260 
Fishery Bulletin 1 10(2) 
All fish were killed by an overdose of buffered MS- 
222 (300 mg/L) in chilled (12°C) seawater. The fish 
were immediately blotted dry, measurements of wet 
weight, fork length, and BIA (in that order) were taken, 
and PIT tag numbers and external abnormalities were 
noted. Internal temperatures (muscle and stomach) 
were determined by inserting an instant-read digital 
thermometer into the dorsal musculature of the fish, 
and down the esophagus into the stomach. Total sam- 
pling time for each fish was ~1.5 min. Each fish was 
then dissected, its liver removed, its gut evacuated, and 
sex and maturity status was determined. Livers and 
carcasses were wrapped separately in aluminum foil 
before being vacuum-sealed in plastic bags and stored 
frozen at -80°C until subsequent analysis. 
Body composition analysis Liver and carcass wet 
weights were determined to the nearest 0.1 mg before 
being freeze-dried to a constant weight and reweighed. 
Each dried sample was ground in a Foss Tecator® 
Cyclotec 1093 sample mill (FOSS, Hilerqd, Denmark) 
and stored at -20°C in glass scintillation vials under 
nitrogen gas until further analysis. Total water ( TWa ) 
was calculated by subtracting total dry weight (liver 
dry weight plus carcass dry weight, DW) from total wet 
weight. 
Freeze-dried carcasses were analyzed for proximate 
body composition (protein, fat, ash) by an indepen- 
dent laboratory (A&L Great Lakes Laboratory, Fort 
Wayne, IN) by using Association of Official Analytical 
Chemists international certified methods and were 
reported to us on a percent DW basis. Nitrogen was 
determined by using a LECO nitrogen combustion ana- 
lyzer (LECO Corp., St. Joseph, MI; Dumas method), 
protein was calculated by multiplying nitrogen values 
by 6.25 (Jones, 1931), fat was obtained with a 4-hr 
ether reflux extraction, and ash was determined after 
combustion at 600°C for 2-4 hr. Body composition (g) 
(total amount of each proximate body constituent) were 
calculated from percent dry weight concentrations by 
dividing the independent laboratory values by 100 and 
multiplying by the total dry weight. To conform to the 
format most often reported in the literature, percent 
dry-weight-based concentrations were converted to a 
percent wet-weight-based concentration by dividing 
body composition (g) by wet weight and multiplying by 
100 (body composition [%WW]). 
Liver lipids, which are often mobilized first during 
fasting (Love, 1970; Black and Love, 1986), were mea- 
sured separately in order to detect changes more easily. 
Liver lipid content was determined in-house by using a 
modification of Folch et al. (1957). Entire freeze-dried 
livers were first extracted by ultrasonic homogenization 
with 2:1 methylene chloride:methanol solvent (20 mL/g 
tissue), then back extracted with aqueous 0.1 M KC1 
and centrifuged to remove water, methanol, and water- 
soluble and water-insoluble tissue components by phase 
separation. The remaining nonaqueous fractions were 
evaporated to remove methylene chloride, and the non- 
volatile lipid residue was weighed on a Mettler® AE240 
balance (nearest mg, Mettler-Toledo, Inc., Columbus, 
OH). Individual livers were not analyzed for protein or 
ash because of their small size; therefore body composi- 
tion values were obtained for carcass water, liver water, 
total water (liver water plus carcass water), carcass fat, 
liver fat, total fat (liver fat plus carcass fat), carcass 
protein, and carcass ash. 
Growth-rate calculations 
Individual instantaneous wet-weight based growth rates 
were calculated with the following formula (Ricker, 
1979): 
growth rate (per d) = (In WW l2 -\nWW tl )l(t 2 - tj ) , (1) 
where WW = the wet weight of an individual at time t 
(day). 
Growth rates for fish in the fed and fasted treat- 
ments were calculated from day 0 (t ; ) until the day 
they were sacrificed ( t 2 ). For the fasted portion of the 
fasted, then refed treatment, growth rates were cal- 
culated from day 0 (t 7 ) until day 11 (< 2 ); for the refed 
portion, growth rates were calculated from the first 
day of refeeding (day 11, t : ) until the day they were 
sacrificed (t 2 ). Growth rates calculated over intervals 
of less than five days were excluded from our analyses 
because minimal weight changes over those short time 
intervals, combined with the inherent variability of 
measuring wet weight, resulted in inaccurate growth 
rate estimates. 
BIA measurement protocol and BIA measures 
BIA measurements were determined with a Quantum- 
X® (RJL Systems, Point Heron, MI) four-electrode single 
frequency (800 pA, 50 KHz) analyzer. Needle electrode 
probes were constructed in-house according to Cox and 
Hartman (2005). For each probe, two 12-mmx28-gauge 
electroencephalographic (EEG) needles (Grass Telefac- 
tor, West Warwick, RI) were mounted in balsam wood 
1 cm apart and with 0.5 cm of the needle exposed. The 
fish were placed on their right sides on a nonconduc- 
tive board. The detector electrode of the anterior probe 
was inserted midway between the posterior edge of 
the operculum and the leading edge of the dorsal fin, 
and midway between the base of the dorsal fin and the 
lateral line. The signal electrode of the posterior probe 
was inserted at the leading edge of the adipose fin, 
and midway between the base of the adipose fin and 
the lateral line. Serial R, serial Xc, and the distance 
between the inside (detector) electrodes, were recorded 
for each fish. 
All BIA measures were initially calculated by using 
both their series and parallel forms. Results of statis- 
tical analyses indicated that the parallel forms were 
more highly correlated to the independent variables. 
For this reason, as well as the instrument manufac- 
turer’s recommendation that the parallel forms most 
