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Distribution of Exotic Freshwater Fishes in the Wet Tropics Region, Northern Queensland, Australia Report 09/19 Damien W. Burrows Australian Centre for Tropical Freshwater Research, James Cook University. Townsville, Qld 4811 Phone 07-47814262 Supported by the Australian Government’s Marine and Tropical Sciences Research Facility CONTENTS List of Figures................................................................................. ................................. List of Tables................................................................................................................... Introduction....................................................................................................................1 Methods and Data Acquisition......................................................................................1 Distribution of Exotic Fish Species..............................................................................2 Species Summaries.......................................................................................................7 Geographic Summaries................................................................................................10 Discussion.....................................................................................................................22 References….................................................................................................................25 List of Figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Maps Showing Frequency of Occurrence of Exotic Species Across the Wet Tropics Catchments. ........................................................................5 Map showing the distribution of exotic fish species in the Mossman, Daintree and Bloomfield Catchments.......................................................11 Map showing the distribution of exotic fish species in the Barron catchment including Cairns urban streams..............................................14 Map showing the distribution of exotic fish species in the RussellMulgrave catchment, including Trinity Inlet..............................................16 Map showing the distribution of exotic fish species in the Johnstone catchment, including Liverpool and Maria Creeks......................................................................................................17 Map showing the distribution of exotic fish species in the Tully-Murray catchment including the streams around Cardwell and Hinchinbrook Island………………………………………………………………………….19 Map showing the distribution of exotic fish species in the Herbert catchment……………………………........................................................21 Map showing the distribution of exotic fish species in the Wet Tropics region………………………………….......................................................23 List of Tables Table 1. Table 2. No. Sites Surveyed for Freshwater Fish in the Wet Tropics Region (listed by basin from north to south)……..............................................................3 List of Exotic Fish Species Recorded from the Wet Tropics region………………....................................................................................4 Introduction Exotic fish species pose a serious threat to the biological integrity of aquatic ecosystems. They are particularly serious in the Wet Tropics region for three primary reasons. Firstly, the Wet Tropics region contains numerous relatively undisturbed and unmodified aquatic ecosystems for which the introduction of exotic fish represent the greatest disturbance they have been subject too. Secondly, Wet Tropics streams have very high environmental values and many species of high conservation value. Finally, the number of exotic species in the region is high. The region between Townsville and Cairns has more exotic species than any other in Australia (Webb 2007). Additionally, although not specifically discussed in this report, the Wet Tropics also has more native fish species that have been translocated to waterways where they don’t belong, than any other region in Australia. Burrows (2004) provides a comprehensive summary of the status of translocated fish species in the Wet Tropics region. Recent years have seen significant, even exponential, range extensions for some of the exotic species of most concern. Guppies and mosquitofish have been recorded from several new catchments and tilapia, the species of most concern, has invaded several major catchments. Managing exotic fish requires up-to-date knowledge of their distribution. Most new incidents of pest fish result from releases by members of the public. Thus, preventing the spread of exotic fish species requires a well-informed public. It is important for managers and the general public to realize the current distribution of exotic fish. Webb (2007) summarized the distribution of exotic fishes in north-east Queensland up to that point. This report provides a more-detailed catchment by catchment description of the distribution of exotic species in the Wet Tropics region and also updates their known distribution, which for several species, has greatly increased since 2007. This report also describes not just locations where exotic fish have been recorded, but where they have not been recorded (also of relevance to managers) and provides a summary of the level of effort which has been expended in searching in each catchment, any gaps in search effort, and priorities for further search effort. Methods and Data Acquisition All fish survey effort for the Wet tropics region was compiled, from a wide range of sources. This included obtaining the major fish survey datasets from relevant researchers. Much of this data is unpublished. Database records were also obtained from the Queensland and Australian Museums. Database records were also obtained from the Queensland and Australian Museums. Unpublished records were obtained from sources considered reliable by the author. These included various naturalists and recreational fishers as well as information recorded in publications of the Australia New Guinea Fishes Association (ANGFA) and their database (http://db.angfa.org.au/). The most comprehensive surveys of freshwater fishes for the Wet Tropics are those of Pusey and Kennard (and colleagues from Griffith University) and the series published by John Russell and colleagues from QDPIF. Pusey and Kennard (1994) surveyed 93 sites across all catchments between Cardwell and the Bloomfield River in the first and most systematic survey of the Wet Tropics region, during the period 1992-1994. They have 1 subsequently surveyed 116 sites from the Mulgrave, Tully and Johnstone rivers (unpublished data obtained for this report from Pusey from 1994-1997) and 26 sites in 2005-2006 from four tributaries of the Mulgrave as part of the Catchment to Reef CRC program. The series by Russell et al. covered 78 sites in the Hull, Liverpool, Johnstone, Russell-Mulgrave, Moresby, Barron, Daintree and Mossman catchments, over the period 1992-1998. That work is reported across six reports (Russell and Hales 1993, Russell et al. 1993, 1996, 1997, 1998, 2000). In addition, the Queensland Department of Primary Industries and Fisheries (QDPIF) has surveyed a further 64 sites across the Wet Tropics (with data available in various reports). Recent work by ACTFR have surveyed 91 sites covering the Cape Tribulation, Daintree, Barron, Mulgrave, Johnstone, Tully, Herbert, and