Scientific Research on Cultured Mussels

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Science is the key to an environmentally sustainable aquaculture industry. Fisheries and Oceans Canada scientists and researchers have initiated a number of studies to improve the production of mussel farming in Canada through innovative techniques for seed collection and transfer, as well as grow-out and harvesting. Research has also focused on the benefits and potential impacts of mussel farming on the marine ecosystem, including benthic areas and wild fish and shellfish species. This includes investigating the role of mussel culture in integrated multi-trophic aquaculture.

Innovation

In co-operation with the mussel aquaculture industry on the Magdalen Islands, a multi-disciplinary research team explored how the flows of matter and energy across the food web could be managed to increase production of high-quality, harvestable shellfish. The research is expected to have a strong influence on government policy and to eventually translate into novel production methods.


Researchers in Newfoundland are conducting a three-year project to compare the health and condition of cultured mussels from deep and shallow water sites, with reference to environmental conditions, condition index, physiological stress and lipid biochemistry. Results from this study will contribute to a better understanding of the potential development of offshore mussel culture in Newfoundland.


A federal-provincial funded study in Newfoundland and Labrador investigated the feasibility of submerging mussel long-lines in deeper water during winter. With good results during the first phase of the study, a deep-water site was selected for early commercialized trials in 2008-09.


Researchers in Prince Edward Island are evaluating novel processing plant holding systems and holding methods to improve the length of time live mussels can be held in wet storage. These new systems and practices will help improve the industry’s ability to complete in international markets.


Dutch technology used to produce cooked mussel meat was adapted and tested for shelling rate, yield, and quality of cooked meat using three categories of mussels. Results were used to develop cooked meat standards for small and large mussels.


To help mussel growers more effectively manage their mariculture equipment and mollusc stocks, researchers in Quebec designed a new farm management software application and offered industry training on the software.


Multi-disciplinary research was undertaken in Quebec to test a modified venturi system to save time when harvesting mussel spat and commercial-sized mussels, and to reduce losses from mussel fall-offs. Sea trials of the automated system showed that harvesting could be carried out 3.5 times faster compared to the conveyor system.


A more efficient hydraulics system with the oil capacity to operate multiple hydraulic motors was developed to enable automation of mussel seeds collection to seeds socking operation in Newfoundland at a significantly lower cost.


Integrated multi-trophic aquaculture

The idea of growing finfish, shellfish, and marine plants together for the benefit of the environment and all three crops is known as integrated multi-trophic aquaculture or polyculture. Canadian researchers are studying various aspects of this model with the rearing of blue mussels and kelp near pre-established Atlantic salmon aquaculture sites in the Bay of Fundy. Research is also underway in British Columbia.


Genomics

A major program was launched in British Columbia to develop a genomics tool for use with mussels; a known ecosystem bio-indicator genus. The researchers hope to devise an accurate way to measure the activity of specific genes that respond to a variety of stressors in order to correlate levels of stress with environmental conditions and understand what ultimately determines a fatal response. The genomic information and tools for studying marine mussels will also be used in assessments of coastal environmental health.


The influence of routine husbandry practices in mussel farming and trait selection on genetic diversity was examined to assess their implications for future broodstock programs. The study included blue mussels from three aquaculture populations in British Columbia, as well as a wild population from its native range in PEI.

  • Canadian Aquaculture R&D Review article: 2011

Production

Mussel seed (spat)

DNA-based tests to distinguish between two species of mussels, Mytilus edulis and Mytilus trossulus, were improved so they could be used with more samples at a lower cost. The assays were then used to look at the species composition of seed-sized mussels collected around Nova Scotia to identify good regions for seed collection. Researchers also investigated the ratio of the two species and their respective physiological fitness throughout growth in the natural population and at aquaculture sites throughout the Province.


A five-year project was undertaken in Newfoundland to search for quality mussel seed using seed collector arrays. The Mussel Seed Project compared biological and physical oceanography information on how the two different mussel species grow and survive in different bays when transported to new sites.


