ASC Improves Consistency of its Approach to Assessing Freshwater Salmonids

Introduction

The Aquaculture Stewardship Council (ASC) Freshwater Trout Standard has been updated and strengthened following a rigorous multi-stakeholder, science-based review process, as part of ASC’s ongoing commitment to continuously improve standards and adapt to changes in industry best practice.

The ASC operates a number of standards dedicated to different species groups and production systems; including the freshwater production of Tilapia and Pangasius and the production of Seriola, Cobia, flatfish and a number of tropical finfish species in the marine environment. The shrimp standard covers production in marine, brackish and freshwater systems.

It is widely acknowledged that since 2014, with the rapid development of aquaculture over the previous two decades, farmed finfish production has contributed more into global food supply than from wild capture fisheries. Perhaps less well known is that of the approximately 50 million tonnes of finfish farmed in 2016, 88% of this was farmed in freshwater. Only 6.3 mt of finfish were farmed in the marine environment and 35% of this is salmon.

The ASC operates two salmonid standards: one covering freshwater and the other marine, both however include provisions applicable to the production of freshwater smolts that were not well aligned.

Inconsistencies to resolve

The Freshwater Trout Standard applies to “…any salmonid grown in fresh water.” and audits require site inspection. The Salmon Standard also included requirements (Principle 8) regarding the production of freshwater smolts. Audits against Principle 8 are only based on information supplied by the smolt producer and no physical site visit is required.

Prior to these revisions cage-farmed salmon smolts assessed under Principle 8 were not allowed to be used to stock adult salmon grow out sites, even if they had been assessed and certified under the Freshwater Trout Standard.

A Science-led Process informed by robust governance and stakeholder consultation

In March 2019 the ASC’s Technical Advisory Group recommended to the Board that the scopes of the two standards be made consistent, that the Freshwater Trout Standard be applied to all freshwater salmonid farming and that for smolt production this would involve an on-site audit not previously required.

The proposed revisions were very actively debated within both the TAG and the Supervisory Board in response to public consultation feedback. A key concern identified recognised the risk of smolt escapes into fresh water habitats, particularly where they are not native. It was also recognised that the effectiveness of management to address the impacts of smolts production in freshwater lakes varied across regions. Recognising these concerns the update to the ASC trout standard does not now allow farms to raise smolts in freshwater where that species is not indigenous. This precautionary approach recognises that lake fauna are often unique to a region and at increased threat of any accidental introductions.

Additionally, revisions to the trout standard build on best management practices as outlined below.

Better Performance and Transparency for Fresh Water Smolt Production

ASC consistently looks to ensure better outcomes for the environment, farmers and the communities where fish is produced through controlled management of both the freshwater and saltwater environments. These revisions are consistent with the ASC’s vision and are grounded in sound science that will provide even greater insights of farm performance.”

Establishing production limits for smolts produced in lakes. A number of requirements are improved to ensure that the lake’s capacity to assimilate the farmed production is not exceeded. Modelling guidance is provided based on OECD guidelines (e.g. for establishing trophic status, phosphorous load limits, mixing dynamics etc.) and requirements to ensure no change to the trophic status can occur.

Genetic introgression of wild salmon stocks. The impacts and causes of wild salmon genetic introgression continue to be debated within the scientific and stakeholder community. Key unknowns continue to be the extent and rate of genetic introgression that has occurred and whether this results from farmed adult salmon escapes, freshwater smolt escapes, from the deliberate release of farmed salmon for stock enhancement or from natural straying. To address these uncertainties new indicators will require the development of genetic baselines and studies of the farmed and local wild salmonid populations. This historic baseline will provide a benchmark to assess future rates and sources of introgression into wild salmonid populations. Certified farms are also required to collaborate with local fisheries trusts and stakeholders in monitoring programmes and that fish escapes are communicated to the trusts.

Improvements to indicators for escapes and fish health

The revisions also strengthen the existing Appendix IV (Containment Plan) in order to improve the escape requirements. As an example, reference is made to the Technical Standard for Scottish Finfish Aquaculture as a best practice guide regarding overall containment improvements. Also, to bring the revised trout standard in line with other ASC standards antibiotics listed as critically important for human medicine are prohibited; although a temporary exemption for oxolinic acid is made, whose use is legally required in some jurisdictions.