Project number: 2010-202
Project Status:
Completed
Budget expenditure: $299,998.30
Principal Investigator: Michael J. Keough
Organisation: University of Melbourne
Project start/end date: 31 Dec 2010 - 8 Sep 2014
Contact:
FRDC

Need

Biofouling has emerged as the main bottleneck to production in the mussel farming industry. For example, since 2003, mussel production has declined by approximately 50% in Victoria. Concurrent with this decline has been the rise of several problematic biofouling species, including the invasive hydroid (Ectopleura crocea), the invasive sea star (Asterias amurensis), and several ascidian and algal species. Many of these biofouling taxa are common across Victorian, South Australian, Western Australian, Tasmanian and New South Wales mussel farms. Combined, these biofouling species are believed to have had a range of effects on production, including: 1) reducing natural mussel spat settlement rates; 2) preying upon mussel spat and juveniles; 3) competing for food with mussels; and 4) smothering established mussels.

A clear need exists to develop methods to avoid, prevent and treat biofouling to reduce costs and improve production. Typically, biofouling management accounts for 30-40% of production costs. Current biofouling removal methods (stripping of lines or fresh-water baths) are time consuming and labour-intensive. As a consequence, biofouling often develops to damaging levels before farmers are able to remove it.

Farmers require knowledge of the timing, location and depth of key fouling species so biofouling outbreaks can be avoided. Further, there is a need to test whether the type of equipment used (e.g., rope type and colour) or its arrangement (dropper spacing and dropper depth) may reduce biofouling. As some biofouling will inevitably develop on mussel lines, new biofouling treatments that are cheap, easy to use and effective must be tested. These include acetic acid, hot water baths, high pressure hot air and their combinations. Acetic acid has proved promising against many biofouling species in the New Zealand mussel industry, but has not been trialled on key biofouling species in southern Australian waters (e.g. hydroids).

Objectives

1. Measure the effects of key biofouling species on mussel spat survival and grow-out.
2. Test farm management methods that will discourage and/or avoid biofouling episodes.
3. Test the effectiveness of existing and new biofouling treatment methods to develop cost-efficient, implementable, on-farm treatments.
4. Measure the effects of key biofouling species on mussel spat survival and grow-out.

Final report

ISBN: 978 0 7340 5016 8
Author: Michael Keough
Final Report • 2014-08-01 • 25.78 MB
2010-202-DLD.pdf

Summary

Biofouling negatively affects shellfish production through several pathways, including: 1) reducing natural mussel spat settlement rates; 2) preying upon mussel spat and juveniles; 3) competing for food with mussels; and 4) smothering established mussels. These problems are well documented in the culture of other bivalves such as oysters and scallops, where water flow is restricted to such an extent by fouling organisms that the availability of food and growth of stock are impeded (Claereboudt et al. 1994; Taylor et al. 1997). However, the effects of fouling organisms in long-line mussel culture remain poorly known (LeBlanc et al. 2003). Various native ascidians, hydroids, tunicates, macroalgae and seastars are common biofoulers across the mussel farming industry in Australia’s southern waters. In Victoria, as in other parts of the world, introduced species are also emerging as key pests. 

At present, Australian farmers deal with biofouling reactively, with treatment strategies implemented only after outbreaks have occurred. Current treatment protocols are largely based on a 2001 study in Victoria investigating measures to reduce the risk of moving noxious aquatic species via aquaculture stock or equipment (Gunthorpe 2001). Individual farmers have tried several methods on an ad-hoc basis to try to manage their fouling loads but they do not have the time or resources to carry out rigorous scientific testing and trials. Similarly, they are not aware of the basic biology or life history of the fouling species they are dealing with, and have no documented monitoring program in place to assess when fouling episodes are to be expected, and what species to be on the lookout for. Effective strategies to control biofouling must integrate information over the complex of biofouling species and their various effects. As fouling will always develop on mussel lines, it is important to develop and test cheap, easy to implement on-farm treatments that are effective against a range of biofouling species that do not affect mussel production.

Final Report • 2014-08-01 • 8.65 MB
Biofouling Management Guidelines for Mussel Culture Handbook.pdf

Summary

This guide was written utilising information from FRDC project 2010-202: Tackling a critical industry bottleneck - developing methods to avoid, prevent and treat biofouling on mussel farms.

The research was funded by the FRDC on behalf of the Australian Government.

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