Courtenay, Canada
Courtenay, Canada

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Webb J.L.,Canadian Department of Fisheries and Oceans | Webb J.L.,University of Victoria | Vandenbor J.,Vancouver Island University | Pirie B.,Vancouver Island University | And 8 more authors.
Aquaculture | Year: 2013

Filter-feeding shellfish could act as biological agents in the control of parasitic sea lice (Caligidae) at salmon farms as a benefit of integrated multi-trophic aquaculture. Determining the extent to which various bivalve species ingest sea lice (Lepeophtheirus salmonis) larvae under controlled laboratory conditions was an important first step towards understanding the potential for shellfish to reduce the number of these copepod larvae in the water column at net pens. A series of laboratory experiments examined the effects of temperature (~. 5, 10, and 15. °C), diet (larvae alone or with phytoplankton), and bivalve size (small, medium, and large) on the amount of L. salmonis larvae ingested by basket cockles (Clinocardium nuttallii), Pacific oysters (Crassostrea gigas), mussels (Mytilus spp.), and Pacific scallops (unconfirmed hybrid: Mizuhopecten yessoensis x Patinopecten caurinus). Feeding rate was assessed by placing bivalves individually in 2-l containers holding approximately 450 larvae in 750. ml of filtered seawater. Results of the temperature/diet experiments indicated that all four species of bivalves ingested sea lice larvae, regardless of phytoplankton presence or absence, and that temperature had no significant effect on the proportion of larvae ingested. All three sizes of oysters and scallops ingested sea lice larvae, with large shellfish consuming a significantly greater proportion of the larvae than small individuals. Future research, examining the role of bivalves in the control of sea lice, should be continued at a commercial scale at a salmon farm. © 2013.

Hannah L.,Canadian Department of Fisheries and Oceans | Pearce C.M.,Canadian Department of Fisheries and Oceans | Cross S.F.,University of Victoria | Cross S.F.,SEA Vision Group Inc.
Aquaculture | Year: 2013

In a 12-month field trial we examined the growth and survival of California sea cucumbers (Parastichopus californicus) in suspended culture underneath net pens of sablefish (Anoplopoma fimbria) at an experimental integrated multi-trophic aquaculture (IMTA) site. We tested the effects of sea cucumber size (small: 7-99g and large: 100-565g whole wet weight) and stocking density (12, 17, and 21indm-2) on growth and survival in a completely-crossed experimental design. We also compared growth and survival of experimental animals cultured directly under the fish pens with control sea cucumbers grown ~250m away from the farm. The ability of the sea cucumbers to reduce total organic carbon and total nitrogen from the sablefish faeces was also examined. Small experimental animals grew significantly faster than large experimental individuals, the former increasing in whole wet weight by 27-56% over the 12months and the latter decreasing by 10-33% over the same period. It was concluded that stocking densities of large animals were too high to produce net positive growth. Stocking density had a significant effect on growth of both size classes, lower densities producing higher growth rates, or less negative growth rates in the case of large animals. Small sea cucumbers suspended directly below the sablefish net pens grew significantly faster than control individuals grown ~250m away from the farm, which had negative growth over the 12-month period. The small sea cucumbers cultured under the net pens had a high survival rate (mean: 99.5%) and their feeding reduced the total organic carbon and total nitrogen contents of the sablefish faeces by an average of 60.3% and 62.3%, respectively, demonstrating their potential as an important organic-reducing component in IMTA. Suspending sea cucumbers below fish net pens, as opposed to growing them on the seabed, makes their collection and monitoring easier and moves them away from potential seabed predators such as sea stars. This study demonstrated that P. californicus is well suited to utilise the heavy fraction of waste from a sablefish farm while providing an additional valuable harvestable product. © 2013.

