Canada's Approach to Aquatic Animal Biosecurity: Experience and Evolution

McGladdery, S. E.; Zurbrigg, Richard E.

doi:10.1002/9780470376850.ch4

Cited by 5 publications

(9 citation statements)

References 11 publications

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“…While these diseases are not present in our study area, it is important to note that the causative agent of Malpeque disease has never been identified (DFO, 2017) and that it is still present in the study area, as experimentally demonstrated by massive mortalities following transfer of naïve oysters to the Gulf of Saint Lawrence (McGladdery & Zurbrigg, 2006). Malpeque disease appears to be restricted to higher salinity regions of Atlantic Thus, while oyster populations in the Gulf of Saint Lawrence do not suffer currently large mortalities, Malpeque disease may still exert an influence on extant oyster population structure and this may be mediated by abiotic variables, as for other diseases (Bergquist, Hale, Baker, & Baker, 2006;Burreson & Ragone-Calvo, 1996;Eastern oyster Biological Review Team, 2007;Hofmann et al, 2009;Mann, Southworth, Harding, & Wesson, 2009;McGladdery & Zurbrigg, 2006;McGladerry & Bower, 1999).…”

Section: Environmental Effects On Genetic Variationmentioning

confidence: 85%

“…Despite regulations prohibiting the transfer of oysters from Malpeque Bay after mortality was observed, the disease spread to other PEI bays, with characteristic mass mortalities of >90% across all age classes. Eventually, the Malpeque stock appeared to acquire resistance to Malpeque disease and disease‐resistant broodstock were transferred to other bays in an effort to accelerate the recovery of oyster populations (McGladdery & Zurbrigg, ). By the 1950–1960s, Malpeque disease appeared in New Brunswick (NB) and Nova Scotia (NS), presumably from prohibited transfers of asymptomatic disease carriers from PEI, causing the same widespread mortalities and decimating oyster beds.…”

Section: Introductionmentioning

confidence: 99%

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Seascape genomics of eastern oyster (Crassostrea virginica) along the Atlantic coast of Canada

Bernatchez

Xuereb

Laporte

et al. 2018

Evolutionary Applications

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Interactions between environmental factors and complex life‐history characteristics of marine organisms produce the genetic diversity and structure observed within species. Our main goal was to test for genetic differentiation among eastern oyster populations from the coastal region of Canadian Maritimes against expected genetic homogeneity caused by historical events, taking into account spatial and environmental (temperature, salinity, turbidity) variation. This was achieved by genotyping 486 individuals originating from 13 locations using RADSeq. A total of 11,321 filtered SNPs were used in a combination of population genomics and environmental association analyses. We revealed significant neutral genetic differentiation (mean F ST = 0.009) between sampling locations, and the occurrence of six major genetic clusters within the studied system. Redundancy analyses (RDAs) revealed that spatial and environmental variables explained 3.1% and 4.9% of the neutral genetic variation and 38.6% and 12.2% of the putatively adaptive genetic variation, respectively. These results indicate that these environmental factors play a role in the distribution of both neutral and putatively adaptive genetic diversity in the system. Moreover, polygenic selection was suggested by genotype–environment association analysis and significant correlations between additive polygenic scores and temperature and salinity. We discuss our results in the context of their conservation and management implications for the eastern oyster.

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Section: Environmental Effects On Genetic Variationmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Seascape genomics of eastern oyster (Crassostrea virginica) along the Atlantic coast of Canada

Bernatchez

Xuereb

Laporte

et al. 2018

Evolutionary Applications

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“…The rate of spread of epidemics appears to be much greater in marine environments and they tend to be more devastating (McCallum et al . ), making the open aquatic environment a major challenge for the development of biosecurity (McGladdery & Zurbrigg ). This is illustrated by the rapid spread of most viruses from the sites where they were first recognized (Flegel ; Lightner et al .…”

