EXECUTIVE SUMMARY

Purpose and scope

Regional councils and the marine farming industry have identified a lack of publicly available information summarising the ecological effects of non-finfish marine farming in New Zealand (e.g. culture of mussels and oysters) as a critical information gap in relation to regional aquaculture planning and development.

Although a large amount of research and monitoring has been conducted in New Zealand (especially with regards to Greenshell™ mussels), the information is generally not readily available to the public (e.g. Fisheries Resources Impact Assessment (FRIA) documents), or in a form that is easily assimilated by non-scientists. Hence, the Ministry of Fisheries (MFish) contracted Cawthron Institute (Cawthron) to conduct a review of existing information and to summarise knowledge of ecological effects associated with non-finfish species.

The scope and structure of this review reflects three specific objectives as prescribed by MFish; these are to collate and review information on the ecological effects of farming

(1) Greenshell™ mussels including spat catching,

(2) intertidal oysters, and

(3) other non-finfish species.

The other species considered include: dredge oysters, scallops, blue mussels, black-foot paua, sponges, crayfish, kina, sea cucumber and seaweeds.

Greenshell™ mussel farming is, by far, New Zealand’s largest aquaculture activity (~85% by area) and information pertaining to environmental effects is accordingly extensive. Oysters comprise a much smaller industry and locally derived literature is less common. The ecological effects of new and developing culture species are often unknown; in which case the guidance provided in this report is general in nature and based more on overseas examples and comparable species.

This report focuses on ecological effects only, whereas a broader range of effects and benefits on the coastal environment and communities will be relevant to resource management decisions (e.g. social and cultural aspects). The scope is limited to sea-based aquaculture and does not include managed wild fisheries like scallop enhancement.

The review also focuses on coastal issues relating to farm structures and operations (including sea-rearing stages and spat catching) and does not consider wider ‘off-site’ effects (i.e. land-based hatchery rearing and product processing).