Burdekin (Paluma) catchments, mostly in the period 2006-2009. Webb (2003) published a long list of sites (n=80) from which exotic species were known to him from the Wet Tropics region and these are included in the analysis presented in this report. This is the most comprehensive list of exotic fish species locations available till this current report. Webb (2007) has summarized the distribution of exotic fishes within coastal catchments of the Townsville to Daintree coastal catchments. Searches were also made of the Queensland, Australian and Northern Territory museums databases for additional records of exotic fishes from the region. Apart from the data of Shipway (1947/1948) and Russell (1987) and Barlow et al. (1987), all other data are from 1992-present. This reflects how little formal freshwater fish survey occurred, or was at least formally recorded from the Wet Tropics region, prior to 1992. The literature search and a search of unpublished data from researchers yielded records for fish survey at a total of 796 freshwater sites within the Wet Tropics region. In addition, museum records and others sources yielded an additional 69 records for exotic fishes. It must be remembered that we can only report on formally recorded or verifiable records. There may be numerous unrecorded locations where exotic species are present, especially in degraded streams near urban areas, and many observations that have not been formally recorded. The vast majority of these surveys were undertaken for the purposes of general fish survey, not specifically for exotics species. Only the studies of Webb (2003, 2007), Webb et al. (1996) and various ACTFR surveys from 2006-2009 were for the express purpose of detecting exotic species. This difference in survey purpose affects site selection and detection methods, and thus the probability of detecting exotic species. Distribution of Exotic Fish Species Survey effort is reasonably well-distributed across the various Wet Tropics catchments (see Table 1). Greatest effort has been in the central catchments (Daintree, Johnstone, Russell-Mulgrave, Tully-Murray). Of the 77 sites surveyed in the Herbert catchment, 44 were in the upstream area around Herberton. The Herbert catchment was not included in the studies of Pusey and Kennard (1994) or the series by Russell et al. and because it is not known to have tilapia or many translocated native species, was not included in recent ACTFR surveys. Thus, there has been less survey work in this catchment 2 compared to other Wet Tropics rivers. However, given that tilapia have now been found in the uppermost reaches of this catchment near Herberton (Hogan and Vallance 2004) and gambusia in the upper (Burrows unpublished data) and lower catchments (Burrows unpublished data), this catchment warrants more effort. The streams of the Moresby catchment remain unsurveyed since the study of Russell et al. (1996) and the creeks around Cardwell have barely been assessed at all. Table 1. No. Sites Surveyed for Freshwater Fish in the Wet Tropics Region (listed by basin from north to south) Catchment/Basin No. Sites Surveyed No. sites with exotic species Bloomfield/Cape Tribulation Daintree/Mossman Upper Barron Lower Barron/Cairns urban Johnstone Russell-Mulgrave Morseby Liverpool Tully-Murray 23 154 80 8 170 140 11 40 86 0 20 19 7 44 27 0 0 15 Herbert Cardwell Creeks Hinchinbrook Island Total 77 5 8 764 14 0 0 144 Records for exotic species were found for 158 sites in the Wet Tropics region (Table 1). A total of 9 exotic fish species have established in waters within the Wet Tropics region. The only major rivers that, as far as is evident from formally recorded data, are free of exotic species, are the Bloomfield River and Cape Tribulation streams, Saltwater Creek and Mowbray River (near Mossman), Moresby River, Liverpool Creek, Hinchinbrook Island and the creeks around Cardwell. 3 Table 2 presents the number of sites each of the exotic fish species in the Wet Tropics region have been found at in that region. Guppies have been found at the greatest number of sites, more than twice as many sites as the next most commonly encountered species. Given how widespread they are throughout many parts of Australia, gambusia are perhaps surprisingly not as common as might be thought. Table 2. List of Exotic Fish Species Recorded from the Wet Tropics region. Listed in order of most widely distributed to least, based on the number of sites they have been recorded from within the region. Family Poeciliidae Cichlidae Poeciliidae Cichlidae Poeciliidae Poeciliidae Cichlidae Cichlidae Cichlidae Species Poecilia reticulata Oreochromis mossambicus Xiphophorus maculatus Tilapia mariae Gambusia holbrooki Xiphophorus helleri Hemichromis bimaculatus Amphilophus labiatus Amphilophus citrinellum Common Name Guppy Mozambique tilapia Platy Spotted tilapia Gambusia Swordtail Jewel cichlid Red devil Midas cichlid No. Sites 131 61 66 51 26 7 2 1 1 The maps presented in Figures 1a-1f graphically illustrate the number of fish surveys and samples in each major catchment area and the frequency of occurrence of exotic species, as well as areas from which exotic species have not been reported. 4 Figure 1. Maps Showing Frequency of Occurrence of Exotic Species Across the Wet Tropics Catchments. Figure 1a: Mossman-Daintree Catchment (incl. Bloomfield). Figure 1b: Barron Catchment (incl. Cairns urban). Figure 1c: Russell-Mulgrave Catchment. Figure 1d: Johnstone Catchment (incl. Moresby). 5 Figure 1e: Tully-Murray Catchment (incl. Cardwell streams and Hinchinbrook Island) Figure 1f: Herbert Catchment 6 Species Summaries This section summarises the distribution of the exotic fish species of the Wet Tropics region. Other ecological information on the six most well-established species is covered in Fact Sheets that have been prepared on these species and are available in the Appendix to this report. These Fact Sheets are available on the ACTFR Pest Fish website (www.actfr.jcu.edu.au) along with Fact Sheets for other exotic species found elsewhere in north Queensland. For the 9 species found in the Wet Tropics, these all occur in two families – the Cichlidae and the Poeciliidae. The cichlids include tilapia, as well as other popular aquarium fish such as oscars. The Poeciliidae are known as live-bearers (give birth to live young rather than lay eggs) and include many smaller species that have been introduced widely around the world. In the Wet Tropics, this includes gambusia, guppies, platys and swordtails. Mozambique Tilapia – Oreochromis mossambicus This species is widely considered the most problematic exotic fish species in the region. It was first found in the wild in Australia in 1977 and in the Wet Tropics in the Cairns area in 1978. It is also known from several rivers around Brisbane and south-east Queensland (such as the upper Burnett River) and the Carnarvon/Gascoyne region of central, coastal Western Australia. In north Queensland, it is also abundant in the Townsville area (present there since 1978) and has recently invaded the Burdekin catchment (2004), the Endeavour River catchment, Cooktown (first report 2004, confirmed as established 2007) and a single specimen was recently collected (Oct 2008) in Eureka Creek, a tributary of the Walsh River (Mitchell River catchment). Within the Wet Tropics region, it is commonly reported from a variety of locations. Its known range is from coastal streams north of Cairns (eg, Hartleys Creek), the upper and lower Barron catchments, Trinity Inlet streams, Russell-Mulgrave catchment and the lower North and South Johnstone catchments. The Mozambique tilapia is most infamously known from a golf course pond at the Sheraton Mirage Resort at Port Douglas where it was introduced. After 18 months, the golf course pond was cleaned out and 13 tonnes of Mozambique tilapia were removed. The Queensland Museum also holds a record from the Resort at Port Douglas. There have been no reports of tilapia from Port Douglas in recent years and surveys have not detected the species there (Burrows and Perna unpublished data). Thus, apart from the recent confirmation of a population near Cooktown, the most northerly contemporary location of Mozambique tilapia appears to be creeks of the northern beaches of Cairns. Two distinct strains of Mozambique tilapia are present in Queensland: a hybrid, “Zanzibar Gold” strain (O. mossambicus x O. honorum – and possibly O. niloticus and O. aureus) in the Cairns and Wet Tropics regions and a pure strain around Townsville and south-east Queensland (Blühdorn et al. 1990). 