Wednesday, October 27, 1999

Colwood Room

Chair: Bill Heath

BC Ministry of Fisheries

• David J. Scarratt - Development of the Mussel industry in Eastern Canada

• P. Darnell - Adapting the New Zealand Method of Mussel Seeding for Use in Nova Scotia

• I.W. Jefferds - Farming Mussels, M. trossulus and M. galloprovincialis, in Puget Sound - Similarities and Differences

• C. Day - To Investigate Various Methods to Optimize the Grow-out Yield of Mediterranean Mussels

• S.M. Bower and S.E. McGladdery - Shellfish Health Protection Regulations in Canada

• P. Simpson and M. Salo - Mediterranean Mussel Culture in BC - Results of Nursery and Grow-out Trials

• K.R. Freeman, E. Kenchington and S.P. MacQuarrie: Comparative Depth Settlement of M. edulis and M. trossulus in Controlled and Natural Environments

Mussel Culture for BC: Climbing the Learning Curve

Development of the mussel industry in Eastern Canada

David J. Scarratt

David Scarratt & Associates, Halifax, NS.

Wild mussels have been harvested in eastern Canada for centuries, but it was not until the early 1970's that there was serious experimentation with their culture. Early trials based on Spanish experience using rafts were unsuccessful, and was no real success until the Japanese floating longline technology was adopted in the late 1970's. This technology was adapted to winter conditions where the lines could be sunk below the ice, and harvested through it, allowing year-round operation. Seed mussels are collected in one year, socked later that same fall, and ongrown for 15-18 months depending on location. The industry successfully survived the domoic acid crisis of 1987, and current harvest in Atlantic Canada exceeds 30 million lbs. There is evidence that some areas are approaching, or have reached their natural production capacity.   Early ventures relied heavily on hand labour for loading socks, and for harvesting. Initial mechanization focussed on the adoption of hydraulic harvesting systems for lifting  heavy socks out of the water, but recent developments include the use of automated continuous socking systems which allow better management of mussel leases. This technology is not universally adopted. There has been some specialization in that some farms in favourable areas supply seed to others where seed is less suitable. While there are some very large, vertically integrated growing and processing enterprises serving international markets, there remain many smaller farms that meet purely local requirements. There is increasing market diversification and a move toward value-added products.   In contrast to the cultured oyster industry which still suffers from the impediment of regulations designed to protect wild stocks, licensed mussel growers are free to manage their stocks according to best commercial practice, commensurate with meeting the normal sanitation and toxicological standards. This has undoubtedly contributed to the success of the industry.

Mussel Culture for BC: Climbing the Learning Curve

Adapting the New Zealand Method of Mussel Seeding for Use in Nova Scotia 

Peter Darnell 

Indian Point Marine Farms Ltd. R.R.2, Mahone Bay, N.S. B0J 2E0 

Having switched our mussel sleeving method from the old style socking to the New Zealand continuous sleeving technology, I will discuss the limitations of the old method, give a summary of the New Zealand mussel industry, and describe the New Zealand system and how we imported the technology to Nova Scotia.  There have been many difficulties and successes in getting local manufacturers interested in producing the machinery, specialized “hairy rope”, and biodegradable cotton sleeving.   We have experienced difficulties and successes in learning to use the new system.  New options and strategies result from being able to sleeve or seed mussels quickly and relatively inexpensively. Although the transition was far from seamless, right from the beginning we were determined to make the new system work for us because its advantages were so obvious.

Mussel Culture for BC: Climbing the Learning Curve

Farming Mussels, M. trossulus and M. galloprovincialis, in the Puget Sound - Similarities and Differences 

Ian W. Jefferds 

Penn Cove Shellfish, LLC  P.O. Box 148, Coupeville WA, USA 98239 

Penn Cove Shellfish, LLC. is a joint venture company involving two Washington State shellfish companies, Penn Cove Mussels, Inc. and Coast Seafoods Co., Inc. Upon coming together in the joint venture, the Coast Seafoods Company’s shellfish hatchery in Quilcene, Washington was tasked with proving their capability to produce mussel seed in the hatchery.  The type of mussel chosen for the hatchery program was the Mediterranean Mussel, or M. galloprovincialis, due to its ability to resist disease, particularly haemic neoplasia, a viral blood disorder to which the Penn Cove Mussels, or M. trossulus, prove extremely susceptible to.  The decision to produce Mediterranean Mussels at the hatchery was also part of a program to diversify the products sold by the joint venture partners, as it was a new product for both members of the partnership.   Fortunately for us, the Coast Seafoods hatchery staff was very successful with initial spawning attempts and also successful with our follow up request to produce triploid Mediterranean Mussel larvae. The lessons learned from others who were farming M. galloprovincialis in Europe and the Puget Sound, as well as those lessons learned in farming M. trossulus were broadly applied to our efforts in Penn Cove, on Whidbey Island, Washington.  As in most things, the more we learned, the more we realized that we did not know.  Since that time, we have adapted our methods and machinery to fit each species, and continued to search out new information from others involved in mussel culture in order to become as efficient as possible.   Spawning and setting are the two largest differences between our culture of the two different mussel species; although we have run into other differences as well, such as in the thinning, grow out, harvesting and marketing aspects of farming Mediterranean and Penn Cove Mussels.  Although much of what we had learned in farming Penn Cove Mussels was transferable to growing Mediterraneans, we found that issues such as socking density, growth rates and harvest machinery requirements do vary.  This pointed out that mussel aquaculture is not only very site specific but even in similar species, it is very species specific as well.  Both species have certain advantages over the other, with one not necessarily better than the other; they are just different; as if one were raising and selling two different species of oysters or clams. 

