Fisheries Research Articles

Climate variability affecting the contranatant migration of Panulirus cygnus, the western rock lobster

Document Type

Article

Publication Date

8-14-2015

Journal Title

Marine Biology

ISSN

Print: 0025-3162 Electronic: 1432-1793

Keywords

Ocean Current, Catch Rate, Spiny Lobster, Environmental Index, Fishing Season

Disciplines

Aquaculture and Fisheries | Marine Biology

Abstract

Large-scale animal migrations have high energetic costs and are only undertaken for specific biological outcomes, including opening up habitat resources or for reproduction. Juvenile western rock lobsters (Panulirus cygnus) migrate firstly offshore and then northwards from their inshore nursery areas (<40 m) into breeding grounds (40–100 m). In the 2000s, catches of migrating lobsters in the northern part of the western rock lobster fishery declined and concerns were raised as to the sustainability of this stock. This study has documented the substantial inter-annual variation in the latitudinal distribution (between latitudes 27° and 30° S) of migrating lobsters in deep water. This distribution was found to be highly correlated with the sea-floor meridional current strength in January and mean latitude and abundance of puerulus (post-larvae) settlement 3–4 years previously. Combined, these indices explained 92 % of the annual variation in the latitude of migration, and the majority of the variation in commercial catches towards the north of the fishery. These indices are all either directly or indirectly impacted by the south-flowing Leeuwin Current. This current, which is influenced by ENSO conditions, has increased in strength over the last 20 years, a trend that has been identified as a relatively short-term decadal shift, while climate change models project a progressive reduction in the strength of this current in the longer term. This may result in greater northward lobster migrations and a shift in the biomass of lobsters more towards the northern end of the fishery.

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