Aquaculture-environment interactions

NIWA contacts: 

 

Coastal aquaculture provides one of New Zealand’s biggest opportunities to generate new wealth from the primary production sector. Uncertainty about potential environmental effects of aquaculture expansion is a major impediment to realising this potential.

Conversely, there is an increasing evidence that environmental fluctuations (whether natural or human-induced) influence crop performance.  Whilst marine farms can have effects upon the coastal environment, that environment is also subject to disturbance by other human activities. Consent conditions for marine farms often impose environmental standards. In practise, however, if standards are breached, it can be difficult to determine the cause of the breach with sufficient certainty to permit enforcement action to be taken. Knowing that enforcement will be difficult, regulators adopt precautionary tactics. In some cases, these may be warranted, in others they inhibit economic development unnecessarily.

The challenge

Sustainable development of marine farming requires providing opportunities for investors while maintaining coastal ecosystem health and integrity.

When considering whether to invest in a marine farm, the farmer requires a clear understanding of the extent to which environmental factors will influence/constrain both their long-term average returns and the variability of annual returns.  They also need to be confident that they will not penalized for environmental breaches which are not of their making.

Conversely, when considering a new application, regulators require information that will enable them to satisfy themselves that the:

  1. environmental changes arising from the additional farm (in concert with those of pre-existing farms) are likely to remain within acceptable bounds,
  2. environmental monitoring regimes can detect changes that would be unacceptable large
  3. the monitoring data (in concert with other tools and appropriate follow-up studies) will enable them to determine the cause(s) of any changes that have deemed to be too large to be acceptable.

Both farmers and regulators seek monitoring methods that yield reliable results without imposing excessively onerous costs upon either party.

The solution

Our Aquaculture-Environment Interactions program seeks to address all of these topics. It is split into three projects.

  • Aquaculture: Sources
  • Aquaculture: Transformations and Sinks
  • Aquaculture: Applications

Aquaculture: sources is focussed upon finfish (particularly salmon and hapuku). We are seeking to determine how key physiological characteristics (food assimilation efficiency, respiratory and excretory rates) vary in response to changing age, diet and environment (temperature, dissolved oxygen). This will enable us to better forecast:

  • Site-suitability and potential crop yields when farmers are under-taking site investigations
  • how much nutrient (dissolved and particulate) a farm will put into the environment

Aquaculture: transformations and sinks is the largest individual project. Some parts of the project relate to finfish and others to mussels. Major themes include:

  • Development of novel methods for measuring fluxes of oxygen and hydrogen sulphide across the seabed/water interface (relevant to monitoring of benthic effects) 
  • A nationwide synoptic study to determine how environmental conditions influence mussel characteristics (shell-strength, many aspects of tissue composition)
  • Development and testing of pen-scale and farm-scale models of water flow and particulate matter deposition rates to enable better prediction of marine farm benthic footprints in eddying environments
  • Development of spatially explicit regional-scale biophysical models to quantify the cumulative effects of multiple marine farms upon the trophic status of a bay or larger system

Emerging themes include:

  • Quantification of ecosystem-service provision by marine farms
  • Maternal effects upon mussel performance

Aquaculture: applications is focussed upon exploiting existing data to deliver new insights and tools to industry and regulators. Themes include:

  • Analysis of remote-sensing data to determine whether there is any evidence that large-scale mussel farming induces localized (or large-scale) phytoplankton depletion
  • Development of methods to permit real-time, in-situ monitoring of faecal coliform concentrations within marine farming zones to reduce crop-wastage and food safety risks.
  • Development of models to forecast water temperatures (3-6 months into the future) for marine farming zones to help farmers with production-planning
  • Development of a web-based tool to deliver forecasts of (summertime) mussel-growth potential within Pelorus Sound.  This tool is now being trialled by our industry partners. 

 

Page last updated: 
9 August 2017
Mussel farm in Pelorus Sound (Barb Hayden, NIWA)