Achieving Post-Eradication Biosecurity on South Georgia
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M.G. Richardson and J.P. Croxall Richardson, M.G. and J.P. Croxall. Achieving post-eradication biosecurity on South Georgia Achieving post-eradication biosecurity on South Georgia M.G. Richardson and J.P. Croxall South Georgia Heritage Trust, Verdant Works, West Henderson’s Wynd, Dundee, DD1 5BT, UK. <[email protected]>. Abstract The world’s largest island rodent eradication programme to date was carried out on South Georgia between 2009 and 2018 (baiting on island in 2011, 2013 and 2015) by the South Georgia Heritage Trust (SGHT). A comprehensive survey in 2017/18 found no signs of rodents. Although SGHT planned and executed this eradication under permits issued by (and with collaboration from) the Government of South Georgia and the South Sandwich Islands (GSGSSI), the scale and complexity of the multi-year project was not conducive to prior agreement on post-eradication biosecurity to prevent rodent re-invasion. Thus by 2013, two years after initial baiting, biosecurity measures for rodents remained inadequate, relying mainly on rodent detection boxes on vessels and at the island’s main point of entry. The more substantive post- eradication biosecurity measures implemented by other administrations were absent. In late 2014, after more than three years with no rodent sign, there was unambiguous evidence of a rat within the island’s settlement. This coincided with a vessel berthed alongside a nearby jetty. Between 2015 and 2017, SGHT formally submitted recommendations to the GSGSSI on enhanced biosecurity provisions. Some of these recommendations have been implemented but arguably the most important, relating to vessel berthing and secure handling of imported cargo, remain to be addressed effectively. We summarise what remains to be done, recognising the logistic and financial challenges involved, but conscious that, until all measures are in place, there is significant risk of re-infestation of South Georgia by invasive rodents, compromising a decade of work (and funding) by multiple stakeholders. Keywords: baiting, poison, rodents, sub-Antarctic INTRODUCTION Tentative plans for the possible eradication of rodents In the 2017/18 austral summer, a comprehensive from the sub-Antarctic island of South Georgia date monitoring survey, organised and led by SGHT in back to 2000 (S. Poncet, pers. comm.). The subsequent collaboration with GSGSSI, was undertaken to determine success of the eradication programme on Campbell Island the results of the eradication project. The five-month survey (McClelland & Tyree, 2002; Towns & Broome, 2003) deployed over 1,500 inert devices (chew-sticks, tunnel and encouraged the Government of South Georgia and the camera traps and analogous devices) and, augmented by South Sandwich Islands (GSGSSI) to undertake a feasibility trained rodent-detection dogs (which travelled 2,420 km), study of the practicalities of a large-scale (island-wide) covered a minimum of 8,600 ha across 120 sites. No signs eradication of rats and mice on South Georgia (Christie & of rodents were detected, allowing the conclusion that the Brown, 2007). However, due to resource limitations at the eradication phases had been successful. time, the Government opted not to proceed. This paper aims to review the rodent-related biosecurity Nevertheless, the small UK charity (NGO) South status of South Georgia before and during the eradication Georgia Heritage Trust (SGHT) agreed to take up the project and to summarise proposals to enhance this in the challenge and started to develop fundraising and project light of events during the project, and after its successful management structures and initiatives to address this. conclusion. It highlights the remaining measures to be GSGSSI accepted the involvement and lead role of SGHT implemented to minimise the risk of inadvertent re- in principle and practice, subject to the project conforming introduction of rodents. to the relevant legislation and permitting processes. In 2009, SGHT established a Steering Committee (SC) RODENT BIOSECURITY AT SOUTH GEORGIA to oversee the management of the whole operation. The SC PRIOR TO 2014 comprised Trustees from SGHT and the Friends of South The need for biosecurity measures to be integral to any Georgia Island (FOSGI), key GSGSSI officials (Chief eradication efforts on South Georgia was recognised back Executive and Environmental Officer), representatives of in 2007, with a governmental report stating then that: 'First British Antarctic Survey (BAS), and the SGHT Project and foremost, an effective and robust biosecurity regime Director (Prof. Tony Martin of the University of Dundee). needs to be in place on South Georgia before eradication The SC met quarterly from 2010 to 2015 and its main is attempted' (Christie & Brown, 2007). roles were to ensure the effective execution of the plans for the acquisition and shipment of equipment, vessels, Although SGHT submitted Biosecurity Plans to helicopters and staff, and that all documentation required