The Good, the Bad and the Recovery in an Assisted Migration

Abstract

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

Investigation of Genetic Structure between Deep and Shallow Populations of the Southern Rock Lobster, Jasus edwardsii in Tasmania, Australia

“…Between 2004 and 2008, 30,000 lobsters were translocated from deeper water (>60 metres depth) locations in Tasmania, Australia, and released in shallower water locations (0-30 m depth) [5,7]. Importantly, there are clear phenotypic differences between these shallow and deep water populations of southern rock lobster [6].…”

Avoiding a crisis of motivation for ocean management under global environmental change

“…A good example is "assisted colonisation" (also known as "managed relocation") to overcome dispersal barriers as species' ranges shift (Hoegh-Guldberg et al, 2008). Assisted migration can have benefits; for example, with the fishery of the southern rock lobster in Australia, assisted migration of approximately 10,000 climate-resilient lobsters produced a population with faster growth and higher fecundity (Green, Gardner, Linnane, & Hawthorne, 2010). However, the practice of assisted migration does not come without costs as possible stress from translocation caused a yearlong delay in fecundity for translocated populations (Green et al, 2010).…”

“…Assisted migration can have benefits; for example, with the fishery of the southern rock lobster in Australia, assisted migration of approximately 10,000 climate-resilient lobsters produced a population with faster growth and higher fecundity (Green, Gardner, Linnane, & Hawthorne, 2010). However, the practice of assisted migration does not come without costs as possible stress from translocation caused a yearlong delay in fecundity for translocated populations (Green et al, 2010). Yet strategies and theory to operationalize assisted migration are in their infancy in the ocean even though they have considerable merit given the highly connected nature of marine ecosystems linked by larval dispersal (Kling, Sanchirico, & Wilen, 2016).…”

Ethical consideration in invasion ecology: A marine perspective

“…Although not a movement of a NIS, the following example illustrates the difficulty of a translocation approach. Over 10,000 individuals of a morph of the southern rock lobster (Jasus edwardsii) were moved over hundreds of kilometres and from deep water to inshore sites to enhance depleted populations of the more valuable red morph with a view to improving the yield and sustainability of the fishery (Green et al 2010). The authors acknowledged that as they were working with invertebrates no ethical approval was required, but they did follow ethical guidelines for the humane treatment of animals in research.…”