Abstract

The accumulation of biofouling organisms on farm infrastructure is an on-going problem for the global salmon aquaculture industry. Most salmon farmers in production regions worldwide undertake regular in situ net cleaning using specialised high-pressure washing rigs. Generally, the material removed from the net during cleaning is discharged into the surrounding environment. This 'cleaning waste' consists predominantly of biofouling organisms (intact and fragmented), but may also contain fish pathogens and antifouling coating particles containing bio- cides. The suspension, dispersal and deposition of this material are associated with a range of potential risks that can be grouped into 4 main categories: (1) health or disease risks (e.g. direct damage to sensitive tissues upon contact with cleaning waste, and facilitation of infection by patho gens); (2) deposition and pollution risks (impact on benthic communities around farms through deposition of organic material and antifouling biocides); (3) invasive species risks (localised dispersal of non-indigenous propagules and fragments); and (4) biofouling exacerbation (e.g. 'self-seeding' of downstream production cages). Here, we describe and discuss these 4 potential risks associated with in situ cleaning and present an agenda and research priorities to better understand and manage these risks.

Highlights

  • The accumulation of biofouling organisms on farm infrastructure is an on-going problem for the global salmon aquaculture industry

  • To avoid the impacts associated with biofouling development, salmon farmers in most global growing regions undertake regular in situ net cleaning

  • The annual cleaning waste arising from individual salmon farms is a function of local biofouling intensity and the maintenance strategy employed by the farm

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Summary

Biofouling exacerbation

Ecological sustainability of aquaculture is a key goal for environmental managers and scientists, and a wealth of studies have examined the impacts of fish and shellfish farms and how they could be minimised (Hargrave 2010, Taranger et al 2015 and references therein). The annual cleaning waste arising from individual salmon farms is a function of local biofouling intensity and the maintenance strategy employed by the farm (net types deployed, use of antifouling coatings, net cleaning frequency) All of these factors vary geographically and between companies; based on available data, biofouling waste generated by individual salmon farms can be in the order of dozens of tonnes (Table 1). Given this scale of release, the continued use of biocidal antifouling coatings in some global production regions. We present and discuss the potential environmental risks associated with in situ cleaning of production nets in fish farms (Fig. 1) and present operational and technological avenues and research priorities for improved, ecologically sustainable biofouling management

POTENTIAL ENVIRONMENTAL RISKS OF IN SITU NET CLEANING
Health and disease risks
Deposition and pollution risks
Invasive species risk
Exacerbated biofouling rates
RESEARCH NEEDS
Understanding risk
Managing risk
CONCLUSIONS
Findings
LITERATURE CITED
Full Text
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