Indicator: AAT-20 Fishing by-catch numbers and/or weight taken as bycatch

Data

Estimated total potential seabird by-catch in the illegal, unregulated and unreported Dissostichus species fishery in the Convention Area from 1996 to 2004
Subarea/Division Year Estimated total potential seabird by-catch
Lower Median Upper
48.3 2004 0 0 0
1996-2003 1811 3441 56031
58.5.2 2004 596 727 1941
1996-2003 31857 38870 103787
58.4.3 2004 522 636 1699
Lower and upper confidence refer to 95% confidence limit

Source: Scientific Committee for the Conservation of Antarctic Marine Living Resources 2004, Commission for the Conservation of Antarctic Marine Living Resources, Hobart, Table 7.15

By-catch (tonnes) estimates from longline fisheries for the 2003/04 season
Subarea/Division 58.4.2 58.4.3b 58.5.2
Total rajid (a species of fish) 0.04 0.11 61.71
Total Macrourus (bird) species 0.63 0.13 42.33
Total rajid as a % of the species being targeted 0.2 1.67 11.18
Total Macrourus species as % of the species being targeted 3.18 1.92 7.67

Source: Scientific Committee for the Conservation of Antarctic Marine Living Resources 2004, Commission for the Conservation of Antarctic Marine Living Resources, Hobart, Table 6.3

By-catch (tonnes) estimates from trawl fisheries for the 2003/04 season
Division 58.5.2
Total rajid (a species of fish) 7.77
Total Macrourus (bird) species 2.88
Total rajid as a % of the species being targeted 0.44
Total Macrourus species as % of the species being targeted 0.16

Source: Scientific Committee for the Conservation of Antarctic Marine Living Resources 2004, Commission for the Conservation of Antarctic Marine Living Resources, Hobart, Table 6.4

What the data mean

By-catch commonly refers to the part of a fisher’s catch that is not the target species. The data estimates the by-catch associated with longline and trawl fishing in specified areas. The by-catch is estimated for a fish species and a bird species. The data shows that by-catch continues to be of concern especially when we consider the tonnage of by-catch compared to the tonnage of the fish species being targeted as part of the fishing operations. As high as 11% of longline catches (tonnes) is comprised of the by-catch fish species rajid but this varies between areas. Trawling seems to have less of an impact.

Data Limitations

It is difficult to accurately know the extent and level of by-catch.

Issues for which this is an indicator and why

Australian Antarctic Territory — Environment - Human Pressures on the environment 

Each year thousands of seabirds and fish are accidentally killed on longline hooks and trawling lines (i.e. they are not the target species for the fishing operation). The level of by-catch that occurs in these fisheries is not sustainable for many populations of fish and especially for seabirds. Changes in the total numbers of other animals affected may be at least initially ambiguous: increases may reflect improved reporting, decreases a decline in wildlife species themselves, so that they are no longer available to accidentally catch or interact with. However, changes would be a reasonable indicator of reduced or increased pressure.

Other indicators for this issue:

Coasts and Oceans — Direct pressure of human activities on coasts and oceans - Pressure of fishing 

Each year thousands of seabirds and fish, in Antarctic, as well as other fisheries, are accidentally killed on longline hooks and trawling lines (i.e. they are not the target species for the fishing operation), including in . The level of by-catch that occurs in these fisheries is not sustainable for many populations of fish and especially for seabirds. Changes in the total numbers of other animals affected may be at least initially ambiguous: increases may reflect improved reporting, decreases a decline in wildlife species themselves, so that they are no longer available to accidentally catch or interact with. However, changes would be a reasonable indicator of reduced or increased pressure.

Other indicators for this issue:

Biodiversity — Utilisation and value of biodiversity - Harvesting and trade in wildlife 

In terms of mass and number of individuals killed, harvesting of wild fish, including bycatch, is the principal commercial harvesting of wild animals in Australia and the AAT.

Other indicators for this issue:

Biodiversity — Pressures on biodiversity - Pressures on marine biodiversity: pressures of fishing 

Each year thousands of seabirds and fish, in Antarctic, as well as other fisheries, are accidentally killed on longline hooks and trawling lines (i.e. they are not the target species for the fishing operation), including in . The level of by-catch that occurs in these fisheries is not sustainable for many populations of fish and especially for seabirds. Changes in the total numbers of other animals affected may be at least initially ambiguous: increases may reflect improved reporting, decreases a decline in wildlife species themselves, so that they are no longer available to accidentally catch or interact with. However, changes would be a reasonable indicator of reduced or increased pressure.

Other indicators for this issue:

Further Information