condition of the permit. Certification standards are developed by buyers, public agencies, nongovernmental organizations, or marketing groups as a means of providing consumers with information about a product with the goal of influencing growers through the leverage of consumer choice and market forces. Pursuit of certification is voluntary for growers.

All these practices and standards may have multiple objectives including, for example, reducing the likelihood that mollusc farming will have unacceptable ecological effects. When designing and formulating a BMP or performance standard, the following are some of the major decisions to be made (Breyer, 1982):

  • Targets of the regulation—What specific ecological goals are to be achieved or ecological harm(s) are to be guarded against?

  • Scope of the regulation—Does the standard address specific forms of mollusc farming or the broad spectrum?

  • Performance or design specification—Does the standard specify what level of effects are acceptable, or, alternatively, how to do the farming?

  • Technology forcing—Should the standard set objectives not achievable with current practice and technology?

A performance standard may set targets for a parameter (e.g., ambient phytoplankton concentrations should not be reduced by more than X% below baseline levels) that is a proxy or surrogate for the ultimate objective (e.g., maintenance of suitable conditions for health of native filter-feeder populations). The choice of the specific parameters targeted by the code or regulation has to take into account its relationship to the ultimate objectives and the cost of monitoring and enforcement.

In settings where bivalve mariculture is carried out by a number of small, independent operators (none of whom individually approaches carrying capacity limits), it makes sense for the mariculture regulator(s) to focus on system-wide carrying capacity questions, taking into account the cumulative effects of all farming operations. BMPs or standards that target parameters related to ecological and social carrying capacity (see Chapter 5) can be focused on bivalve mariculture broadly and may not have to address each location, species, and culture technique separately. However, given that the ability to quantify and measure ecological carrying capacity remains limited (see Chapter 5), adopting this approach will require careful consideration of the risks, the acceptable level of ecological change, and the appropriate parameters to monitor.

The choice between performance and design specifications embodies a fundamental tension between flexibility and enforceability (Helfand, 1991; Montero, 2002; Bruneau, 2004). Design standards are easier to

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