Effect of the extreme 2011 Western Australian marine heatwave on invertebrate fisheries in Western Australia. — Australian Meteorological and Oceanographic Society

Effect of the extreme 2011 Western Australian marine heatwave on invertebrate fisheries in Western Australia. (#103)

Nick Caputi 1 , Mervi Kangas 1 , Arani Chandrapavan 1 , Anthony Hart 1 , Ming Feng 2 , Maxime Marin 2 , Simon de Lestang 1
  1. Western Australian Fisheries & Marine Research Laboratories, Department of Primary Industries and Regional Development, North Beach, WA, Australia
  2. CSIRO Oceans and Atmosphere, Indian Ocean Marine Research Centre, Crawley, WA, Australia

The extreme Western Australia 2011 marine heatwave had a major effect on the marine ecosystem and after seven years, parts of the ecosystem showed good signs of recovery while others did not.  Scallop fisheries in the Abrolhos Is. and Shark Bay were closed for 3-5 years, while the Shark Bay crab fishery was closed for 18 months. These have shown some improvement or have recovered due to better environmental conditions and protection of spawning stock.  Roe’s abalone suffered catastrophic mortality near the centre of the heatwave in the mid-west coast and has not recovered as spawning stock remains very low.  The Perth abalone fishery which was outside the peak heatwave area had a major stock reduction but remained opened with reduced catches.  The heatwave had a marked indirect effect on brown tiger prawns in Exmouth Gulf due to loss of seagrass habitat.  There was also a decline in western king prawn recruitment in Exmouth Gulf but an improved recruitment in the cooler waters of Shark Bay.  Western rock lobsters near the heatwave peak also appear to have been indirectly affected and are recovering.  Factors influencing the recovery rate from the heatwave included: species near their upper temperature range and/or sensitive to warming temperatures; spatial overlap between the warming event and species distribution; whether spawning stock was affected to the point of recruitment impairment; life-cycle duration of invertebrate (or habitat) species affected; and management intervention.  This study provides a framework for managing the consequences of heatwaves on fisheries by highlighting the value of early identification of the event and its effect on fisheries and having flexible harvest strategies for early management action. This is particularly important as long-term increases in water temperatures will increase the frequency of marine heatwave events and the fisheries stocks would have less time for recovery.

#amos2020