GSGSSI for each of the three phases of baiting, those plans by the regulatory authorities (mainly GSGSSI but also dealt with biosecurity solely in relation to the operational the UK's Civil Aviation Authority (CAA)) was submitted requirements of the project itself – for example, the on time. A list of all such documentation can be found at importation into South Georgia of materials needed for the <http://www.sght.org/newsletters-and-publications/>. baiting operation, or the movement of equipment, including helicopters, within the island. The wider issue of South From 2010, there followed three phases of baiting using Georgia's biosecurity (the responsibility of Government), brodifacoum poison bait distributed by helicopters. Each was not addressed in discussions between SGHT and baiting phase was spaced two years apart (2011, 2013 and GSGSSI either before or during the earlier years of the 2015) to allow both for further fundraising between baiting eradication project. In hindsight, this lapse was the result seasons and for evaluation of methods and results before of both organisations trying at that time to cope with the proceeding further. This work is reported on elsewhere considerable challenges of the baiting operations. Faced (Martin, 2015; SGHT, 2016; Martin & Richardson, 2017). In: C.R. Veitch, M.N. Clout, A.R. Martin, J.C. Russell and C.J. West (eds.) (2019). Island invasives: scaling 489 up to meet the challenge, pp. 489–493. Occasional Paper SSC no. 62. Gland, Switzerland: IUCN. Island invasives: scaling up to meet the challenge. Ch 3A Strategy: Biosecurity with what was clearly going to be a multi-year, complex was mid-2015, following completion of the last phase of operation it would have been difficult in the initial 'proof-of baiting, that the Government requested SGHT input to concept' stages of the project to have developed a realistic an apparent major review of South Georgia's biosecurity and pragmatic prescription for post-eradication biosecurity. arrangements. The SGHT response, submitted in late July, In consequence, biosecurity arrangements were held, at was a series of 10 recommendations to enhance island- least in respect of rodents, under relatively rudimentary wide biosecurity (Table 1). provisions. For example, the governmental Biosecurity Protocols of 2013 and 2014 (GSGSSI, pers. comm. 2013 These recommendations were based on the fact that, and 2014) did little more than stipulate the need for rat with aircraft unable to operate into South Georgia, the guards on vessels, the deployment of rodent bait boxes (a re-introduction of rodents to South Georgia could only requirement for yachts only), and the requirement that all come about via shipping. That is: by shipwrecks on the vessels be inspected for the presence of rodents. coast, or by animals swimming ashore from a vessel; gaining access along mooring warps or down gangplanks; Despite what, in retrospect, was a deficiency in project or coming ashore in cargo or luggage. Although none of planning, the HR Project progressed well. By mid-2014 these potential introduction pathways can be ruled out, the (more than three years after the initial baiting) the Phase greatest risk of a rodent re-introduction to South Georgia 1 area (c. 14,000 ha) had been tentatively declared free of is most likely to be via one or other of the last two routes. rodents, and a relatively extensive survey in March of that year by SGHT detected no signs of rodents in the 60,000 SGHT's recommendations included the requirement ha. of the more extensive Phase 2 area. to maintain an adequate supply (at least three tonnes) of in-date brodifacoum bait at KEP, the need for a series of Deficiencies in the biosecurity provisions became pre-baited box traps (which would be inspected frequently) evident on 23 October 2014 when the unambiguous signs of around the base area, and the deployment of effective rat- a rat were seen in newly fallen snow at King Edward Point guards on vessels moored alongside. (KEP) – the administrative centre of the island in the heart of the Phase 1 area. The Government rapidly set in train its The Trust's four main recommendations are shown in contingency plan for just such an incident. Brodifacoum bold in Table 1. These were: the use of rodent-detection bait was spread by hand out to an arc perimeter of 1.5 km dogs at ports in the Falkland Islands and on vessels destined from the sighting and many more rat traps were placed for South Georgia; prohibiting the mooring alongside of around the KEP base area. In the event, no more sign of vessels except for tightly prescribed activities; the erection this animal was seen; nor was a corpse found. This was of rodent-proof fences around offloading jetties in South unfortunate since, through DNA analysis, the origin of this Georgia; and the construction of rodent-proof containment lone animal could have been determined (see Piertney, et areas at KEP within which shipping containers and other al., 2016). The presumption was that the rat succumbed to large-scale cargo could be held, and unpacked, in a the poison bait.