7 Spotted Tilapia (or Black Mangrove Cichlid) – Tilapia mariae This species of tilapia is generally considered to be of lesser concern than the Mozambique tilapia, though this may reflect the latter’s greater distribution. Recent anecdotal evidence suggests that the spotted tilapia is overtaking the Mozambique tilapia in the Barron catchment. The spotted tilapia is known from the upper and lower Barron catchment, the Russell-Mulgrave and the lower North and South Johnstone catchments. This species was recently (Oct 2008) the subject of a rotenone (a fish poison) control exercise in Eureka Creek a tributary of the Walsh River (Mitchell River catchment). The success of this control effort is still being monitored (ACTFR and QDPIF unpub. data). Gambusia (or mosquitofish) – Gambusia holbrooki Gambusia are also commonly known as mosquitofish or plague minnows. They are native to the eastern and south-eastern USA but have been introduced to many countries, primarily for supposed control of mosquito populations. They were widely distributed in Australia for that reason, though their efficacy in that regard is questionable (Courtenay and Meffe 1989). They are similar in appearance to guppies and have sexual dimorphism with females growing to 8cm (max.) and males only to 4cm (max.). Females live longer (2yrs) than males (1 yr) so may be more abundant in populations. They have high tolerance for a range of water quality conditions and in tropical waters, may breed year round. Gambusia feed upon aquatic invertebrates as well as eggs and fry of small fish and amphibians. They are also known for their habit of ‘nipping’ the fins of larger fish and their generally aggressive behaviour affecting the normal behaviour of other fish species. They have been implicated in declines of various fish and frog species in Australia and overseas. Given their wide distribution, research on their impacts in Australia is generally limited however, as most focus has been on carp or tilapia. Gambusia were first introduced into Australia in the 1920’s and into Cairns in 1929 (Lloyd et al. 1986). Gambusia were spread to many waterways, for mosquito control, around the time of World War 2. Like guppies, gambusia are now more commonly used as aquarium fish and are thus often found near urban areas after being discarded from aquaria. Considering this history, it is perhaps surprising how few locations they have been recorded from, though they have been recorded from a number of new Wet Tropics locations more recently. They were only recently (2004) recorded from the upper Burdekin River (Burrows unpublished data) and (2008) from Thursday Island (Burrows and Perna 2009). In north Queensland, they are more common around the Townsville area than the Wet Tropics (where guppies are more prevalent). They were only recently (2006) recorded for the first time from the upper Herbert catchment and the lower Herbert catchment (2008) (Burrows unpub. data). Guppies – Poecilia reticulata Guppies are sexually dimorphic with females being much larger than males. Females are plain olive colour whereas males have a variety of bright colour patterns which are 8 used to attract mates. Mate selection in this species has been the subject of considerable scientific study. Like gambusia, guppies tend to be commonly used as aquarium fish and are thus often found near urban areas after being discarded from aquaria. Guppies are native to northern Brazil, Venezuela and other north-east states of South America, as well as some southern Caribbean Islands. They have been introduced to 48 countries around the world, largely for control of mosquito populations, though their efficacy in that regard is questionable. Guppies feed upon aquatic invertebrates as well as eggs and fry of small fish. Like gambusia, guppies are tolerant of a wide variety of water quality conditions and have been implicated in the decline of a number of fish and invertebrates in other countries to which it has been introduced. They are more common in the Wet Tropics than other poeciliids. Surprisingly, although they have been extremely well-studied for their mate selection behaviour, there have been few studies on their ecological impact in introduced locations. Platy (Xiphophorus maculatus) and Swordtails (Xiphophorus helleri) Two species are present, X. maculatus and X. helleri, with the former being more common in the Wet Tropics. Both species are sexually dimorphic with females being larger. Platys grow to 4-6cm and swordtails to 14-16cm. In male swordtails, the ventral rays of the caudal fin are elongated to form a ‘sword’. Both species are omnivorous, feeding on invertebrates and plant matter and both species breed almost year round in tropical regions. Both species are native to Mexico and central America. Platys have been introduced to 18 other countries and swordtails to 33 other countries. Both species are less tolerant of poor and variable water quality than gambusia, guppies or tilapia, which probably explains their lesser ‘success’ as invaders. Though both species are considered to be pests, there is very little known about their ecological impact in nay of the countries to which they have been introduced. This is probably due to greater focus on other, more serious exotic fish pest such as gambusia and tilapia. Swordtails have been shown to displace native fishes through their habit of ‘fin-nipping’ and have been suggested to impact upon amphibians via tadpole predation. Other Cichlids The midas cichlid has been confirmed (2007) as present in Alice River, a stream draining Eubenangee Swamp, north of Innisfail (unpublished data). The Queensland Museum has a record of Jewel cichlids (Hemichromis bimaculatus) from ponds at Cairns Civic Theatre in 1985 and they are still present there today (Webb pers. comm.). The Queensland Museum has a record of red devils from a resort pond at Port Douglas in 2001, though their current status is unknown. 