While the use of transferred M. edulis mussel stocks has been recommended to industry rather than collecting seed on sites with high ratios of M. trossulus, the transferred mussels have not always consistently out-performed indigenous mixed-species stocks. Researchers suspected that this was due to genetic variation within the M. edulis mussel genotype and therefore tested the performance of M. edulis mussel stocks on recipient sites to determine their true potential as donor seed-stock. The results of the study indicated that donor sites for seed transfer operations should be evaluated individually for performance parameters and/or managed to the where only the best final product is made available to growing and market.


DFO researchers in Newfoundland and Labrador studied variability in performance of different mussel seed stocks when confronted with stresses related to temperature and salinity. The team established standardized testing protocols for “heat shock protein” and other stress proteins in the hopes of developing a quantitative way to identify hardy strains of mussels that can be used for inter-site transfers.

  • Canadian Aquaculture R&D Review article: 2009 

To optimize mussel seed collection in the Gaspé Peninsula in Quebec, a multi-disciplinary team of researchers set out to acquire basic knowledge about the mechanisms governing mussel larval distribution in order to determine peak periods of abundance, origin, and diversity of M. edulis and M. trossulus. Results obtained in the Cascapedia Bay sector included the appearance of small larvae beginning in mid-June. In the Gaspé sector, three cohorts of small veliger larvae were observed, including a very large peak around mid-July.


A simple, effective, and low-cost method for monitoring recruitment and growth of mussel seed was developed by a group of researchers in Quebec using mussel spat found on navigation buoys at various sites in the Gulf of St. Lawrence.


To help the PEI and NB mussel industry reduce the risk of costly high mortalities throughout the grow-out phase, researchers developed and assessed seed quality criteria, such as physiological and pathological health. The study also examined the economical and ecological benefits of new culling techniques to maintain or increase seed quality.


Between 2002 and 2003, a multi-disciplinary team of researchers worked to develop standardized monitoring and data acquisition systems of shellfish productivity in culture bays. This includes developing a series of standardized protocols for the monitoring of mussel growth, survival, and yield in relation to husbandry and environmental conditions on several mussel grow-out sites.


Mussel attachment

“Fall-offs” of mussels from suspended socks are most likely related to the attachment strength of mussels to each other, as well as to the sock. The main findings of research undertaken in 2004 and 2005 revealed that a significant decline in attachment strength in summer appeared to be associated with spawning, while the increased strength in fall appeared to be associated with water turbulence.

  • Canadian Aquaculture R&D Review article: 2007 

The relationship between passive losses caused by “fall-offs” and mussel attachment strength to socks was studied to understand the underlying biological mechanism and to quantify losses for mussel growers.


Researchers in Quebec worked to determine the best approach to calculate mussel fall-offs that occur with self-operating collectors and to provide a preliminary estimate of the fall-off process. The study was used to compare ecosystem effects of conventional suspension culture and mussel culture using self-operating collectors.


Mussels use their byssal threads to attach themselves to each other and suspended socks. Research was undertaken to understand the factors that may influence the byssus production rates, such as temperature, salinity, byssal thread cutting, water agitation, and others. Preliminary analysis indicated byssus production: increases with temperature, but only with a low water flow rate; is very sensitive to the amount available food; is not directly affected by water flow; and, when cut, causes a clear reduction in body growth rate.

  • Canadian Aquaculture R&D Review article: 2007 

Mussel gaping

A research team in Quebec investigated whether the propensity of mussels for gaping is voluntary and occurs when they are exposed to air or is related to decreased adductor muscle tone.

  • Canadian Aquaculture R&D Review article: 2009 

Mussel storage

Researchers in Newfoundland and Labrador are evaluating the effects of long-term storage on the mussel to determine how long mussels can effectively be kept in holding and still maintain the necessary product quality. The lipid and fatty acid composition of mussels will also be investigated in terms of palatability and taste during extending holding conditions.


Potential effects and benefits of blue mussel culture on wild fish and shellfish and/or the marine environment

An international research initiative is providing scientific knowledge, sustainability indicators, modeling capacity, sustainable ecological engineering approaches to mussel farm management, and expertise that can meet the demands of large-scale mussel aquaculture assessments. Known as ESSMA – the Ecological Sustainability of Suspended Mussel Aquaculture project is addressing the science needs generate by maritime regulatory policies in Canada and the European Union related to ecosystem-based management.

