Public Engagement for the Detection of the Introduced Marine Species Charybdis Japonica in Western Australia

Management of Biological Invasions (2015) Volume 6, Issue 3: 243–252 doi: http://dx.doi.org/10.3391/mbi.2015.6.3.03 Open Access © 2015 The Author(s). Journal compilation © 2015 REABIC Research Article Public engagement for the detection of the introduced marine species Charybdis japonica in Western Australia Mathew Hourston*, Justin I. McDonald and Matthew J. Hewitt Department of Fisheries, Western Australia, PO Box 20, North Beach W.A. 6020, Australia E-mail: [email protected] (MH), [email protected] (JIM), [email protected] (MJH) *Corresponding author Received: 29 October 2014 / Accepted: 10 March 2015 / Published online: 8 April 2015 Handling editor: Vadim Panov Abstract The introduced crab, Charybdis japonica, was captured in the Swan River Estuary in Western Australia during October 2012. This constitutes the second documented report of this species in Western Australia after a single specimen was reported in 2010 from a nearby estuary. Given the invasive history of this species in locations such as New Zealand, a rapid-response delimiting survey was conducted to assess the prevalence of this crab within this estuary. A large public engagement campaign was run concurrently with the delimiting survey to inform and enlist the recreational crab fishers that use the Swan River and other nearby estuaries to report any more specimens that they caught. These activities yielded a total of three specimens, all handed in by recreational fishers as a result of the public engagement campaign. All three specimens were caught within a very limited area within the estuary, approximately 8 kilometres from the entrance. The two specimens that were able to be sexed were mature males, with carapace widths of 10.1 and 10.3 mm. The very small number of specimens caught, relative to the abundant native species indicates that C. japonica may be relatively scarce in the Swan River Estuary. This result highlights the importance of engaging members of the public to help detect introduced marine pest species in the early stages of incursions. Key words: marine biosecurity, alien, invasive species, non-indigenous, delimiting survey, citizen science Introduction Many crabs of the genus Charybdis have a documented history of human-mediated dispersal Introduced marine pests are regarded as one of outside of their natural range. Charybdis hellerii the greatest threats to global marine biodiversity, (A. Milne-Edwards, 1867) is a recorded Lessepsian with the potential to cause considerable economic, invader in the Mediterranean Sea and currently is ecological, social and cultural impacts (Bax et al. regarded as an invasive species in Brazil (Sant’ 2003; Charles and Dukes 2007). While prevention Anna et al. 2012a) and in the USA (Dineen et al. is by far the preferred option for managing 2001). Charybdis longicollis Leene, 1938, Charyb- introduced marine pests, in the event of an dis feriata (Linnaeus, 1758) and Charybdis lucifera incursion, early control measures are often most (Fabricius, 1798), are also species reported in the practical and economically viable and may prevent Mediterranean (Galil et al. 2011; Abelló and Hispano the population becoming established (Bax et al. 2006; Mizzan and Vianello 2009, respectively), 2003). Several introduced marine pest species while Charybdis variegata (Fabricius, 1798) has are identified under Australia’s current marine been recently found in Brazil (Sant’ Anna et al. biosecurity regime as having a high potential to 2012b). Charybdis japonica is another known have serious impacts on local biodiversity and a introduced marine pest, with the most significant high risk of establishment (Hayes and Sliwa incursion to date detected in New Zealand during 2003). One of which is the Asian paddle crab, 2000 (Smith et al. 2003). Repeat surveys in 2003 Charybdis japonica (A. Milne-Edwards, 1867) and 2009 determined that C. japonica is now (Hayes et al. 2005). abundant at several marine and estuarine locations 243 M. Hourston et al. Table 1. Details of the four confirmed specimens of Charybdis japonica caught in Western Australian from the Peel Harvey and Swan River Estuaries. WAM = Western Australian Museum; DOF = Department of Fisheries. Peel Harvey Specimen #1 Specimen #2 Specimen #3 Figure Figure 2A Figure 2B Figure 2C Date of capture Unknown 19/10/2012 28/10/2012 15/12/2012 Date of report 9/11/2010 19/10/2012 20/11/2012 8/01/2013 Date of identification 9/11/2010 25/12/2012 20/11/2012 11/01/2013 Location Peel-Harvey Swan River Swan River Swan River Latitude Unknown -32.008334 -32.009116 -32.007053 Longitude Unknown 115.77307 115.773585 115.772203 Capture method Unknown Drop Net Drop Net Drop Net Material received Frozen specimen Cooked specimen Photograph Frozen specimen Sex M M Unknown M Size (carapace width) 9.5 cm 10.1 cm Unknown 10.3 cm Light tan with dark pattern Dark olive carapace, Dark olive carapace, Dark olive carapace, Colouration on carapace violet limbs violet limbs violet limbs Stored