Issue: Direct pressure of human activities on coasts and oceans - Pressure of fishing
This is an issue under the Coasts and oceans theme of the Data Reporting System.
Humans place pressures on the ocean through their demand for organic materials harvested from marine biodiversity, mainly for food. In addition to biodiversity removed from the oceans to satisfy human demands, these activities result in further losses of biodiversity via bycatch (including animals and plants both accidentally retrieved and those killed, eg drowned, by the process but not retrieved), benthic disturbance, and indirect impacts of depletion of one species on other species. Fishing activities may also introduce new species from one part of the ocean to another which may place pressure on resident organisms. The effects of harvesting marine species include the effects of both legal and illegal commercial harvesting and of recreational and Indigenous fishing. They also include impacts of both wild fisheries and aquaculture.
- CO-16 Status of Australian fisheries
Commercial fishing is a direct human pressure on the coastal and marine environment. Changes in the status of commercial fisheries is indicative of changes in this pressure and of the effectiveness of responses to this pressure.
- CO-17 Change in species and trophic structure of fish species caught
Change in trophic structure in commercially exploited species could be indicative of significant ecological change. Although any such change may not be entirely attributable to the impacts of fishing, fishing (including illegal, recreational and Indigenous) is the most probable cause of this kind of change because larger (and generally more predatory fish) are the most sought after in terms of food value and are also more vulnerable to modern netting techniques.
- CO-19 Estimated tonnage taken by illegal fishing; estimated number of illegal boats, estimated number of individuals of threatened species taken
The suggested indicators, read collectively, would provide some baseline for estimating the contribution of illegal fishing to pressures on the condition of marine biodiversity.
- CO-20 Non-target effects: Area of seabeds trawled
Area of the seabed trawled would provide a surrogate for the extent of benthic ecosystems potentially disturbed by commercial fishing activities. It is a crude indicator because it does not estimate either the sensitivity or the ecological importance of different areas of seabed disturbed, nor the extent or particular effects of the actual disturbance. However, in the absence of any more sophisticated assessment tools, it would give us a rough idea.
- CO-21 Non-target effects: Number and/or weight taken as bycatch, and change since introduction of exclusion devices
As well as affecting harvested species, commercial fishing affects a wide range of non-target animals. 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.
- CO-22 Aquaculture: extent of habitat disturbed or removed
Except where purpose-built artificial water bodies are created, aquaculture requires the resumption of natural water bodies and the removal and modification of their existing ecosystems. The extent of habitat disturbed is a surrogate indicator for the extent of ecosystem damage caused by this removal and/or modification.
- CO-23 Aquaculture: volume of discharged sediments and nutrients
Aquaculture involves more intensive production of fish than would occur in a natural ecosystem. Large numbers of fish in a relatively small volume of water will produce more nutrients in the form of body waste and dead fish and are also likely to stir up more sediments than a natural fish population. Additional nutrients provided as feed may add to the nutrient excess. If this excess nutrient and sediment is discharged into natural water bodies, it may have impacts on resident species and communities, resulting in poisoning or suffocation of some species or explosions of others (eg algal blooms). Volumes of nutrients released will some measure of the extent of this pressure.
- CO-24 Aquaculture: origin species and tonnage of stockfeed used
Farmed fish are generally provided with other aquatic and marine animals and plants as food, rather than maintained under natural ecological conditions. These feed species may not be native to the area and, if they escape, may compete with or prey on native species, or otherwise degrade the environment. They may also carry diseases or parasites which, if they escape, can impact on the natural ecosystem. Origin species and tonnage of stock feeds are crude indicators of this pressure. They give no indication of escape rates, or what the impacts (if any) would be if they did escape. However, they do give some indication of the potential risk.
- CO-25 Aquaculture: instances of disease and exotic species introduction from movement of live material
Fish farmed in a particular location may not be native to that location. In addition, they are generally provided with other aquatic and marine animals and plants as food, rather than maintained under natural ecological conditions. These feed species may also not be native to the area. If either escape, they may compete with or prey on native species, or otherwise degrade the environment. They may also carry diseases or parasites which, if they escape, can impact on the natural ecosystem. Reported instances of disease and exotic species escapes from the movement of live aquacultural material is a crude indicator of this pressure. It does not measure the actual or potential impacts of the escape and there may also be escapes that go unreported. However, it does give some indication of the potential risk.
- CO-32 Number of injuries to marine animals from marine debris
Fishing activity produces a range of debris distinct from normal shipping debris, such as ropes and nets. Number of injuries reported that are attributable to this cause are one indicator of the intensity of this pressure.
- CO-53 Evidence or examples of noise or visual disturbance of marine species by human activities
Many marine organisms rely on sound and visual signals for their survival. It is reasonable to assume that noise and visual cues from fishing activities may be disruptive to these signals and potentially uncomfortable, even lethal to some marine organisms.
No indicator has been developed for measuring or assessing the extent of this pressure or its actual impact on marine organisms. Some examples of impacts of sound and visual pollution from exploration and extraction activities on marine animals may be available.
- CO-62 Estimated number of marine animals harvested by recreational fishers
Changes in number of animals harvested by recreational fishers is broadly indicative of changes in the pressure exerted on marine ecosystems by recreational fishing. Comparison of the number of animals harvested by Indigenous, recreational and commercial fishers also gives a basis for comparison of the significance of these pressures.
- CO-63 Estimated number of marine animals harvested by indigenous fishers
Changes in number of animals harvested by Indigenous fishers is broadly indicative of changes in the pressure exerted on marine ecosystems by Indigenous fishing. Comparison of the number of animals harvested by Indigenous, recreational and commercial fishers also gives a basis for comparison of the significance of these pressures.
- CO-65 Correlation between various human activities and introduction of coastal and marine species
Species can be introduced to an ecosystem from various sources, including from fishing activities, on exploration rigs and from coastal activity. However, the principal means of introduction is believed to be from ballast water and on the hulls of ships.
While number of introduced species is not indicative of anything in its own right, some introduced species do have the capacity to impact on resident species and ecosystems, especially in combination with other anthropogenic factors. However, the correlation between intensity of shipping activity (or other marine uses) and intensity of species introduction may shed light on the relative importance of the various ways in which species are introduced to new waters.
- AAT-19 Annual catch in tonnes of marine species harvested in Australian Antarctic and sub-Antarctic waters - legal and illegal
By examining both legal and illegal, including fishing in Antarctic waters, unregulated and unreported fishing, and comparing those catches to agreed catch limits, this indicator provides an indication of who sustainable the use of resources are.
- AAT-20 Fishing by-catch numbers and/or weight taken as bycatch
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.
- LD-40 Current research into pressures and contributions of naturalised introduced species
Other indicators for pressures of fishing, including the relationship between aquaculture and species introduction, do not inform on whether naturalised populations are exerting pressure on native species or ecosystems. Current research into this issue, even in the absence of national data, may shed some light on these effects.
- BD-09 The change in extent of selected nationally significant invasive species
Species can be introduced to an ecosystem from fishing activities, especially, potentially, aquaculture. While it is difficult, on the basis of any available data, to establish whether and how invasive any species might be, changes in distribution and population of one species may be an indicator of more profound ecological changes. Additionally, where there is a concern that a particular species is behaving invasively, changes in its distribution may signal an increase in area at risk, either from the species itself, or from the environmental modifications that are favouring its expansion.