spf 93mar 25mar93-15may93 Krill spawning frequency experiments were conducted on board in a flow-through aquarium at ambient temperature according to the method of Ross and Quetin (1983). These experiments yield estimates of spawning intensity, i.e. the percent of the females in the reproductive cycle spawning per day, and the interbrood period or interval between multiple batches of eggs. Female total length. Number of females spawned for each observation period and total number in the entire experiment. Temperature of the seawater in the individual spawning jars in each period. Spawning frequency (% spawning per day) is: 100 * (no. spawners/no. females in experiment)/days of experiment The inverse of the spawning frequency is the interbrood period. Experiments are conducted as indicated by female status, i.e. adequate number of females with red thelycums, with the objective of one experiment per transect line. Euphausia superba are collected with the 2-M trawl for these experiments, either with standard tows or with targetted tows. Experiments are conducted on board in the aquarium room in flowing seawater tables. All live individuals with red thelycums from a catch are gently transferred from the initial catch tub to a second tub filled with cold seawater. The red thelycum indicates that the female is in the reproductive cycle. Fifty females are randomly selected from the total by picking a spot in the tub and only removing those individuals that swam through the spot. Each female selected is placed in a 2-liter glass jar filled with filtered seawater and with a 3000 µm mesh circle partway down the jar to prevent the female from damaging the eggs after release. Each jar is checked for the presence of eggs every 12 h for 4 days. If eggs are seen, the female is given an additional 6 h to completely release the batch. The female is then removed, the total length measured, and then preserved individually in 5% buffered formalin. Total length is measured with digital calipers from the tip of the rostrum to the end of the uropods. At the end of the experiment all non-spawners are measured fresh and either frozen individually or preserved as a group of non- spawners. Spawning frequency experiments are planned for the outer edge of each transect line (grid stations 160, 180 or 200) in order to observe any alongshore gradients in spawning intensity or reproductive output. For this austral fall cruise, spawning experiments were not a primary objective as the reproductive season is nearly at an end. Experiments were conducted during this cruise where mature/gravid females (with red thelycums) were found. Experiments were only conducted on the inner shelf of the 700 and 600 lines spawning intensity, spawning frequency, interbrood period, In the first row a "!" is preceded by the number of columns of data (n) and followed by information about the experiment. Each column is described in the subsequent n rows. Data follows as comma separated text. ICESS, University of California at Santa Barbara /home/data3/data/93mar/SPF for data /home/data3/datainfo/93mar for the documentation Raw data from each experiment is in files named SPF(experiment number).raw. The header for each file contains the study, spawning frequency experiment number, date and time of the start of the experiment, and average temperature. Columns of data are: female total length (mm), spawning period, female id and notes. SPF_sum is a summary file for all experiments during the cruise. Data include experiment number, event, tow, time and date of start of experiment, LTER grid location, number of spawners, number of females in experiment, and spawning frequency over the experiment. SPFdet.per is a file with details of temperature and number of spawners for each of the observation periods (usually 8) for each experiment. Robin M. Ross, Langdon B. Quetin Robin M. Ross, Langdon B. Quetin Experiments conducted and females measured by RM Ross and the research team on board the RV Polar Duke. No laboratory analysis was conducted because eggs were not collected. Robin M. Ross Robin M. Ross Robin M. Ross 4/1/96 Ross, RM and LB Quetin. 1983. Spawning frequency and fecundity of the Antarctic krill Euphausia superba. Marine Biology 77, 201-205. At start of data collection PIs train and supervise new members of the research team to ensure that measurements are consistent across experiments and cruises. Data entry checked by a second person, both by proofing and by inspecting graphs for outliers.

Datafile Form V1.2 for describing a data file.