Project number: 2011-762
Project Status:
Completed
Budget expenditure: $175,096.72
Principal Investigator: Lachlan Strain
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 31 Dec 2011 - 29 Jan 2014
Contact:
FRDC

Need

In the summer of 2010/11, the abalone stocks in Kalbarri region of Western Australia suffered a devastating mortality as result of a sustained period of elevated water temperatures, now being termed the "2011 marine heatwave" off Western Australia. Both commercial and recreational abalone fisheries have subsequently been closed to fishing to protect any remaining animals and promote natural recovery. Unfortunately however, the severe extent of the mortality (>99.9%) means that natural recovery is unlikely within the next 10-20 years. One of the key predictions of the impacts of a changing environment on fisheries is increased variability as well as increased average SST, with consequent effects of range contractions or extension of species at the edges of their natural range. This particular case represents a perfect example of this effect, as this abalone fishery (Area 8 fishery) is located at the northern end of the species (Haliotis roei) range.

The question now being asked by stakeholders is whether recovery of this fishery can be assisted using the latest knowledge in translocation, stocking and restocking methodology, which the Department holds particular expertise in. This incident provides an opportunity to test an important management strategy, namely will the establishment of a founder population be a viable tool for fishery restoration, particularly in stocks like abalone that have localised recruitment? This can be determined by comparing natural and assisted recovery rates and evaluating the genetic contribution of existing and founder populations. Such a study is relevant to all Australian abalone fisheries and an integral part of understanding how fisheries populations can be sustained in a changing environment.

Objectives

1. To establish founder populations of roe's abalone in areas of mass mortality
2. To evaluate the genetic structure of existing and founder populations
3. To compare natural and assisted recovery rates of roe's abalone populations
4. To evaluate the genetic contribution of existing and founder populations to stock recovery

Final report

ISBN: 978-1-921258-39-8
Authors: Lachlan W. S. Strain Jamin M. Brown and Anthony M. Hart
Final Report • 2019-10-01 • 5.43 MB
2011-762-DLD.pdf

Summary

A Roe’s Abalone (Haliotis roei) fishery in Western Australia (Area 8) suffered catastrophic mortality (99.9%) due to an anomalous environmental event in the summer of 2011. During this extreme marine heatwave there was a sustained period of elevated sea surface temperatures that rose to lethal levels for this species and effectively wiped out an entire stock at its northern distribution. Natural recovery within the foreseeable future was considered unlikely, thus providing a unique opportunity to test fishery restoration strategies for abalone. Over the course of this assisted recovery program (5.5 years) no natural recovery was observed in the region most affected by the mortality event. 
The objective of this study was to investigate the viability of recovering a collapsed Roe’s Abalone population through the creation of founder populations. Given the extent of the mortality event north of the Murchison River, near Kalbarri, Western Australia, reef platforms devoid of abalone were identified as release sites to create founder populations. For these founder populations to be viable breeding populations, the aim was to achieve at least 500 adult Roe’s Abalone at densities greater than 3 per m2 on the reef platforms.

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