California Sea Cucumber (<i>Apostichopus californicus</i>) Abundance and Movement on a Commercial Shellfish Aquaculture Farm
California sea cucumbers (<i>Apostichopus californicus</i>) are often abundant at oyster farms in British Columbia, Canada both on the suspended gear as juveniles and on the seafloor beneath them as a mixture of juveniles and adults. Their natural abundance, high value, and potential to...
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MDPI AG
2023-08-01
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| Online Access: | https://www.mdpi.com/1424-2818/15/8/940 |
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| author | Daniel L. Curtis Christopher M. Pearce Paul van Dam-Bates Nicholas M. T. Duprey Stephen F. Cross Laura L. E. Cowen |
| author_facet | Daniel L. Curtis Christopher M. Pearce Paul van Dam-Bates Nicholas M. T. Duprey Stephen F. Cross Laura L. E. Cowen |
| author_sort | Daniel L. Curtis |
| collection | DOAJ |
| description | California sea cucumbers (<i>Apostichopus californicus</i>) are often abundant at oyster farms in British Columbia, Canada both on the suspended gear as juveniles and on the seafloor beneath them as a mixture of juveniles and adults. Their natural abundance, high value, and potential to mitigate benthic organic loading has led to an interest in their coculture with oysters. Whether farmed sea cucumbers ought to be contained to physically separate them from wild stocks is debated. The present three-year field study examined the movement of wild California sea cucumbers on/off an operational oyster farm (~3000 m<sup>2</sup>) to help inform future sea cucumber aquaculture development. Sea cucumber effects on organic loading, immigration to/emigration from the farm, and the efficacy of various containment-material mesh types and sizes were examined. Juvenile and adult sea cucumber densities on the farm steadily increased from the end of winter through the end of summer, likely due in large part to juveniles falling off the suspended oyster gear, which occurred at an average rate of ~780 ind d<sup>−1</sup> (for the whole farm) in the summer months. The largest increase in abundance on the farm was observed between January and March/April, when the population increased by 100–350 ind d<sup>−1</sup>. Between late summer and early winter, sea cucumbers emigrated from the farm at a rate of 50–90 ind d<sup>−1</sup>, neither juvenile nor adult densities on the farm changing appreciably over the winter. The sea cucumber density showed a progressive decrease in the first 20 m from the farm, after which the animals were scarcely noticed. <i>Apostichopus californicus</i> did not significantly decrease sediment organics beneath the farm compared to a nearby control site, but such an effect may have been lost due to their seasonal feeding cycles and/or the presence of other benthic grazers that were not part of our exclusion trial. Overall, our findings suggest that the separation of farmed and wild California sea cucumbers on a shellfish farm can only be guaranteed through containment, given the dynamic immigration and emigration patterns of wild stocks. Through laboratory trials, we found that individuals of <i>A. californicus</i> were able to squeeze through mesh as small as 32% of their contracted width and could escape fenced areas (90 ± 4% escape from nylon fencing and 40 ± 8% escape from Vexar<sup>TM</sup> fencing) unless the fencing extended above the water surface (where there was no escape from either type). |
| first_indexed | 2024-03-11T00:00:38Z |
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| spelling | doaj.art-d9e8587d932d47bc85673f309f9c8b8e2023-11-19T00:49:56ZengMDPI AGDiversity1424-28182023-08-0115894010.3390/d15080940California Sea Cucumber (<i>Apostichopus californicus</i>) Abundance and Movement on a Commercial Shellfish Aquaculture FarmDaniel L. Curtis0Christopher M. Pearce1Paul van Dam-Bates2Nicholas M. T. Duprey3Stephen F. Cross4Laura L. E. Cowen5Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, CanadaPacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, CanadaPacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, CanadaPacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, CanadaDepartment of Geography, University of Victoria, Victoria, BC V8P 5C2, CanadaDepartment of Mathematics and Statistics, University of Victoria, Victoria, BC V8W 3R4, CanadaCalifornia sea cucumbers (<i>Apostichopus californicus</i>) are often abundant at oyster farms in British Columbia, Canada both on the suspended gear as juveniles and on the seafloor beneath them as a mixture of juveniles and adults. Their natural abundance, high value, and potential to mitigate benthic organic loading has led to an interest in their coculture with oysters. Whether farmed sea cucumbers ought to be contained to physically separate them from wild stocks is debated. The present three-year field study examined the movement of wild California sea cucumbers on/off an operational oyster farm (~3000 m<sup>2</sup>) to help inform future sea cucumber aquaculture development. Sea cucumber effects on organic loading, immigration to/emigration from the farm, and the efficacy of various containment-material mesh types and sizes were examined. Juvenile and adult sea cucumber densities on the farm steadily increased from the end of winter through the end of summer, likely due in large part to juveniles falling off the suspended oyster gear, which occurred at an average rate of ~780 ind d<sup>−1</sup> (for the whole farm) in the summer months. The largest increase in abundance on the farm was observed between January and March/April, when the population increased by 100–350 ind d<sup>−1</sup>. Between late summer and early winter, sea cucumbers emigrated from the farm at a rate of 50–90 ind d<sup>−1</sup>, neither juvenile nor adult densities on the farm changing appreciably over the winter. The sea cucumber density showed a progressive decrease in the first 20 m from the farm, after which the animals were scarcely noticed. <i>Apostichopus californicus</i> did not significantly decrease sediment organics beneath the farm compared to a nearby control site, but such an effect may have been lost due to their seasonal feeding cycles and/or the presence of other benthic grazers that were not part of our exclusion trial. Overall, our findings suggest that the separation of farmed and wild California sea cucumbers on a shellfish farm can only be guaranteed through containment, given the dynamic immigration and emigration patterns of wild stocks. Through laboratory trials, we found that individuals of <i>A. californicus</i> were able to squeeze through mesh as small as 32% of their contracted width and could escape fenced areas (90 ± 4% escape from nylon fencing and 40 ± 8% escape from Vexar<sup>TM</sup> fencing) unless the fencing extended above the water surface (where there was no escape from either type).https://www.mdpi.com/1424-2818/15/8/940dive survey<i>Holothuroid</i>movementocean ranchingsedimentation |
| spellingShingle | Daniel L. Curtis Christopher M. Pearce Paul van Dam-Bates Nicholas M. T. Duprey Stephen F. Cross Laura L. E. Cowen California Sea Cucumber (<i>Apostichopus californicus</i>) Abundance and Movement on a Commercial Shellfish Aquaculture Farm Diversity dive survey <i>Holothuroid</i> movement ocean ranching sedimentation |
| title | California Sea Cucumber (<i>Apostichopus californicus</i>) Abundance and Movement on a Commercial Shellfish Aquaculture Farm |
| title_full | California Sea Cucumber (<i>Apostichopus californicus</i>) Abundance and Movement on a Commercial Shellfish Aquaculture Farm |
| title_fullStr | California Sea Cucumber (<i>Apostichopus californicus</i>) Abundance and Movement on a Commercial Shellfish Aquaculture Farm |
| title_full_unstemmed | California Sea Cucumber (<i>Apostichopus californicus</i>) Abundance and Movement on a Commercial Shellfish Aquaculture Farm |
| title_short | California Sea Cucumber (<i>Apostichopus californicus</i>) Abundance and Movement on a Commercial Shellfish Aquaculture Farm |
| title_sort | california sea cucumber i apostichopus californicus i abundance and movement on a commercial shellfish aquaculture farm |
| topic | dive survey <i>Holothuroid</i> movement ocean ranching sedimentation |
| url | https://www.mdpi.com/1424-2818/15/8/940 |
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