The good, the bad and the recovery in an assisted migration

Assisted migration or translocation of species to ameliorate effects of habitat loss or changing environment iscurrently under scrutiny as a conservation tool. A large scale experiment of assisted migration over hundreds of kilometreswas tested on a morph from a commercial fishery of southern rock lobster Jasus edwardsii, to enhance depletedpopulations, improve the yield and sustainability of the fishery, and test resilience to a changing climate.Methodology and Principal Findings: Approximately 10,000 lower-valued, pale-coloured lobsters were moved from deepwater to inshore sites (2 in Tasmania [TAS] and 2 in South Australia [SA]) where the high-value, red morph occurs. In TAS thiswas a northwards movement of 1u latitude. Growth was measured only in TAS lobsters, and reproductive status wasrecorded in lobsters from all locations. Pale females (TAS) grew 4 times faster than resident pale lobsters from the originalsite and twice as fast as red lobsters at their new location. Approximately 30% of translocated pale lobsters deferredreproduction for one year after release (SA and TAS), and grew around 1 mm yr21 less compared to translocated palelobsters that did not defer reproduction. In spite of this stress response to translocation, females that deferred reproductionstill grew 2–6 mm yr21 more than lobsters at the source site. Lobsters have isometric growth whereby volume increasesas a cube of length. Consequently despite the one-year hiatus in reproduction, increased growth increases fecundity oftranslocated lobsters, as the increase in size provided a larger volume for producing and incubating eggs in futureyears.Conclusions and Significance: Assisted migration improved egg production and growth, despite a temporary stressresponse, and offers a tool to improve the production, sustainability and resilience of the fishery.