318 
Fishery Bulletin 114(3) 
Previous studies regarding the trophic habits of red 
porgy and gray triggerfish in the SAB were limited in 
scope or are dated and, therefore, may not reflect possi- 
ble recent dietary shifts that result from natural or an- 
thropogenic disturbances. There has been, for example, 
only one published study on the feeding habits of red 
porgy in the southeast (Manooch, 1977). Although that 
study was very comprehensive and had a large sample 
size (72=779), it was completed more than 40 years ago. 
Additionally, we found a report from 1984 (SCWMRD"^) 
on feeding of red porgy in the SAB in which diet by 
size class and calculated diet overlap were examined 
in relation with other common reef fishes. Information 
on the food habits of gray triggerfish is also limited, 
and the few studies that have been undertaken have 
focused on their feeding behavior on artificial reefs 
(Blitch, 2000; Kauppert, 2002) and on their interactions 
with sand dollars (Frazer et ah, 1991; Kurz, 1995). 
Ecological dynamics and processes can be influenced 
by changing environmental conditions and anthropo- 
genic disturbances (Byron and Link, 2010), such as 
fishing. It is likely that intense fishing pressure has an 
impact on predator-prey relationships, and when these 
relationships are altered the food web can become un- 
stable (Holling, 1973). Therefore, it is reasonable to 
postulate that intense fishing pressure over the last 
several decades not only has affected predatory fish 
species, such as red porgy and gray triggerfish, directly 
but has also altered other ecological interactions. An 
additional change in the trophic dynamics of fish spe- 
cies of the U.S. southeastern waters has been the ac- 
cidental introduction of piscivorous lionfishes {Pterois 
spp.) (Whitfield et ah, 2002; Meister et ah, 2005) The 
scale of the ecological impact of lionfishes is uncertain 
as its range expands, but studies have indicated that 
lionfish predation has caused a reduction in prey com- 
munities and, therefore, a decrease of prey for native 
predators (Albins and Hixon, 2008; Morris and Akins, 
2009). 
This article provides descriptions of the current 
feeding habits of red porgy and gray triggerfish col- 
lected from natural, live bottom habitats in the SAB. 
This study is the first one on feeding habits of gray 
triggerfish on natural reefs off the Carolinas and 
Georgia. The primary objectives of this study were 1) 
to qualitatively and quantitatively describe the diet 
of red porgy and gray triggerfish; 2) to determine 
whether prey consumption differs significantly among 
seasons, depth zones, and latitudes; 3) to describe on- 
togenetic shifts in diet; 4) to determine the feeding 
strategy of each species; and 5) to provide data on diet 
to managers that use ecosystem-based models for fish- 
eries management. 
^ SCWMRD (South Carolina Wildlife and Marine Resources 
Department). 1984. Final report: South Atlantic OCS 
Area Living Marine Resources Study, Phase III, vol. 1, 223 
p. Prepared for Minerals Management Service, Washing- 
ton, D.C., under contract 14-12-0001-29185. [Available from 
Mar. Resour. Library, South Carolina Dep. Nat. Resour., 217 
Fort Johnson Rd., Charleston, SC 29412.] 
Materials and methods 
Collections 
Red porgy and gray triggerfish were collected during 
seasonal cruises (May-October) from 2009 through 
2011 in the SAB (Fig. 1) with hook-and-line fishing. 
The hooks were baited with cut squid (lllex sp.) and cut 
round scad (Decapterus sp.). Sampling was conducted 
during the day and night while the research vessel was 
anchored or drifted over hard-bottom reef habitat. Ten 
specimens of each species were targeted in each of 16 
sampling zones. Each sampling zone consisted of 1 of 2 
depth zones (20-50 m or >50 m) and 1 of 8 latitudinal 
zones (1° from 27°N through 34°N). 
All specimens were weighed to the nearest gram, 
and total length (TL) was measured in millimeters. The 
digestive tract (gut) was excised from the esophagus 
to the anus and individually labeled. Intestines were 
included because both species consume prey with some 
anatomical features that are particularly resistant to 
digestion, and gray triggerfish lack a distinct stomach. 
Guts were fixed in 10% formalin for at least 14 days 
and then rinsed with freshwater. After rinsing, gut con- 
tents were scraped into individual jars containing 70% 
ethanol and stored for identification. 
Identification of gut contents 
Gut contents were sorted by taxa, enumerated, and 
weighed (wet weight to the nearest 0.001 g) with a 
Sartorius® balance, model BP211D (Sartorius AG, Goet- 
tingen, Germany). Prey items were identified to the 
lowest possible taxon. Multiple fragments of individual 
organisms were counted as single individuals, unless 
the number could be estimated by counting structures, 
such as eyes, claws. Colonial organisms (i.e., bryozoans 
and tunicates) were counted as one individual. Fishes 
were identified according to the identification guide 
of Carpenter (2002a, 2000b), decapods were identi- 
fied by using Williams (1984), bivalves and gastropods 
were identified by using Abbott (1968), zooplankters 
were identified by using Johnson and Allen (2005) and 
Boltovsky (1999), echinoderms were identified by us- 
ing Hendler et al. (1995), and isopods were identified 
by using Schultz (1969). Voucher specimens from the 
Southeastern Regional Taxonomic Laboratory of the 
South Carolina Department of Natural Resources were 
used to confirm some identifications. 
Diet analyses 
Description of general diet To quantify feeding habits, 
the relative contribution of food items to the total diet 
was determined by using 3 traditional indices: percent 
frequency of occurrence (%F), percent composition by 
number (%N), and percent composition by weight (%W). 
® Mention of trade names or commercial companies is for iden- 
tification purposes only and does not imply endorsement by 
the National Marine Fisheries Service, NOAA. 
