Sea Louse Abundance on Farmed Salmon in the Southwestern New Brunswick Area of the Bay of Fundy

Chang, B. D.; Page, Fred H.; Beattie, Michael J.; Hill, B.

doi:10.1002/9780470961568.ch3

Cited by 15 publications

(19 citation statements)

References 38 publications

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“…Westcott et al (2008) In conclusion, this analysis presents evidence of a reduction in emamectin benzoate treatment effectiveness over time and between geographical locations for the period of time examined, 2004 to 2008. These results correspond with the clinical picture witnessed in the field of a decline in treatment effect, which became a concern in 2008 (Chang et al 2011). Further investigation is warranted to confirm the underlying cause of this decline in treatment effectiveness.…”

Section: Discussionsupporting

confidence: 84%

“…Only one treatment met the inclusion criteria during the winter season (December to March) and this was an effective treatment in 2004. One could speculate that we would expect to see overall lower L. salmonis abundance around treatment episodes during the winter months as sea lice levels in New Brunswick tend to be lowest throughout the winter (Chang et al 2011). However, time to maximum treatment effect may be delayed in winter, as was shown in an efficacy study on ema mectin benzoate that found treatments applied during colder months took longer to reach maximum effect (Stone et al 2000c).…”

Section: Discussionmentioning

confidence: 99%

“…Given the location, sea farms in this area would be more exposed to the open ocean than other locations closer to the New Brunswick mainland. These fish are exposed to different environmental variables (farm density, tidal excursion, current speeds), which may have resulted in lower sea lice infection pressure than fish on farms close to the New Brunswick mainland (Chang et al 2011). Farms in this region are physically farther away from farms closer to the mainland and perhaps the resistant sea lice had not migrated that far between farms, or resistance had not yet developed locally from repeated treatments leading to selection of emamectin-resistant sea lice.…”

Section: Discussionmentioning

confidence: 99%

“…After almost a decade of use, isolated treatment failures were observed in late 2008, resulting in suspicions about changes in sea lice sensitivity to emamectin benzoate. During 2009, it became evident that a more serious problem was occurring, which compelled industry and government to investigate other methods of treatment for sea lice (Chang et al 2011).…”

Section: Introductionmentioning

confidence: 99%

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Effectiveness of emamectin benzoate for treatment of Lepeophtheirus salmonis on farmed Atlantic salmon Salmo salar in the Bay of Fundy, Canada

Jones¹,

Hammell²,

Dohoo³

et al. 2012

Dis. Aquat. Org.

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Emamectin benzoate (an avermectin chemotherapeutant administered to fish as an in-feed treatment) has been used to treat infestations of sea lice Lepeophtheirus salmonis on farmed Atlantic salmon Salmo salar in the Bay of Fundy, New Brunswick, Canada, since 1999. This retrospective study examined the effectiveness of 114 emamectin benzoate treatment episodes from 2004 to 2008 across 54 farms. Study objectives were to establish whether changes in the effectiveness of emamectin benzoate were present for this period, examine factors associated with treatment outcome, and determine variables that influenced differences in L. salmonis abundance after treatment. The analysis was carried out in 2 parts: first, trends in treatment effectiveness and L. salmonis abundance were explored, and second, statistical modelling (linear and logistic regression) was used to examine the effects of multiple variables on post-treatment abundance and treatment outcome. Post-treatment sea lice abundance increased in the later years examined. Mean abundance differed between locations in the Bay of Fundy, and higher numbers were found at farms closer to the mainland and lower levels were found in the areas around Grand Manan Island. Treatment effectiveness varied by geographical region and decreased over time. There was an increased risk for unsuccessful treatments in 2008, and treatments applied during autumn months were more likely to be ineffective than those applied during summer months.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effectiveness of emamectin benzoate for treatment of Lepeophtheirus salmonis on farmed Atlantic salmon Salmo salar in the Bay of Fundy, Canada

Jones¹,

Hammell²,

Dohoo³

et al. 2012

Dis. Aquat. Org.

View full text Add to dashboard Cite

show abstract

“…The resulting strong tidal currents were considered to be a major benefit for the development of a salmon farming industry in SWNB, because they would prevent waste buildup under farms, except in rare cases (Saunders 1995). The strong tidal circulation, combined with relatively low freshwater input, result in weak stratification: surface salinities in the SWNB farming area usually remain between 25 and 33 psu (Chang et al 2011b). The salmon farming industry in SWNB is also characterized by a very high density of farms: the entire industry is located within a 60 × 60 km area (Fig.…”

Section: Introductionmentioning

confidence: 99%

Variables affecting sediment sulfide concentrations in regulatory monitoring at salmon farms in the Bay of Fundy, Canada

Chang¹,

Page²,

Losier³

2013

Aquacult. Environ. Interact.

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Annual monitoring of sediments is conducted under salmon farms in the southwestern New Brunswick (SWNB) area of the Bay of Fundy, Canada, from August to October. We examined the relationships between the average sediment sulfide concentrations at salmon farms monitored from 2006 to 2009 and some variables related to farm operations: farm age, predicted average near-surface current speed, and estimated biomass of salmon at the time of monitoring. Data for all of these variables were available for 87% of salmon farms monitored in these years (farms that had been inactive for >1 yr were excluded). The year of monitoring had no significant effect, so data from all 4 yr were combined. The ability of the 3 variables to predict sulfide concentrations at the time of monitoring was analyzed using a linear model with log-transformation of variables (except farm age). Each variable individually showed a significant correlation with sulfide concentration, but the model including all 3 variables explained only 37% of the variation. Current speed and biomass explained the highest proportions of sulfide variation (together 35%). Almost 30% of monitoring events occurred at farms holding no fish. When these fallowed sites were excluded, the model explained only 24% of sulfide variation, with current speed being the most important predictor variable. Management actions targeted at farm size (biomass) and physical aspects of sites (especially current speed) may help to reduce the risk of causing adverse benthic impacts, but measurable effects may not be observed due to the large amount of sulfide variation that is not explained by these variables.

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Drug resistance in sea lice: a threat to salmonid aquaculture

Aaen

Helgesen

Bakke

et al. 2015

Trends in Parasitology

352

287

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Sea Louse Abundance on Farmed Salmon in the Southwestern New Brunswick Area of the Bay of Fundy

Cited by 15 publications

References 38 publications

Effectiveness of emamectin benzoate for treatment of Lepeophtheirus salmonis on farmed Atlantic salmon Salmo salar in the Bay of Fundy, Canada

Effectiveness of emamectin benzoate for treatment of Lepeophtheirus salmonis on farmed Atlantic salmon Salmo salar in the Bay of Fundy, Canada

Variables affecting sediment sulfide concentrations in regulatory monitoring at salmon farms in the Bay of Fundy, Canada

Drug resistance in sea lice: a threat to salmonid aquaculture

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