9 Geographic Summaries This section describes the occurrences of exotic fish species in each of the major catchments/basin areas of the wet Tropics. Bloomfield/Cape Tribulation Streams No exotic species are known from these streams (Figure 2). The Bloomfield River (12 sites) and several Cape Tribulation streams (10 sites from 7 coastal creeks) were surveyed by Pusey and Kennard (1994). These streams are also popular with naturalists and fish enthusiasts and thus subject to considerable unofficial survey effort, with no records of exotic species being known from those sources either. Limited development and human visitation compared to other Wet Tropics catchments has probably prevented the introduction of exotic species to these catchments. However, development and resident populations in these areas have increased in recent years as has the risk of introduction to these high value streams, especially of smaller aquarium fish such as the poeciliids. Daintree River This river has been surveyed by Pusey and Kennard (1994 -17 sites), Russell et al. (1998 – 43 sites); Kroon (unpub data 2004/2005 – 8 sites), DPIF (2007, 7 sites surveyed annually from 2000-2005) and Perna and Burrows (unpub data. 2007-2009 – 4 sites). It is also a popular river for investigation by naturalists and fish enthusiasts. Two exotic fish species are known from this catchment though their known distribution is limited (Figure 2). Gambusia were reported from a creek draining into the Daintree River in 2009 (ACTFR unpub. data), this being the only record of this species from this catchment. Guppies have been recorded from Douglas Creek (Russell et al. 1998), a major tributary of the Daintree River. They have also been recorded from two sites in the main Daintree River channel well, upstream of the Douglas Creek confluence, in the DPIF long-term monitoring program (Hagedoorn and Smallwood 2007). Given that none of the surveys of the main Daintree River channel in the 1990’s found any guppies, their occurrence there are probably the result of more recent spread from Douglas Creek. Further surveys to determine the current distribution of guppies in this catchment are warranted. Kroon (2004) listed Mozambique tilapia as being present in this catchment, but this record is considered to be erroneous as it is not mentioned in the supporting documents used to compile the species list for the Daintree catchment in Kroon (2004). Also, there are no specimens or confirmed records of tilapia from that catchment. Russell et al. (1998) report that there have been anecdotal reports of tilapia from this catchment but none have been verified. 10 Figure 2. Map showing the distribution of exotic fish species in the Mossman, Daintree and Bloomfield Catchments. Mossman River The only exotic fish species currently known from this area is the guppy, which has been recorded in several sites in the Mossman River, as well as tributaries such as Carsons Creek (Kroon unpub. data 2004/2005), an unnamed tributary crossing Santa Catarina Road (Russell et al. 1998) and Cassowary Creek (Pusey and Kennard 1994). Mozambique tilapia were found in a golf course pond at the Sheraton Mirage resort in the late 1980’s. This is one of the famous eradication activities where two fish stocked by the greenkeeper turned into 13 tonnes of tilapias within 18 months and had to be removed from the ponds with a front-end loader. This is one of the iconic tales of tilapia in north Queensland, which is widely quoted in the media. It is perhaps surprising that there have been no surveys to follow this up and demonstrate whether tilapia had spread to other nearby creeks or estuarine areas prior to their removal from this resort. The Queensland Museum also has a record of the Mozambique tilapia from a resort at nearby Wonga Beach in 1989. There have been no recent reports of tilapia from the Port Douglas area and it is considered (fortuitously) that the species is not currently known from the area. 11 Kroon (2004) recorded mozambique tilapia as being recorded from this catchment, but this is probably due to the above records. Because of the efforts to remove tilapia from the ornamental sites where it was located, it is assumed that tilapia are no longer present in this catchment. It is recommended that further surveys be undertaken of the streams within this catchment to confirm this assumption. The red devil cichlid, Amphilophus labiatus has also been recorded from ponds at the Rydges Reef Resort in 2001 (Qld Museum data) but their current status there is unknown. Burrows and Perna (2009) found gambusia at a small creek at Wonga Beach. No exotic fish species have yet been recorded from Saltwater Creek or the Mowbray River systems. Saltwater Creek was surveyed by Kroon (2004, 2005 unpub. data) but the Mowbray River remains unsurveyed. The proximity of the Mowbray River to Port Douglas suggests some chance that exotic species have been introduced there, and this should be investigated. Barron River (above Barron Falls) The Barron River has the most modified fish fauna of any river in the Wet Tropics region and probably in all of Australia (Burrows 2004). Three exotic species (Mozambique tilapia, spotted tilapia and guppies) are known from the catchment (Figure 3). In addition to exotic fish species, Burrows (2004) tallied 36 native fish species as having been translocated into various parts of this catchment, nearly all above the Barron Falls. This would probably qualify the Barron River (above Barron Falls) as having the most highly modified fish fauna of any river in Australia. Mozambique tilapia were first reported from this catchment in aquaculture ponds adjacent to Leslie Creek (a tributary of Tinaroo Dam) in 1986, having apparently entered these ponds from a neighbouring property following heavy rain (Webb et al. 1996). It is widely believe that this infestation began in a farm dam in the area. No official action was taken and the fish apparently disappeared from these ponds but were again detected in them in early 1995. Fisheries staff were alerted and a field inspection located mozambique tilapia in Kenney Creek and in two large dams and feeder streams which flow into Leslie and Kenney Creeks (Webb et al. 1996). Several planning meetings ensued throughout 1996 and from October-December 1996, Webb et al. (1996) surveyed 50 sites in that area, looking for mozambique tilapia. They found them widespread in a number of creeks (Leslie, Kenney, Gwynne), farm dams, aquaculture and ornamental ponds and drainage channels, as well as the Barron River down to about 2km upstream of Tinaroo Dam (but not in the dam itself). The distribution of mozambique tilapia within the area (in upstream reaches of different creeks) led Webb et al. (1996) to suggest that more than one introduction may have occurred. During these surveys, Webb et al. (1996) also found the first spotted tilapia from this catchment (in a farm dam in the upper part of the Leslie-Kenney Creek system) and the first guppies recorded from above Tinaroo Dam (guppies had previously been recorded in the upper Barron catchment from an irrigation channel below Tinaroo Dam) also in a farm dam adjacent to those containing tilapia. Mozambique tilapia were first recorded from Severin Creek (Tinaroo Dam) in 1997 and were widely spread through the dam by 2000 (Barron Mitchell Tilapia Management 12 Group 2000). Tilapia are abundant enough in Tinaroo Dam to support a popular annual tilapia fishing competition held as part of the ‘barra bash’. Recent catch data, such as from routine DPIF post-stocking fisheries surveys and catch data from the annual barra bash tilapia fishing competition, suggests that the spotted tilapia may have now overtaken the Mozambique tilapia as the most abundant of the two tilapia species in Tinaroo Dam. A working group for the regional management of tilapia was formed in 2000, representing various community, government and industry stakeholders groups. They produced a tilapia management plan for the