Preprints
https://doi.org/10.5194/bg-2021-128
https://doi.org/10.5194/bg-2021-128

  09 Jun 2021

09 Jun 2021

Review status: this preprint is currently under review for the journal BG.

Using an oceanographic model to investigate the mystery of the missing puerulus

Jessica Kolbusz1, Tim Langlois2, Charitha Pattiaratchi1, and Simon de Lestang3 Jessica Kolbusz et al.
  • 1Oceans Graduate School and the UWA Oceans Institute, The University of Western Australia, Crawley, WA 6009, Australia
  • 2School of Biological Sciences and the UWA Oceans Institute, The University of Western Australia, Crawley, WA, Australia
  • 3Western Australian Fisheries and Marine Research Laboratories, Department of Primary Industries and Regional Development, Government of Western Australia, North Beach, WA, Australia

Abstract. Dynamics of ocean boundary currents and associated shelf processes can influence onshore/offshore transport of water, critically impacting marine organisms that release long-lived pelagic larvae into the water column. The western rock lobster, Panulirus cygnus, endemic to Western Australia, is the basis of Australia's most valuable wild-caught commercial fishery. After hatching, western rock lobster larvae (phyllosoma) spend up to 11 months in offshore waters before ocean currents and their ability to swim, transport them back to the coast. The abundance of western rock lobster puerulus (settlement phase post phyllosoma) has historically been observed to be positively correlated with the strength of the Leeuwin Current, and an index of puerulus numbers is used by fisheries managers as a predictor of subsequent lobster abundance 3–4 years later. In 2008 and 2009 the Leeuwin Current was strong, yet a settlement failure occurred throughout the fishery prompting management changes and a rethinking of environmental factors associated with their settlement. Thus, understanding factors that may have been responsible for the settlement failure is important for fisheries management. Oceanographic parameters likely to influence puerulus settlement were derived for a 17 year period to investigate correlations. Analysis indicated that puerulus settlement at adjacent monitoring sites have similar oceanographic forcing with kinetic energy in the offshore and the strength of the Leeuwin Current being key factors. Settlement failure years were synonymous with “hiatus” conditions in the south-east Indian Ocean, and periods of sustained cooler water present offshore. Post 2009, there has been an unusual but consistent increase in the Leeuwin Current during the early summer months with a matching decrease in the Capes Current, that may explain an observed settlement timing mismatch compared to historical data. Our study has revealed that a culmination of these conditions likely led to the recruitment failure and subsequent changes in puerulus settlement patterns.

Jessica Kolbusz et al.

Status: open (until 21 Jul 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Jessica Kolbusz et al.

Jessica Kolbusz et al.

Viewed

Total article views: 137 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
118 16 3 137 1 1
  • HTML: 118
  • PDF: 16
  • XML: 3
  • Total: 137
  • BibTeX: 1
  • EndNote: 1
Views and downloads (calculated since 09 Jun 2021)
Cumulative views and downloads (calculated since 09 Jun 2021)

Viewed (geographical distribution)

Total article views: 132 (including HTML, PDF, and XML) Thereof 132 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 18 Jun 2021
Download
Short summary
Western rock lobster larvae spend up to 11 months in offshore waters before ocean currents and their ability to swim, transport them back to the coast. In 2008, there was reduction in the number of puerulus (larvae) settling into the fishery. We use an oceanographic model to see how the environment may have contributed to the reduction. Our results show that a combination of effects from local currents and wide-spread “quiet” period in the ocean off WA likely lead to less puerulus settlement.
Altmetrics