Aquaculture potential of the basket cockle (Clinocardium nuttallii). Part 1: effects of stocking density on first year grow-out performance in intertidal and off-bottom suspended culture

Abstract

The basket cockle (Clinocardium nuttallii) is a candidate species for aquaculture in the northeast Pacific. The aim of the current research was to assess the feasibility of C. nuttallii grow‐out, with an emphasis on growth performance and qualities affecting product marketability. In this article, we investigated the combined effects of culture mode (intertidal and off‐bottom suspended culture) and initial stocking density (1500, 3000, 10 500 and 21 000 ind m−2) on C. nuttallii survival and growth during the first year of grow‐out (May through October). In intertidal culture, cockles exhibited low survival and poor growth rates. In suspended culture, survival was consistently high (>96%) at all stocking densities tested; growth and condition parameters had the highest values at 1500 and 3000 ind m−2. The edible portion (meat yield) exceeded 40% of the whole wet weight at all stocking densities, occurrences of fouled and deformed cockles were <1% and no commensal species were observed. Depending on the minimum harvestable size and stocking density chosen, harvestable proportions constituted from 1.1% to 15.2% by October of the first grow‐out year in the suspended system. The effects of stocking density and depth on second year grow‐out performance of C. nuttallii are reported in a companion paper (Dunham et al. in this issue).

Aquaculture potential of the basket cockle (Clinocardium nuttallii). Part 2: effects of stocking density and depth on second year grow-out performance of three size cohorts in intertidal and off-bottom suspended culture

“…Together, these cohorts represent a size range that a shellfish farmer could expect to obtain after the first year of growing C. nuttallii in suspended culture at stocking densities of ≤ 3000 ind m −2 (for details, see Dunham et al . , in press).…”

“…The study site and intertidal lease characteristics are described in more detail in a companion article (Dunham et al . , in press). The intertidal grow‐out system consisted of a series of plastic totes equipped with mesh bottoms and removable mesh lids.…”

“…The intertidal grow‐out system consisted of a series of plastic totes equipped with mesh bottoms and removable mesh lids. Detailed descriptions and data on the suitability of these totes as experimental enclosures (siltation effects, sulphide levels) are presented in a companion article (Dunham et al ,. in press).…”

“…Water samples for chlorophyll a analysis were taken once a month near the substratum surface on a low tide in the intertidal system and at 2, 4 and 6 m depths using a Niskin water sampler Model 1010 (General Oceanics, Miami, FL, USA). Chlorophyll analysis methods are described in a companion article (Dunham et al ,. in press).…”

“…Our previous research showed that during the first year of grow‐out in an off‐bottom suspended culture system, C. nuttallii exhibited fast growth and a number of qualities favourable from a standpoint of product marketability: meat yield exceeded 40% at all stocking densities tested, occurrences of fouled and deformed cockles were < 1% and no commensal species were observed (Dunham et al . , in press). Depending on the minimum harvestable size and stocking density chosen, a shellfish farmer could expect to harvest from 1.1 to 15.2% of the outplanted cockles by October of the first year of grow‐out.…”