Shellfish Research Articles, Reports & Documents
date August 4th, 2009:
Mechanized Clam Harvesting for Coastal BC – Environmental Implications – This report is a paper from the Aquaculture Association of Canada Proceedings of the 2009 AAC Conference. The author David Stirling is completing his MSc from UVic Geography.
Updates July 15th, 2009:
Canadian Aquaculture R&D Review – 2009 – Congratulations to Tim DeJager (Project Coordinator) and funding agencies DFO ACRDP and BCARDC for producing yet another great R&D Review publication.
Also, we have recently received a couple important academic papers on Manila clam recruitment and the effect of predator netting.
July 10th, 2008 - Liu, Alabi & Pearce (2008). Fertilization and embryonic development in the basket cockle, Clinocardium nuttallii. Journal of Shellfish Research, Vol 27, No 2, 393-397.
Abrstract: Sperm mobility, fertilization, and embryonic development were investigated in the hermaphroditic basket cockle, Clinocardium nuttallii. Motility of the sperm was more prolonged over a 2-h storage period at 4°C than at 19°C. The sperm-to-egg ratio resulting in the highest fertilization rate was 10,000:1, or an equivalent final sperm concentration of 6 x 105 cells mL-1, using a density of 60 eggs mL-1. However, at least some degree of self-fertilization appeared to be unavoidable during the release of the eggs from the broodstock. The biological zero point, below which embryonic development ceased, was estimated to be 2.8°C to 2.9°C for C. nuttallii.
July 10th, 2008 - Liu, Alabi & Pearce (2008). Broodstock conditioning in the basket cockle, Clinocardium nuttalli. Journal of Shellfish Research, Vol 27, No 2, 399-404.
Abstract: Factors affecting broodstock conditioning in the hermaphroditic basket cockle,Clinocardium nuttallii, were examined in laboratory experiments. Although a 13-wk experiment conducted at 16°C failed to bring C. nuttalliibroodstock into spawning condition under different dietary treatments, initiation of gametogenesis was apparent for those broodstock maintained at 2.5°C. Condition indices were significantly greater when broodstock were fed a combination of Isochrysis galbana (Tahitian strain, T-iso) and Chaetoceros gracilis (CG) or T-iso and Thallasiosira pseudonana (3H) than when fed a combination ofTetraselmis suecica (TS) and 3H or TS and CG, indicating that T-iso may be a better food source than TS for cockle broodstock conditioning.
March 25th, 2008 - Paltzat, Pearce, Barnes, McKinley (2008). Growth and production of California sea cucumbers (Parastichopus californicus) co-cultured with suspended Pacific oysters (Crassostrea gigas). Aquaculture. 275. pp 124-137.
Abstract: Growth and production of California sea cucumbers (Parastichopus californicusStimpson), co-cultured with suspended Pacific oysters (Crassostrea gigas Thunberg), were investigated in a 12-month (January 2004 -January 2005) study conducted at two sites of deep-water, suspended oyster culture in British Columbia, Canada. Rates of oyster biodeposition (faeces and pseudofaeces) and the utilization of this particulate material as a food source by P. californicus were also examined. Peaks in sedimentation rates through 8.5 m water depth, below the oyster rafts, were observed in April (93.6 g dry wt m-2 d-1) and July (91.9 g dry wt m-2 d-1) 2004. At the two study sites, maximum mean total organic carbon deposition rate at 8.5 m depth occurred in July 2004 and amounted to 3123 and 3830 mg dry wt C m-2 d-1. Maximum mean total nitrogen deposition rate at the two sites was 524 and 568 mg dry wt N m-2 d-1 which occurred in November and July 2004, respectively. Mean C/N ratios of particulate material in the sediment trap samples collected at the two sites between January and November 2004 ranged between 5.9 and 12.4 and may be considered to be of high nutritional value. Growth and survivorship of sea cucumbers held in experimental trays below the suspended oysters were measured, growth being assessed using split weight as well as muscle and skin wet weights. There were no sea cucumber mortalities in any of the trays deployed at either site during the study. Sea cucumbers grown in trays at both sites successfully utilized biodeposits from the cultured oysters and showed a mean weight increase of 42.9 g in approximately 12 months (average growth rates at both sites ranged from 0.061 to 0.158 g d-1). Overall growth was affected by the absence of visceral organs and the cessation of feeding activity observed in the November 2004 sampling period. Overall mean values for organic content were significantly higher in the foregut of the sea cucumbers (24.7 % or 224.6 mg g-1 dry sediment) than in the sediment (5.9% or 51.6 mg g-1 dry sediment) or in the hindgut (14.5% or 157.9 mg g-1 dry sediment), showing both active selection of organic material from the sediments and digestion/assimilation of these organics in the gut. Organic material deposited in the trays was assimilated by P. californicus at the two study sites with an average efficiency of 40.4%. The successful utilization of the naturally-available biodeposits from the cultured Pacific oysters by California sea cucumbers suggests the feasibility of developing a commercial-scale co-culture system that would both reduce the amount of organic deposition underneath shellfish farms and produce a secondary cash crop.
April, 2006 - McCallum Thesis MA Geography 2006. “Strategies for Use and Protection of the Marine Environment”