EARTH SCIENCE > AGRICULTURE > AGRICULTURAL AQUATIC SCIENCES > FISHERIES
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Publication of these results is currently in progress with the Journal of Animal Ecology. Summary 1.An efficient method of describing change in Antarctic marine ecosystems is long-term monitoring of land-breeding marine predators. High-level predators are used to index the state of environment on the notion that perturbations in the ecosystem will affect their diet, reproductive performance and other demographics. For this purpose, Weddell seals breeding at the Vestfold Hills have been marked and re-sighted for the past 28 years (1973 - 2000). 2.Successful reproduction requires considerable energetic resources. The difference between rates of conception and rates of parturition suggests pregnant females abort reproductive attempts when their energy stores are low. In this way, annual rates of reproduction (i.e. parturition) are a measure of foraging efficiency. 3.Previous attempts to estimate Weddell seal reproduction have been biased by different rates of re-sighting breeding and non-breeding females. We used multistate mark and re-sight models to account for this and other variables when estimating reproductive rate. 4.The amplitude of temporal variation was much greater for reproduction than for survivorship, indicating that parous (breeding) females maximised survival by reproducing less. This strategy could be successful in fluctuating environments because seals live longer and experience more reproductive occasions. 5.The population had low reproductive rates from 1983 to 1985 and throughout the 1990s. In those years, potential recruitment into breeding groups was reduced to 50 - 60 % of the cohort before viable pups were even born. 6.Even in years of low reproductive rate, typically half (52%) of the breeding females produced pups. It seemed that individuals differed in their foraging success and thus body condition and / or their functional response to this. 7.There was no evidence for costs of reproduction. We infer that the seals responded to environmental conditions prior to parturition, as opposed to proceeding with reproduction when inadequately resourced and depleting energy resources such that they had lower probability of surviving or reproducing the following year. 8.Synthesis and applications: This study demonstrates a method of estimating reproductive rate that overcomes bias inherent in traditional methods. Estimated in this way, we propose that reproductive rate is the best indicator of the state of marine ecosystems that can be indexed for Weddell seals. The fields in this dataset are: Year Standard Error Upper confidence interval Lower confidence interval Breeding probability Upper error bar Lower error bar
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From the abstract of the referenced paper: 1. Incidental mortality in fisheries is causing declines in many albatross populations around the world. To assess potential interactions with regional fisheries satellite tags were used to track black-browed albatrosses (Thalassarche melanophrys) and light-mantled sooty albatrosses (Phoebetria palpebrata) breeding on Heard Island during the chick-rearing periods of 2003/2004. This was the first time individuals from either population had been tracked. 2. Black-browed albatrosses foraged largely within the Heard and McDonald Islands Economic Exclusion Zone (EEZ) north-east of the island, although 20% of foraging trips were to areas north of the EEZ into Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) areas 58.5.1 and 58.5.2 and into the Iles Kerguelen EEZ. 3. In contrast, the light-mantled sooty albatrosses foraged well south of Heard Island along the southern boundary of the Antarctic Circumpolar Current. Both species appear to face minimal risk of incidental mortality during the chick-rearing period in the regulated, legal fisheries, but are threatened by illegal, unreported and unregulated (IUU) fishing vessels operating in the southern Indian Ocean. The data have been loaded into the ARGOS database held by the Australian Antarctic Data Centre. An excel spreadsheet detailing PTT number (position tracking terminal), date of attachment, date of retrieval and species is also provided as an aide to searching the ARGOS database. Two articles are also associated with this record, a refereed journal article, plus an article in the Australian Antarctic Division's Antarctic Magazine. The fields in this dataset are: Species PTT number Date of attachment Date of retrieval Latitude Longitude Time
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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.
