The risks posed by potentially invasive species associated with keeping and live trading of ornamental Fish is a growing concern globally. The popularity of keeping ornamental Fish and reducing import costs has seen a marked increase in the demand and trade of exotic species. In Australia, the ornamental aquarium Fish trade is estimated to be worth approximately $350 million annually, encompassing Fish breeders, wholesalers and traders, retail outlets and hobby sales. Approximately 8.7 million pet Fish are estimated to be kept in Australia, with yearly imports of non-native Fish exceeding 15 million individuals per annum. Of the roughly 2000 species that are traded nationally, most are exotic to Australia, with many species having particular life history traits that render them suitable for naturalisation in Australian freshwater ecosystems. Of these species many are highly invasive, with the potential to impact directly on native biodiversity through predation or outcompeting for resources, or indirectly by altering vegetation structure, ecological and physical processes or landscape resilience. This can result in widespread environmental degradation, loss of biodiversity and creation of monospecific fisheries, loss of genetic purity, and localised Fish and/or Invertebrate extinctions.
The impacts of invasive species are mediated through complex biotic and abiotic interactions that occur habitat-wide, often altering ecosystems and community assemblages irrecoverably. Recent research has indicated that the introduction of invasive species poses a higher risk to threatened species than other anthropogenic factors such as agricultural or human disturbance, ecosystem disturbance, pollution or climate change. Indeed the detrimental effects of non-native species introductions have been cited as a contributing factor in 68% of North American Fish extinctions in the last 100 years, and an instrumental factor in the threatened status of up to 55% of Australian endemic freshwater Fish species. In aquatic environments, once established in the wild invasive Fish are almost impossible to eradicate, with methods limited to poisoning whole waterbodies and subsequently destroying all local Fish and Invertebrates in the process. It is also an expensive process in which complete eradication is rarely achieved. Once an invasive Fish has naturalised, there may also be larger ongoing costs associated with mitigating spread, including funding alternative measures of containment (i.e. installing Fish screens), conducting long term Fish-down activities, and providing industry subsidisations. The environmental cost can rarely be quantified.
The Jaguar Cichlid, Parachromis managuensis, also known as the Guapote Tigre, is one of the largest members of the Cichlidae family, growing to around 55 cm total length in the wild. Native to the freshwater ecosystems of Central America from Honduras to Costa Rica, it is a highly aggressive piscivorous species that prefer warm, highly eutrophic lakes and ponds with mud and silt benthic substrates. The species is sensitive to cold temperatures, only able to withstand with lower lethal temperatures to around 12°C, but can thrive in temperatures up to 33°C. It is a fecund Fish, and females reach sexual maturity at around 10 cm total length, and can deposit several thousand eggs on rocks or other hard substrates each spawn. Both parents will guard eggs and resulting fry. Jaguar Cichlids are readily identifiable by their projecting lower jaw, prominent canine teeth, black spots on fins and body, and row of black blotches along the lateral line.
Jaguar Cichlids have a long history of successful establishment in nonnative ecosystems around the world. Naturalised populations were reported early on in other parts of Honduras in 1956, followed by neighbouring countries El Salvador and Guatemala in 1958, believed to be attributed to their use as an aquaculture species. In the late 1970s they were discovered in Panama, followed by Cuba in 1983. After the species began becoming a popular ornamental Fish, the first incursion in North American waterways was reported in 1986 in Florida, followed soon after by reports of naturalisations in Taiwan, China, Hawaii, and Puerto Rico. As global trade of live Fish increased significantly post-2003, more recent reports of Jaguar Cichlids establishing in other countries include Singapore, and Brazil.
The history of the arrival of Jaguar Cichlids in Australia is uncertain. The species has never been permitted for importation into Australia and that illegal smuggling of Fish probably occurred sometime in the early 1980s. Shortly thereafter, the aquarium industry attempted to withdraw Jaguar Cichlids from trade, however captive populations continue to persist to present day. The first assessment on the probability of successful establishment in Australian native waters for jaguar cichlid was completed in 1999, and deemed to be moderate-high based on their history of successful establishments elsewhere at the time. In 2010, another ornamental fish risk assessment was completed by the Australian Government, which also determined that Jaguar Cichlids were a high-risk species based on suitable climatic matches in the tropics, and the potential for impact on habitats and other species in Australian freshwater ecosystems.
Mackay is a small coastal city located in central Queensland in north eastern Australia, and has a humid sub-tropical climate. The city sits within the Pioneer River catchment, which covers an area of around 1550 km², and incorporates as many as 10 major tributaries that are used for agricultural irrigation in the region. The Pioneer River itself also has a number of water storage facilities built along its course, including Teemburra and Kinchant Dams, the Mirani, Marian and Dumbleton Rocks Weirs, as well as off stream wetland lagoons that are popular with locals. In December 2014, the Department of Agriculture and Fisheries in Queensland was first notified of a potential incursion of Jaguar Cichlids in a stormwater retention dam in Mackay.
