November 2007 Northern Guf Resource Management Group Freshwater fish and bugs in the Gilbert River

Inside : Collecting the facts Increasing local awareness 2 During June 2006, the Depart- catching fish, the scientists thing in this short newsletter Fishing with electricity 2 ment of Primary Industries and enjoyed fantastic local hospi- will interest you. Fisheries (DPI&F) and Ecowise tality and support, for which The information gathered will Where are the fish? 3 Environmental Pty Ltd surveyed we were most grateful. assist the NGRMG and locals the fish and visible aquatic In this newsletter you will find to make and contribute to Water quality and habitat 3 invertebrates (bugs) in the Gil- out how an electrofisher management decisions for the bert River catchment. The works, how we determined northern Gulf region. Floods and flows are vital 3 survey was initiated by the the health of the Gilbert River Northern Gulf Regional Man- catchment and why aquatic agement Group (NGRMG) to Aquatic macroinvertebrates 4 habitat is important. This is a address the lack of knowledge quick summary of the findings of the diversity of life in the No water - what happens? 5 and an explanation of the region’s waterways. importance of maintaining Over a 10 day period, 20 sites river flows and floods. A Acknowledgements 5 were sampled to identify the much more detailed report is visible bugs, which fish and available from the NGRMG Recommendations 6 how many lived there, and how office. healthy the catchment was at So whether you are keen List of fish found 7 the time. While the trip was fisher, a budding naturalist or hectic and involved being just interested in the water bogged, bush bashing, croco- quality and aquatic biodiver- dile wrestling and of course Special points of sity of the local area, some- Surveying near Mt Surprise interest:  1557 fish measured Gilbert catchment clean and healthy  38 fish species found

 9 fish species re- The fish and invertebrate to access funds to reduce community, water quality and weed and pig infestations. corded for the first aquatic habitat in the Gilbert time in the Gilbert At the sites surveyed, current catchment are in a very pasture condition had no ob-  2 totally new species healthy state. The obvious vious influence on fish diver- and 3 requiring fur- threats to this healthy status sity or abundance or water ther investigation are weeds and feral pigs. quality. Weeds can smother trees and  3599 “bugs” col- grazing land. Pigs destroy However any changes in wa- Attempting to get the boat to the lected river and lagoon banks and ter management practices will water need careful consideration as  75 families of degrade water quality. river flows are the single most aquatic invertebrates The technical report from this important factor influencing (bugs) study will assist the NGRMG catchment health. Page 2

Increasing local awareness

An important part of this basic habitat assessments. project was to increase the All landholders were supplied capacity of NGRMG staff with a written summary of and Gulf residents to under- aquatic habitat, water quality stand and become familiar Station owners/managers participated and fish species found in their with the different ways to in sampling at most sites waterbodies. describe and assess catchment condition. Feedback from participants was extremely positive and Several members of the requests for return visits have NGRMG, local residents and been received. landholders participated in field sampling which provided The skills learned will assist them with basic aquatic ecol- landholders to develop farm ogy skills. This included iden- management plans and to tification of fish and bug spe- understand “jargon” often cies, measurement and inter- used by government consulta- Savannah guides also partici- pretation of water quality and tive committees. pated in sampling Backpack electrofisher in a small wa- terbody Catching fish with electricity

Electrofishing is the best way fluence its effectiveness, in- unconscious for up to 90 sec- “it’s powerful enough to capture large numbers of cluding water hardness, water onds. And before you ask, yes to kill a human yet fish fish quickly with no harm to temperatures and operator it does stun crocodiles … are only unconscious the fish. We use two types of skill. It is not as easy as it briefly! for up to 90 seconds” electrofishers. For very small looks and requires lots of Fish were identified and up to waterbodies we have a back- experience to pick the most 20 of each species measured pack unit powered by a bat- effective settings to collect and recorded then returned tery, and for everywhere else, whatever fish are present. An unharmed to the water. a boat mounted unit powered electric current basically an- by a 7.5KVA generator. aesthetizes fish. We use up to Any fish that were “new” or 1000 volts and 7 or more different were preserved and Electrofishing only works in sent to the Mu- freshwater. Many factors in- amps, more than enough to kill a human, yet fish are only seum for positive id.