The specific differences in culture of the two species will be further identified during the presentation.

Mussel Culture for BC: Climbing the Learning Curve

To Investigate Various Methods to Optimize the Grow-out Yield of Mediterranean Mussels

C. Day

Hillingdon Point Oyster Co Ltd, Delta. B.C. V4K 2J1

The grow-out yield (the number of mussels harvested compared to the number seeded) of commercially cultivated Mediterranean Mussels (Mytilus galloprovincialis) is relatively low, only 12% in Washington State. The chief reason for this is the sloughing (dropping off) of the mussels from their growing socks. The objective of this study is to examine different techniques that may be used to improve the grow-out yield. The techniques include: 1) reduced socking density, 2) reduced stocking density, 3) central rope through the socks, and 4) pegged central rope. The study is being conducted over a 15 month period commencing in July/August 1998 and the results will determine which techniques offer the best economic return for the mussel farmer.

Mussel Culture for BC: Climbing the Learning Curve

Shellfish Health Protection Regulations in Canada

Susan M. Bower*¹ and Sharon E. McGladdery²

¹Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, BC V9R 5K6

²Fisheries and Oceans Canada, Gulf Fisheries Centre, Moncton, NB E1C 9B6

Canada has economically significant shellfish aquaculture, commercial and recreational industries. As Canadian shellfish aquaculture continues to develop there is increasing demand for acquisition of stock that demonstrates optimal culture characteristics and for transfer of seed from distant producers. However, transplantation comes with an increased risk of accidental introduction or spread of infectious agents, as occurred in other countries where live transplants were linked to significant disease-related losses. Details of these diseases are presented on our SeaLane Web Site at: http://www.pac.dfo-mpo.gc.ca/sci/sealane/aquac/ pages/title.htm.  In Canada, shellfish health is currently protected under the Fisheries (General) Regulations (VIII) Section 56(b), through an introductions and transfers risk assessment process (which also includes ecological and genetic risk evaluations) that is managed by a committee of Federal and Provincial representatives in each Province. However, unlike salmonids, shellfish health certification is not a regulatory requirement. The proposed regulatory objective is to reduce the risk of introduction or spread of shellfish disease agents, which could threaten wild and cultured shellfish resources, while still providing opportunities to transfer live shellfish for production, enhancement or maintenance prior to sale. In October 1998, a Technical Committee of industry and government representatives from across Canada took on the challenge of reviewing and refining the Draft Shellfish Health Protection Regulations, aimed at making the current ad hoc process better defined and more consistent. The reviewed draft should be ready for public comment/scrutiny in the near future.

Mussel Culture for BC: Climbing the Learning Curve

Mediterranean Mussel Culture in BC – Results of Nursery and Grow-out Trials 

P. Simpson¹* and M. Salo¹*

¹Island Sea Farms Inc., Box 445 Ganges PO, Saltspring Island, B.C. V8K 2W1

Beginning in 1997 Island Sea Farms has conducted trial hatchery, nursery, grow-out and harvesting operations to determine the feasibility of Mediterranean mussel, (Mytilus galloprovincialis) culture in BC. Seed nursery challenges including predation and transmigration will be discussed and survival rates of various techniques reviewed. Two methods of grow-out, lantern nets and continuous sock on longlines will be contrasted along with costs, predation effectiveness, growth-rates and scalability. Harvest methods including sorting and re-socking of undersized mussels will be discussed. Lastly the critical challenges facing this fledgling industry will be identified and possible solutions discussed.

Mussel Culture for BC: Climbing the Learning Curve

Comparative Depth Settlement of Mytilus edulis and M. trossulus in Controlled and Natural Environments

K.R. Freeman*¹, E. Kenchington¹ and S.P. MacQuarrie²

¹Dept Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth, NS, B2Y 4A2

²National Research Council, Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, B3H 3Z1 

Mytilus trossulus has been associated with reduced production in many Eastern Canadian mussel farms where this species often co-occurs, in varying proportions, with the commercially more desirable M. edulis.  Interest in reducing this negative production effect resulted in a search for species-specific behaviour that might be exploited by growers having both mussel species.  Pre-and post-settlement observations were made of laboratory-reared M. edulis and M. trossulus in separate, replicated, 8.5 m deep mesocosms, with and without thermoclines, and of naturally-settled mussel spat at a two-species farm in Nova Scotia.  Field collections of spat to 5 m deep were sub-sampled and the animals subjected to DNA assays to determine proportions, by depth, of M. edulis, M. trossulus and their hybrids.  Analysis of variance tests performed on data from the mesocosm and field experiments consistently indicated statistically significant settlement depth differences between species (a significant interaction term).  The relative depth patterns of species within mesocosms differed from those from the field.  Results suggest that at least on the farm site examined, collectors placed below 1.0 m could have collected 100% more M. edulis while reducing the collection of M. trossulus by as much as 50%.  However, the proportions of the species will be site specific.

Mussel Culture for BC: Climbing the Learning Curve