Midwater fish data report for warm-core Gulf Stream rings cruises 1981-1982

Abstract

This data report is for midwater fishes collected during the multidisciplinary Warm-Core Rings Program in 1981 and 1982. Stations were made in and near three warm-core rings on five cruises within a period of 14 months. On Atlantis II cruise 110 (September-October 1981) six stations were made in and around ring 81-D (age two months). Stations were made in the vicinity of ring 82-B on three cruises in 1982--twelve stations during Oceanus 118 (April) when the ring was two months old, 15 stations during Oceanus 121 (June) at age four months, and 19 stations during Oceanus 125 (August) at age 5.5 months. Finally, twelve stations were made in and near meander/ring 82-H (age 0) during Knorr 98 in September/October 1982 (Tables 1-10). The collections were made with a new midwater trawl - the MOCNESS-20 (MOC-20) (Wiebe et al., 1985), a scaled-up version of the MOCNESS-1 (an apparatus for collecting zooplankton; Wiebe et al., 1976) and successor to the MOCNESS-10 (like the MOC-20, a midwater trawl). (The number forming the distinctive part of the name of these nets is equal to the area of the projected mouth in square meters when the apparatus is in a common fishing attitude.) The MOC-20 consists of a set of 3-mm mesh rectangular nets that can be opened and closed by command from the surface via a signal-conducting towing warp. Apparatus attached to the net frame measures and transmits depth, temperature, conductivity, flow, and net-frame angle to the towing ship's laboratory. Flow (net speed), vertical velocity, and net-frame angle allow computation of the water volume filtered . On the WCR cruises a set of five or six nets was used. One net (not used for quantitative analyses) was fished down to 1000 m, then closed and a second net opened. The second and successive nets were closed and opened sequentially at intervals as the apparatus was brought back to the surface. A surface-to-surface cycle with the gear is referred to as a station, the contents of a single net as a collection. In addition to be1ng described by latitude and longitude, stat1ons are located in the same radial coordinate system used to composite the warm-core rings physical data, that is, by distance and bearing from the moving ring center.