Barron and Mitchell catchments in 2001. One of the key items in that plan was the installation of fish exclusions devices to keep fish such as tilapia from transferring from the Barron catchment to the Mitchell catchment via irrigation water which is transferred across the basin as part of the MareebaDimbulah Irrigation Area. Such fish exclusions had first been mooted in 1996 (Webb et al. 1996) and they were established at the Tinaroo Dam off-take by 2005. A summary of community efforts to combat tilapia can be found in the Catchment Management Plans for the Barron (1997) and Mitchell River catchments (2000) and the Regional Management Plan for Tilapia (Barron and Mitchell Catchments) produced in 2000 by the Barron/Mitchell Tilapia Management Group. Guppies have been recorded from Emerald Creek (Russell et al. 1998, Webb 2003) as well as Maude, Mazlin and Gwynne Creeks (Russell et al. 1998) and Walkamin Research Station (Webb 2003). Hansen (2000) reports guppies and swordtails from Jumrum Creek, Kuranda. Russell et al. (1998) noted that guppies were usually only found at disturbed sites where there was reduced numbers of native species, especially predators. Briggs (2007) report gambusia in Leslie Creek, the only record for this species in the upper Barron catchment. Pusey and Kennard (1994), Russell et al. (1998) or Burrows and Perna (2008) did not locate any exotic species from Flaggy Creek or Clohesy-Davies Creek, two important sub-catchments of the upper Barron River, although Briggs (2007) does report guppies from lower Davies Creek. Burrows (2004) also reports a sighting of an undetermined exotic species from Lake Eacham, a waterbody that has been the recipient of many introduced fish species. Pusey and Kennard (1994) surveyed the upper Barron River before the arrival of tilapia and Russell et al. (1998) surveyed the Barron River only a few years after its arrival, finding the Mozambique tilapia at four sites only (of the more than 40 surveyed) and the black mangrove cichlid not at all (though they had only just arrived in the upper Barron catchment at that time). Both tilapia species are now well-established in Tinaroo Dam and mozambique tilapia are now found in the Barron River below Tinaroo Dam though recent surveys by QDNRW of the Barron River between Mareeba and Kuranda (as part of the Water Resource Plan monitoring) did not locate any (R. Hunt pers. comm.). The spotted tilapia may also be established below Tinaroo Dam but there are no official records to support this. 13 Figure 3. Map showing the distribution of exotic fish species in the Barron Catchment, including Cairns urban streams. Barron River (below Barron Falls, including Cairns urban streams) The creeks around Cairns, and the Barron River and its major lowland tributary – Freshwater Creek – are relatively heavily impacted streams and surrounded by a large human population, increasing the risk of exotic species introduction. Seven of the nine exotic fish species known from the Wet Tropics region are known from streams in the Cairns urban area (Figure 3). Spotted tilapia have been recorded from both the Barron River and Freshwater Creek (Russell et al. 1998, Webb 2003) as well as a variety of smaller streams in the area (unpub. data). Pusey and Kennard (1994) record the Mozambique tilapia from Freshwater Creek but this is likely a misidentification of the spotted tilapia (B. Pusey pers. comm.) as both species were relatively new and unfamiliar at that time. Russell et al. (1998) found the spotted tilapia to be abundant at all Freshwater Creek sites they sampled downstream of Crystal Cascades. Surprisingly, apart from the erroneous report of Pusey and Kennard (1994), there are no formal records of Mozambique tilapia from Freshwater Creek, and Russell et al. (1998) did not locate any there, even though they are present in nearly all streams in the Cairns urban area and have been recorded from Lake Morris, upper Freshwater Creek catchment, (Qld Museum data), the drinking water supply for Cairns. Mozambique tilapia are also known from Palm Cove (Qld Museum 14 data), Deep Creek (J. Russell unpub. data) and most other creeks in the northern beach suburbs of Cairns (Webb 2003) and Trinity Inlet streams (see below). Thus, the Mozambique tilapia are common in urban streams of Cairns and streams to the north and south, but not in Freshwater Creek. Swordtails have been recorded from Delaney’s Creek, Clifton Beach, guppies from Deep Creek and Half Moon Creek, gambusia from Avondale Creek, Smithfield (Webb 2003), black mangrove cichlids and jewel cichlids (Hemichromis bimaculatus) from ponds at Cairns Civic Theatre (Webb 2003, Qld Museum data) and guppies and swordtails from Forest Gardens, south Cairns (Webb 2003). Russell et al. (1998) found a single gambusia at one site (tributary of the lower Barron River near Kamerunga) in 1999 and also found guppies and swordtails in tributaries of Freshwater Creek, but not the main creek channel itself. Several exotic fish species have been recorded from Cairns Centenary Lakes such as, gambusia, swordtails and Mozambique tilapia (Webb 2003). Guppies are the most commonly recorded exotic species in streams around the Cairns urban area (Russell et al. 1998, Webb 2003). Trinity Inlet These streams are normally overlooked in freshwater fish surveys as the creeks are small and their habitat condition is poor. Because of this and their proximity to the urban areas of Cairns, it is expected that several exotic species would be present. So far, guppies are known from Blackfellow Creek (Webb 2003), Chinaman and Collinsons Creeks and Woree (Qld Museum data) and guppies and Mozambique tilapia from Wright Creek (Webb 2003) (Figure 4). These creeks warrant further survey as additional occurrences of exotic species are likely. Russell-Mulgrave River Pusey and Kennard (1994) surveyed 48 sites in the Mulgrave River catchment, finding guppies at 8 sites in tributaries, including Little Mulgrave River and Behana Creek. They also found the swordtail X. maculatus at one tributary site. They also surveyed at 11 sites in the Russell River catchment, not finding any exotic species. Pusey et al. (2007) surveyed 26 sites in Behana, Little Mulgrave, Babinda and Woopen Creeks. They found guppies to be present at six sites across all four creeks, as well as the spotted tilapia at three sites in Behana Creek and swordtails at two sites in Babinda Creek. Schaffer and Burrows (2006 unpub. data) found them at the Bruce Highway crossing of Behana Creek and further downstream at the next road crossing. Pusey et al. (2007) surveyed several sites in Behana and Babinda Creeks in 2006. They found that sites with highly degraded riparian areas had more exotic fishes than sites with better riparian condition. However, although this effect was statistically significant, even in the poor condition sites, exotic fishes did not dominate the fish community, probably due to the cold water and high flow conditions, which most exotic species present in the region do not prefer. Russell and Hales (1993) surveyed 47 sites in the catchment. They found guppies at two sites and swordtails at three tributary sites (Babinda, Nirringa and Rusty Creeks). 