788 
Fishery Bulletin 95(4), 1997 
two five-gallon screened buckets. Two additional fish 
died during the transfer process. Fifteen of the re- 
maining 16 fish survived until the end of the experi- 
ment. At four days after marking, four fish were sac- 
rificed. An additional four fish were sacrificed five 
days after marking. Three fish were sacrificed eight 
days after marking. 
To add a second mark, the remaining four fish were 
immersed a second time (12 days after the initial 
marking) and were fed amphipods and brine shrimp 
that had been immersed in a 450mg/L OTC seawa- 
ter solution for five hours. These fish were held and 
fed in a fresh 450 mg/L concentration of OTC for 16 
hours. Ten days after the second immersion the re- 
maining four fish were sacrificed. 
All specimens were placed in 95% ethanol for pres- 
ervation. Otoliths were dissected from fish and placed 
in immersion oil on glass slides. Otoliths were ground 
with a size-600 carborundem grit and mineral oil 
slurry. The tetracycline mark was viewed under a 
Zeiss ultraviolet microscope with a Zeiss FITC acri- 
dine-orange excitation filter set. Increments were 
counted blindly by one reader, a minimum of three 
times. If the number of increments between counts 
differed by more than one, the otolith was not used. 
The number of increments present after the mark 
was regressed against the number of days since 
marking; the regression coefficient was compared 
with unity by using a Ctest. 
Otolith ageing 
Otolith ageing was performed to determine a length- 
age relationship for our combined Peprilus spp. 
samples. The presence of daily increments in tem- 
perate and tropical water fishes has been noted by 
Pannella (1971, 1974). Fish fixed and preserved in 
95% ethanol and ranging in size from 6 to 28 mm SL 
were aged from 1988 spring (n=30) and summer 
(n=33) samples to determine seasonal growth rates. 
Sagittae and lapilli were removed from each fish fol- 
lowing the techniques of Brothers (1984). Otoliths 
were placed in type-B immersion oil and left to clear 
for one month. Sagittae were analyzed with a video- 
enhanced digitizing system (Optical Pattern Recog- 
nition System) viewed at 250x with an oil immer- 
sion lens. 
Increments were counted blindly by one reader a 
minimum of two times. If counts differed between 
1 Secor, D. H., E. D. Houde, and D. M. Monteleone. 1995. 
Development of otolith-marking methods to estimate survival 
and growth of early life stages of natural and hatchery-produced 
striped bass in the Patuxent River in 1991. Maryland Depart- 
ment of Natural Resources, Chesapeake Bay Research and 
Monitoring Division, CBRM-GRF-94-1, 145 p. 
readings by more than three increments, they were 
not used. Counts were made along the longest radial 
axis whenever possible (Brothers, 1980). When 
otoliths were too thick to see increments clearly, they 
were ground with size-600 carborundem grit and im- 
mersion oil to create thinner sections (Brothers, 
1980). 
A length-at-age relationship was determined by 
regressing standard length on age. Because most fish 
deposit increments on their otoliths either at hatch- 
ing or yolk-sac absorption (Brothers et al., 1976), a 
y-intercept of hatch size (1.72 mm; Colton and Honey, 
1963) was assigned to the regression. The slope of 
the spring regression, i.e. growth rate, was compared 
with the slope of the summer regression by means of 
a homogeneity of slopes test. To determine date of 
hatching, an age-on-length relation was first deter- 
mined. The y-intercept for this equation was deter- 
mined by the best fit of the data. This regression 
equation was solved for age by using standard 
lengths of all 1988 and 1989 Tucker- and Frame- 
caught fish (size range of 6.0-28.0 mm SL). Hatch- 
ing dates were backcalculated by subtracting age at 
capture from the capture date. Hatching date distri- 
butions were then plotted to determine spawning 
date distributions for all 1988 and 1989 Frame- 
trawl-caught and Tucker-trawl-caught butterfish. 
Results 
Collection 
During 1988, 3,980 Peprilus were collected in the 
Tucker trawl (4 cruises; 196 hauls), and 388 in the 
Frame trawl (8 cruises; 404 hauls). In 1989, 880 
Tucker-trawl-caught (4 cruises; 128 hauls) and 364 
Frame-trawl-caught (6 cruises; 158 hauls) Peprilus 
were collected. In 1988, the greatest number of lar- 
vae and juveniles were caught in Tucker trawls in 
the MAB, July (n=l,191; 24.3 per haul) through mid- 
August (az= 1063; 21.7 per haul). There were no Tucker 
trawl collections during the spring of 1988 in the 
SAB. The highest numbers of Peprilus were collected 
in 1989 cruises from mid-July through early August 
in the MAB (n=445; 17.8 per haul). In general, the 
number of fish collected in the Frame trawl was less 
than in the Tucker trawl. In the 1988 Frame trawls, 
Peprilus were most numerous during late May {n= 29; 
1.8 per haul) in the SAB and from mid-July (n=99; 
2.0 per haul) through mid-August (n=110; 2.2 per 
haul) in the MAB. Frame trawls for 1989 had the great- 
est abundances of larvae during late April (n=158; 4.3 
per haul) in the SAB and from mid- July through early 
August in the MAB (n=170; 4.4 per haul). 
