Filtration of king scallops ( Pecten maximus)

Abstract

Filtration rates of hatchery-reared king scallop ( Pecten maximus L.) juveniles, fed a single species alga diet ( Pavlova lutheri (Droop) Green), were measured at a range of temperatures (6–21 °C). Weight specific filtration rate (ml min −1 g −1 (live weight)) of juveniles of a selected size range of 17–19 mm shell height (0.26–0.36 g live weight) increased with temperature above 16 °C and decreased below 11 °C, but was not significantly different between these two temperatures. Measurements at 16 °C using juveniles with a wider size range of 10–25 mm shell height (0.05–0.8 g live weight) gave the allometric equation: filtration rate (ml min −1)=12.19×weight (g) 0.887. Filtration rate decreased significantly when the cell concentration was greater than 200 cells μl −1 (4.25 mg (organic weight) l −1). With six other algae food species, filtration rates similar to those with P. lutheri were only achieved with Chaetoceros calcitrans (Paulsen) Takano. All other algae species tested were cleared from suspension at significantly lower rates. Experiments with diet mixtures of P. lutheri and these other algae suggested that this was usually a reflection of lowered filtration activity, rather than pre-ingestive rejection of cells. In experimental outdoor nursery rearing systems, the filtration rate was inversely proportional to the concentration of cells in the inflow, in the range 5–210 cells μl −1. It was not affected by flow rate (2–130 l h −1, equivalent to 0.12–28.38 l h −1 g −1 (live weight)) with scallop juveniles stocked from 2 to 62 g l −1. The results are discussed in relation to on-growing scallops at field sites.