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Marine farming is a key issue because of its importance to the Tasmanian economy, its reliance on the quality of the water it receives, and the potential to cause environmental harm if unregulated. The coastal waters of Tasmania are generally well-suited to marine farming activities, with cool, clean waters and an abundance of sheltered estuaries providing an ideal environment for marine farming. Marine farming in Tasmania has grown rapidly since the establishment of shellfish culture in the 1960s and finfish culture in the 1980s. Marine farming is susceptible to a variety of environmental influences, including catchment condition, reduction of environmental flows, pollution of estuarine waters and algal blooms. For example, micro-organisms, algae or bio-accumulating chemicals can become concentrated in the flesh of filter feeding shellfish. Marine pest species, such as the Northern Pacific seastar (Asterias amurensis), also pose a potential threat to some marine farming operations. Over the longer-term, sea-temperature increases associated with climate change pose a potential threat to the industry in Tasmania. Marine farming activities can also have a potentially detrimental effect on the marine environment. The major issues in relation to marine farming impacts are associated with potential: Other potential issues that are of concern include the introduction of pest species and the transfer of disease through relocation of farm gear and stock. A comprehensive discussion of these and other environmental impacts can be found in the Environmental Impact Statement accompanying the Draft D'Entrecasteaux Channel Marine Farming Development Plan (February 2002). The culture of finfish such as salmonids has a much greater impact on the marine environment than shellfish farming as finfish require a direct input of nutrient rich feed, while the majority of shellfish filter feed or graze on naturally occurring phytoplankton, algae and detritus. Soluble wastes generated from farmed fish have the potential to significantly increase the nutrient loading of the water column. Uneaten feed pellets and solid faecal material are the major sources of localised organic enrichment of sediments. In many cases these impacts are visible, localised directly under stocked pens and generally appear as a pen 'footprint' on the seabed. An elevated organic loading of the sediments in these footprint zones under the pens can result in a shift in the benthic faunal composition, with pollution tolerant species dominating the faunal assemblage. Extreme cases of organic enrichment under pens can result in the development of anoxic conditions with sulphide reducing bacteria forming extensive mats at the sediment water interface. A critical management tool is the use of fallowing to mitigate these environmental impacts under pens. Fish farmers need to rotate stocked pens within or across lease sites, thereby enabling the sediments underlying recently stocked sites to recover. The frequency of fallowing is largely related to a combination of stocking stress, current flow and background physico-chemical characteristics of a site. The relative level of risk associated with excessive nutrient loading depends to a large extent on the stocking density of cultured fish and the flushing rate of the system. A collaborative research project between researchers from the CSIRO and TAFI is currently being undertaken to identify the most suitable parameters for monitoring the system wide effects of soluble waste emissions from marine farming operations into the marine environment. Since the last SoE Report was published, an industry wide environmental monitoring program has also been implemented to monitor the effect of marine farming activities on the benthic environment. Pacific Oysters and Atlantic Salmon remain the dominant sectors of the industry in terms of value, total leased area and overall production, with the combined value of these sectors growing from $7.5 million in 1988/89 to $134 million in 2001/02 (DPIWE, unpublished data). There are currently a total of 185 marine farming leases around the State, many of which are licensed to grow several species. While there has been an overall increase in the number of leases, there has been a decline in the range of species attached to licences. The bulk of Tasmania's finfish production is located in the south-eastern and western coastal waters, while shellfish farms have a more widespread distribution and are present in most Marine Farming Development Plan (MFDP) Areas. The total lease area available for marine farming within development plan areas is 8,263 ha and equates to approximately 1.8% of the total area of waterways covered by Marine Farming Development Plans.
