Terms of Reference

Evaluating transfers of harvested shellfish products, from the west to the east coast of Vancouver Island, as a potential vector for European Green Crab (Carcinus maenas) and other non-indigenous invertebrate species

Regional Peer Review - Pacific Region

December 3-4, 2013
Nanaimo, British Columbia

Chairperson: Nicholas Duprey

Context

Wild and cultured shellfish harvested on the west coast of Vancouver Island (VI) are currently sent to processing plants on the east coast of VI or to the lower mainland as no commercial shellfish processing facilities exist on the west coast of VI. Historically, processors were allowed to 'wet store' large quantities of harvested product in the intertidal zone next to their plants or on aquaculture tenures, processing product as time and markets allowed. It was identified that this practice of wet storage could present the potential for the introduction of non-target aquatic invasive species – in particular, high risk species such as the European Green Crab (Carcinus maenas) that can negatively impact shellfish aquaculture (Therriault et al. 2008) – to areas where they currently are not present in the Strait of Georgia.

In order to address concerns regarding the possible introduction and/or movement of Green Crabs as a result of wet storage practices, and without research into this question, DFO adopted a precautionary approach to the management of the commercial intertidal bivalve wild fishery and aquaculture operations in 2010 that restricts wet storage and requires visual inspection and rinsing of all shellfish products harvested on the west coast of VI.

In 2011–2013, under the Program for Aquaculture Regulatory Research (PARR), research to investigate transfer potential of Green Crab on shellfish product was conducted. With this PARR program now complete, Fisheries Management, Aquaculture Division has requested Science Branch to provide advice respecting the potential for transfers of harvested shellfish products to be a vector for the movement of European Green Crab and other non-indigenous invertebrate species from the west to the east coast of VI and, should such a potential exist, advice on measures to mitigate the risk. This advice will also be provided to the Canadian Food Inspection Agency (CFIA) for consideration respecting the design of their biotoxin monitoring program.

Objectives

This Regional Peer Review (RPR) meeting will review and provide advice based on the following working paper: 

“Evaluating transfers of harvested shellfish products, from the west to the east coast of Vancouver Island, as a potential vector for European Green Crab (Carcinus maenas) and other non-indigenous invertebrate species” by L.J.F. Curtis, D.L. Curtis, H. Matkin, M. Thompson, F. Choi, P. Callow, G.E. Gillespie, T.W. Therriault, and C.M. Pearce. CSAP Working Paper 2013/P33.

The objective of this RPR is to assess the potential for transfers of commercially harvested shellfish products to be a vector for the movement of European Green Crab and other non-indigenous invertebrate species from the west to the east coast of VI and, should such a potential exist, advice on measures to mitigate the risk.

Specific outcomes and considerations include:

1. Identification and review of the potential processes by which the transfer of a range of cultured shellfish products provide a mechanism by which non-target aquatic invertebrate invasive species may be relocated to new ecosystems using present aquaculture processes.
2. Description of the attributes of European Green Crab that could influence their ability to establish populations in a receiving ecosystem.
3. Description of the range of transfer potential of European Green Crab as measured through experimental research and as extrapolated to current and historical commercial shellfish transfers. Provision of considerations around areas of uncertainty and assumptions introduced during the experimental research and extrapolation process.
4. Evaluation of whether the information, data, and analysis presented for European Green Crab can be used to provide advice on the potential for current bi-valve harvest practices to be a vector for other non-commercially harvested aquatic invertebrate invasive species.
5. Advice on potential mitigation measures, including their efficacy, which may be utilized to reduce the potential for transfer of non-target aquatic invertebrate invasive species.  

Expected Publications

• CSAS Science Advisory Report (1)
• CSAS Research Document (1)
• CSAS Proceedings (1)

Participation

• DFO Science
• DFO Fisheries Management
• Province of BC
• Commercial and recreational fishing interests
• First Nations
• Non-government organizations
• Academia

References Cited

Therriault, T.W., Herborg, L.M., Locke, A., McKindsey, C.W.  2008. Risk assessment for European green crab (Carcinus maenas) in Canadian waters. DFO Can. Sci. Advis. Sec. Res. Doc. 2008/042.