Plankton (zooplankton and large phytoplankton) are collected using the Continuous Plankton Recorder (CPR) in the Northwest (NW) Atlantic along tracks transited by container ships from Reykjavik (Iceland) to St. John’s, NL (the Z line), and between St. John’s and the New England Coast, along the Scotian Shelf (the E and MD lines). The CPR Survey is the longest running, most geographically extensive marine ecological survey in the world, providing comparable data on the geographical distribution, seasonal cycles and year-to-year changes in abundance of plankton over a large spatial area. The first northwest Atlantic samples were collected in the Irminger Sea in 1957, and sampling was extended farther west to the Scotian Shelf a few years later. Sampling has continued to the present with some interruptions during the late 1970s and 1980s. Sampling is nominally once per month along the E, MD, and Z lines. DFO Sample collection and analysis are led by the Continuous Plankton Recorder Survey program at the Marine Biological Association of the UK. DFO provides partial support for the northwest Atlantic survey carried out on the E, MD, and Z lines and incorporates CPR data in Atlantic Zone Monitoring Program ocean environmental status reporting.