What about river frontage land condition?

“Most pleasing was the lack of urban rubbish” At each site the condition of “wet” had just finished, a lot to manage. land adjacent to the water- of it was weeds and grass spe- No link was found between body was assessed using the cies not desired by the grazing GLM land condition, water ABCD rating system adopted industry. This meant most quality, fish distribution or by the Grazing Land Manage- sites were rated C. The best abundance. Whether this ment (GLM) project (A = rating was a B and two sites remains the same throughout excellent to D = poor). Our rated D. the year is unknown. assessment was reviewed by a The greatest disturbance to What was noticeable through- member of the GLM team river banks was caused by pigs out the catchment was the (Kev Shaw) from photos. which contributed to the sites absence of rubbish. Obviously While most sites had good with a “D” rating. Unfortu- the community cares about its ground cover because a good nately this damage is difficult catchment. Page 3

Where are the fish?

While site specific data was 195m above sea level (AHD). Three species, the Papuan kept confidential by request, Only two fish species were river sprat, northwest glassfish trends within the fish popula- found at all sample sites: and freshwater anchovy, were tion on a catchment scale spangled perch and rainbow- only found in offstream la- were obvious. No secret fish- fish. Five fish species were goons. ing spots revealed in this seg- found only above 195m AHD Sites closer to the coast Fish captured during ten minutes ment … sorry. while 12 species were only tended to have a greater Barramundi were scarce in the found below. number of fish species. middle to upper reaches of The most widespread and Even more species are likely the catchment despite suitable common species of interest to to exist in the lower reaches habitat. The timing and size anglers include sleepy cod, of the Gilbert River. However of the wet season may influ- archerfish, sooty grunter, gulf wet weather prevented access. ence how far and where bar- grunter and barramundi. ramundi travel. It appears that The great news was that no There were also eight differ- feral or exotic fish were de- in 2006, barramundi were ent species of catfish. limited to areas less than tected. Sleepy cod being measured Water quality and habitat “excellent”

Water quality across the Dissolved oxygen, pH, tem- the more oxygen there was in catchment was generally ex- perature and turbidity (water the water and the more spe- cellent. One spring had sur- clarity) were also measured. cies it contained. prisingly low conductivity Water in offstream lagoons Fish habitat was excellent at (almost as pure as rainwater). tended to be cloudier than the most sites, with overhanging instream waterholes. This is Conductivity is basically a trees, snags and aquatic plants Water quality monitoring measurement of dissolved usually because floodplain plentiful. Erosion and silta- minerals. Spring and bore lagoons are filled by sediment tion was generally low with water normally contains high laden floodwaters. the exception of one site levels of dissolved minerals Dissolved oxygen is critical to which had major pig damage. and is classified as “hard”. aquatic life. All sites had good The banks had been uprooted The reasons for such a low levels of oxygen. We found and the water quality was also reading are a mystery. that the wider the water body, lower than at similar sites. Floods and flows are vital

According to historical re- Fish within the Gilbert catch- and the juveniles don’t get an cords, rainfall is surprisingly ment require both flood peaks opportunity to migrate up- evenly distributed across the and a good steady flow in the stream and across floodplains. Gilbert catchment. There is river to move about, spawn Managers (this includes land- distinct seasonality though, and access permanent water holders) of streams within the with most rain falling between to sustain them through the catchment require a good November and March. This dry season. Reduced floods understanding of the flow does not always translate to or flows will reduce fish distri- characteristics and their rela- regular river flows. The only bution, abundance and diver- tionship with aquatic ecology. months to always have some sity. The timing of the flows Any development that is likely flow are February and March. is also important to species to change the flow of streams There may be multiple flood such as barramundi that move within the Gilbert catchment peaks in between low or no between salt and freshwater. needs to be thoroughly as- flows. If flows are too early or late sessed for potential impacts What does this mean for fish? they miss the chance to mi- on the aquatic environment. grate downstream to spawn

