This dataset includes depth-stratified, stage-specific Calanus spp. abundance (C. finmarchicus, C. glacialis and C. hyperboreus copepodites and adults) collected on the Newfoundland and Labrador Shelves (NL), in the Gulf of St. Lawrence (GSL), on the Scotian Shelf (SS), and in the Gulf of Maine (GOM). The data were collected under a variety of programs and compiled to describe northwest-Atlantic-wide patterns of Calanus spp. vertical distribution and assess their environmental drivers. The dataset spans years 2001 and 2006 for NL, 1994-2009 for GSL, 1997-2011 for SS, and 1978, 1995-2007, and 2016 for GOM. Sampling and data processing methods are summarized in Krumhansl et al. (2018). Calanus spp. abundance data are reported for a total of 531 distinct sampling events and a total of 2574 stratified net samples. Zooplankton samples were collected using different gear types, including Multinet, BIONESS and MOCNESS, with several configurations of mouth opening area ranging from 0.25 to 1 m², and with several net mesh sizes ranging from 150 to 335 µm. Calanus spp. abundance is reported in individuals/m² and in individuals/m³ for each depth layer of the stratified tows. The dataset also includes environmental metrics (temperature, salinity and density), where available, collected concurrently with the zooplankton net tows as well as parameters derived from ocean color remote sensing data. Temperature, salinity and density metrics were derived from CTD profiles collected either simultaneously with the net tows or from the sampling event nearest to the net occupations and within ±0.2° latitude and longitude and ±3 days. For each net in a station occupation, environmental metrics include the mean, minimum, and maximum temperature, salinity, and density values. For each station, metrics include the 0-50 m mean and near-bottom temperature, salinity, and density, the minimum subsurface temperature and its depth, depths of the upper and lower boundary of the cold intermediate layer (CIL) and its thickness, and the water temperature at the bottom of the CIL. For NL (shelf and slope), GSL, and SS and slope regions, the CIL was defined as the subsurface layer (>25 m depth) bounded by the 0°C, 1°C, 4°C temperature thresholds, respectively, and in the GOM, different temperatures were used to define the upper (10°C) and lower (7°C) boundaries of the CIL. Each net tow was assigned a season relative to the initiation of the spring phytoplankton bloom in a corresponding sub-regional polygon, which was estimated from chlorophyll-a concentrations derived from ocean color measurements from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua sensor. Light attenuation (diffuse attenuation coefficient Kd at 490 nm) was estimated for each sampling event based on binned satellite remote sensing observations from the Medium Resolution Imaging Spectrometer (MERIS), SeaWiFS, Visible and Infrared Imaging Radiometer Suite (VIIRS), Coastal and Ocean Colour Scanner (CZCS), and MODIS Aqua sensors.

Data sources included in this data compilation and published references associated with each data set are provided in Supplementary Table S1 of Krumhansl et al. 2018. The dataset compiles data from the original sources in a common format. Variables that were not included or are not available for a station occupation are represented as blank cells.