Fig 1.
Study location showing the standardised discard rate (number of individuals standardised by swept area (see methods)) of all study species groups (elasmobranchs, crustaceans and fish combined) per trawl trip in all zones.
Also shown are shaded depth increments (30 m). New South Wales is shown as grey in the inset. Shape and raster files used to create this image are available at https://data.gov.au/dataset/ds-dga-a1b278b1-59ef-4dea-8468-50eb09967f18/details and https://www.gebco.net/data_and_products/gridded_bathymetry_data/.
Table 1.
Number of observed ocean prawn trawl trips by fishery year, season, zone and depth (< = 75 m is shallow and > 75 m is deep).
Table 2.
Number of discard species or higher taxa summarised by study groups by fishery zone and depth (< = 75 m is shallow and > 75 m is deep).
Table 3.
Generalised additive mixed model results for species groups relationship with environmental and operational factors (the discard drivers), shown are final reduced models (i.e. only statistically significant factors).
Fig 2.
Significant effects plots from the discarded elasmobranchs response generalised additive mixed models, shaded area represents the 95% confidence limits whilst the surfaces represent the effect of 2-d smoothing on spatial coordinates.
Fig 3.
Significant effects plots from the discarded crustacean response generalised additive mixed models, shaded area represents the 95% confidence limits whilst the surfaces represent the effect of 2-d smoothing on spatial coordinates.
Fig 4.
Significant effects plots from the discarded fish response generalised additive mixed models, shaded area represents the 95% confidence limits.
Fig 5.
Significant effects plots from the discarded commercial crustacean response generalised additive mixed models, shaded area represents the 95% confidence limits whilst the surfaces represent the effect of 2-d smoothing on spatial coordinates.
Fig 6.
Significant effects plots from the discarded commercial fish response generalised additive mixed models, shaded area represents the 95% confidence limits whilst the surfaces represent the effect of 2-d smoothing on spatial coordinates.
Fig 7.
Relationship between log standardised count of discarded fish and net haul level weighted mean of retained catch.
Fig 8.
Relationship between log standardised count of all discarded functional groups (fish, crustaceans and elasmobranchs) and net haul level weighted mean of retained catch.
Table 4.
Sample of studies that model the rate of discarding in demersal trawl fisheries.