15 Rayner (2008) studied 6 sites along the lower Mulgrave River, finding both species of tilapia, with the spotted tilapia most abundant (found at 5 sites), as well as finding swordtails at his most downstream site. Interestingly, they did not find any tilapia at his most upstream site despite repeated sampling trips there. Figure 4. Map showing the distribution of exotic fish species in the Russell-Mulgrave Catchment, including Trinity Inlet. Lake Barrine is part of the Mulgrave River catchment. The presence of spotted tilapia in this lake were first reported to the report author in April 2007 and confirmed by DPIF shortly after. This population is established and breeding. Studies by DPIF on how to reduce the population are ongoing. Lake Barrine drains through Toohey Creek into the upper Mulgrave River. Although these tilapia re not known from Toohey Creek, they are known from the upper Mulgrave River so there escape from Lake Barrine would not greatly add to their known distribution. In 2007, a fish strongly resembling the midas cichlid, was observed in the Alice River (C. McPherson pers. comm.), a stream draining Eubenangee Swamp, north of Innisfail. The Australian Museum holds a record from 1980 of platy’s in Harvey Creek overflow. The majority of fish survey in this catchment has been in the Mulgrave catchment, rather than the Russell catchment. Surprisingly, there are no official records of either tilapia species from the Russell River catchment (Figure 4), though they are certainly present there. Their distribution in that catchment warrants further survey as does their 16 distribution in upper reaches of tributaries of the Mulgrave catchment. tributaries such as Harvey Creek, also warrant further survey. High value Moresby River Russell et al. (1996) surveyed 11 freshwater sites in the Moresby River catchment, finding no exotic species. No further surveys are known from this catchment, though they are clearly warranted. The lack of exotic species from this catchment (Figure 5) probably reflects the smaller catchment size, limited freshwater stream length and its low population base. Figure 5. Map showing the distribution of exotic fish species in the Johnstone Catchment including Liverpool and Maria Creeks. Johnstone River Four exotic species have been found in this catchment but not Mozambique tilapia (Figure 5). Russell and Hales (1993) surveyed 77 sites and found guppies at 7 sites (Wadda, Bora, Berner, Cleminson, Meuanbah and Mena creeks as well as the North Johnstone River. They also found platy’s at 6 sites (Victory, Tregothanaan, Mena and Nind’s creeks). They only found the spotted tilapia at one site on the South Johnstone 17 River. They did not find any gambusia in this catchment. Pusey and Kennard unpub. data) surveyed 55 sites in the Johnstone catchment from 1994-1997. They found guppies at 13 sites (on Dirran Creek, Mena Creek, Fishers Creek, Pine Forest Creek, South Johnstone River) and platy’s at 9 sites (in Wharrapa Creek, Fishers Creek, Mena Creek, Polly Creek and Cassowary Creek). Like Russell and Hales (1993), they did not record any tilapia or gambusia, though at least tilapia are known from this catchment. The Australian Museum holds records of gambusia from Utchee Creek and guppies from Utchee and Mena Creeks, all collected in 2001, as well as a 1997 record of platy’s from Ninds Creek. Briggs (2007) reports finding guppies and platy’s in Utchee Creek. The ANGFA database contains a record of platy’s from Etty Bay Creek. Burrows and Perna (2006) surveyed 19 sites in the North and South Johnstone rivers on the tablelands. They found guppies at three sites (Wells Creek, Malanda Creek and an unnamed tributary crossing Glenn Allyn Road) and gambusia at Gardener Creek and Malanda Creek (same site as had guppies). These are the only known official records of gambusia in this catchment. Schaffer and Burrows (2007) found guppies at Berner and Wadda Creeks and swordtails at Malanda Creek. They also found spotted tilapia at Shew Creek (South Johnstone River) and Fitzgerald Creek (North Johnstone River). The DPIF long-term monitoring program (Hagedoorn and Smallwood 2007) surveyed five sites in the North Johnstone River and two sites in the South Johnstone River annually from 2000-2005. They found guppies at 5 sites (including a site on the upper tablelands), gambusia at two sites, spotted tilapia at six sites (but all the lowland sites) and swordtails at one site. One site (site 2) had four exotic species present (swordtails, guppies, gambusia and spotted tilapia) and site 3 had the last three of these species present. Liverpool Creek/Maria Creek Russell et al. (1997) surveyed 40 sites in the Liverpool and Maria Creeks, without finding any exotic fish species (Figure 5). No other surveys have been conducted in these streams and no records of any exotic fish species could be found for these streams. Tully-Murray River and Hull River Only two exotic species have been recorded from this catchment (Figure 6). There are no official records of tilapia from the Tully-Murray catchment although there are occasional anecdotal reports. Veitch et al. (2006) investigated one of these, including undertaking survey of 12 sites in a section of the Tully River between the Jarra and Banyan Creek junctions in 2006, without finding any tilapia. However, they did find guppies at Banyan Creek and platy’s in the Tully River and lower Jarra Creek. Burrows et al. (2006) surveyed upper Jarra Creek (within the military training area), which contains what is probably the largest intact lowland river system in the Wet Tropics region and did not find any exotic species. Platy’s are known from the lower Jarra Creek (Veitch et al. 2006), where it has been heavily modified by surrounding agriculture. 18 Hogan and Graham (1994) surveyed 16 lagoons and riverine sites in this catchment, only finding platy’s at two sites (though which sites was not identified in that report and their locations have been approximated in Figure 6). The ANGFA database contains a record of platy’s at a creek near the rubbish tip (location not specified but assumed to be near Tully in Figure 6). Pusey and Kennard (1994) surveyed 25 sites and Pusey and Kennard (unpub. data) 11 sites, in the Tully-Murray catchment. The only exotic species they found were guppies at two sites (Murray River and Woodfield Creek, both near the confluence with the North Murray River). There are no records of exotic species from the Tully River above Tully Falls, despite survey there by Pusey and Kennard (3 sites) and several surveys of Koombooloomba Dam by QDPIF (unpublished data). Only 5 sites have ever been surveyed in the Hull River catchment, these being by Russell et al. (1997). No exotic species were found, which may not be surprising, given the very low human population here and the relatively short stream length in this catchment, most of which is difficult to access. Thus, overall, there are relatively few records of exotic fish species from the Tully-Murray catchment. Figure 6. Map showing the distribution of exotic fish species in the Tully-Murray Catchment including the streams around Cardwell and Hinchinbrook Island. 