spf 97jan 11 January to 13 February 1997 Krill spawning frequency and egg production 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. Measurements of egg size and the batch volume are indices of individual reproductive output during the cruise. Female total length, egg batch volume, egg diameter. 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. The eggs are collected by attaching a funnel apparatus terminated with a scintillation vial to the 2-liter jar, inverting the jar, and allowing the eggs to sink into the scintillation vial over the next 1-2 h. The entire batch of eggs is then preserved in 5% buffered formalin. With this timing, eggs are preserved by a maximum age of 18-20 h and before the diameter of the egg begins to decrease (Quetin and Ross, 1984). At the end of the experiment all non-spawners are measured fresh and either frozen individually or preserved as a group of non- spawners. In the laboratory at UCSB or Palmer Station, diameters, including the perivitelline membrane, of 30 eggs from each batch are measured under a dissecting microscope at 640x. The total volume of the batch of eggs was measured to the nearest 0.025 in a narrow (0.4 mm ID) tube calibrated and marked in 0.05 ml increments. 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. During Jan97 no experiment was conducted at the outer edge of the 300 and 200 lines. There were not enough mature females in catches for experiments. spawning intensity, spawning frequency, interbrood period, fecundity, reproductive output 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. ~lter/data/97jan/SPF Velella on MSILTER Apple network Raw data from each experiment is in files named SPF(experiment number).dat. The header for each file contains the study, spawning frequency experiment number, event number for the source of the females, date of the start of the experiment. Columns of data are: female total length (mm), spawning period, egg batch volume, mean egg diameter, counted or estimated number of eggs in that volume, and notes. SPF.sum is a summary file for all experiments during the cruise. Data include experiment number, event, tow, date and time of start of experiment, LTER grid location, average temperature in during experiment, number of spawners, number of females in experiment, and spawning frequency over the experiment. SPF.details is a file with details of checking times, 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 and Langdon B. Quetin Marine Science Institute University of California at Santa Barbara Santa Barbara, CA 93106 Experiments conducted and females measured by RM Ross and the S028 research team on board the RV Polar Duke. CT Shaw measured the batch volumes and egg diameters from batches of eggs. RM Ross, CT Shaw CT Shaw, RM Ross RM Ross 6/22/99 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.