"If we'd estimated white shark abundance in the past using digital-DNA, we'd know whether shark attacks are increasing because there are more sharks around or for other reasons" Read more about the digital-DNA method and its application to estimating abundance of sharks in a recent press release from UQ.
At the MFL, we are keen to develop genetic methods for assessing abundance of fisheries populations. One method being explored is genetic effective population size. We are focusing on shark and ray populations, because they are generally less abundant than species like finfish and shellfish and the math is easier. A new study that was published today trials this method on leopard sharks. Christine Dudgeon and Jenny Ovenden found that genetic and conventional estimates of the numbers of adults in an aggregation off the coast of south-east Queensland were similar. This is one of very few studies worldwide that have been able to make this type of comparison. Its important it demonstrates how abundance can be inferred from DNA. Assuming tissue samples are available, the DNA method is quick and easy compared to tagging sharks and observing their occurrence over the years as a way of estimating abundance. Species can be more adequately protected when estimates of abundance are available. Email Christine Dudgeon (c.dudgeon at uq.edu.au, where at = @) for a copy of the paper. To find out more about Christine's leopard shark project in Thailand, click here.
Dean and Jenny presented their work to the final workshop for the FRDC-funded project "Shark Futures: sustainable management of the NSW whaler shark fishery". Their role within the project was to genetically resolve the effective population size of the dusky and sandbar sharks targeted in the Ocean Trap and Line Fishery. Vic Peddemors, Paul Butcher and Will Macbeth (project co-investigators) talked about other components of the work such as tagging data, bycatch mitigation, the efficacy of the shark identification guide-book and data collection from landed catch. Left to right: Trevor Daly (Fisheries NSW - threatened species), Jessica Morris (Humane Society International), Tooni Mahto (Australian Marine Conservation Society), Fiona McKinnon (Fisheries NSW - fishery manager), Paul Butcher (Fisheries NSW), Will Macbeth (Independent - NSW Fisheries Observer Program), Joshua Fielding (FRDC), Damian Collins (NSW DPI Biometrician) and Dean Blower (MFL, UQ) with Vic Peddemors (Fisheries NSW - out of frame).
In 2015 the Molecular Fisheries Laboratory will use DNA from historical remains to study how shark species respond to changes in the environment. The changes include gradual changes (associated with long-term changes in sea-levels, current patterns and thermal regimes) and abrupt changes (associated with anthropomorphic events such as exploitation, habitat alteration). Tiger sharks (Galeocerdo cuvier) are important to fishers and well as conservationists and are relatively common. Please contact us if you can help with the study, such as locating shark material that we can work with in the lab. We'd also like to hear from you if you have comments or questions about the study. The project will add value to studies on tiger sharks by PhD student Bonnie Holmes and link to the work of an honours student, postdoctoral researcher (Carlos Bustamante) and sabbatical visitor Professor Einar Nielsen. Photo: Bonnie Holmes
On Tuesday, 7th October 2014, the team met to discuss new scientific information coming out of the project. The workshop was held at the Sydney Institute for Marine Science. Here Dean Blower, PhD student at the University of Queensland, explains how the removal of sharks of breeding age is likely to effect estimates of effective population size made with genetic markers. The latest knowledge about the shark resource will be used to develop new assessment methods and management indicators for the dusky and sandbar shark fishery on the eastern Australian coastline. Workshop participants left to right: Vic Peddemors (Fisheries NSW – research), William Macbeth (independent consultant – research), Dean Blower (MFL, UQ), Paul Butcher (Fisheries NSW – research), Veronica Silberschneider, (Fisheries NSW – management), Andrew Goulstone (Fisheries NSW – management), Jenny Ovenden (MFL, UQ), Damian Collins (NSW DPI – biometrician) and Kathryn Lee (independent consultant – research).
Dean Blower and Jenny Ovenden are at the Sydney Institute of Marine Science today. Along with collaborators Vic Peddemors and Paul Butcher from NSW Fisheries and others, Dean and Jenny have been gathering new scientific data to assist the sustainable management of the whaler shark fishery on the eastern Australian coastline. Click here to see more about the project. The workshop today will review new scientific discoveries and integrate the results across disciplines.
Life history and genetic structure of three commercially targeted sharks in temperate eastern Australian waters
Pascal Geraghty has completed his PhD thesis at Macquarie University, Sydney. Pascal studied three shark species (dusky shark - Carcharhinus obscurus, , spinner shark - C. brevipinna, and sandbar shark - C. plumbeus). The thesis addresses important questions about the resilience of populations to fishing-induced mortality and the sustainability of the local fishery in inshore waters adjacent to the Australian states of New South Wales and southern Queensland. New data is also presented about the biological stock status of these species in Australia and surrounding waters, which will assist in managing these important fisheries. Pascal's thesis is available for download here. Congratulations to Pascal for his graduation in May 2014.
MFL members among 301 scientists who reject Western Australian Government’s lethal approach to shark mitigation
MFL members feel strongly that there is no scientific evidence in favour of the Western Australian Government's proposed use of drum lines (baited hooks suspended from large floats called drums) to reduce the shark hazard to ocean users. Jennifer Ovenden and other MFL members have added their names to the joint submission prepared by Jessica Meeuwig and colleagues. Read the submission here. A major focus of the work of the laboratory is the analysis and dissemination of new information about shark populations. Dean Blower's paper on Great White Sharks, and Jessica Morgan's paper on hybridisation in sharks are examples of MFL's work with sharks.
PhD student Pascal Geraghty led a team of scientists to uncover genetic aspects of shark populations on the eastern coast of Australia. The findings will be used in the management and conservation of these commercially harvested species. Here is the reference for the published paper :- Geraghty PT, Williamson JE, Macbeth WG, et al. (2014) Genetic structure and diversity of two highly vulnerable carcharhinids in Australian waters. Endangered Species Research 24, 45-60. or contact us for a reprint.
This pamphlet is a jargon-free zone for everyone interested the sustainable exploitation and conservation of marine and freshwater fishes. A download link to the pdf document can be found here.