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The main aim of this research program was to determine the potential for reducing the density of urchins to encourage the return of seaweeds and an improvement in urchin roe quality and quantity from remaining urchins. Tasmanian Sea Urchin Developments used two widely-separated sub-tidal experimental lease areas. One of these areas was at Meredith Point, on the east coast, and the other at Hope Island, on the south coast. Both sites had been subject to some overgrazing by urchins. At Meredith Point, the study area was divided into plots containing urchins at three densities: artificially enhanced, continually harvested and control (undisturbed). At Hope Island, controlled clearings of urchins and limpets from barrens areas were conducted. Recovery of vegetation was monitored as well as urchin roe quality and quantity. The data represented by this record was collected at Meredith Point.
In fishing trials, the short term survival rates for hook caught flathead (Platycephalus bassensis in Tasmania and P. fuscus in Queensland) were examined to determine critical factors affecting post-release survival. Biological information (size) and hooking location/damage were recorded and fish held for several days in aquaria to assess survival rates. In order to relate hooking location and catch rates for a range of hook types (including circle hooks) structured fishing trials and volunteer fishers (using a diary system) provided information on fish size, hook type and hooking location.
Gillnet fishing trials at a number of sites off the east coast of Tasmania have been undertaken to collect samples of the banded morwong, which are characterised based on size, age, maturity stage and sex structure. Otoliths are sectioned for age determination. The dataset comprises a major component of work carried out from the beginning of 2001 and available historic data (1995 to 2000) have also been uploaded into this database to provide a complete dataset. See attached reports for further information.
Metadata record for data from ASAC Project 2301 See the link below for public details on this project. ---- Public Summary from Project ---- This study develops and combines the latest molecular and electronics technology into a comprehensive investigation of diet and food-web relationships of Southern Ocean predators (whales, seals, penguins) and commercial marine resources (krill, fish, squid). This type of information is essential for ecosystem models that set sustainable catch limits for fisheries. From the abstract of the referenced paper: We describe seven group-specific primer pairs that amplify small sections of ribosomal RNA genes suitable for identification of animal groups of major importance as prey items in marine ecosystems. These primer sets allow the isolation of DNA from the target animal groups from mixed pools of DNA, where DNA-based identification using universal primers is unlikely to succeed. The primers are designed for identifying prey and animal diets, but could be used in any situation where these animal groups are to be identified by their DNA. Progress report from the 2006/2007 Season: Overall objective This new multi-year initiative project within the AMLR program aims to develop and combine the latest molecular and electronics technology to facilitate a comprehensive investigation of appropriately scaled and strategically located trophodynamics of Southern Ocean higher marine predators and commercial marine living resources. The objectives and early experimental design are largely responsive to needs determined by the Australian Antarctic Division's core-function obligations to CCAMLR, as well as other international organisations, the most relevant of which are the International Whaling Commission (IWC) and Southern Ocean Global Ocean Ecology Dynamics (SO-GLOBEC). Traditionally studies of diet of higher predators have often relied upon the use of a single, uncalibrated, methodology, and samples are usually collected in a manner that precludes stratification by age and sex class. Such studies are often subordinate experiments to a larger overall project. In contrast, the power of this new initiative project will be its focus on calibration across a suite of established and novel molecular and macroscopic techniques, feeding trials in controlled situations, direct linkage of samples to age and sex classes, and a detailed knowledge of the foraging behaviour of a sub-set of sampled animals. The parallel development and incorporation of electronic tools to measure predator foraging ecology further strengthens this work. In order to achieve the aims of this study a multi-disciplinary, widely collaborative and multi-streamed program has been developed. Methodological development underpins the potential power of this project to delivery its objectives. The detailed design-phase of incorporating these new approaches into an experimental framework will follow this developmental phase. In order to best represent the sub-objectives of each phase of this study, the work has been divided into the following core components: * Experimental Design (phase 1: methodological development) * Development of DNA-based molecular techniques to measure prey harvesting * Validation trials of molecular techniques * Modelling/analysis to develop a matrix of methodologies to best predict prey composition in predator diet * Development of electronic equipment to measure prey harvesting * Validation trials of electronic equipment * Experimental Design (phase 2: ecological experiments) * Integrated, question driven, field experiments Some components of this work will run contemporaneously (eg. development of molecular and electronic tools). This project has now been completed. The novel DNA based methods for studying animal diet have been researched thoroughly in controlled conditions and demonstrated to be useful and an advance on existing methods. The DNA based dietary methods have also been successfully applied to studying the diet of Blue whales, Fin whales, Antarctic fur seals, Macaroni penguins, Antarctic krill and bottlenose dolphins.
Quantitative surveys were undertaken at four sites in the Kent Group, north eastern Tasmania (southern and northern shores of East Cove at Deal Island, Winter Cove at Deal Island, NE coast of Dover Island) by divers using underwater visual census methods to survey the reef habitat.