Sterling A.M.,University of Victoria | Cross S.F.,University of Victoria | Cross S.F.,SEA Vision Group Inc. | Pearce C.M.,University of Victoria | Pearce C.M.,Canadian Department of Fisheries and Oceans
Aquaculture | Year: 2016

In a field study, five different stocking densities (i.e. 0, 30, 60, 90, 120 ind. net-1 or 0, 2.46, 4.91, 7.37, 9.82 ind. m-2) of adult green sea urchins (Strongylocentrotus droebachiensis) were randomly assigned to 30 predator-exclusion nets (i.e. n = 6) around cultured mussels (Mytilus spp.) to test the effect of urchin density on biofouling intensity (percent net occlusion) and urchin/mussel growth. After 174 days of culture, nets in all treatments containing sea urchins were significantly less fouled than those in the control treatment without urchins. Fouling intensities on nets with the two highest stocking densities of urchins (90 and 120 ind. net-1) were approximately 40% less than that on nets with urchins held at the lowest stocking density (30 ind. net-1) and 45% less than that on nets without urchins. The differences in fouling intensity among nets with 60, 90, and 120 ind. net-1 were not statistically significant. While fouling was significantly reduced in the presence of urchins compared to the control treatment with no urchins, it was not completely eliminated since they were only able to access the inside surface of the nets. Sea urchin somatic and gonad growth declined with increasing stocking density, but there was no significant difference in mussel growth at the different urchin stocking densities. Mussels and sea urchins can be successfully co-cultured with no food input, but there may be a trade-off between the effectiveness of biofouling control and sea urchin growth. Statement of relevance: This paper examined the use of sea urchins (Strongylocentrotus droebachiensis) to mitigate biofouling in mussel (Mytilus spp.) aquaculture and the effect of sea urchin density on biofouling coverage and mussel growth. Treatments containing sea urchins showed significantly less fouling than a control treatment without urchins. Urchin density had no significant effect on mussel growth. © 2016.

Orr L.C.,Canadian Department of Fisheries and Oceans | Orr L.C.,University of Victoria | Curtis D.L.,Canadian Department of Fisheries and Oceans | Cross S.F.,University of Victoria | And 6 more authors.
Aquaculture | Year: 2014

The ability of the green sea urchin (Strongylocentrotus droebachiensis) to consume and subsequently reduce the organic content of sablefish (Anoplopoma fimbria) culture waste was assessed and properties influencing the dispersal of fecal pellets egested by the sea urchins were quantified in laboratory trials. Ingestion rate, absorption efficiency, and oxygen uptake in sea urchins and the shape, size, and settling velocity of fecal pellets were determined for individuals fed sablefish waste or a natural control diet (giant kelp, Macrocystis pyrifera). Results showed that S. droebachiensis consumes sablefish waste at a dry weight ingestion rate of 0.43±0.039gindividual-1d-1 and absorbs 40±4.84% (mean±SE) of the organic material ingested, with no significant (P<0.05) differences between the diets tested. Oxygen consumption was significantly (P<0.05) higher in sea urchins fed sablefish waste than in those fed kelp at 0 and 2d after feeding. The fecal pellets egested by sea urchins fed sablefish waste were significantly rounder and smaller and had a higher settling velocity than those from individuals fed kelp. This study demonstrates that green sea urchins actively ingest and absorb organic material from the waste produced by sablefish culture. Further research is recommended to determine the effect of the sablefish-waste diet on sea urchin survivorship, growth, and gonad quality. Culture of S. droebachiensis integrated with sablefish is warranted on an experimental scale. © 2013 Published by Elsevier B.V.

Wan D.,University of Victoria | Wan D.,Institute of Ocean science Fisheries and Oceans Canada | Klymak J.M.,University of Victoria | Foreman M.G.G.,Institute of Ocean science Fisheries and Oceans Canada | And 2 more authors.
Continental Shelf Research | Year: 2015

Barotropic M2 tidal dynamics are studied in a subsidiary tidal channel in Kyuquot Sound, Canada, a site proposed for multi-trophic aquaculture. A regional model with no stratification or forcing other than the tide found that the sea level in the subsidiary channel responded in phase with the rest of Kyuquot Sound, but that the velocity response was almost 180° out of phase. Further, this velocity difference was strongly dependent on the choice of viscous parameterization in the model. A simple linear analytical model was developed to explain the simulated changes in terms of the phase lag induced by viscosity, and allowed a larger parameter regime to be explored. These results suggest that verifying models of smaller channels using sea level measurements alone is inadequate, and velocity measurements are necessary. © 2015 The Authors.

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