19 Cardwell Area Streams No exotic species are recorded from these streams (Figure 6). Pusey and Kennard (1994) surveyed at 5 sites in 5 creeks (Broken Pole, Porter, Five Mile, Bridge and Waterfall creeks) without finding any exotic species. In 2003, Webb (2003) recorded swordtails from Whitfield Creek, Kennedy. There has been no recent surveys of the creeks in this area, though these are warranted as the distribution of exotic species is probably more widespread than is currently recognised. Tilapia are not expected to be present here but guppies or gambusia may be present. Herbert River Although exotic species have not been commonly reported from streams in the Herbert catchment, four species are present (Figure 7). Mozambique tilapia were reported from the Herberton town weir, high up in a tributary of the Wild River, in 2003. This location has only one road access which has a locked gate and members of the public are not allowed. A cohort of juvenile sooty grunter were also found here around the same period, indicating that they too were also translocated to this location. Hogan and Vallance (2004) removed 1,800 Mozambique tilapia in three days from the top two weirs. A single Mozambique tilapia was also found further downstream. No surveys were undertaken any further downstream as it was thought that they were not more widely distributed. No further survey or removal work occurred here until 2005 (Burrows et al. unpub data) surveyed the Wild River from just below the top two weirs to as far as its junction with the Millstream on several occasions from 2005-2007 but found no mozambique tilapia. Regular fishdowns of the top two weirs by QDPIF and ACTFR have reduced the populations to low catch rates but recent surveys have indicated that the populations have increased again. This location may be too cold for Mozambique tilapia to proliferate. When dispersing downstream they would have to negotiate two large drops over the weirs and cold water habitats further downstream and with the regular fishdowns within the weir, the numbers of tilapia dispersing must be limited. After the first detection of tilapia in the top weir, and the subsequent capture of 1,800 specimens shortly thereafter, it was thought that tilapia had a good chance of establishing further downstream and this in effect would open the entire Herbert River catchment to colonization by this species. However, this has not yet occurred. The weirs where the tilapia occur are the drinking water supply for Herberton township so cannot be drained or poisoned to rid of the tilapia. Fishdowns to reduce the resident population, thus limiting the chance of establishing new populations downstream offer the best solution to contain this problem from taking over the entire catchment. Research should be undertaken to determine the population size and on improved capture methods, as traditional methods are limited in the deep water of the weirs. 20 Figure 7. Map showing the distribution of exotic fish species in the Herbert Catchment. Hogan and Graham (1994) surveyed 11 lagoon and riverine sites on the Herbert floodplain but did not find any exotic species. The Queensland Museum has records of guppies from Ingham (incl. Palm Creek) from 1978 and Webb (2003) also recorded them there. Webb (2003) also found gambusia at several Ingham urban sites and in Ripple Creek at the Bruce Highway crossing. ACTFR (1999) surveyed 16 sites in creeks of the Herbert floodplain, finding gambusia at three sites in Ripple Creek, but none in other creeks such as Arnot, Cattle, Lannercost, Trebonne, Lagoon and Palm Creeks. Burrows et al. (unpub. data) have recently found gambusia on Mungalla, a wetland grazing property behind Forrest Beach that is part of lower Palm Creek (which runs through Ingham). Whilst surveying the Wild River for tilapia, ACTFR staff made the first records of gambusia from the upper Herbert catchment. Leggett (2003) recorded guppies at Flaggy Creek, a tributary of the upper Herbert River. DPIF (2007) surveyed 7 sites in the Herbert River (2 in the upper catchment and 5 in the lower) each over 5 years. They also found gambusia and guppies at one site near Rock Creek in the upper catchment and gambusia at the Bruce Highway crossing of the lower Herbert River. Malcolm and Graham (1998) surveyed for fish at 8 sites on Hinchinbrook Island, finding no exotic fish species there (Figure 6). Given the isolation of this island, this is not surprising. 21 Overall, there are three exotic species known from the Herbert catchment. The Mozambique tilapia have been present in the upper reaches of the Wild River since at least 2003 and are currently confined to the top two weirs on that system, in the uppermost tributaries. It is imperative that they do not spread from those locations (or are removed) as the amount of downstream stream length that would be invaded should they escape is considerable. The first official catchment records of gambusia for the lower catchment are from Webb (2003) and for the upper catchment, from Burrows et al. (unpub. data). Guppies have been known from the Ingham urban area since 1978 and from the upper catchment (Flaggy Creek, near Princess Hills) only since 2003. Discussion This report provides the most up-to-date and comprehensive analysis of the distribution of exotic fishes in the Wet Tropics region. This analysis was built up by compiling an extensive database of published and unpublished records from the region. Nine exotic species have been found at 144 of 764 (~19%) of sites surveyed in the region. Exotic species tend to be found closer to urban areas, which are more likely to have been subject to survey effort, and may therefore be disproportionately represented in fish surveys based on site occurrences. Additionally, some surveys included in the analysis were specifically searching for exotic, by including sites where exotics were more likely to be present, thus overestimating their occurrence. Nonetheless, it is clear that exotic species are reasonably widely distributed in the Wet Tropics region (Figure 8). Quantitative comparisons with other regions in Australia are not available but the Wet Tropics is likely to have among the most frequent occurrences of exotic fishes in Australia. The poeciliid guppy, Poecilia reticulata, was the most commonly encountered exotic species, being recorded from most major catchments in the region, and twice as many sites as the next most commonly found exotic species. Another poeciliid – the gambusia (or mosquitofish) Gambusia holbrooki, has only been recorded from 25 sites. This is surprisingly low, especially given that this species has been widely spread across many parts of Australia for several decades. The Herbert catchment is the only catchment within the Wet Tropics where gambusia are more commonly found than guppies. In other north Queensland catchments, south of the Herbert, such as around Townsville, gambusia are more widespread than guppies (Webb 2007). 22 Figure 8. Map showing the distribution of exotic fish species in the Wet Tropics region. The two tilapia species present in the region capture the greatest public and media attention. Spotted tilapia are known from the Barron, Cairns urban, Mulgrave and Johnstone catchments. Mozambique tilapia are known from the Barron, Cairns urban, Mulgrave, and upper Herbert catchments. Mozambique tilapia have also been previously recorded from resort ponds around Port Douglas and Wonga Beach but are no longer thought to be present there. Thus the most northerly contemporary location 23 for Mozambique tilapia are the beach areas north of Cairns, probably around Hartleys Creek. The distribution of both tilapia species within the region appears to be relatively even. However, spotted tilapia are only known from a single site outside of the Wet Tropics region (this being a cooling pond for a power station in Victoria – Cadwallader et al. 1980) whereas the Mozambique tilapia are well established in the Townsville and Burdekin regions plus in the Endeavour River, Cooktown and in catchments in SE Queensland and Western Australia. Generally speaking, the colder