Metadata record for data from ASAC Project 2295 See the link below for public details on this project. ---- Public Summary from Project ---- Longline fisheries represent a serious threat to the survival of Southern Ocean albatrosses and petrels. During line setting operations seabirds become entangled with baited hooks and are drawn underwater and drown. In the past 10-20 years populations of some species have decreased at an alarming rate and some species are considered to be threatened with extinction. The Antarctic Divisions seabird by-catch program is attempting to minimise mortality in longline fisheries by a multi-faceted approach involving mitigation research on fishing vessels, research on seabirds and initiatives of a semi-political nature. We chartered F/V Assassin for three days to trial a series of line weighting regimes under fishing conditions experienced in the east coast tuna fishery. Sink rates of lines with 52 combinations of swivel weight, bait type and bottom length were recorded. In Mooloolaba they don't use leaded swivels. Therefore it is an unweighted snood. Files Tuncurry_order_of_sets.xls Assassin TDR metadata.xls indicate the factors tested in the experiment, and the order in which they were undertaken. The Tuncurry_order_of_sets.xls file is the order in which the snoods (numbered by regime code) were put out during each line set. Should be read in conjunction with the metadata file. The D1, D2, D3 numbers denote the end of a working day when we downloaded the data from the day's line sets (4 on day 1, 6 on day 2, 5 on day 3). Files assassin summary means.xls assassin summary seconds to depth for analysis.xls assassin_means_to_depth.xls Assassin_time_to_depth_graphs.xls are files summarising the sink rates. The folder Final_data_files contains all the raw time depth recorder files. The fields in these datasets are: Bait type YT - yellowtail, SM - slimy mackerel, SQ - squid, SA - Saury, LYT - Live Yellow Tail, LSM - Live Slimy Mackerel, DYT - Dead Yellowtail, DSM - Dead Slimy Mackerel, DSQ - Dead Squid, DSQ + light/Sau - Dead Squid plus lightstik/Saury, DSQ + light - Dead Squid plus lightstik Bait life status (D - dead, L - live) Swivel weight (grams) Bottom length (metres) Number (n) Standard Deviation Time to depth (seconds) Light stik Side (SB - Starboard, P - Port) Day Replicate Regime (codes are the number of the snood (just a way to keep a track of the treatments)) Depth (metres) TDR Time Depth Recorder (number in each shot represent the individual time depth recorder number that was attached to the snood just near the hook) Taken from the 2008-2009 Progress Report: Progress against objectives: We have consolidated two research streams for pelagic longline fisheries. One is to conduct "conventional" mitigation research, principally focusing on methods to expedite gear sink rates, and the other is to develop an underwater bait delivery system for tuna and swordfish gear. Both streams are dealt with below. The conventional research focuses on operational aspects of gear, and at this stage does not involve seabird avoidance research (this will come later). In the last 12 months I have a) completed a designed experiment on a chartered tuna vessel off Mooloolaba, Queensland, examining the effect of mainline tension (created by use of a line shooter) on the sink rate of baited hooks in the shallow depth ranges; b) a designed experiment in Coquimbo, Chile (as part of Birdlife Internationals Albatross Task Force) examining the effect on initial sink rates of the five branch line deployment methods used by tuna vessels in the southern hemisphere, and c) completed five weeks in Mooloolaba with a chartered fishing vessel and in collaboration with DeBrett's Seafoods and Amerro Engineering, on the R and D of the underwater setting machine. Taken from the 2009/2010 Progress Report: In the past 12 months research work has focused on: a) the development of the underwater bait setting capsule, b) the effects of propeller turbulence on the sink rates of baited tuna hooks, c) the effect of improved line weighting on the catch rates of fish taxa. We have made considerable progress with the underwater setting machine and are intending to complete a "proof-of-concept" experiment with the device in Uruguay this winter/spring. Project "b" was completed on two vessels (one in Chile and one in Australia, as opportunities arose) and a paper was submitted to the Seabird Bycatch Working Group meeting of ACAP in April 2010. Part "c" above was completed in January 2010 and has morphed into a second trial that may show more promise that the first. When that trial has been completed the work will be written up for publication. Taken from the 2010/2011 Progress Report: Public summary of the season progress: Line weighting trials: A trial was completed on the effects of seabird friendly (fast sinking) tuna branch lines on the catch rates of target and non-target fish. No effects on catch rates were detected, clearing the way for test on effectiveness in deterring seabirds. Out of this trial grew a second study, involving weights placed at the hook. This trial probably has more promise than the first, and is currently underway in the Australian tuna fishery. Underwater setter: A prototype version was tested experimentally off Uruguay in the spring of 2010. The experiment revealed the potential of underwater setting to near-eliminate seabird interactions. We are currently finessing the technology with a view to returning to Uruguay (with the finished product) in autumn 2012 to complete the experiment.
The effect of barrens formed by the long spined sea urchin, Centrostephanus rodgersii, on the standing stocks of southern rock lobsters (Jasus edwardsii) and black lip abalone (Haliotis rubra) was estimated by divers using underwater visual census methods to compare lobster and abalone abundance in barrens with that in adjacent kelp habitat. Abalone (H. rubra) and rock-lobster (J. edwardsii) populations were compared on C. rodgersii barrens and in adjacent algal-dominated habitat at the same depth and on the same substratum type at three sites in eastern Tasmania (Elephant Rock:Binalong Bay, St Helens Is, and Mistaken Cape:Maria Island). At Elephant Rock and St Helens Island , the barrens are extensive and well established Type 1 barrens, while at Mistaken Cape the barrens in 8-14 m are incipient Type 4 barrens, comprising small barren patches in the algal bed (see FRDC report for classification of barren types). Note that while there are extensive barrens in deeper water (>18 m) at Mistaken Cape, at these depths working time is limited and it was difficult to locate intact macroalgal beds on equivalent substrata.