SoE 2006 > Biodiversity > 6.10 Aquatic harvesting

6.10 Aquatic harvesting

Most key fish stocks are fully fished, while some fish species are overfished, prompting further refinement of harvesting controls

Exploitation levels were at their highest in the early to mid-1990s, when commercial fishers held open licences and the size and capacity of the fishing fleet were above sustainable levels. Since then a more rigorous management of commercial fishing effort and landings has contributed to a stabilisation of commercial fish stocks.

Fisheries management techniques have become more sophisticated, focusing on the specific needs of the resource and the environment. Fisheries management strategies are now being developed to address the sustainability of all commercial fisheries.

Recreational fishing also has impacts on aquatic resources, and bag and size limits for recreational fishing have been reviewed and are being strengthened.

NSW indicators

Introduction

Fishing has a range of impacts on aquatic ecosystems. Overexploitation can lead to reduced biodiversity and the depletion of local fish stocks, accompanied by considerable ecological, economic and social impacts (DPI 2006).

Fisheries resources can display substantial natural variability in population size, structure, condition and spatial extent. The difficulty in directly observing the state of the resource makes it hard to assess and manage stocks. Assessment of fisheries resources has been identified as a priority in the development of fisheries management strategies and environmental assessments. An expansion of the resource assessment program is underway.

Current status and trends

Commercial wild fish stocks

Harvested fish stocks face pressure from a range of human activities and are monitored on an ongoing basis. Records illustrate that the stocks of some species remain stable, despite significant harvesting, usually because of rapid individual growth and high fecundity. Other species, such as sharks and rays, are prone to overfishing because of low growth rates and low fecundity.

Table 6.22 shows the status of various commercial fish stocks in NSW, using an assessment approach under development by the NSW Department of Primary Industries (DPI) in 2006. Data is not presented for species that are not harvested by commercial fisheries.

Table 6.22: Status of various NSW commercial fish stocks

Source: NSW DPI data Octobert 2006

Notes: Exploitation status:
Lightly fished: The stock may have the potential to sustain catches significantly higher than those currently being taken.
Moderately fished: The stock is thought to be fished at levels that would probably allow only limited increases in catches.
Fully fished: Current catches are probably sustainable.
Growth overfished: Fish are being harvested at a size smaller than the biological and economic optimum.
Overfished: Current fishing levels may not be sustainable or yield may be higher in the long term if the fishing effort is reduced.
Uncertain: There is little or no information about the status of this stock (no catch data or only very recent catch data).

Abundance trend: Catch rate/catch corrected for effort.

With the exception of European carp and yabbies, no freshwater commercial fisheries have operated since 2001. There are, however, pressures on freshwater species including:

• dams and weirs, which affect river flows and patterns of fish migration
• recreational fishing
• destruction of habitat, and declining water quality and quantity
• the introduction of exotic species (Harris & Gehrke 1997) (see Biodiversity 6.9).

Commercial fisheries catch

Managing and reporting on fisheries in NSW is complicated by the many fish populations which span the jurisdictional boundaries between NSW, Victorian, Queensland and Commonwealth waters.

NSW has several thousand fish species and several hundred are harvested regularly by commercial and recreational fishers. Most of the commercial catch is derived from the State's marine waters (75% in 2003–04), with smaller proportions harvested from estuarine waters (25%) and very minor quantities from inland waters (< 1%). Figure 6.4 illustrates the trend in the total commercial catch of finfish, crustaceans and molluscs since 1997–98, after catch reporting became more systematic.

Figure 6.4: Commercial marine fisheries catch

Source: DPI data August 2005

The aggregate commercial landings from 1997 have generally stabilised. Since the late 1990s there has been a decrease in the reported catch from estuarine and coastal waters which can be attributed to reductions in the number of commercial operators and the establishment of 'recreational fishing havens' and aquatic protected areas. In some cases, this decline was balanced by increases in the commercial catch of species such as pilchard, Australian salmon and ocean leatherjacket. Historical landings of individual species are variable and require careful interpretation.

Figure 6.4 does not include the by-catch associated with commercial fishing. 'By-catch' refers to the non-target species that are caught as part of a fishing operation. These fish are usually discarded because they are less desirable eating quality, or no market exists for them. These discards may be significant, given the number of unwanted fish and other organisms caught by commercial fishers. Independent observer programs of commercial operations are used to quantify by-catch and discards.

