trawlgen 97jan 11 Jan to 13 Feb, 1997 [Palmer Station to Palmer Station dates] Macrozooplankton community abundance and composition 1) from two trawls with different size mouth opening and mesh. - 1m metro trawl (333 um nytex mesh) towed obliquely between the surface and 300 m - 2m metro trawl (~700 um stretch mesh) towed obliquely between the surface and 120 m 2) Target tows to verify acoustic targets seen on the acoustic trace. - Tucker open/closing trawl for target tows, ~700 um stretch mesh towed at depth of target Two files are generated from trawling activities. (1) trawl.list is a record of the trawl information for all trawls (32 variables): event.number tow.number Palmer LTER grid.line Palmer LTER grid.station GMTtime.begin(hr) GMTtime.begin(min) GMTtime.end(hr) GMTtime.end(min) day(D) or night(N) tow.duration(min) julian.day date.mm date.dd begin.latitude begin.longitude end.latitude end.longitude tow.heading ship speed.over.ground(kts) water.depth(m) %cloud.cover wind.speed (units vary) wind.direction net(1=1meter.square; 2=2meter.square; tucker=open/close; 1mring=1meter ring net) tow.type(std obl=standard oblique, i.e. to standard depth; shal obl=shallow oblique; target=aim.for.aggregation; abort = did not complete; bottom.trawl = hit bottom) net.depth(from depth transducer at point of attachment of net to sea cable) wire.out(m) wire.rate(m/min) volume.filtered(m3)(General Oceanics flow meter#13583) catch split? Y=yes; N=no organisms removed: Y=yes; N=no comments The meaning of 'organisms removed' depends on whether or not there was a split of the catch. If there was no split, organisms were removed for other purposes (experiments or chemistry for example) so the preserved sample is not a totally random sample; the preserved sample represents the community composition only if the organisms removed are added back into the sample analysis. If the catch was split, often all rare organisms were removed before the split and preservation, for example, fish larvae, ctenophores or tomopterid worms. Sometimes either all krill or all salps were removed before the remaining samples was split. (2) trawl.catch is a record of the trawl catch composition with quantitative information that varies with the type of trawl and taxonomic group. For 2 m trawls, all euphausiids are identified to species. The most common amphipods and pteropods are identified to genus. Fish larvae are separated into either silverfish larvae (Pleuragramma antarcticum) and other fish larvae. For other taxa, numbers and volumes of groups of species are recorded. Copepods and ostracods are noted, not counted. For 1 m trawls, presence (p) or absence is noted. Sometimes the number and volume of krill, and the volume of salps is also recorded. All fish larvae are removed and counted. The 50 variables are: event.number tow.number Palmer LTER grid.line Palmer LTER grid.station GMTtime.begin(hr) GMTtime.begin(min julian.day net(1=1meter.square; 2=2meter.square; tucker=open/close) tow.type(std obl=standard oblique, i.e. to standard depth; shal obl=shallow oblique; target=aim.for.aggregation; abort = did not complete; bottom.trawl = hit bottom) net.depth(from depth transducer at point of attachment of net to sea cable) volume.filtered(m3)(General Oceanics flow meter#13583) catch split? Y=yes; N=no organisms removed: Y=yes; N=no total catch volume (ml) Euphausia superba# Euphausia superba vol (ml) Thysanoessa sp.# Thysanoessa sp vol (ml) Euphausia crystallorophias# Euphausia crystallorophias vol (ml) Euphausia triacantha # Euphausia triacantha vol (ml) Salpa thompsoni (mature, digestive gland red)# Salpa thompsoni (mature, digestive gland red) vol (ml) Salpa thompsoni (eleoblast, colorless or yellow)# Salpa thompsoni (eleoblast, colorless or yellow) vol (ml) Amphipod (non T. gaudichaudii) # Amphipod (non T. gaudichaudii) vol (ml) Themisto gaudichaudii # Themisto gaudichaudii vol (ml) Chaetognaths # Chaetognaths vol (ml) - medium and large; small (< 20 mm)not counted Clione # Clione vol (ml) Limacina # Limacina vol (ml) silverfish larvae # other fish larvae # Ctenophore # Ctenophore vol (ml) Siphonophore # Siphonophore vol (ml) Polychaetes - non Tomopterids # Polychaetes- non Tomopterids vol (ml) Tomopterid # Tomopterid vol (ml) Copepods Ostracods Split.Factor used to calculate the total from the split for the non-rare taxa Comments (adult fish; decapod larvae) trawl.list & trawl.catch 1) volume filtered (meters cubed) = Net area * ((flow meter final reading - flow meter initial reading) * (26873/999999)) 2) For thirteen events, the Palmer grid line and station were calculated from the beginning latitude and longitude: events 389, 433, 434, 492, 494, 496, 667, 668, 1100, 1108, 1110, 1131, 1133. With standard stations the Palmer grid line and station given are for the approximate center of the trawl path. Trawling with the 1m and 2m trawls was conducted at cardinal stations on 5 cardinal lines (600.*, 500.*, 400.*, 300.* and 200.