Tactical Research Fund: Development and deployment of sterile ‘Judas fish’ to assist carp eradication in Lake Sorell, Tasmania - surgical and chemical sterilisation
Critically, sterile Judas fish need to be developed/deployed by spring of 2013, before remaining females from the 2009 cohort begin to mature. Delay in project commencement beyond 2012 spring will critically hamper carp eradication in Tasmania.
To date, Integrated Carp Management (ICM) strategy has resulted in eradication of carp from Lake Crescent and contained their population to Lake Sorell, repeatedly demonstrating an ability to fish down new cohorts rapidly. Use of radio-tagged "Judas" male carp to locate and remove aggregations has been the largest contributor (e.g. accounting for >80% of carp captured in Lake Crescent). Despite low adult carp numbers spawning occurred in Lake Sorell (2009), prompted by exceptionally high water levels. Relatively large size of the lake (than Crescent) and resource limitations did not help. Male Judas carp were implicated in this recruitment prompting their removal and replaced by juvenile Judas in 2011- ID feeding aggregations; mature Judas also ID spawning aggregations.
In absence of Judas technique, it is deemed impossible to achieve control let alone eradication, prompting preliminary sterilization trials in 2010. Albeit with low success rate (1/11) the trials were encouraging with further comparative anatomical examinations revealing valuable clues for future refinement. In light of this progress multiple sterilized fish will be ready for deployment by October 2013, should the refinement/experiments commence this spring (2012). Two annual carp programme reviews (10-11 May 2011 and 19-20 May 2012) have recommended the technique/s be developed systematically—including alternative approaches along with hormonal, histological, behavioural and fertility assessment.
Primary objective is to develop/deploy behaviourally least compromised sterile Judas fish. Fish with compromised reproductive behaviour though not preferred are useful in betraying the numerically dominant non-reproductive aggregations.
Expected outcomes will contribute to long-term goals of recreation and commercial fishing sectors in inland waters of Tasmania, with likely interest to other states.
Final report
In a world first, the project successfully developed reliable procedures for surgical sterilization of male carp and demonstrated that these when deployed as sterile ‘Judas’ fish are as competent as male ‘Judas’ carp in betraying the locations of feral populations thus assisting their capture. Significantly, the sterile Judas fish will mitigate future risks associated inadvertent contributions to spawning and recruitment. The sterile Judas carp are now an integral component of the ongoing carp eradication program at Lake Sorell, Tasmania.
Following the discovery of the carp Cyprinus carpio in lakes Crescent and Sorell in 1995, the Inland Fisheries Service (IFS) decided to eradicate both the populations. While, the Lake Crescent population has been successfully eradicated, the Lake Sorell population has been lingering, owing to inadvertent spawning and recruitment in 2009 —contributed by Judas carp, which are otherwise central to the eradication strategy at the lakes. Responding to the crisis and urgent need to mitigate future recruitment risks this project explored chemical and surgical sterilization options with a view to replace male ‘Judas’ carp with sterile ‘Judas’ carp.
The primary objective of the project was to develop reliable sterilization technique/s that did not significantly compromise the behavior of the sterilized individuals. Behavioral integrity of the sterilized individuals when fitted with radio-transmitters and deployed as Judas fish (i.e. to assimilate and integrate seamlessly into the wild populations) was/is critical to betraying the locations of aggregations allowing targeted fishing and removal of feral populations.
Keywords: Common carp, Cyprinus carpio, steroid hormones, Superlorin, testis, tubectomy, Radio-tracking, Ultra sound.
Seafood CRC: A Final Seafood Omnibus: Evaluating changes in consumers attitudes and behaviours
The influence of fish movement on regional fishery production and stock structure for South Australia's Snapper (Chrysophrys auratus) fishery
Rock Lobster Post Harvest Subprogram: the effect of on-board cold water stunning on the survival and growth of caught and returned western rock lobsters (Panulirus cygnus)
Fish movement and migration - an ASFB workshop
Most fish and other exploited aquatic species exhibit movement and / or migrations during some part of their life cycle. In recent years the importance of these migrations to fish and fisheries management has been increasingly realised. Changed fish behaviour due to varying environmental conditions has significant impacts on species availability/catchability and hence the interpretation of abundance indices. In freshwater, improved fish passage is seen as one of the major areas for river rehabilitation to be conducted over the next decade. Spatial models which take into account, explicitly or implicitly, fish movements are now widely used. Recent technological developments allow for greatly improved analysis of the patterns of fish movement and migration. This Australian Society for Fish Biology workshop will be the first time that migration and movement has been considered in a national forum.
The workshop will bring together scientists, managers and other stakeholders with general or specific interests in movement and migration. The workshop will cover theoretical aspects; techniques for measuring movement and migration, particularly new approaches and technologies (such as radio-telemetry, smart tags and otolith micro-chemistry); environmental determinants, barrier and human interference; analysis and input into spatial models; and management implications.
Final report
Development of Fish Health Indicators for the Gladstone Harbour Report Card
Effects of Trawl Subprogram: evaluation of the effectiveness of reducing dolphin catches with pingers and exclusion grids in the Pilbara trawl fishery
The performance report on the Pilbara Trawl Fishery to Environment Australia reported a dolphin catch of approximately 50 per year. The initial reaction of EA to this level of dolphin catch indicated that continued exports from this fishery could be in jeopardy, making it necessary to reduce the dolphin mortality. Industry are aware of this need and are willing to participate in trials.