trawlgen 94jan 11jan94-06feb94 Macrozooplankton community abundance and composition from three trawls of different size 1m metro trawl (333 um mesh) towed in the upper 300 m 2m metro trawl (1000 um mesh) towed in the upper 120 m midwater trawl (10 m) or 2 m Isaacs Kidd Midwater Trawl (IKMT) Two files are generated from trawling activities. (1) trawl.list is a record of the trawl information for all trawls event #, trawl #, date, time begin (GMT), day/night, tow duration (min), LTER grid location, begin latitude decimal degrees and minutes, begin longitude decimal degrees and minutes, tow direction (heading), ship speed (kts), water depth (m), cloud cover (%), wind speed (kts), wind direction, gear (1 m or 2 m or midwater trawls), tow type (oblique to standard depth, targetted tow or oblique to shallower depth because the bottom depth is shallow), target depth, volume filtered (m^3), time-depth-recorder (TDR) depth indication, TDR tow duration, catch split (yes or no), fish removed (y or n), other organisms removed (yes or no), preserved sample (yes or no; yes for the IKMT means specific items not a random sample). ¥ Organisms removed means different things depending whether or not there was a split of the catch. If there was no split, organisms may have been removed for other purposes (experiments or chemistry for example) so the preserved sample is not a totally random sample and therefore can only represent the community composition if the organisms removed are added back into the sample analysis. OR all rare organisms were removed before the split and preservation, for example, all silverfish larvae. OR salps were counted, a volume taken, representative individuals preserved, and the remainder thrown away. (2) trawl.catch is a record of the trawl catch composition with information of varying quality depending on the type of trawl and taxonomic group Event number, trawl number, transect, station, volume filtered (m^3), net size, tow type, tow depth (m from TDR), total volume of catch (ml), number and volume of E. superba, Thysanoessa sp., salps; number of E. crystallorophias, E. triacantha, Limacina sp., other pteropods, Themisto gaudichaudii, other amphipods; presence or absence of chaetognaths; number of antarctic silverfish larvae (Pleuragramma antarcticum), other fish larvae, and siphonophores. Method identification: 1=quantitative count on board of macrozooplankton; 2=quantitative for krill only; 3=qualitative (-5=present; -10=many). Comments include adult fish, tomopterid worms, whether salp numbers and volumes are also quantitative if qa/qc=2. trawl.list volume filtered (meters cubed) = Net area * ((flow meter final reading - flow meter initial reading) * (26873/999999)) The last digit of the 7 digit flowmeter reading is 0.1 revolution and is simply dropped from the reading, so only 6 digits are recorded. When the meter "turns over", i.e., goes past 999999 back through zero a 1 should be added in front on the meter reading. For example, if FM initial = 878361, and FM final = 052787, it actually should be 1052787. Trawling with the 1m and 2m trawls was conducted at cardinal stations on 4 cardinal lines (600.*, 500.*, 400.* and 300.*) and at selected stations 'inside north' (LeMaire and Grandidier) and 'inside south' (Crystal Sound) as ice permitted. The 2m trawl was also fished at selected stations within the 50 km radius of the Adelie penguin rookeries near Palmer to verify targets. The IKMT was fished within the presumed foraging range of the south polar skuas (about 100 km) and at the stations in the Lemaire and inside the Biscoe Islands. There were 38 1m trawl collections, 59 2m trawl collections, and 24 IKMT collections. The 10 m midwater trawl was lost on the first attempt at retrieval. (1) trawl specifications: ¥ the 1m trawl 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 2m trawl 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 1000 µm and the codend is 500 µm; ¥ the IKMT is a 2m trawl with a depressor, and mesh size gradations down to 500 um at the cod end. (2) protocol for deployment: ¥ for both the 1m and 2m trawls a time-depth-recorder (TDR) was attached to the top of the frame, and 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 (1m 300 m; 2m120 m) and back, water depth permitting. Wire out (m) and wire angle, measured from the stern, plus a wire angle chart was used to target the fishing depth of the net. The depth was verified by the TDR and the relationship between targetted depth and actual depth has been used to develop an empirical wire angle chart for this particular net/ship combination. The TDR depth is verified periodically by attaching it to the Bio-Optical Profiling System and comparing the BOPS depth and the TDR depth. ¥ all information for the trawl.list for each tow was recorded on a TRAWL RECORD data sheet; the TDR paper is taped to that sheet and the time and depth of the tow as measured by the TDR is recorded. ¥ the IKMT tows were to the deepest depth possible, and double oblique (up and down twice) if distance was adequate (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) trawl1m 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) trawl2m 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 ethanol and frozen as detailed in trawl2m.info. (c) IKMT All adult fish are removed and frozen in ziplock bags labeled inside and outside in -70 freezer. Antarctic silverfish (Pleuragramma antarcticum) adults are frozen individually, after being measured for total and standard length and weighed on a spring scale. The remainder of the catch is tossed. 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 ¥ trawl1m, to the deepest depth from which larval krill have been collected in this region ¥ trawl2m, to 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. 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/94jan/trawlgen/* robin's mac trawl.list trawl.catch Robin M. Ross, Langdon B. Quetin none Robin M. Ross, Langdon B. Quetin Robin M. Ross, Tim Newberger, Jen Zamon, Kathi Neidermeyer, Chris Johnson, Sharon Stammerjohn On board sample analysis by above. Robin M. Ross, Kathi Neidermeyer, Chris Johnson Robin M. Ross inspected the data sets for quality control. Robin M. Ross trawl.list and trawl.catch submitted 19 December 1996 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 pre-preservation. Calculations are done on board and checked by a second person as the data are entered. Trawl.list and trawl.catch information has been proof read once, and checked against original records.

Datafile Form V1.2 for describing a data file.