Spatial distribution of suspended particulate wastes at open-water Atlantic salmon and sablefish aquaculture farms in Canada

• Published in: Aquaculture Environment Interactions
• Main Authors: LM Brager, PJ Cranford, J Grant, SMC Robinson
• Format: Article in Journal/Newspaper
• Language: English
• Published: Inter-Research 2015
• Subjects: Aquaculture. Fisheries. Angling; SH1-691; Ecology; QH540-549.5; Canada; British Columbia; Atlantic salmon; Salmo salar
• Online Access: https://doi.org/10.3354/aei00120; https://doaj.org/article/544e9ae225f744d198833f87610fe209

Finfish aquaculture results in the production of particulate waste products that include uneaten feed and faeces. The impact of these wastes on the suspended particle field at 4 open-water fish farms in Canada was studied using high-resolution in situ particle sensors. Within-pen sampling at a sablefish Anoplopoma fimbria farm in British Columbia provided some evidence of the release of low levels (mean effect <0.2 mg l-1) of waste feed near the surface (1-3 m depth), but no waste signal was detectable in surface waters outside this farm. Enhancement of the particle field was also not apparent in surface waters (0.5-2 m depth) within the boundaries of an Atlantic salmon Salmo salar farm in the Bay of Fundy. However, data collected outside 2 adjacent farms indicated periodic, low-level particle enhancement (significant mean effect of <1.0 mg l-1; p < 0.001) near the surface immediately down-current from the net-pens. Despite the large sample numbers obtained, consistent detection of waste particle enhancement was confounded by the apparently small effect size and natural seston patchiness. These results suggest that any farm-induced effect on the surrounding particle field at the study sites would be highly localized and episodic. Consequently, the potential for enhanced production by co-cultured bivalve filter-feeders at these integrated multi-trophic aquaculture farms is limited by available space close to net-pens and the periodic availability of low levels of suspended particulate fish wastes.