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This project aims to assess the vulnerability of and risks to habitats in Australian fisheries in the Australian Exclusive Economic Zone (EEZ)/Australian Fishing Zone (AFZ) of the Southern Ocean to impacts by different demersal gears - trawl, longline and traps. The project which is a collaborative initiative between the Australian Antarctic Division (AAD), the Australian Fisheries Management Authority (AFMA), industry and research partners, and substantially funded by the Fisheries Research and Development Corporation, was developed in order to resolve outstanding questions relating to the potential impacts and sustainability of demersal fishing practices in the AFZ at Heard Island and the McDonald Islands (HIMI). It will also help resolve similar outstanding questions for other fisheries in the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) in which Australian industry participates and provide technology for use in other fisheries to address similar questions. The proposed project will assess the degree to which demersal gears interact with and possibly damage benthic habitats. It will also assess the degree to which these habitats might be damaged within the AFZ in the HIMI region. The project is not intended to estimate rates of recovery of benthic habitats following damage by demersal gears. However, information from the literature on rates of recovery of different benthic species and habitats will be used to assess the risks of long-term sustainability of these habitats. Objectives To develop deep sea camera technologies that can be easily deployed during fishing operations, to facilitate widespread observations of demersal fishing activities (trawl, longline and trap) and their interactions with benthic environments. To assess the vulnerability of benthic communities in Sub-Antarctic (Australian AFZ) and high latitude areas of the Southern Ocean (Australian EEZ) to demersal fishing using trawls, long-lines or traps, using video and still camera technologies. To assess the risk of demersal fishing to long-term sustainability of benthic communities in these areas, based on the assessment of vulnerability and information from the literature on potential recovery of benthic species and habitats. To recommend mitigation strategies by avoidance or gear modification, where identified to be needed, and practical guidelines to minimise fishing impacts on benthic communities. Target Outcomes 1. Assessment of the vulnerability of benthic habitats and species to damage by demersal fishing practices, based on field observations and experiments. 2. Assessment of risks from demersal fishing to the sustainability of benthic habitats based on field work and knowledge from the literature on recovery of different types of benthic species and habitats. 3. Modifications, as needed, to either fishery management or fishery practices in the HIMI and/or other Southern Ocean fisheries resulting in long-term sustainability of benthic habitats. 4. Improved knowledge of the distribution and species composition of marine benthic ecosystems in the Australian EEZ. 5. Video and still camera technologies that can be easily used by AFMA Observers and marine research institutions (both domestic and international) investigating the interactions of demersal gears (trawls, longlines and traps) with benthic environments. Notes from the Word document written by Kirrily Moore: The original core of the database (ie the taxa tree) was copied from a similar taxonomic database at CSIRO Marine Research in late 2005. At the time I was just starting to sort the benthic samples obtained in the cruise Southern Champion 26 (SC26) which formed the main part of the assessment of the conservation values of the HIMI Conservation Zones. There wasn't a database immediately available and applicable to the species or taxa I was likely to encounter so we (Tim Lamb and I) sourced the taxa tree and all the taxonomic hierarchy from CSIRO as a starting point. Tim then designed the forms and tables for the cruise, haul and sample details based on the existing FishLog database. There are many species in the taxa tree which are not Antarctic or sub-Antarctic, they were simply already in the taxa tree when we obtained the sanctioned copy. The database is a work in progress which has developed as Tim has responded to my requests for changes. The demands of the database have changed in the last few months as we've been working through the backlog of invertebrate taxa in the freezer. It has extended from the original cruise (SC26) to many cruises and thus now includes pelagic invertebrates more commonly associated with fishing gear (rather than purely benthic taxa collected in beam trawls and benthic sleds). The download file includes an access database and a word document detailing some information about the database. A folder containing photos that needs to be associated with the database is also available, but as it is over 3 GB in size, it is not available as a download, but will be available on request to the AADC (once this dataset is publicly available). Taken from the 2009-2010 Progress Report: Project objectives: 1/ To develop deep sea camera technologies that can be easily deployed during fishing operations, to facilitate widespread observations of demersal fishing activities (trawl, longline and trap) and their interactions with benthic environments. 2/ To assess the vulnerability of benthic communities in Sub-Antarctic (Australian AFZ) and high latitude areas of the Southern Ocean (Australian EEZ) to demersal fishing using trawls, long-lines or traps, using video and still camera technologies. 3/ To assess the risk of demersal fishing to long-term sustainability of benthic communities in these areas, based on the assessment of vulnerability and information from the literature on potential recovery of benthic species and habitats. 4/ To recommend mitigation strategies by avoidance or gear modification, where identified to be needed, and practical guidelines to minimise fishing impacts on benthic communities. Progress against objectives: 1/ Progress against objective 1 is well advanced. Underwater camera system units have been developed, refined and are currently deployed on commercial vessels fishing in the subantarctic. 2/ Progress against objective 2 is well advanced. Underwater camera system units, beam trawls and benthic sleds have been used to assess the types and distribution of benthic habitats in the sub-Antarctic and in high latitude areas of the Southern Ocean. Theoretical and empirical analyses of the resistance of key habitat-forming benthic invertebrates to impact from demersal fishing gear is ongoing. This will form the basis of an assessment of the vulnerability of the various habitat types to demersal fishing operations. 3/ Progress against objective 3 is ongoing. Theoretical analysis of the resilience of key habitat-forming benthic invertebrates to impact from varying levels of demersal fishing pressure is ongoing. Analysis of current fishing effort and future fishing scenarios is ongoing. The risk of fishing to the sustainability of benthic communities in these areas will be assessed from their vulnerability to impact, their resilience or ability to recovery from impact, and from current and potential future patterns of demersal fishing. 3/ Progress against objective 4 is ongoing. Analysis of in-situ video footage of commercial and simulated demersal fishing operations captured with the underwater camera systems, with reference to factors such as depth, habitat type, wind, sea-state, current and gear configuration is revealing strategies for mitigating and minimising the impact of demersal fishing.