  • Canadian Aquaculture R&D Review article: 2011 

Between 2012 and 2013, researchers in Quebec are using modeling approaches to: estimate biodeposit production by mussel culture and its influence on the seabed; evaluate predictions through a series of in situ experiments; and parameterize an index of benthic conditions for Eastern Canada.

  • Canadian Aquaculture R&D Review article: 2011 

The interactions between mussel farms and American lobster populations in eastern Newfoundland were investigated to determine whether mussel culturing caused a decline in lobster landings. Research results indicated that a causal link was unlikely.

  • Canadian Aquaculture R&D Review article: 2011 

An extensive environmental sampling program was conducted between 2008 and 2009 on a St. Ann’s Harbour, Nova Scotia mussel farm to test both the environment impact assessment predictions and the effectiveness of the environmental monitoring program design. Data collected will be used to advance regulatory science.


Researchers set out to test the hypothesis that benthic productivity in mussel culture sites is greater than that in adjacent sandy and eelgrass habits. Secondly, they modified organic (mussel feces) loading rates to develop close-response curves to determine how different stocking densities influenced benthic infaunal communities. Results indicated that benthic infaunal productivity is greater in areas with mussel culture than in areas without it.


Between 2004 and 2008, researchers sought to: determine whether rock crabs are effectively attracted to mussel socks on a long-line; examine whether there is a decline in the abundance of rock crab on and under mussel lines during and following the directed fishery; verify the widespread assertion that rock crabs are beneficial to mussel long-line productivity; and to evaluate the impact of green crab on mussel line productivity.

  • Canadian Aquaculture R&D Review article: 2007 

To determine whether Skeleton Shrimp are harmful to mussel culture, research was undertaken to study: mussel seed set density and Skeleton Shrimp biomass as a function of depth; the diet of Skeleton Shrimp; and the effect of various weight-line maintenance protocols on Skeleton Shrimp populations. Results indicated that Skeleton Shrimp do not feed on mussel larvae or seed.


Researchers also examined interactions between Skeleton Shrimp, hydrozoans, and mussels at culture sites in Cascapédia and Gaspé bays in Quebec to verify the effectiveness of an epibiont control protocol and to develop cost/benefit criteria to determine whether treatment is worthwhile. During the course of this three-year study, researchers documented the biology, ecology, and spatial and temporal variability of skeleton shrimp and hydrozoans on mussel spat collection and growth over the short- and long-terms to quantify the impact.


Between 2009 and 2010, researchers characterized food particle depletion within the zone of influence downstream of mussel leases, and investigated the extent that mussel crop layout could modulate this zone. Results indicated that food depletions rarely extended beyond lease boundary.


Indicators to monitor phytoplankton depletion by mussels were developed by an international team of researchers from Canada and Norway in order to assess the effect of mussel culture on the concentration and size of phytoplankton. This five-year, international study is also working to develop a reliable method for rapidly mapping the spatial scale of phytoplankton depletion within and outside suspended mussel farms; obtain field data from a wide range of geographic and aquaculture settings; and identify critical phytoplankton depletion limits for assessing the ecological carrying capacity of suspended mussel farms.


Aquatic invasive species

Tunicates are aquatic invasive species in Canadian waters, and their arrival has caused some devastating infestations on shellfish aquaculture operations by attaching to mussel socks and other culture gear. Research activities are contributes to the development of management strategies and rapid response procedures.


Animal health

The correlation between a toxic episode in mussels relative to scallops, and the necessary time required for detoxification, was evaluated during a study to assess the contamination dynamics of scallops cultured in Gaspé and Chaleur bays.

  • Canadian Aquaculture R&D Review article: 2011 

Results from a five-year study on two parasites affecting shellfish aquaculture in Atlantic Canada suggested that the parasitic mussel castrator, Prosorhynchus squamatus, is normally at a low level and sporadic infection does not present a significant threat to Atlantic mussel populations.


A historical database on the prevalence and intensity of parasites present in various shellfish populations at commercial and experimental culture facilities in Quebec was undertaken between 2004 and 2007. The project included a component comparing the parasites present in mussel populations on both natural and farmed beds.


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