The monitoring of salmon farms in Tasmania is more comprehensive than that in most other parts of the world and is based on rigorous and broad-ranging research and monitoring that has been ongoing for over 20 years. The success of this integrated research framework has been enhanced through very strong links between government, industry and researchers. Robust regulatory controls have been used to manage benthic impacts from salmon farming activities, and through the adoption of adaptive management strategies, organic loading effects from marine farming operations have been effectively managed using the environmental monitoring framework administered by the Tasmanian Government. The salmon industry-funded Broadscale Environmental Monitoring Program (BEMP) for the D'Entrecasteaux Channel region (which commenced in 2009) has further enhanced the understanding of impacts to include the detection of broadscale impacts to water quality and sediment health. The only marine habitats not subject to broadscale assessment of potential impacts from salmon farming are rocky reef communities. As the Tasmanian salmon industry expands, both in terms of production and growing areas, commercial and recreational fishing groups are concerned that their targeted fishing grounds, which are predominantly based around rocky reef systems, may be impacted by nutrient emissions released through marine farming activities.

This proposal seeks to provide an immediate response to characterising reef community health prior to the development of new growing areas in south eastern Tasmanian waters.

Previous research has shown a clear impact gradient associated with cage salmon farming operations, and that presence of bacterial mats (Beggiatoa) and proliferation of opportunistic species are features commonly associated with high levels of organic enrichment (e.g. Pearson & Rosenberg, 1978). The presence of opportunists, such as Capitellid worms, being classified as representative of “unacceptable impact” (Macleod et al., 2004). This premise has been validated in SE Tasmania and underpins regulatory monitoring requirements statewide (DPIPWE, 2004).

The understanding that proliferation of opportunists represents deteriorating conditions was translated to monitoring protocols in Macquarie Harbour, but the relationship between opportunists and the level of enrichment was not explicitly tested in this region. However, video surveys suggest that in Dorvilleid worms rather than Capitellids were the species most indicative of organic enrichment effects(DPIPWE, 2004). Dorvilleids can tolerate anaerobic sediments and high levels of hydrogen sulphide (Levin et al. 2013) and are known to be indicators of the impacts of finfish aquaculture (e.g. Paxton et al. 2010).

However, Macquarie Harbour is ecologically very different to other farming areas in SE Tasmania; the sediments are inherently depauperate, largely epibiotic and spatially patchy. A recent study in Canada has highlighted the need to better understand the relationships and compliance thresholds for established enrichment indicators (i.e. Beggiatoa sp and opportunistic polychaete complexes) in systems where ecological patchiness may occur (Hamoutene et al 2014); suggesting that, where there is significant potential for small scale spatial variability, normal successional responses may not be as reliable. Consequently, the responses may not be consistent with expectations developed from southern Tasmanian regions.

In this context it is important to identify the relationship between Dorvilleids and sediment condition; determining the reliability of this species as an indicator of sediment condition, and characterising the environmental conditions associated with changes in Dorvilleid abundance.

CFP is an illness caused by consumption of fish that have accumulated ciguatoxins (CTXs), which are naturally produced by marine microalgae (Gambierdiscus spp), and not degraded by freezing and heating processes. It is well known from Queensland, with more than 1000 cases in the past 15 years, including 2 fatalities, despite only ~20% of cases reported. Around 90 species of fish can be contaminated with CTXs, which accumulate, and are often associated with larger and carnivorous fish. Species of Gambierdiscus may be invasive: internationally, increases in abundance and expansion into new areas have occurred. Our recent work (shown in http://theconversation.com/explainer-what-is-ciguatera-fish-poisoning-21835) has now found Gambierdiscus spp is present in NSW.

No study has been conducted on the presence of CTXs in fish from NSW, and knowledge about its distribution within Australian waters is poor. The recent illnesses at Scotts Head and Evans Head show that CTX may occur in fish caught in NSW. The NSW Food Authority has advised the public not to eat Spanish Mackerel weighing over 10 kg, based on the Sydney Fish Market management plan, which restricts the sale of fish based on size limits, high-risk species and location where fish were caught. However, no data exist regarding sizes, location and risk from Spanish Mackerel in NSW. Smaller Spanish Mackerel may represent a potential risk. However, these guidelines may be excessively restrictive, as some of the fish discarded may be safe for consumption.

We are now able to quantify marine biotoxins in Sydney using a newly obtained LC-MS, and links with a group of collaborating experts. We propose to undertake a thorough sampling and testing program to determine the presence of CTXs in Spanish Mackerel (Scomberomorus commerson) from NSW, to provide the baseline data necessary for the revision of guidelines for the management of CFP in NSW.