Assessing and measuring the current situation Available measures are presently limited to leased area, production, catchment and estuarine water quality and condition information. Estuary reviews have been compiled by the Environment Division of DPIWE for this SoE Report and these are available for some estuaries in which marine farming occurs (e.g. Tamar, Macquarie Harbour and Huon) and are described in the Water Quality in Tasmanian Estuaries Issue Report. Preliminary baseline information on any proposed marine farming zones is undertaken by TAFI in order to obtain information on the suitability of sites for different types of marine farming activities. More detailed baseline surveys are undertaken by lease holders prior to the development of any new leases. Details of the baseline survey specifications for each proposed culture method can be found in the Environmental Impact Statement accompanying the Draft D'Entrecasteaux Channel Marine Farming Development Plan (February 2002). An environmental monitoring program has been implemented to monitor environmental conditions under and around finfish marine farms as specified in the Marine Farm Development plans and each individual licence. This is a requirement under the Living Marine Resources Management Act 1995 and the Marine Farming Planning Act 1995. The data are reported to the Marine Resources Division of DPIWE and a report covering the monitoring results and compliance with monitoring from 1997-2002is due to be released in late 2003. Research has been conducted by TAFI on the effects of organic enrichment of the seabed from salmon cages. Several measures of environmental condition around the fish farms were assessed. The TAFI study found that the abundance and species composition of the macrofauna in the sediment was found to be the most sensitive indicator of organic enrichment. Video footage of the marine farm environment was a very practical measure of environmental change. TAFI has also conducted a pilot study to define the spatial and temporal scales of recovery during fallowing (TAFI 2000). Further information on these programs is provided in the section on Management Responses. The Tasmanian Shellfish Quality Assurance Program run by the Department of Health and Human Services assesses shellfish growing areas for public health risks. These include levels of toxic algae or biotoxins that can become concentrated in the flesh of filter feeding shellfish potentially contaminating those in marine farms. Such contamination results in health risks to human consumers and poses serious economic impacts on these industries. There has been some data collection for algal cell (total and toxic) concentrations and chlorophyll a concentrations (indicator of algal biomass) in various estuaries around that State, which are discussed in the Algal Blooms Issue Report. Other water quality parameters that can also be associated with the health of marine farms and/or the effects of marine farms on estuary water quality include turbidity and water nutrients (nitrogen), both of which are discussed in the Water Quality in Tasmanian Estuaries Issue Report. It is not possible to quantitatively assess the relationship between these parameters and marine farming, because of the lack of data. For example, an assessment of the nutrients in North West Bay, southern Tasmania, (Jordan et al. 2002) highlights that the contribution of nutrients to the estuary from marine farming relative to other sources, such as catchment landuse activities, sewage and septic inputs and Sub-Antarctic water is largely unknown. The interactions between finfish (salmonid) farms and seabirds, seals and cetaceans are a problem with occasional native animal fatalities (sometimes threatened species) and reductions in farm production and farm fisher safety (R.Gales pers. comm. and Kemper et al. 2003). Shellfish culture does not experience the same problems. The Marine and Marine Industries Council has produced a 'Seal/Fishery Interaction Management Strategy' (2002) and Background report for Tasmania, which includes information on the interaction and mitigation of seals with the salmonoid industry. It was suggested that there is a need for industry and DPIWE to develop a process for collecting relevant data to be used in the future monitoring and management of seal interactions. The Strategy reported a 2001 survey that estimated the total costs due to seals to be $1000 per tonne of salmon produced, amounting to $12.1 million in 2001 (see MMIC 2002). This figure includes mortalities and escapees, production losses through stress, depreciation on capital invested in protective measures, increased operating costs and the cost of seal relocations.
