Casazza and Ross: Fishes associated with pelagic Sargassum and open water off North Carolina 
357 
50 
40 
30 
20 
10 
0 
75 
Sargassum 
Parexocoetus brachypterus 50 - 
1 IL^ Ml 
Open water 
Parexocoetus brachypterus 
(n= 156) 
Decapterus punctatus 
(n= 165) 
■n 
75 i 
Decapterus punctatus 
(n= 150) 
Coryphaena hippurus 25 - 
Coryphaena hippurus 
(n=1 3) 
t-FH- 
i ■ w 
<o ^ ^ A <o ^ ^ 
Standard length (mm) 
Figure 2 (continued) 
in Sargassum habitat ranged from 
13 to 253 mm SL, but the majority 
(84%) were juveniles <150 mm SL. 
Cheilopogon melanurus collected 
in open-water habitat ranged from 
12 to 257 mm SL, and the major- 
ity (77%) were also juveniles <150 
mm SL (Fig. 2). Coryphaena hippu- 
rus collected in Sargassum habitat 
ranged from 25 to 1020 mm SL, the 
majority (80%) of which were at the 
juvenile stage (<300 mm SL), and 
C. hippurus collected in open-water 
habitat ranged from 26 to 623 mm 
SL, 45% of which were juveniles 
(<300 mm SL) (Fig. 2). 
Overall, fishes collected from 
neuston net tows containing Sar- 
gassum habitat (8-374 mm SL, 
mean = 26 mm [±0.2 mm]) were 
significantly larger (Kolmogorov- 
Smirnov test: df=7464, P<0.001) 
than fishes collected from open- 
water habitat (8-138 mm SL, 
mean=23 mm [±0.4]) by the same 
method. Individuals collected in 
neuston net tows with Sargassum 
were significantly larger (Kolmogo- 
rov-Smirnov test, P<0.05) than 
individuals of the same species 
collected in neuston tows in open 
water for seven of the nine most 
abundant species (Table 3). 
Sargassum abundance and fish distribution 
Despite variability, the quantity of Sargassum habitat 
was correlated with fish species richness and density. A 
significant positive linear relationship existed between 
the overall numbers of fishes and Sargassum wet weight 
from neuston net samples (Fig. 3A). For five (S. hispidus, 
C. melanurus, B. capriscus, S. rivoliana, P. brachypterus ) 
of the eight most abundant Sa/'gassum-associated fish 
species collected by neuston net during 2000-03, a 
significant positive relationship existed between num- 
bers of individuals and Sargassum wet weight (Fig. 4). 
Table 3 
Mean standard length (SL) (±standard error [SE] in mm) of abundant fish species collected with neuston nets from Sargassum 
(S) and open-water (OW) habitats off North Carolina during 1999-2003. n=number of fishes, * = statistically significant (Kol- 
mogorov- Smirnov test, P<0.05). 
Mean SL ±SE (mm) 
Species 
S 
n 
OW 
n 
Stephanolepis hispidus 
22* (±0.2) 
2872 
18 (±0.4) 
470 
Caranx crysos 
28* (±0.4) 
1007 
27 (±0.7) 
276 
Cheilopogon melanurus 
35* (±0.8) 
392 
27 (±1.2) 
57 
Batistes capriscus 
23* (±0.7) 
336 
17 (±1.7) 
17 
Seriola rivoliana 
32 (±0.7) 
257 
35 (±2.6) 
12 
Monacanthus ciliatus 
17* (±0.2) 
176 
14 (±0.8) 
7 
Parexocoetus brachypterus 
31* (±1.0) 
158 
22 (±1.0) 
44 
Decapturus punctatus 
21 (±0.5) 
143 
23* (±0.6) 
149 
Coryphaena hippurus 
40* (±2.6) 
142 
29 (±5.1) 
21 
