These data cannot be considered as one continuous time series unless an adequate calibration between the NORPAC and SCOR nets is available. Please see: Waddell, Brenda J., and Skip McKinnell. 1995. Ocean Station "Papa" detailed zooplankton data: 1956 - 1980. Can. Tech. Rep. Fish. Aquat. Sci. 2056: 21 p.
The samples were collected by personnel of the Pacific Oceanographic Group from C.C.G.S. "ST. CATHERINES", "VANCOUVER", and "QUADRA" in the earlier years, and by personnel of the Offshore Oceanography Division and the Ocean Chemistry Division of the Institute of Ocean Science in the latter years. Samples collected prior to 1969 were from one ship which occupied Ocean Station P (OSP) for alternate 6 week periods, whereas samples since 1969 were taken on a nearly continuous basis. Data collected from ships of opportunity sampling within 1-degree (96.6 km) of OSP are also included in the dataset. As the collecting ship was not specified in the data format, all stations were assigned to the vessel "OWS-P".
Vertical hauls were taken daily during daylight, usually in the morning, depending on weather and other duties. Occasionally more than one sample was taken in a day. A standard haul consisted of hauling the net from 150 m to the surface at 1 m/s. The ship was manoeuvred during sampling to attempt to keep the wire vertical; wire angle and the length of wire out were recorded. The nets were considered 100% efficient and estimates of volume of water filtered were considered to be the product of the mouth opening area and the wire out. All samples were preserved in 1.5% formalin and analyzed on shore. Different nets were used throughout the years to collect zooplankton at OSP, although all had mesh sizes of 351 microns. A NORPAC conical net of white Nitex with a mouth opening of 42 cm diameter, a mouth area of 0.16 m2, and a filtration ratio of 4.9:1 was used until 1966. This was subsequently replaced with a modified cylinder-cone design SCOR net having a mouth area of 0.25 m2 and a filtration ratio of 14.7:1. In 1966 and 1967, both dark and light coloured SCOR nets were used, frequently as replicate tows. From 1968 onwards, only dark coloured nets were used. A Miller net with a 0.10 m2 mouth opening was occasionally used.