CPR zooplankton biomass from Cook Inlet and Cook Shelf 2012-2023

Zooplankton biomass estimates within the Cook Inlet and Cook Shelf region of the Gulf of Alaska from 2012-2023. Calculated following Planque and Batten (2000) method. NOTE: Only selected taxa have been included in this data extract, for specific taxa requirements please email [e-mail]. Excel file contains two sheets, the first A: midpoint of sample local date and time B: midpoint of sample latitude in decimal degrees C: midpoint of sample longitude in decimal degrees D:GeoRegion E:onwards = CPR abundance counts multiplied by Body mass as µgC per individual. The taxa_info sheet give more information on the taxa included; the counting method (1=eyecount, 2=traverse) and if the category is a grouping that includes other categories (to avoid double counting in your analyses). The Continuous Plankton Recorder (CPR) is a marine sampler that is towed behind volunteer ships of opportunity at speeds of up to ∼20 knots and samples at a depth of ∼7 m below the surface. The CPR unit is a metal casing in the shape of a ∼1 m torpedo that houses a roll of silk which automatically rotates using a geared propeller system. The seawater enters the front aperture where plankton and small particles are captured onto the rotating silk, which has a mesh size of 270 µm. This silk is stored in 4 % buffered formalin to preserve the sample until microscopic analysis at the laboratory in Plymouth. The silk is cut into pre-defined sections that represent one sample and equate to 10 nautical miles of tow. Phytoplankton and zooplankton are identified and counted at different stages of the microscopic analysis: semi-quantitative count of phytoplankton across 20 fields of view per sample, quantitative count of all zooplankton >= 2 mm (these are picked off the silk for identification), and semi-quantitative traverse count of all zooplankton 2 mm. For a more in-depth description of the sampling methodology please refer to Richardson et al. (2006).