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Marine Farming Effort - at a glance
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Marine Farming Production - at a glance
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Major management actions taken since the last SoE Report (SDAC 1997) related to the marine farming and the marine environment include:
Legislation and management The growth of shellfish culture in the 1960s and finfish in the 1980s was largely subject to an ad hoc allocation process that had the potential to hinder sustainable industry development. As a consequence, the State Government passed the Marine Farming Planning Act 1995 and the Living Marine Resources Management Act 1995. The marine farming management and environmental protection provisions of the Marine Farming Planning Act 1995 and the Living Marine Resources Management Act 1995 provide a framework for management of marine farming activities and protection of the marine environment. Following the passing of these Acts, a development planning process for marine farming was initiated, with a number of marine farming regions around the State being identified as MFDP areas. A total of 14 plan areas have been identified as being suitable for the controlled development of the industry. Each plan area has specific management controls that relate to the environmental and operational management of all designated marine farming zones. These controls set specific guidelines for the management of carrying capacity, environmental monitoring, disease, chemical usage and waste removal. Environmental monitoring The type and frequency of marine farm environmental monitoring is dependent on the species licensed to a particular marine farming lease and the relative level of impact associated with the culture method. Generally speaking, the monitoring programme has been divided into finfish (salmonid) and shellfish (bivalve and univalve) monitoring, as these two groups have different levels of impact on the marine environment. Because of the increased level of risk to the environment associated with finfish farming, more rigorous and frequent monitoring has been required than for shellfish farms. Finfish sites have been required to follow this regime for a minimum period of four years, after which lease areas will be monitored on a site-by-site basis employing standard adaptive management principles. The four year program consists of regular six-monthly underwater video surveys and more comprehensive two-yearly surveys of lease sites. The six-monthly surveys assess the visual condition of the sediments at set compliance points outside lease boundaries and under pen stations within the lease area, while the two-yearly surveys also involve assessment of benthic fauna and sediment chemistry within the farm and at designated compliance points. The majority of farms have now completed this sequence of surveys and it is envisaged that each site's monitoring requirements will be adjusted according to a combination of site specific parameters, including but not limited to, compliance with environmental licence conditions, stocking stress and environmental conditions. The specific parameters to be assessed for the ongoing monitoring of shellfish farms are currently being developed. An environmental risk assessment of shellfish farming, together with a research project into the environmental impacts of shellfish farms have recently been completed by TAFI. The results of this research will be used to assist in the development of ongoing monitoring protocols for the shellfish industry. Research has been conducted on the effects of organic enrichment of the seabed through the deposition of faeces and waste food from salmon cages. Several measures of environmental condition around the fish farms were investigated to assist the development of a practical, cost-effective and scientifically credible monitoring program. The TAFI studies recommended that several environmental parameters are measured every time a farm is monitored because no one parameter is consistently representative of environmental change. Video footage of the marine farm environment was a very practical measure of environmental change because the results were immediate, permanent and readily interpreted, however, only major changes were observed (TAFI 2000). TAFI is also undertaking research into post-stocking sediment recovery in order to assess the time that is required for sediments to return to near normal conditions, and the effects of environmental conditions and production levels at each farm on the rate of this recovery (TAFI 2000). The management of diseases that affect marine farming is a further challenge for the future. For example, the marine protozoan pathogen Neoparamoeba pemaquidensis that occurs seasonally in Atlantic Salmon in Tasmania is now regarded as a major disease which costs the industry $10 to $15 million annually (Australian State of Environment Committee 2001). TAFI is investigating the relationship between gill changes and environmental and husbandry factors. Amoebic gill disease was the only significant condition identified in the gill survey. The disease occurred mostly in summer and the prevalence was greater at greater temperature and salinities There is an established ongoing monitoring programme in place for water quality testing in shellfish growing areas. This is because filter feeders have a high propensity to accumulate substances or micro-organisms from the surrounding environment. If there has been heavy flooding (decreased salinity), a toxic algal bloom or a chemical spill, various micro-organisms, algae or bio-accumulating chemicals can become concentrated in the flesh of filter feeding shellfish and therefore pose a threat to human health. The Tasmanian Shellfish Quality Assurance Programme (TSQAP) was set up in the mid-1980s to evaluate and classify all commercial shellfish farming areas in the State by way of routine bacteriological, chemical and biotoxin monitoring. In cases where monitoring indicates a possible health risk, farms in affected regions are closed until further testing indicates that consumption of shellfish will pose no risk to human health. There has been a substantial increase in the number of marine farming leases in Tasmania, with the dominant farmed species being Pacific Oysters and Atlantic Salmon. Research undertaken by TAFI has confirmed that the level of risk to the marine environment associated with marine farming activities is considerably greater for finfish farming compared to shellfish farming. The recognition of potential impacts associated with marine farming has led to the identification of a number of mitigation measures and has included the implementation of legislative controls applicable to all MFDP areas.
Tasmania Together and the RMPS Relevant Tasmania Together goals and standards for 'Coastal, Estuarine and Marine' are listed in the linked file. The Tasmania Together Progress Board reported on progress toward targets for benchmarks set (Tasmania Together Progress Board 2003). Indicators, targets and baseline data are available in the latest Progress Report June 2003. Further information, including progress report updates, is available from Tasmania Together. Involvement of the community, and the fair and orderly use of resources are also fundamental principles of the RMPS. The RMPS objectives have been developed to advance the principles of sustainable development.
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