Terms of Reference

Review of potential impacts of hydrated lime treatments associated with proposed expansion of mussel production in Malpeque Bay, PEI

Regional Peer Review – Gulf Region

February 8-9, 2016
Moncton, New Brunswick

Chairperson: Darlene Smith

Context

Shellfish (mussel, oyster) aquaculture is an expanding industry in Atlantic Canada and particularly in the bays of Prince Edward Island. In many areas, the growth of invasive tunicates on the infrastructure used to culture shellfish requires control interventions by the producers to maintain the production of the target shellfish. Hydrated lime treatment has been used for several decades in PEI to control to control biofouling and predators (tunicates and starfish), and is particularly used to control the invasive tunicate Styela clava. A treatment of hydrated lime on shellfish is also commonly required as a condition on DFO issued Introductions and Transfer licenses to prevent the introduction or transfer of fellow travellers along with shellfish that are being moved from one area to another. Burridge et al. (2011) reviewed the pathways of effects of a number of chemical inputs from the aquaculture industry and concluded: “the risk posed by the use of hydrated lime to water column organisms is estimated to be low based on known hazard information and exposure durations. Risk posed to sediment dwelling organisms due to smothering or direct chemical toxicity is less well known but expected to be low”, however, a number of knowledge gaps remained (DFO 2010).

Requests have been made to increase the leases and the production of mussels in Malpeque Bay, Prince Edward Island. Recent science advice concluded that under current and projected levels of mussel culture and relative to the metrics of changes in chlorophyll and growth rate of cultured mussels the production carrying capacity would not be exceeded in Malpeque Bay (PEI) (DFO 2015). In support of continued consultations on the proposed lease expansion, DFO Aquaculture Management has asked for advice on whether the current use of lime in the mussel aquaculture industry changes significantly the environmental footprint of a mussel lease, specifically in the context of the expanded use of hydrated lime associated with proposed mussel lease expansions in Malpeque Bay. Decisions on lease expansions in Malpeque Bay will be based on consideration in part of this advice.

Objectives

The science peer review meeting will formulate advice by considering the following points:

• review the current state of knowledge regarding hydrated lime use in aquaculture operations and its effect on the aquatic ecosystem including changes in water quality (extent and duration), benthic impacts, and effects on marine organisms (lethal, sublethal and behavioural),
• review the current industry practices in the use of hydrated lime in Malpeque Bay including treatment methods, timing of treatments, and quantities of material used,
• based on field studies in Malpeque Bay, quantify the duration of the treatment plume as indicated by pH changes from baseline within the lease boundaries,
• based on field studies and literature, quantify the extent to which non-target organisms (specifically lobster) are present in areas being considered for the expanded leases in Malpeque Bay,
• based on field studies and literature, quantify the extent to which non-target organisms (specifically lobster) would respond to chemical changes of the water expected with current industry practices for the expanded leases in Malpeque Bay, and
• advise on the extent to which the environmental footprint of the proposed leases and the associated expanded use of hydrated lime treatments in Malpeque Bay would be increased relative to the footprint of expanded leases in the absence of liming inputs.

Expected Publications

• Science Advisory Report
• Proceedings
• Research Documents

Participation

• Fisheries and Oceans Canada (DFO) (Ecosystems and Oceans Science, Ecosystems and Fisheries Management)
• Provincial government of Prince Edward Island
• Industry
• Invited external experts

References

Burridge, L.E., Doe, K.G., Ernst, W. 2011. Pathway of effects of chemical inputs from the aquaculture activities in Canada. DFO Can. Sci. Advis. Sec. Res. Doc. 2010/017. vi + 57 p.

DFO. 2010. Pathways of Effects for Finfish and Shellfish Aquaculture. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2009/071.

DFO. 2015. Carrying capacity for shellfish aquaculture with reference to mussel aquaculture in Malpeque Bay, Prince Edward Island. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2015/003.