PROJECT NUMBER
•
1997-113
PROJECT STATUS:
COMPLETED
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
258 results
PROJECT NUMBER
•
1997-139
PROJECT STATUS:
COMPLETED
Mesoscale oceanographic data analysis and data assimilative modelling with application to Western Australian fisheries
The more that is understood about the factors controlling the abundance of an exploited fish stock, the more optimally it can be harvested for sustainable yield and profit. It has been known for some time that catches of western rock lobster are closely related to the number of larvae surviving...
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
PROJECT NUMBER
•
1998-102
PROJECT STATUS:
COMPLETED
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
PROJECT NUMBER
•
1993-237
PROJECT STATUS:
COMPLETED
Development of software for use in multi-frequency acoustic biomass assessments and ecological studies
The development of the ECHO software has enabled the collection and analysis of large multifrequency acoustic data sets. The data can now be processed in a timely manner (via overlays) to quality assure and interpret underlying acoustic characteristics in the signals. From these analyses we can...
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
PROJECT NUMBER
•
1996-128
PROJECT STATUS:
COMPLETED
Use of archival tags for studying the movement and swimming behaviour of school sharks
There has been serious concern over the status of the school shark fishery for many years, and it has been the subject of numerous stock assessments (Punt & Walker 1998). It is a well researched species: Olsen (1954) showed that school shark can make extensive migrations, and that females moved...
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
PROJECT NUMBER
•
2002-014
PROJECT STATUS:
COMPLETED
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
SPECIES
Development of acoustic methods to survey orange roughy in the eastern and southern zones
Project number:
1995-031
Project Status:
Completed
Budget expenditure:
$144,588.00
Principal Investigator:
Tony Koslow
Organisation:
CSIRO Oceans and Atmosphere Hobart
Project start/end date:
20 Sep 1995
-
5 May 1999
Contact:
FRDC
1. Conduct 2-3 acoustic surveys of orange roughy spawning ground off St Helens, TAS during the peak spawning period 1995
2. Determine the species composition of acoustic marks through trawl sampling of the acoustic marks and the ensonification of targets with several frequencies
3. Determin the relative biomass and spawning condition of orange roughy in the Eastern and Southern zones during the spawining period based upon a survey of selected hills in the Southern Zone that contain the principal concentration of orange roughy
4. Assess the biomass of orange roughy in the area between St. Helens and the Southern Hills through a series of zig-zag transects between 700-1200m and to assess their spawning condition
Final report
ISBN:
0643 06191 6
Author:
Tony Koslow
Final Report
•
1999-04-09
•
9.30 MB
1995-031-DLD.pdf
Three acoustic surveys were carried out between 17 and 20 July 1996 on the orange roughy spawning ground off St. Helens, Tasmania. A combination of 22 demersal trawls and ensonification with three frequencies (12, 38 and 120 kHz) was used to assess the species composition around the spawning hill. Both methods showed that orange roughy were aggregated on only the north/northwestern half of the hill. Acoustic marks on the south/southwestern sector of the hill were composed predominantly of macrourids (rattails) and deepwater cods. This was the first successful use of multi-frequency acoustics to discriminate among species groups in a deepwater environment and should greatly enhance the resolution of deepwater acoustic surveys. Acoustic estimates of orange roughy biomass on the spawning hill ranged from 5649 - 9706 tonnes, down from 16,777 tonnes in 1993. A survey of the trawl ground off St. Patrick's Head noted a single moderate-sized aggregation on a single transect.
If the school as assumed to be spherical in cross-section, its biomass was 6% the biomass of the largest orange roughy school observed at St. Helens. The biomass at St. Patrick's Head thus appears to have been a small proportion of the biomass around St. Helens Hill during the survey, but the data were insufficient to derive a biomass estimate from this area with confidence. Acoustic surveys were also carried out on a small hill just north of St. Helens and on the seamounts in the Southern Zone but no significant acoustic marks associated with orange roughy were observed in these areas.
Several changes were made to the methods of analysis. First, the area of the strata comprising the St. Helens hill were re-calculated based on improved bathymetric and GPS data,. Secondly, we changed the method used to account for targets within the deep scattering layers (DSL) that extend across the survey area. A constant fraction of the ensonified targets were previously assumed to belong to the DSL, but this assumption was no longer tenable considering both the decline in orange roughy abundance on the hill and the ~2-fold variation in the abundance of midwater scatterers between surveys in 1996. Acoustic backscattering from areas outside the survey area were now measured for each survey and subtracted from the backscattering observed around the hill itself. These changes were applied retrospectively to biomass estimate from previous orange roughy surveys.
PROJECT NUMBER
•
2022-091
PROJECT STATUS:
CURRENT
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
PROJECT NUMBER
•
1994-115.80
PROJECT STATUS:
COMPLETED
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
PROJECT NUMBER
•
1995-058
PROJECT STATUS:
COMPLETED
Seamount fauna off southern Tasmania: impacts of trawling; conservation and role within the fishery ecosystem
In September 1995, the deepwater trawl fishing industry agreed not to trawl in an area of 370 km2 on the continental slope south of Tasmania for three years, as stated in a Memorandum of Understanding between the former Australian Nature Conservation Agency (now Environment Australia) (EA) and the...
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
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