and faster flowing waters of most Wet Tropics streams do not favour the exotic species that have been introduced. Both tilapia species and the various poeciliids do best in slower-flowing and warmer waters. In the Wet Tropics, these conditions can be created in disturbed habitats which allow for dense waterside grasses such as paragrass to establish (providing slow water habitat) and the loss of riparian cover allows greater thermal heating of streams, further favouring exotic species. Retention/replanting of riparian vegetation is one of the few management measures available for exotic fish populations that are already established within Wet Tropics streams. Although exotic species are common in the region, it is clear that the amount of stream habitat without exotic species is much greater than that which contains exotic species. Thus there is still much to lose by the further spread of exotic species and measures to prevent spread, such as community education programs remain just as important and valid in these streams as they are in streams that contain no exotic species at all. This report is the first to provide a comprehensive documentation of the existing distribution of exotic fishes such that the streams with and without various exotic species are identified and can be protected from further invasions. 24 References ACTFR. 1999. Milestone report to SRDC. Unpublished milestone report. ANGFA. 2009. Online database. http://db.angfa.org.au/ Barron Mitchell Tilapia Management Group. 2000. Regional Management Plan for Tilapia (Barron and Mitchell Catchments). Barron River Integrated Catchment Management Association and Mitchell River Watershed Management Group. Barlow, C.G., Hogan, A.E. and Rogers, L.G. 1987. Implication of translocated fishes in the apparent extinction in the wild of the Lake Eacham rainbowfish, Melanotaenia eachamensis. Australian Journal of Marine and Freshwater Research 38: 897-902. Blühdorn, D.R., Arthington, A.H. and Mather, P.B. 1990. The introduced cichlid, Oreochromis mossambicus in Australia: a review of distribution, population genetics, ecology, management issues and research priorities. Pages 83-92 In: Pollard, D.A. (ed.) Introduced and Translocated Fishes and Their Ecological Effects. Proceedings No. 8 Australian Society for Fish Biology Workshop, 24-25 August 1989, Magnetic Island, Townsville, Queensland. Briggs, G. 2007. A week in the Wet Tropics. Fishes of Sahul 21(2): 318-333. Burrows, D.W. 2004. Translocated Fishes in Streams of the Wet Tropics Region, North Queensland: Distribution and Potential Impact. Cooperative Research Centre for Tropical Rainforest Ecology and Management.77 pp. Burrows, D.W. and Perna, C. 2006. A Survey of the Distribution and Abundance of Translocated and Exotic Fish Species in the Upper Catchment of the North and South Johnstone Rivers, North East Queensland. Report 06/34 Australian Centre for Tropical Freshwater Research, James Cook University, Townsville. Burrows, D. and Perna, C. 2009. A Survey for Exotic Freshwater Fish on Saibai Island and Thursday Island, Torres Strait. Report 09/01 Australian Centre for Tropical Freshwater Research, James Cook University. Burrows, D.W., Loong, D., Veitch, V., Williams, Y., Butler, B. and Dowe, J.D. 2007. Aquatic Ecology Monitoring of the Tully Training Area – 2007 Wet Season. Australian Centre for Tropical Freshwater Research, James Cook University, Townsville. Cadwallader, P.L., Backhouse, G.N. and Fallu, R. 1980. Occurrence of exotic tropical fish in the cooling pondage of a power station in temperate south-eastern Australia. Australian Journal of Marine and Freshwater Research 31: 541-546. Courtenay, W.R.Jr. and Meffe, G.K. 1989. Small fishes in strange places: a review of introduced poeciliids. Pages 319-331 In: Meffe, G.K. and Snelson, F.F.Jr. (eds.). Ecology and Evolution of Live-Bearing Fishes (Poeciliidae). Prentice Hall, New Jersey. 25 Hagedoorn, W.L. and Smallwood, D.G. 2007. Fisheries Long-Term Monitoring Program Summary of Freshwater Survey Results: 2000-2005. Department of Primary Industries and Fisheries, Brisbane. Hansen, B. 2000. “Starcke” raving mad. Fishes of Sahul 14(3): 699-708. Hogan, A. and Graham 1994. Herbert River Floodplain Fish Distributions and Fish Habitat. Interim Report to Consultants, Herbert River Sugar Industry Infrastructure Package. Freshwater Fisheries and Aquaculture Centre, DPI Walkamin. Hogan, A. and Graham 1994. Tully-Murray Floodplain Fish Distributions and Fish Habitat. Interim Report to Consultants, Herbert River Sugar Industry Infrastructure Package. Freshwater Fisheries and Aquaculture Centre, DPI Walkamin. Hogan, A. and Vallance, T. 2004. Wild River weir tilapia infestation: Internal Report, Agency for Food and Fibre Sciences, Fisheries and Aquaculture, March 2004. Queensland Department of Primary Industries and Fisheries. Kroon, F. 2004. A Review of Available Information on Aquatic Biodiversity in the Douglas Shire Catchments. CSIRO Land and Water Technical Report No. 31/04. Malcolm, H. and Graham, P. 1998. Freshwater Fish of Hinchinbrook Island. Queensland Department of Primary Industries. Poon, L., Westcott, D.A., Hilbert, D.W., Burrows, D. and Webb, A. 2007. Assessment of Research Needs for the Management of Invasive Species in the Terrestrial and Aquatic Ecosystems of the Wet Tropics. Marine and Tropical Sciences Research Facility, Cairns. 135pp. Pusey, B.J. and Kennard, M.J. 1994. The Freshwater Fish Fauna of the Wet Tropics Region of Northern Queensland. Report to the Wet Tropics Management Authority. Pusey, B.J., Kennard, M.J. and Arthington, A.H. 2007. Freshwater Fish as Indicators of Ecosystem Health in Wet Tropics Streams. Chapter 5 in Catchment to Reef CRC Final Report. Russell, D.J. 1987. Aspects of the limnology of tropical lakes in Queensland – with notes on their suitability for recreational fisheries. Proceedings of the Royal Society of Queensland 98: 83-91. Russell, D. J., Hales, P.W. and Helmke, S. A. 1996a. Fish Resources and Stream Habitat of the Moresby River Catchment. QDPI, Brisbane, Report No. QI96061. Russell, D. J., Hales, P. W. and Helmke, S. A. 1996b. 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North Queensland Naturalist 14: 25-27 and 15: 5-7, 9-13 and 20-21. Veitch, V, Webb, A. and Burrows, D.W. 2006. An Inspection of the Middle Reaches of the Tully River Catchment for the Exotic Mangrove Cichlid Tilapia mariae. Report 06/20 Australian Centre for Tropical Freshwater Research, James Cook University, Townsville. Webb, A. 2003. The Ecology of Invasions of Non-Indigenous Freshwater Fishes in Northern Queensland. Unpublished PhD Thesis, School of Tropical Biology, James Cook University, Townsville. Webb, A. 2005. Taxonomy, Distribution, Ecological, Social and Economic Impacts and Treatment of the Tilapiine Cichlids, the Mozambique Mouthbrooder, Oreochromis mossambicus and the Black-Spotted Mangrove Cichlid, Tilapia mariae: a Review. Report Prepared for the Queensland Fisheries Service by Aqualogia. Webb, A. C., Hogan, A. E. and Graham, P. A. 1996. Survey to Determine the Distribution of the Mozambique Mouthbrooder (Tilapia) Oreochromis mossambicus, in the Upper Barron River Catchment with Recommendations for Management. DPI Walkamin Research Station, Walkamin. Webb, A. 2007. Status of non-native freshwater fishes in tropical northern Queensland, including establishment success, rates of spread, range and introduction pathways. Journal and Proceedings of the Royal Society of New South Wales 140: 63-78 27