Peter Mumby: It’s a good time to protect herbivorous fish in Australia

Prof Peter Mumby

ACRS Vice President
Marine Spatial Ecology Lab
The University of Queensland

November 2011

Reef managers world-wide are trying to take action to build the resilience of coral reefs to climate change, as well as local pressures such as pollution. Much is known about the resilience of reefs and large seaweeds can cause problems for corals throughout the world. Seaweeds can compete with corals by usurping space, overgrowing living coral, and leaking noxious chemicals. Not surprisingly, keeping seaweed under control has long been a priority for managing reef resilience.

In many areas, seaweed levels fluctuate naturally from season to season. However, outbreaks of seaweeds can occur if the flux of nutrients is unnaturally high or the level of grazing by fishes and urchins becomes unnaturally low. Great progress is being made to manage nutrient runoff in Australia’s coastal watersheds, but nothing is being done to manage herbivores.

It is often said that herbivorous fish, such as parrotfish, surgeonfish and rabbitfish, don’t need to be protected because they’re not threatened in Australia. This is certainly true today; there is no fishery for herbivorous fish in Australia. So why then should we bother?

There are several reasons we should consider protecting herbivorous fish in Australia. Some strategically benefit Australia. Others are more altruistic.

  1. While there is no fishery for herbivores today, experience elsewhere tells us that this may change in future. When I first began working in Belize (Central America, and host to the second-largest barrier reef), nobody ate parrotfish. People would look incredulous at the idea of consuming such a ‘trash fish’: Oh no, Belizeans only fished for prize groupers and snappers. Yet 13 years later, the grouper and snapper were heavily depleted and parrotfish had become the dominant catch. A similar story may unfold in the Bahamas. Here, one of the drivers of change is immigration of people into the islands who have a different set of values and quite a taste for parrotfish. So, taking action today will help future-proof this aspect of resilience for Australia’s reef. For example, who knows whether we’ll see a change in the species sought-after by recreational fisheries as tourism grows and continues to diversify?
  2. It is easy; hardly anyone is likely to object.
  3. Australia is a world leader in coral reef management. Taking action on this issue would signal the importance of conserving herbivores throughout the world.

The only likely objection to conserving herbivorous fishes in Australia is the cost of implementation (consultation, preparation of legal instruments, etc). This is clearly a judgement call for governments but as interventions go, it’s not that difficult.

Read more…

Mumby PJ, Steneck RS, Edwards AJ, Ferrari R, Harborne AR, Coleman R, Gibson JP (2012) Fishing down a Caribbean food web relaxes trophic cascades. Marine Ecology Progress Series 445: 13-24

Mumby PJ, Harborne AR (2010) Marine reserves enhance the recovery of corals on Caribbean reefs. PLoS One 5: e8657

Mumby PJ, Steneck RS (2008) Coral reef management and conservation in the light of rapidly-evolving ecological paradigms. Trends in Ecology and Evolution 23: 555-563