Recreational fishing

Recreational fishing is also not included in the total catch figures and has only recently been recognised as having a potentially significant impact on aquatic resources. Estimates from a recent national survey of fishing indicate that NSW recreational fishers catch around 13 million fish each year, as well as 17 million prawns, crabs and lobsters, and 2 million bait fish (Henry & Lyle 2003). The total NSW recreational harvest was estimated to be about 30% of the commercial harvest, but the share of the resource varied greatly among species. Several common estuarine fish species (bream, dusky flathead and whiting) were harvested in greater numbers by recreational than commercial fishers. Undersize fish discarded by recreational fishers experience variable mortality rates depending on the species caught and how they are handled during capture.

Response to the issue

A range of responses is available to manage fish stocks in NSW. Measures that directly limit the impact of operations upon stocks include:

• regulation of commercial fishing through licence and gear restrictions
• application of catch quotas to control harvest rates (rock lobster and abalone only)
• bag limits for recreational fishers
• application of minimum legal lengths to protect immature fish and, less commonly, maximum legal sizes to protect highly fecund individuals
• improvement of the selectivity of both commercial and recreational fishing gear to minimise the rate and mortality of by-catch.

Strategic management through broad frameworks for protecting fish habitats or stock levels is also available through:

• fisheries management strategies
• establishment of various types of aquatic protected areas
• implementation of spawning closures to protect reproductive cycles
• implementation of share management plans.

There have been major changes to the management of fisheries in NSW since the early 1980s. Many of these are related to jurisdictional changes between the Commonwealth and State governments through the Offshore Constitutional Settlement 1990, and the passage of the Fisheries Management Act 1994 (FM Act) and its amendment to incorporate environmental assessment in 2000. The FM Act provides for the protection of marine areas as well as a range of other fish and habitat protection strategies. Marine protected areas may include highly protected sanctuary zones where fishing is not permitted, providing safe breeding areas and protection for key species (see Biodiversity 6.7).

Fishery management strategies are being developed for all commercial fisheries, with restrictions on entry, gear and operations. Resource assessments have been conducted for a number of fish species and detailed plans are in place for a suite of scientific studies to update or complete the assessments.

The NSW Government is involved in projects to develop by-catch reduction devices for commercial and recreational fisheries. These devices have been successful in minimising the waste of resources in a number of fisheries and can reduce the by-catch of some species by 90%, while having no impact on the catch of targeted species. By-catch reduction devices are now mandatory in some NSW commercial fisheries, such as commercial prawn trawling. Research is also underway into minimising the mortality of line-caught fish discarded by recreational fishers.

A general recreational fishing fee, introduced in 2001, is generating funds to buy out commercial fishing businesses, establish 30 'recreational fishing havens', and protect and restore fish habitat. The number of commercial operators in NSW has fallen from about 3000 in the mid-1990s to 1250 in 2006. Overall, about $18 million has been spent buying back around 250 commercial fishing operations. Marine park buy-outs have also contributed considerably to the reduction in the number of fishing businesses.

This is expected to reduce pressure on fish stocks as well as mitigate conflict over access for recreational and commercial fishing. While it is too early to assess the general impact of these measures, the removal of commercial fishing from Lake Macquarie and Tuross Lakes has seen an improvement for recreational fishing in those areas.

Bag and size limits for recreational fishing have been reviewed and are being strengthened following public consultation in 2005. Daily bag and possession limits are currently applied to 37 fish species.

Aquaculture has the potential to reduce pressure on demand for wild fish stocks, but also poses environmental risks. These include the spread of pollution and disease to nearby aquatic ecosystems and increased pressure on wild stocks of fish used as feedstock or breeding stock. Structures such as oyster racks and fish cages can also have impacts on marine life and bring hydrodynamic changes to estuaries. These issues will be addressed in environmental guidelines for the aquaculture industry currently being developed, together with whole-of-government regional strategies for sustainable aquaculture.

Future directions

There has been a significant effort to regulate commercial fishing and stabilise the harvest of aquatic resources in NSW, and refinement of the framework is ongoing. However, it will take some time to measure the statewide benefits to fish stocks from the extensive reforms to commercial and recreational fishing.

The stresses on available resources are likely to increase because of improvements in the technologies used to harvest fish, as well as coastal development, which has the potential to degrade fish habitat.

Efforts should continue to assist commercial operators to adjust fishing practices so they minimise impacts on stocks and non-target species and to ensure the development of commercial and recreational fisheries that are ecologically sustainable. Such policies are being developed and implemented through fishery management strategies and environmental assessments of all commercial fishing activities.

An ongoing commitment is required to continue, and improve, the monitoring of fish stocks to ensure that all fisheries are managed sustainably.

Growth in aquaculture developments can reduce the pressures on some fish stocks but must be managed carefully to prevent or minimise their own impacts on the environment.

Commitment to the development of a network of aquatic protected areas should be maintained as this is an internationally recognised strategy to protect aquatic biodiversity, and has also been shown to enhance the stock levels of some fish over time.