356 
Fishery Bulletin 106(4) 
of the total open-water catches with neuston nets (in 
decreasing order of abundance): S. hispidus, D. punc- 
tatus, C. crysos, and C. melanurus. There were sig- 
nificantly more individuals (Mann-Whitney test: df=117, 
P<0.001) and numbers of species (Mann-Whitney test: 
df=117, P<0.001) in Sargassum habitat compared with 
open-water habitat. The three most abundant species in 
neuston net collections containing Sargassum habitat 
also exhibited the highest frequencies of occurrence: 
S. hispidus (70% of samples), C. crysos (64%), and C. 
melanurus (46%), whereas in open-water habitat these 
species occurred in 41%, 19%, and 22% of samples, 
respectively. Forty of the total 65 species collected in 
2000-03 neuston net tows in Sargassum were unique 
to this habitat, whereas only two ( Fistularia sp., Selene 
setapinnis) of the total 27 species collected in open-wa- 
ter habitat were unique (Table 2). 
Day versus night catch composition 
Regardless of sampling time (day or night), Sargassum 
habitat yielded significantly (Kruskal-Wallis test: df=3, 
P<0.05) higher numbers of individuals and species than 
open-water habitat. Daytime neuston net samples from 
Sargassum habitat (n = 47) yielded 8869 fishes from 48 
species, and nighttime neuston net samples from Sargas- 
sum habitat (n = 44) yielded 5254 fishes from 56 species 
(Table 2); however, these differences were not statisti- 
cally significant (Kruskal-Wallis 
test: df=3, P=0.924). Supplemental 
methods used in Sargassum habitat 
(dip nets, hook-and-line, 1999 neus- 
ton net) yielded different results; 
slightly more fishes (350 individu- 
als) were collected at night than 
during the day. This finding was 
likely due to the slightly higher 
effort at night and the attraction 
of fish by the nightlighting. 
As above, most fishes from neus- 
ton net samples in open-water 
habitat were collected during the 
day. Ten of the total 19 daytime 
neuston net tows in open-water 
habitat yielded 840 fishes, rep- 
resenting 20 species, and four of 
the total eight nighttime neuston 
net samples in open water yielded 
553 fishes, representing 18 species 
(Table 2); however, these differ- 
ences were not statistically signifi- 
cant (Kruskal-Wallis test: d f = 3 , 
P= 0.843). Supplemental methods 
used in open-water habitat (dip 
nets, hook-and-line, 1999 neuston 
net, long line), as above, produced 
more fishes at night (213 more in- 
dividuals), probably for the same 
reasons. 
Size distributions 
Sargassum 
Stephanolepis hispidus 1 000 -i 
(n=3834) 
<6 & rlO iS> cP c$> o$> M. cAcsA c- ^ 
rfO 
O' <v> N" \° 
‘Sop CPCpCp' & '■S° 
Open water 
Stephanolepis hispidus 
(n= 487) 
200 
20 
0 
80 - 
20 - 
60 
20 
0 
■flFflFfflTT'rrT 
' l.a>- 
Caranx crysos 
(n= 349) 
! 0“i i m n i i i i i s i i t i 
Cheilopogon melanurus 
- 
(n=1 56) 
,._ll*flQlT!riTrTTn 
i m n i i i i i i i i r i im 
1 
Balistes capriscus 
- 
(n=1 9) 
Seriola rivoliana 
- 
(n=15) 
■T-rT-ff r~ 
£ $ $ & & & £ & 
* 0 ' <£>' rif> <p' <§>' rp <&' 
riP <P 
Standard length (mm) 
Figure 2 
Length-frequency distributions of the nine most abundant fishes collected from 
Sargassum and open-water habitats during summer and fall of 1999-2003 
off North Carolina. Neuston net collections = black bars and supplemental 
gears = white bars. Only juvenile specimens were graphed for Cheilopogon 
melanurus (Atlantic flyingfish) and Coryphaena hippurus (dolphinfish). Note 
differences in y-axis scale. 
Ninety-six percent of all fishes col- 
lected in surface waters during 
these summer and fall cruises were 
juveniles and most (88%) were <50 
mm SL. The majority of S. hispidus 
(79% S, 87% OW), C. crysos (72%, 
61%), B. capriscus (79%, 95%), 
M. ciliatus (100%, 100%), and D. 
punctatus (93%, 86%) collected in 
both Sargassum and open-water 
habitats were <30 mm SL (Fig. 2). 
Cheilopogon melanurus collected 