*) and at selected stations 'inside north' (LeMaire and Grandidier) and 'inside south' (Crystal Sound), and in Marguerite Bay as ice permitted. The 2m trawl and Tucker trawl were also fished at selected stations within the 50 km radius of the Adelie penguin rookeries near Palmer to verify targets. Of the total of 154 tows, there were 62 1-m trawl collections, 73 2-m trawl collections, and 19 target tow collections. One of the 2-m tows was a target tow. One of the 1-m tows hit bottom. Three of the Tucker tows were aborted. (1) trawl specifications: € the 1-m trawl (1 m2) is a Metro net, with a fixed frame 1-m on a side, and the bridle attachments in the middle of the side pieces of the frame; the mesh size for the net is 333 µm and the codend is 333 µm; € the 2-m trawl (4 m2) is a Metro net, with a fixed frame 2-m on a side, and the bridle attachments in the middle of the side pieces of the frame; the mesh size for the net is ~ 700 µm and the codend is 500 µm; € the 2m2 Tucker trawl is an mechanical open/close net with a fixed frame and weighted bottom bar; the mesh size is ~ 700 µm. A General Oceanics double trip mechanism and messengers are used to open and close the net. (2) protocol for deployment: € for both the 1-m and 2-m trawls a flow meter (General Oceanics) was attached to side of the frame so it hangs in the middle of the net opening; snap clips were used for easy removal; € the metro trawl tows were oblique to a standard depth (1-m 300 m; 2-m120 m) and back, water depth permitting; € a depth sensor calibrated to a range of 0-500 m is attached to the end of the sea cable (0.322 conducting wire); the readout on a chart recorder in the laboratory is used to monitor the depth of the trawl; the net is retrieved once it reaches standard depth or is 10-20 m above the bottom € all information for the trawl.list for each tow was recorded on a TRAWL RECORD data sheet; (3) treatment of catch: The TRAWL CATCH LOG for each tow contains the details of the catch processing and disposition of the catch (# and size of preserved jars and preservative (formalin or ethanol), # frozen and size of vial, # into IGR etc). (a) trawl1-m All fish larvae are removed and immediately preserved in 95-100% ethanol in 20 ml scintillation or 7 ml glass vials. The fish larvae are counted and identified on board if possible. The remainder of the catch is qualitatively characterized and preserved in 10% formalin. Larval E. superba are noted. (b) trawl2-m The goal is to characterize the total catch, i.e., numbers and volumes of each type of organism, and to preserve, freeze, or use subsamples of our targetted species for several purposes. The contents of the tub are sorted on board for macrozooplankton and micronekton, and samples measured, preserved in 10% formalin or 100% ethanol or frozen. Tows are done at standard stations along the cardinal lines, i.e., the onshore/offshore resolution is 20 km, and alongshore is 100 km. This is the same spatial resolution as for other biological and physical data. The standard depth for tows was set to correspond € trawl1-m, 300 m is the deepest depth from which larval krill have been collected in this region € trawl2-m, 120 m is the deepest depth at which krill schools have been observed in this region Observations and catch processing information, and disposition of catch are recorded on two forms for each event: trawl record, trawl catch log. The information on the trawl record and trawl catch log for each event for the entire cruise is summarized in two files: trawl.list and trawl.catch. Antarctic krill from these catches were used for 11 instantaneous growth experiments, and three spawning frequency experiments. Others were sexed, measured, then frozen in preweighed vials for later determination of wet weight - total length regressions. zooplankton community composition, Southern Ocean, macrozooplankton ascii The first line is the number of columns followed by ! and the study name. Each subsequent line identifies the variable with units. Data follows in comma separated variable format. ~lter/~lterdata/97jan/trawlgen/* Velella on the MSILTER Apple network trawl.list trawl.catch Robin M. Ross, Langdon B. Quetin none Robin M. Ross and Langdon B. Quetin Marine Science Institute, UCSB, Santa Barbara, CA 93106 (805) 893-2096 robin@crseo.ucsb.edu or langdon@crseo.ucsb.edu RM Ross, JL Jones, CT Shaw, K Sauber, L McDonald, D Conlin, W Widner. On board sample analysis by above. Salp picking assistance provided also by K Carney, E Holm, CR Johnson and B Boczar. K Sauber, L McDonald, RM Ross RM Ross responsible for quality control of data sets. RM Ross 19 June 1999 Keys used to identify species: € Kellerman, A. (ed.). 1989. Identification key and catalogue of larval Antarctic fishes. BIOMASS Scientific SEries No. 10. € Gon, O., and P.C. Heemstra (eds.). 1990. Fishes of the Southern Ocean. J.L.B. Smith Institute of Ichthyology, Grahamstown, 462 pp. 12 pls. € FAO Southern Ocean identification guides € Makarov, R. Larval development of the antarctic euphausiids. BIOMASS Handbook No. 3. SCAR/SCOR/IABO/ACMRR, Group of specialists on living resources on the southern Oceans. € Mauchline, J. Key for the identificaiton of antarctic euphausiids. BIOMASS Handbook No. 5. SCAR/SCOR/IABO/ACMRR, Group of specialists on living resources on the southern Oceans. Trawl catch logs for each tow are set up to show the split factor due to subsamples being counted and only subsamples being preserved. Calculations are done on board and checked by a second person as the data are entered. Trawl.list and trawl.catch information have been checked once against original records, and against the event log. Plots of duration of tow against volume filtered in m3 for each net were used to detect outliers which usually indicated data entry errors. Those errors were corrected. Numbers 76 and 77 were never assigned to a tow. For five tows, the event number initially written on the catch log and on the preserved jar labels is incorrect. The event number has been corrected for the trawl.list and trawl.catch files. Initial Logged Event # Correct Event # 828 829 866 867 1055 1056 1079 1080 1244 1245 Wind speed and wind direction are not available for events 818 through 836. The meterological instruments were not logging data.

Datafile Form V1.2 for describing a data file.