and biomass of herbivorous reef fishes and explore evidence for fishing impacts globally and within regions. We show that biomass is more than twice as high in locations not accessible to fisheries relative to fisheries-accessible locations. Although there are large biogeographic differences in total biomass, the effects of fishing are consistent in nearly all regions. We also show that exposure to fishing alters the structure of the herbivore community by disproportionately reducing bio- mass of large-bodied functional groups (scraper/excavators, browsers, grazer/ detritivores), while increasing biomass and abundance of territorial algal- farming damselfishes (Pomacentridae). The browser functional group that consumes macroalgae and can help to prevent coral–macroalgal phase shifts appears to be most susceptible to fishing. This fishing down the herbivore guild probably alters the effectiveness of these fishes in regulating algal abun- dance on reefs. Finally, data from remote and unfished locations provide important baselines for setting management and conservation targets for this important group of fishes. 

Data type
Scientific article
Research and monitoring

Monitoring Coral Reef Marine Protected Areas. A practical guide on how monitoring can support effective management of MPAs


Marine Protected Areas (MPAs) are an important tool for marine conservation and management; monitoring plays a critical role in managing these MPAs. Monitoring provides the essential information required to
make management decisions and determine if the decisions are working. Without monitoring, managers are essentially operating in the dark! This book was written in response to requests from many managers of MPAs from around the world who asked for advice on how to design and implement monitoring programs that can help them manage their MPAs more effectively.

The goals of this book are to:

  • Demonstrate how monitoring can play a major role in the effective management of MPAs;
  • Provide advice on which monitoring programs to use to facilitate effective management; and
  • Demonstrate how monitoring has played an important role in the effective management of MPAs using case studies from around the world.

Coral reefs around the world are at risk from many threats including global warming causing coral bleaching, over-fishing or destructive fishing, pollution by sediments, nutrients and toxic chemicals, coral mining
and shoreline development, and unregulated tourism. Monitoring the ecology of the reefs and the socio- economics of the people is the only way to understand the extent, nature and causes of the damage, and to identify ways to address these threats.

How can monitoring assist in the effective management of MPAs? Monitoring assists through the following tasks:

  1. Resource Assessment and Mapping
  2. Resource Status and Long-Term Trends
  3. Status and Long-Term Trends of User Groups
  4. Impacts of Large-Scale Disturbances
  5. Impacts of Human Activities
  6. Performance Evaluation and Adaptive Management
  7. Education and Awareness Raising
  8. Building Resilience into MPAs
  9. Contributing to Regional and Global Networks

This book will provide practical advice on how to design and implement ecological and socio-economic monitoring programs aimed at addressing these issues. Many useful references are included at the back along with Internet sites.

We have used case studies from around the world to illustrate how others have used monitoring to assist them in managing MPAs. There are many useful lessons from these case studies and all contain recommendations for other MPA managers.

The book provides information on many of the organisations involved in coral reef monitoring and management, along with the recommendations on coral reef monitoring and information processing from the recent ITMEMS2 (International Tropical Marine Ecosystems Management Symposium, 2003) meeting, which featured MPA managers from all over the world.

This is Version 1 of the book being released at the World Parks Congress in Durban South Africa, September 2003. Our intention is to keep it alive and continually update it. This copy will be lodged on the, and websites where we want to continually update it for use by MPA managers to improve their management and conservation of coral reefs. 

Data type
Research report
Geographic location