The optical plankton counter (OPC) and recently the laser OPC (LOPC) have been used primarily in two measurement applications: (1) identification of specific zooplankton species and (2) changes in zooplankton community structure using size-based spectral measurements. The normalized biomass size spectra (NBSS) are one representation of the size-based approach. The present study is based on utilizing the NBSS to describe the conditions or characteristics of the zooplankton community that allow a reasonable intercomparison of net samples and LOPC measurements made simultaneously for data collected during two oceanographic cruises carried out in the Lower Estuary and the Gulf of St. Lawrence in spring 2001 and 2002, respectively. NBSS linear slopes -0.7, or more "blue water" conditions, indicate the potential for reasonable intercomparison of the two methods. This observation applies to smaller-sized zooplankton such as copepodites of Calanus spp. with equivalent spherical diameter <900 ¿m. The measurement of larger Calanus spp. stages (IV--VI) did not seem affected by the presence of additional aggregates or gelatinous material and reasonable intercomparisons between LOPC and net were obtained for both sampling years. The LOPC signals produced by Calanus spp. (IV--VI) were larger and more easily separated.