Section: Overview Of Strategies For Integrated Management Of Diseasesmentioning

confidence: 99%

Strategies for managing diseases in non‐native shrimp populations

Cock

Salazar

Rye

2015

Reviews in Aquaculture

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The shrimp industry is now largely based on Litopenaeus vannamei. Current strategies for disease management in Asia emphasizing exclusion and eradication with strict quarantine and importation protocols have not been effective in controlling disease epidemics. New diseases have been introduced on illegal importations; commercial shrimp populations are derived from imported SPF stocks susceptible to endemic diseases; and local breeding programmes are based on populations not resistant to a range of diseases. Broodstock are largely poorly adapted to local conditions and repeated disease epidemics occur. Strategies for disease management should concentrate on: (i) minimizing the risk of introducing new diseases to the region; (ii) development of populations more resistant to endemic diseases; and (iii) better management practices that minimize the likelihood of serious epidemics and delay infection, but do not depend on attempts to eradicate diseases already present. This can be implemented by building on the better management practices already established in the region and in addition: (i) applying strict quarantine procedures for diseases not reported in the region whilst making the processes sufficiently agile to reduce illegal introductions; (ii) eliminating standard rigid importation protocols and tailoring protocols in accordance with the disease situation of both the country of origin and destination; (iii) increasing genetic variation available within Asia by public sector support for programmes to enlarge the pool of genetic variation and encouraging collaboration with breeding programmes that encompass a broad genetic base; (iv) establishing selection programmes that permit reincorporation of animals exposed to disease into the breeding nucleus; and (v) establishing propagation systems that provide growers with high health status stocks without requiring overly strict SPF certification of facilities.

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“…The rapid development of the oyster aquaculture industry in Atlantic Canada and the recent appearance of the protozoan parasite, H. nelsoni, in the Bras d'Or Lakes (Cape Breton, NS, Canada), are two main reasons for farmers to consider expanding their operations upriver into lower salinity areas (McGladdery & Zurbrigg ). In Atlantic Canada, most of the oyster aquaculture operations are located in downriver areas, where the salinity is generally conducive to the recruitment and survival of wild oysters (Bastien‐Daigle, Hardy & Robichaud ).…”

Section: Introductionmentioning

confidence: 99%

Stress response ofCrassostrea virginica(Gmelin, 1791) oysters following a reciprocal transfer between upriver and downriver sites

et al. 2014

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This study was designed to assess the physiological impact of transferring oysters between upriver and downriver aquaculture sites, a common practice in North America that is primarily aimed at reducing disease infections and predation on cultured stocks. In May 2009, oysters (Crassostrea virginica) were reciprocally transferred between an upriver and a downriver site in the Richibucto estuary in eastern Canada. Mortality, tissue and cellular stress responses were subsequently evaluated in August and October 2009. Overall, oyster mortality remained low (~5%) throughout the 5-month study period with no significant difference between sites or oyster sources. However, by October oysters reared at the upriver site, regardless of their origin, had significantly higher levels of lysosomal membrane destabilization (63.6%, SE = 1.9) and digestive tubule atrophy (33.3-42.4%, SE = 3.6) than oysters reared at the downriver site (47.5%, SE = 1.8; 15.6-19.1%, SE = 3.8 respectively). They also exhibited a greater salinity differential between their mantle/haemolymph fluids and the ambient seawater, possibly indicating more restricted exchange with the environment. In general, the transfer of upriver oysters to a downriver site had a positive impact, i.e. lower levels of lysosomal destabilization and tubule atrophy, whereas transfer of downriver oysters upriver had the opposite effect. These results suggest that upriver environmental conditions negatively impact cellular and tissue integrity in oysters without leading to mortality during the summer-autumn period.

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Canada's Approach to Aquatic Animal Biosecurity: Experience and Evolution

Cited by 5 publications

References 11 publications

Seascape genomics of eastern oyster (Crassostrea virginica) along the Atlantic coast of Canada

Seascape genomics of eastern oyster (Crassostrea virginica) along the Atlantic coast of Canada

Strategies for managing diseases in non‐native shrimp populations

Stress response ofCrassostrea virginica(Gmelin, 1791) oysters following a reciprocal transfer between upriver and downriver sites

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