In a paper published in the journal BioInvasions Records on 17 January 2020 Bonnie Holmes of the School of Biological Sciences at the University of Queensland, and the Department of Agriculture and Fisheries in Queensland, Samuel Williams, also of the Department of Agriculture and Fisheries in Queensland, and Trent Power of Catchment Solutions Pty Ltd, report on the identification and attempted eradication of the Jaguar Cichlid in the dam, outlines the post-treatment survey and results, and documents successive captures of Jaguar Cichlid in the nearby tributaries of the Pioneer River in subsequent years, indicating successful establishment of this invasive species for the first time in Australian waters.
The incursion site was located between the Pioneer River and Fursden Creek in Mackay, Queensland, Australia. The stormwater retention dam, averaging 1.5 m deep and approximately 1375 m², was designed to capture potentially contaminated stormwater from the site to prevent run off into the nearby watercourses, although in times of significant rainfall the dam has the potential to overflow into these systems. In early January 2015, a pre-treatment Fish survey was undertaken to confirm the presence and delimit the spread of Jaguar Cichlid in both the dam and adjacent creeks using 10mm mesh seine nets. A single pass of each side of the dam at 1.5 m depth was made, approximately 2.5 m from the bank. As Jaguar Cichlid is readily identifiable from Australian native species, the specimens captured were identified morphologically by Fish biologists on site. Fish and Crustacean species composition of the catch was also recorded. There was no detection of Jaguar Cichlid in any section of creek sampled outside of the retention dam, suggesting the population remained confined to the single waterbody.
In early January 2015 an assessment of risk was conducted based on the overflow potential of the dam to nearby waterways, and the population contained within presenting a source for further infestation throughout the catchment. After consultation between local project facilitators (Catchment Solutions Pty. Ltd.), site owners and the Department of Agriculture and Fisheries freshwater fisheries biologists, on 27 January 2015 the site was restricted to access and powdered rotenone (an odorless, colourless, crystalline isoflavone used as a broad-spectrum insecticide, piscicide, and pesticide) was mixed and applied as an eradication treatment to the dam, and the removal of deceased Fish were collected over the subsequent five days. Species composition and a sub-sample of the total catch was measured for fork length to identify size classes and life history stage. Application of rotenone was conducted under an Australian Pesticides and Veterinary Medicines Authority permit and based on meeting the guidelines set out in the Manual for the use of rotenone for Queensland Department of Primary Industries and Fisheries.
Post-treatment Fish surveys were conducted in March, April and June 2015 in the retention dam to determine proof of freedom of the infestation. Surveys utilised a boat mounted electrofishing unit consisting of a 7.5 GPP Smith-Root electrofisher, two dropper anode array and hull cathode. The effective field of this unit was approximately a 3 m radius centred on each anode. Multiple passes of the entire site were performed using a power on, power off technique to ensure the waterbody was sampled in its entirety.
Native Fish species that were removed as a result of the rotenone treatment were re-collected from nearby waterways and reintroduced to the site in June 2015.
Longer term monitoring of the Pioneer River tributaries, including Fursden Creek, Janes Creek, McCreadys Creek and the Gooseponds were conducted by Catchment Solutions Pty. Ltd. as part of other ongoing riverine and fishway monitoring projects in the region. Surveys utilised boat mounted and back pack electrofishers, and to a lesser extent fyke, seine and cast nets. Department of Agriculture and Fisheries community education initiatives regarding the Jaguar Cichlid incursion were promoted through local fishing clubs and tackle stores, where fishers were encouraged to report all invasive Fish captures to the department’s online 'Report a pest Fish' page, or to local Queensland Boating and Fisheries Patrol and biosecurity officers.
The presence of Jaguar Cichlid was confirmed when the project staff deployed seine nets in the pre-treatment dam survey. Gambusia, Gambusia holbrooki, was the only other invasive Teleost captured. Native species included Flyspecked Hardyhead, Craterocephalus stercusmuscarum, Tarpon, Megalops cyprinoides, Eastern Rainbowfish, Melanotaenia splendida splendida, Bony Bream, Nematolosa erebi, and Spangled Perch, Leiopotherapon unicolor. Freshwater Prawns, Macrobrachium spp.) were the only Crustaceans caught, and invasive Cane Toads, Bufo marinus, were the only Amphibians captured.
The surface area of the dam was estimated around 1375 m², with an average depth of 1.5 m. The deepest point was 2.4 m. Water temperature ranged between 30–31°C. In addition to the species recorded during the pre-treatment survey, four large non-native Goldfish, Carassius auratus, and over 40 Agassiz’s Glassfish, Ambassis agassizii, were also recorded. Gambusia were the most abundant species destroyed (about 1500 individuals), with approximately 200 specimens of Jaguar Cichlid also removed. A sub-sample of 16 Jaguar Cichlid were measured for fork lengths, which ranged between 3 cm–18 cm, indicating a breeding population. Individual sexes were not recorded.
An initial post-treatment survey in the dam was conducted on 4 March 2015. A single Tarpon was recorded, resulting in further sampling rather than the reapplication of rotenone at the site. Follow-up surveys were conducted in April and June 2015, with the same Tarpon recaptured each time. The lack of Jaguar Cichlid captures during all post treatment surveys indicated that the eradication was successful, and restocking of the dam was undertaken with local native Fish.
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