Long-term studies of lobster abundance at a salmon aquaculture site, eastern Canada

Abstract

Wild lobster (Homarus americanus) abundance was monitored before, during, and after salmon (Salmo salar) aquaculture production in a bay on Grand Manan Island, New Brunswick, Canada, in an 8-year survey, 2008 to 2015. Diver transects and free-area spot-dives were used to measure the carapace length and determine sex (including berried state) of each lobster encountered both inside (farm) and outside (reference) the lease boundaries. In pairwise comparisons of each sampling date, there was no significant difference between the number of lobsters inside the salmon farming area versus a nearby reference site and no significant difference in the number of berried females inside or out of the farm lease area. Combining data from all lobster surveys (farm and reference sites) indicated an increase over 8 years, similar in slope to the increase of the trap fishery in Lobster Fishing Area (LFA) 38. These results indicate that the fish farm had no obvious impact on lobster density at any point in the salmon production cycle and that inshore lobster abundance followed trends similar to those of the general fishery of LFA 38.

European lobsters utilise Atlantic salmon wastes in coastal integrated multi-trophic aquaculture systems

“…The interaction between salmon cages and wild lobsters is an important area of research, especially in Canada where studies have explored the conflict over use of space between salmon farms and lobster fisheries (Walters 2007, Grant et al 2019. In Canada and Norway, research has also focussed on the potential impact of medicinal treatments used for salmon aquaculture on lobsters (Burridge et al 2014, Cresci et al 2018.…”

Nitrogen budget in recirculating aquaponic systems with different fish stocking density

“…Sediment production was different among treatments with the highest value in APH treatment and the lowest value in HP. This was expected, as sediments derive from deposition of fish feed and feces (Grant et al, 2019) which of course increased with increasing stoking density. No statistical differences among treatments were obtained considering sediment N concentration and content (Table 4).…”

Interactions between American lobster (Homarus americanus) and salmonid aquaculture in the Canadian Maritimes

“…Following the earlier work of Lawton et al (2001) that used diver surveys to assess lobster populations in LFAs 36 and 38 in New Brunswick, the provincial government requested monitoring at a new salmon farm to ensure that the farm had no deleterious effects on lobster, and the direct observation approach was revisited. To circumvent some of the potential limitations associated with other methods, Grant et al (2019) conducted diver transect surveys of American lobster abundance at aquaculture and reference sites, over 8 years and multiple salmon production cycles. There was no significant impact of the Atlantic salmon aquaculture operation on lobster proximate abundance relative to reference and farm locations at a New Brunswick salmon farm over the study period (Grant et al 2019).…”

“…To circumvent some of the potential limitations associated with other methods, Grant et al (2019) conducted diver transect surveys of American lobster abundance at aquaculture and reference sites, over 8 years and multiple salmon production cycles. There was no significant impact of the Atlantic salmon aquaculture operation on lobster proximate abundance relative to reference and farm locations at a New Brunswick salmon farm over the study period (Grant et al 2019). Grant et al (2019) reported independent trends in lobster abundance and farm operational status (i.e., feed and fallow periods) and found that the lowest abundance of lobster was recorded at both the farm and reference sites before the farm became operational.…”

“…This has, at times, resulted in conflict between various stakeholders. In the Province of Nova Scotia, the potential for effects of salmonid aquaculture on the nearshore American lobster (Homarus americanus) fishery is contentious and has been debated in the scientific literature (Loucks et al 2014(Loucks et al , 2016Grant et al 2016Grant et al , 2019Milewski et al 2018Milewski et al , 2021Milewski and Smith 2019) and mainstream media (CBC 2015(CBC , 2020a(CBC , 2020b. Surpris-ingly, only a handful of qualitative and empirical studies have been published on the topic and conclusions differ widely.…”