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Aquatic Macroinvertebrates (visible water bugs) The Aquatic Fauna Biodiver- the ecology of our waterways. our waterways. sity Survey conducted for the Their survival and well-being The current study conducted NGRMG in June 2006 fo- is crucial for the long-term by Ecowise Environmental cused on both fish and survival of fish and water- for the NGRMG had two aquatic macroinvertebrates at birds, many of which use bugs main aims. Firstly, to find out 20 sites in the Gilbert River as a primary food source. Typical small aquatic macroinverte- just what lived in the Gilbert Catchment. Whilst we all brate animals that live in the Gil- Across and overseas, River catchment, as few stud- know what fish look like (and bert River. (Photo: Ecowise Envi- biologists have found that the ies have been conducted in how tasty they can be) very ronmental) diversity (i.e. range of differ- the past in this region. Sec- few of us are familiar with ent species) and abundance ondly, to determine the health aquatic macroinvertebrates, (i.e. numbers of animals) of and condition of the water- the small aquatic animals aquatic macroinvertebrates ways in the catchment. The without backbones that live in can provide an accurate meas- end point of all of this impor- the waterways of the region ure of the health and condi- tant information is the sus- and comprise insects, bugs, tion of our waterways. Essen- tainable management of the beetles, shrimps, worms and tially, the greater the diversity region’s precious water re- snails (amongst other groups). and abundance of aquatic sources and the animals, in- They inhabit the water col- macroinvertebrates the dustries and people that rely umn, stream bed, aquatic healthier the waterway. Long on that water. plants, logs and rocks and term monitoring will show form a very important part of any changes to the health of Sampling for Aquatic Macroinvertebrates

Collecting aquatic macroinver- habitat (i.e. shallow main chan- macroinvertebrates at each site tebrates is relatively easy. A nel section with a coarse sand/ in a reasonable timeframe. specially designed sweep net is rocky substrate) were sampled. Once collected, the bugs were all that is required. The still A nationally recognised, stan- live picked in the field, pre- water environments along the dard sampling method was used served, and returned to the edge habitat, and where avail- which aimed to consistently laboratory for positive identifi- able, the flowing water riffle collect the widest diversity of cation and counting.

What Did We Find? Sampling for aquatic macroinvertebrates using a sweep net and picking live bugs on the river During this project, a total bank of 20 sites were sampled covering approximately (Photo: Ecowise Environmental) 38,000 km2 of catchment. A total of 75 macroinverte- of macroinvertebrates and diversity were also observed brate families and 3,599 water quality. when the current survey data individuals were collected. No obvious differences were for 2006 was compared with historic data collected by the The aquatic macroinverte- River catchment is therefore observed in macroinverte- brate community structure Department of Natural Re- brate data was analysed considered to be in good to ex- sources and Water from the using a series of sophisti- cellent condition with a high between offstream natural lagoons (4 surveyed), springs Gilbert catchment in 2003 cated tools including mod- number of macroinvertebrate and 2004. Ecosystem health elling and a range of com- taxa present, good water quality, (2 surveyed) and instream pools (14 surveyed). All sites ratings were consistent across plex statistical routines. and reasonable physical habitat sampling events indicating The results from this analy- characteristics. This applied showed similar diversity and relative abundance values, that the catchment and water- sis showed that the aquatic across the entire catchment from ways have been relatively sta- macroinvertebrate fauna the upper reaches to the lower with key influences being the diversity and quality of in- ble and in good condition for were diverse and generally regions. Only one of the 20 sur- at least the last three years. characteristic of a healthy veyed sites was considered to be stream habitat. Similar pat- ecosystem. The Gilbert in relatively poor health in terms terns of macroinvertebrate

