Brief description
Vital baseline information on the demersal fish assemblages within the metropolitan area was collected used baited-video stations. The sampling was directed using the knowledge of experienced fishermen, and researchers from the Department of Fisheries and UWA. Recent changes to legislation, banning commercial wetline fishing in the Metropolitan area, have provided an important natural laboratory with which to assess the impacts of fishing on the assemblage of demersal fish. From 5th October 2008 to 12th October 2008 stereo-baited remote underwater video (stereo BRUV) systems were used to sample these areas shown in green in the thumbnail (around Two Rocks). It provides a multi-species measure of the state of the fish community, including length measurements of the fish observed. This data will form an important baseline with which to assess any changes in the community and to investigate whether they are due to changes in fishing pressure or other impacts, such as climate change.Lineage
Statement: Stereo-baited remote underwater video (stereo BRUV) systems were used to sample these areas, providing a multispecies measure of the state of the fish community, including length measurements of the fish observed. This was undertaken using EventMeasure The thumbnail shows locations sampled by the Metro surveys (green) and previous two surveys around Rottnest (red). Each of the Metro survey locations were each surveyed using approximately 45 baited remote underwater video (BRUV) samples during October 2008.
Statement: Baited remote video sampling was conducted in the Two Rocks area in the north of metropolitan waters (see thumbnail). A near-shore to off-shore transect was completed including particular emphasis on the Direction Bank area. In particular sampling was conducted along the Five Fathom Bank (8-14 m), Bomboras to the north and south of Two Rocks in the Middle Ground (16-38 m) and along the inshore and offshore sides of Direction Bank (40-90 m) – see Table 1 for a list of the coordinates of the sampling locations.
Field work was conducted on a local commercial rock lobster fishers boat and the actual sampling plan was stratified for habitat based on the knowledge of the skipper and his father (+60 years of combined fishing experience). The sampling plan was stratified to target sea bed characteristics where high-risk demersal species would be likely to be found. Paul Lewis from the DoF assisted and observed the field work for two days and provided various spatial bycatch data from a gill net fishery that was used to help stratify the sampling.
The initial three days of sampling offshore from Two Rocks (~100 hours of remote video) was reviewed informally in the field to provide an initial estimate of the numbers of high-risk demersal species sampled. These densities appeared to be very low and it was therefore decided that the remaining sampling should be focused on the Two Rocks area. This are was chosen as fisher input suggested that populations of the high-risk species would be less abundant and more dispersed in other parts of the Metropolitan area. The additional samples collected at Two Rocks also allowed for the completion of the near-shore to off-shore transect.
Created: 11 08 2009
text: westlimit=115.1; southlimit=-31.85; eastlimit=115.5; northlimit=-31.3
text: uplimit=83; downlimit=5
Subjects
ANIMALS/VERTEBRATES |
AQUATIC ECOSYSTEMS |
BIOLOGICAL CLASSIFICATION |
BIOSPHERE |
EARTH SCIENCE |
Fish |
Marine Habitat |
bait_sampled |
biota |
depth |
file_name |
frame_number |
oceans |
sampling_code |
tape_reader |
taxonomic_family_name |
taxonomic_genus_name |
taxonomic_group_count |
taxonomic_name |
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Other Information
(Link to data on Data Fabric)
uri :
http://df.arcs.org.au/ARCS/projects/WAMSI/public/Node4/4.2.2b
Identifiers
- global : f8a33169-9228-4620-813d-59346ffa4952
