Effects of Spearfishing on Reef Fish Populations in a Multi-Use Conservation Area

Although spearfishing is a popular method of capturing fish, its ecological effects on fish populations are poorly understood, which makes it difficult to assess the legitimacy and desirability of spearfishing in multi-use marine reserves. Recent management changes within the Great Barrier Reef Marine Park (GBRMP) fortuitously created a unique scenario by which to quantify the effects of spearfishing on fish populations. As such, we employed underwater visual surveys and a before-after-control-impact experimental design to investigate the effects of spearfishing on the density and size structure of target and non-target fishes in a multi-use conservation park zone (CPZ) within the GBRMP. Three years after spearfishing was first allowed in the CPZ, there was a 54% reduction in density and a 27% reduction in mean size of coral trout (Plectropomus spp.), the primary target species. These changes were attributed to spearfishing because benthic habitat characteristics and the density of non-target fishes were stable through time, and the density and mean size of coral trout in a nearby control zone (where spearfishing was prohibited) remained unchanged. We conclude that spearfishing, like other forms of fishing, can have rapid and substantial negative effects on target fish populations. Careful management of spearfishing is therefore needed to ensure that conservation obligations are achieved and that fishery resources are harvested sustainably. This is particularly important both for the GBRMP, due to its extraordinarily high conservation value and world heritage status, and for tropical island nations where people depend on spearfishing for food and income. To minimize the effects of spearfishing on target species and to enhance protection of functionally important fishes (herbivores), we recommend that fishery managers adjust output controls such as size- and catch-limits, rather than prohibit spearfishing altogether. This will preserve the cultural and social importance of spearfishing in coastal communities where it is practised.

[1]  Pat Hutchings,et al.  The Great Barrier Reef: Biology, Environment and Management , 2008 .

[2]  Stephen G. Sutton,et al.  Adapting to Change: Minimising Uncertainty about the Effects of Rapidly-Changing Environmental Conditions on the Queensland Coral Reef Fin Fish Fishery , 2010 .

[3]  D. Bellwood,et al.  Phase Shifts, Herbivory, and the Resilience of Coral Reefs to Climate Change , 2007, Current Biology.

[4]  S. Forêt,et al.  FRoM MIcRobES To PEoPlE: TRAcTAblE bENEFITS oF No-TAkE AREAS FoR coRAl REEFS , 2011 .

[5]  G. Russ,et al.  Age validation and estimation of growth rate of the coral trout , Plectropomus leopardus , ( Lacepede 1802 ) from Lizard Island , Northern Great Barrier Reef , 2008 .

[6]  Surveillance and Poaching on Inshore Reefs of the Great Barrier Reef Marine Park , 2004 .

[7]  R. Evans,et al.  Larger biomass of targeted reef fish in no-take marine reserves on the Great Barrier Reef, Australia , 2004 .

[8]  N. Polunin,et al.  COASTAL FISHERIES IN THE PACIFIC ISLANDS , 1996 .

[9]  K. Bjorndal,et al.  Historical Overfishing and the Recent Collapse of Coastal Ecosystems , 2001, Science.

[10]  J. Hobbs,et al.  A quantitative comparison of recreational spearfishing and linefishing on the Great Barrier Reef: implications for management of multi-sector coral reef fisheries , 2008, Coral Reefs.

[11]  G. Russ,et al.  No-take marine reserves increase abundance and biomass of reef fish on inshore fringing reefs of the Great Barrier Reef , 2004, Environmental Conservation.

[12]  R. Galzin,et al.  Impact of hurricane Dean on coral reef benthic and fish structure of Martinique, French West Indies , 2010 .

[13]  N. Graham,et al.  Effects of Customary Marine Closures on Fish Behavior, Spear‐Fishing Success, and Underwater Visual Surveys , 2010, Conservation biology : the journal of the Society for Conservation Biology.

[14]  Nicholas A. J. Graham,et al.  Multiple disturbances and the global degradation of coral reefs: are reef fishes at risk or resilient? , 2006 .

[15]  S. Wilson,et al.  Gear-based fisheries management as a potential adaptive response to climate change and coral mortality , 2009 .

[16]  S. Jennings,et al.  Population and ecosystem effects of reef fishing , 1996 .

[17]  G. Russ,et al.  Age, growth and mortality of the inshore coral trout Plectropomus maculatus (Pisces: Serranidae) from the central great barrier reef, Australia , 1992 .

[18]  Y. Sadovy.  Reproduction of reef fishery species , 1996 .

[19]  J. Castilla,et al.  Spearfishing to depletion: evidence from temperate reef fishes in Chile. , 2010, Ecological applications : a publication of the Ecological Society of America.

[20]  L. Hay.  The Great Barrier Reef Marine Park. , 1978 .

[21]  H. Hatami-Monazah.  Banding and chromatid separation in Chinese hamster chromosomes , 1974, Nature.

[22]  G. Goeden.  Intensive fishing and a ‘keystone’ predator species: Ingredients for community instability , 1982 .

[23]  D. Bellwood,et al.  No-take areas, herbivory and coral reef resilience. , 2007, Trends in ecology & evolution.

[24]  C. Meyer.  The impacts of spear and other recreational fishers on a small permanent Marine Protected Area and adjacent pulse fished area , 2007 .

[25]  D. Bellwood,et al.  Confronting the coral reef crisis , 2004, Nature.

[26]  M. Phillips,et al.  While stocks last : the live reef food fish trade , 2003 .

[27]  G. Jones,et al.  CoRAl-ASSoCIATED INvERTEbRATES: DIvERSITy, EColoGICAl IMPoRTANCE AND vulNERAbIlITy To DISTuRbANCE , 2011 .

[28]  A. Frid,et al.  Predicting ecological consequences of marine top predator declines. , 2008, Trends in ecology & evolution.

[29]  P. Dalzell.  Catch rates, selectivity and yields of reef fishing , 1996 .