Bamfield Community Huu-ay-aht
Abalone Project

| broodstock | DNA analysis | hatchery | settlement | outplanting |

- Outplanting - Spring 2005

In the spring of 2005, the BHCAP volunteer divers outplanted about 75,000 juvenile abalone in Barkley Sound. This time, the technique used was a bit different - Juvenile abalone were settled onto pieces of concrete blocks, inserted into black plastic crates in the hatchery, then delivered into the study site by divers. These "Abitats" were then surrounded by rocks. Here we have some photos and a video clip to show how it all went.

In the first pinto abalone juvenile out-planting conducted by BHCAP, 1 year old, 8mm average shell length animals were released. Since then, juvenile out-planting has focused on the release of much younger and smaller animals, such that the juveniles that were released in early 2005 were approximately 1mm in length and 1 month old. The out-planting technique used for these tiny juveniles is also different from the larger juveniles. The tiny animals are fragile and must be handled on their settlement substrate, not removed from the substrate. Thus, out-planting modules were developed on which the larvae were set in the hatchery, incubated for 1 month and then transported to the field for out-planting. There are several reasons for out-planting (larvae and) young/tiny juveniles. Animals that have spent less time in the hatchery are less likely to be habituated to hatchery conditions and more able to easily adapt to the field environment. Food sources of young juveniles are the same in the hatchery as in the field (a natural assemblage of diatoms) and due to the use of this "field-type" food source (i.e. before conversion to a largely kelp diet), shell colour of juveniles is the same as in the field. Thus released animals are cryptically coloured and less likely to be identified by visual predators. Innate behavioural responses such as hiding during the daytime and the escape response to certain predators are present in young juveniles and most likely to be preserved if juveniles are released to the field at an early age. And not least of all reasons are the practical considerations of the greater ease and lower cost of production of (larvae and) young juveniles by a hatchery. To accomplish the long-term goal of widespread population rebuilding of pinto abalone by the out-planting of hatchery stock, it is important that the economics of animal production are realistic. Thus BHCAP has chosen larvae and tiny juveniles for their out-planting. The same larval rearing process was used for both larval and juvenile out-planting. Instead of taking competent larvae into the field, and setting them immediately prior to release, larvae for juvenile production were set in the hatchery onto out-planting modules. Later the modules were transferred to the field. The usual BHCAP hatchery practice is to settle competent larvae onto PVC wavy plates, held in baskets and reared in raceway tanks. However, for out-planting, this procedure is altered.

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BHCAP used broken concrete blocks as the substrate for settlement. There is anecdotal evidence to suggest that competent pinto abalone larvae have an affinity for concrete. Concrete and coralline algae both have calcium carbonate (in the cell walls of the algae) in common. For three months prior to settlement, the concrete blocks were conditioned in running seawater, to leach out any undesirable substances present in new concrete. During the conditioning period, the blocks were colonized by a natural assemblage of diatoms that came from the running seawater.