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Have you ever wondered where the animals go when there is no water? droughts. In future ecosystem assess- ments in the northern gulf region, it is strongly recommended that increased attention be paid to the ecology of the hyporheos, given the importance of this unique zone to the maintenance of biodi- versity in streams. The sub-surface zones in many rivers are threatened by siltation, toxicants and increasing acidity, physical damage or altered groundwater levels (e.g. through mine dewatering). Damage to the hyporheic zone could severely impact on the capacity of a river or stream to recolo- nise (recover) following the dry season and this would in turn affect higher forms The Gilbert River is an intermittent temporary stream which flows only after substantial rain- of life such as fish. fall. It dries up to a series of pools and waterholes with large sections of dry sandy stream bed Another underground group of fauna is (Photo: Ecowise Environmental). called stygofauna. These subterranean animals live in caves and aquifers and Whilst on the surface the pools and wa- stages, burrowing and hibernating, utilis- tend to be at greater depths than hypor- terholes in a stream appear isolated, in ing moist leaf litter, and of course surviv- heic fauna (usually some metres to over reality they are closely and intricately con- ing in the last remaining permanent water- 100m below the surface). They have been nected through the saturated sediments holes and pools until the next major rain- largely unexplored in the northern gulf below and beyond the banks of the fall event. The sub-surface zone is a re- region. Along with the hyporheic fauna, stream. This zone is called the hyporheic gion of dynamic exchange of water and any assessment of biodiversity or ecosys- zone and the animals living in it are called materials between the groundwater, under tem health for the northern gulf should hyporheos. This sub-surface zone is criti- bank aquifers and the river flowing above. include stygofauna. Water management cal for the survival of many macroinverte- When the river stops flowing the sub- plans that are developed for the region brates during the dry season and for the surface zone provides a constant and criti- that have the potential to impact on maintenance of water quality. Aquatic cal habitat for a variety of truly stream, groundwater quality or quantity will have macroinvertebrates exhibit a range of rather than subterranean organisms. a direct influence on the biodiversity and strategies for surviving the dry period in Moreover, their total numbers may be health of groundwater dependent ecosys- temporary streams including mobile adult very high and this zone can be a major tems, with the potential for species ex- stages, desiccation resistant eggs or larval source of recruitment after floods and tinctions, even reduced numbers of fish.

What to do? the survey program can be ex- tended over ensuing years to There is a lot left to do. The Northern Gulf cover all the major waterways of Consideration Region covers approximately 194,000 km2, an the region. Consideration should should also be area approximately three times the size of also be given to looking at the given to looking at the unique and . The Region comprises the catch- unique and largely unexplored ments of the Norman, Gilbert, Staaten and largely unexplored biodiversity of the region’s animals in the Mitchell River systems, all of which flow into A small blind animal groundwater aquifers and caves. r e g i o n ’ s the . To date we have that lives its entire life in Such information is essential to groundwater looked at only the Gilbert River catchment. aquifers and caves. groundwater (Photo: enable the sustainable manage- Future aquatic fauna survey work is planned Ecowise Environmental) ment of the region’s precious for the Staaten River in 2008 and it is hoped natural resources.

Acknowledgements

We sincerely thank the NGRMG and staff for commissioning and supporting this study, which was made possible through funding from the Natural Heritage Trust. We are most grateful to the dozens of local pastoralists who provided advice, access and personal knowledge. We hope you continue to enjoy your environment. Thanks also to colleagues in the Queensland museum, DPI&F and DNRW.

Page 6 Further Information

For further information or access to the technical report, For further information on fish, please contact: please contact: Alf Hogan Noeline Gross Alf Hogan and Associates Fish Ecologists NGRMG Georgetown Qld 4871 Phone: 0447 953 186 Phone: (07) 4062 1330 E-mail: [email protected] E-mail: [email protected]

If you would like to discuss the aquatic macroinvertebrate program in more detail please contact: Garry Bennison Ecowise Environmental Pty Ltd Phone: 0407 243 139 E-mail: [email protected] Recommendations

The following recommendations are the views of the authors and may not be adopted by NGRMG. They are considered necessary to increase knowledge and thus assist with informed management. Further discussion is presented in the technical report. 1. Install and reactivate stream gauges in the catchment to accurately measure flows and monitor water management plans. 2. Accurately map and measure sub-surface flows and volumes. 3. Survey the sub-surface fauna, particularly in the bed sand aquifers (whole new ecosys- tems are being discovered in this environment). 4. Increase the effort on weed and pig control. 5. Publicise the litter-free status of the catchment, install road signs and produce educa- tional material particularly for tourists to maintain the litter-free status. 6. Survey the fish and aquatic invertebrates of the lower reaches to complete the inven- tory of fish and aquatic invertebrates in the catchment. 7. Access for the general public to freshwater fishery resources needs to be facilitated which may require the development and adoption of codes for acceptable use. City dwellers won’t appreciate or understand the Gulf if they never get to see it.

