Husbandry

Current Cockle Projects

The basket cockle, Clinocardium nuttallii, occurs on the Pacific coast of North America from San Diego to the Bering Sea, and a disjunctive population has been reported in Hokkaido, Japan. It occurs around the coast of British Columbia on sandy to muddy shores, but it is not generally found in high abundance. cockle fisheries worldwide have been subjected to overfishing due to a lack of management regimes and habitat deterioration through fishing practices, while a lack of seed has halted cockle fisheries in other areas. In BC there is significant commercial interest in basket cockles as an aquaculture species as a result of their relatively fast growth rate, ability to utilize different substrates, adaptation to the cold waters of BC and importance as a preferred First Nations food group.

Basket cockle, Clinocardium nuttallii

The cockle development project was initiated in January, 2005 by the CSR and a consortium of industry, government, and First Nations partners who set out a comprehensive, systematic and integrated multi-year research program to develop the knowledge required to support a cockle aquaculture industry. The activities to be undertaken to achieve this goal were divided into three main phases:

1. Determined the optimal conditions for broodstock development and spawning
2. Determine the optimal conditions for hatchery production of cockle seed
3. Develop successful nursery and grow-out techniques and strategies

Towards the end, Evening Cove Oysters Ltd. and the CSR applied for and received ACRDP grants to undertake the second phase of this multi-year project.

Phase 1. Broodstock

A consistent supply of high quality seed is a prerequisite for a successful cockle aquaculture industry and the development of broodstock is key to ensuring the availability of consistent high quality seed. conditioning refers to several biological processes regulating gametogenesis and spawning and is important for efficient, year round production of all bivalves. Proper conditioning has been shown to improve the performance of larvae, larval settlement, spat growth and juvenile survival. In other bivalves, broodstock conditioning has been shown to be influenced by several factors including temperature and food availability.

To establish the optimal conditioning methods for cockles, the relationships between biotic and abiotic factors (such as temperatures, food type, food concentration, ect.) and gonad maturation needs to be studied.

However, no published information was found about factors influencing the conditioning of Clinocardium species. there is therefore, a lack of information about factors influencing proper maturation of broodstock cockles which this project aims to address.

Before research into commercial cockle production systems can begin, it is necessary to understand the factors influencing broodstock maturation and to develop standard operating procedures to ensure the consistent production of high quality gametes from maturation systems. To this end, our objectives for the project are as follows:

• To determine the optimal feeding rates and feed items for conditioning basket cockle broodstock
• To evaluate the influence of temperature on metabolic rate of adult cockles at temperatures between 5°C and 30°C
• To establish the biological Zero Point (BZP) and the Effective Accumulative Temperatures (EAT's) for gonad maturation in the basket cockle
• To establish the optimal physical requirements to achieve successful fertilization rates

Broodstock holding tanks

Research papers

1. Broodstock_conditioning_in_the_basket_cockle_Clinocardium_nuttallii_Liu_et_al
2. Fertilization_and_embryonic_development_in_the_basket_cockle_Clinocardium_nuttallii_Liu_et_al

Phase 2. Hatchery

Phase 2 research will develop and optimize hatchery production techniques producing information on how to maximize growth and survival through larval rearing to seed production while minimizing production time and cost. The specific objectives of this proposal are:

• Determine optimum rearing densities for all developmental stages of the basket cockle from larvae to 2-mm shell length juveniles
• Determine the species composition and concentration of micro-algae cells required for optimal growth, survival and development of all stages of the basket cockle from larvae to 2-mm shell length juveniles
• Determine optimal temperature for rearing larvae of the basket cockle

Upwelling larval rearing tanks	Downwelling seed tanks

Different culture scales (up to 400L units)	Seven microalgal species

Phase 3. On-growing

This work aims to provide valuable recommendations for the management and sustainable production of basket cockles through the responsible development of a new native aquaculture species of cultural significance. Therefore it is now necessary to conduct research into Phase III of the project, nursery grow-out techniques and strategies. The specific objectives of the on-growing component addressed in the current proposal are as follows:

• To determine optimal seed rearing techniques for maximized production
• To determine growth and survival of cockle seed in different substrata
• To examine post-settlement movement of cockle seed
• To determine optimal seed size, season and site for transplantation
• To determine optimal on-growing aquaculture husbandry methods 9intertidal, off-bottom suspension culture)
• To determine seed stocking densities conducive for optimal growth

Cockle movement studies (seed and adults)	Shore units, Deep Bay

Shell deformities, Deep Bay	In suspended culture, Deep Bay

Projects in collaboration with Dr. Chris Pearce of the Department of Fisheries and Oceans Canada

This project is funded by

All three phases have been funded under separately awarded ACRDP grants