at WAM WAM Not Kept DOF Catalogue number WAM C46162 WAM C51671 DOF 736 Identified by A. Hosie / S. Ayong A. Hosie A. Hosie A. Hosie on New Zealand’s North Island, and is reported campaign involving several government agencies, to have locally displaced native species such as industry, recreational fishers and the broader Ovalipes catharus (White, 1843) (Gust and Inglis community to determine if more C. japonica were 2006; Fowler et al. 2011; Fowler et al. 2013a, b). present in the area. The outcome of those activities An incursion of C. japonica in Western Australia were that during that same austral summer, a has the potential to displace native Western further two specimens were detected. Australian crab species, such as Portunus armatus The use of citizen science, including public (Lai et al. 2010), a highly important recreational engagement campaigns such as used for this and commercial species to Western Australia current program, actively engages the public in (Johnston et al. 2011). scientific research (Bonney et al. 2009). While The first occurrence of C. japonica in Australia citizen science programs have inherent challenges was a single male specimen caught in the Port to overcome, and have received criticism of their River, South Australia in 2000 (Hooper 2001). scientific integrity (Conrad and Hilchey 2011), Despite a large delimiting survey ( 5000 trap the engagement of recreational fishers allows hours), no further specimens were found and it researchers to dramatically increase the effective was concluded that this species did not establish effort used in the search for introduced marine a viable population (Hooper 2001). In late 2010, pests to a level which may be cost prohibitive if a single male C. japonica was discovered in the performed entirely by funded staff. Various Peel-Harvey Estuary (PHE), Western Australia, studies have demonstrated the benefits that public by a commercial fisherman. A delimiting survey engagement can have to introduced marine and public awareness campaign were undertaken species studies (e.g. Crall et al. 2010; Dickinson to determine if more individuals were present, et al. 2010) and their usefulness for crab species but none were detected. The details of the PHE in particular (Delaney et al. 2008), which are specimen have been included in Table 1 for the often conspicuous and a readily identifiable member sake of completeness, however details of the of the aquatic fauna. PHE delimiting survey are not discussed further. This article provides information on the three Although no further specimens have been detected specimens of C. japonica that were collected from the PHE, the first specimen in the Swan from the Swan River Estuary, Western Australia, River Estuary (SRE) was detected in 2012 by a as well as the details of the delimiting study and recreational fisher in response to that initial public engagement campaigns. It highlights the public awareness campaign (from the PHE). In importance of the public engagement and how response, the Department of Fisheries launched a lessons learned can benefit future marine biosecurity coordinated delimiting and community engagement responses. 244 Public detection of Charybdis japonica in Western Australia Figure 1. A: The location of the Swan River Estuary within Western Australia. B: The location of Fremantle Harbour in relation to the survey area. C: Map of the Swan River Estuary showing the location of the three Charybdis japonica captures (labeled #1, #2 and #3 to correspond with Table 1 and Figures 2 and 3), as well as the locations of the traps (irrespective of trap type) set during the 2012/13 delimiting survey (grey circles). Methods unconsolidated sediments such as mud and sand, with significant areas of submerged macrophytes Estuary habitats including seagrass and macroalgal stands. Localised areas of bare limestone rock are also The Swan River Estuary (SRE) is a microtidal present, predominantly in the entrance channel system in the temperate south-west of Western and lower basin (Valesini et al. 2010). The Australia (Figure 1A). It is composed of three commercial port of Fremantle is located at the distinct regions: the entrance channel, the shallow estuary mouth, approximately 6 km downstream basins and the riverine reaches. C. japonica was from the C. japonica capture location. The port detected in the upstream part of the entrance also contains high complexity structures and is a channel, where it joins the basins. This is the hub for international shipping movements (Figure deepest section of the estuary (ca. 20 m) and 1B). experiences marine conditions for most of the year. This area contains many man-made, high- Trap types complexity habitats such as moorings, wharf and jetty piles and breakwaters, which provide suitable Three trap types were used throughout the response habitat for crab species. The estuary contains a activities, operahouse (dome) traps, commercial variety of natural substrates but it is predominately hourglass traps and drop nets.

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