Future research

The Staaten River catchment is an-  aquatic macroinvertebrate diver- other area that has very little infor- sity in the Northern Gulf mation on aquatic life. DPI&F and  Ecowise Environmental successfully Water quality and aquatic habitat submitted an application for funding assessment to NGRMG to conduct fish and  identification of potential threats macroinvertebrate surveys in 2008. to streams and wetlands The Staaten catchment is especially  aquatic ecology information for interesting as it joins with the Gilbert managers to make decisions and Mitchell catchments during ma- about sustainable use of water jor floods. resources The outcomes of this study include:  increased awareness of aquatic  a description of fish species, biodiversity and local skills in monitoring biodiversity in the their distribution and abundance region Page 7 List of fish species found in the Gilbert River catchment during a post wet season survey in 2006.

# of Common name Species name Status Sites

Eastern rainbowfish Melanotaenia splendida 20 widespread (may be a number of subspecies) Spangled perch Leiopotherapon unicolor 20 widespread in northern Australia Bony bream Nematalosa erebi 16 widespread in northern Australia Sleepy cod Oxyeleotris lineolata 14 widespread in northern Australia Archerfish Toxotes chatareus 13 widespread in northern Australia Sooty grunter Hephaestus fuliginosus 12 widespread in northern Australia Long tom Strongylura krefftii 11 widespread in northern Australia Mouth almighty Glossamia aprion 10 widespread in northern Australia Banded grunter Amniataba percoides 10 widespread in northern Australia Hyrtl's tandan Neosilurus hyrtlii 8 widespread in northern Australia Square-blotched goby Glossogobius sp. C 4 widespread in northern Australia Flathead goby Glossogobius giurus 4 widespread in northern Australia Barramundi Lates calcarifer 3 widespread in northern Australia Forktailed catfish Arius graeffei 3 widespread in northern Australia Tarpon Megalops cyprinoides 1 widespread in northern Australia Gulf grunter Scortum ogilbyi 13 widespread in Gulf, Reticulated glassfish Ambassis macleayi 9 widespread in Gulf, Northern Territory Golden goby Glossogobius aureus 7 widespread in Gulf, Northern Territory Berney's catfish Arius berneyi 6 widespread in Gulf, Northern Territory Salmon catfish Arius leptaspis 4 widespread in Gulf, Northern Territory Striped sleepy cod Oxyeleotris selheimi 7 widespread in Gulf, Northern Territory, several colour variants Carpentaria catfish Arius paucus 5 widespread in Gulf, previously recorded as A. midgleyi Northern trout gudgeon Mogurnda mogurnda 4 widespread, but probably several species Snub-nosed gar Arrhamphus sclerolepis 3 widespread, but possibly an undescribed species Fly-specked hardyhead Craterocephalus stercusmuscarum 4 probably a number of genetically distinct subspecies Freshwater anchovy Thryssa scratchleyi 2 reported as uncommon Gilbert's grunter Pingalla gilberti 2 reported as uncommon Elongate glassfish Ambassis elongatus 9 new record for the Gilbert River, range extension Giant glassfish Parambassis gulliveri 3 new record for the Gilbert River, range extension Northwest glassfish Ambassis sp. 2 new record for the Gilbert River, range extension Papuan river sprat Clupeoides cf. papuensis 1 new record for the Gilbert River, range extension Toothless catfish Anodontiglanis dahli 8 new record for the Gilbert River Black catfish Neosilurus ater 6 new record for the Gilbert River Saltpan sole Brachirus salinarum 2 new record for the Gilbert River Rendahl's catfish Porochilus rendahli 1 new record for the Gilbert River Freshwater sole Brachirus selheimi 1 new record for the Gilbert River unknown goby Glossogobius sp. 1 undescribed species Gilbert gudgeon Hypseleotris n. sp. 1 undescribed species

Notes: 1. There were 20 sites surveyed. The number of sites listed is an indication of how widespread in the Gilbert catchment each fish species is. A low number does not necessarily indicate a species is rare. 2. This list is incomplete. A wider survey should find more species, particularly in lower reaches that were too boggy to access.