Utilization of mussel bottom leases to their full potential has been hindered by a lack of information concerning the carrying capacity of open culture systems. Depletion of food particles in the benthic boundary layer above mussel beds has recently been identified as a major factor limiting mussel production in terms of seed/harvest yields, meat yields and mussel lease productivity (yields per area of bottom). Model predictions and field data suggest that as much as 25% of the available food can be removed over a mussel patch length of just one meter at current speeds of 5 cm/sec. Phase I research established an experimental approach to obtain realistic values for the terms of a model which would predict optimal seeding density for a given lease site. Techniques were also developed to analyze mussel food particle selectivity behavior, mussel feeding rates (consumption and assimilation), bulk current speed, bottom roughness, mussel density and bottom patch distribution, and food availability. The objectives of this research are: 1) To document, with a high level of confidence, that the carrying capacity model will result in an increase in meat yield at least 10% over present yields. 2) To develop a carrying capacity model which specifies optimal seeding density for each lease section, and considers the horizontal and vertical distribution of food particles in seawater in relation to flow and mussel consumption. 3) To apply the carrying capacity model to the specific distribution of mussel seed from the seeding vessel, and to use the information about current speed and food availability to find promising new sites for mussel culture. Phase II will continue field experiments at different lease sites and incorporate these data into the carrying capacity model. The results of this research should have direct application to the management of lease sites for optimal yields as well as develop a technique for finding suitable sites for mussel culture, and improving mussel seeding technology.
