317 NOAA First U.S. Commissioner National Marine Fishery Bulletin established 1881 of Fisheries and founder Fisheries Service of Fishery Bulletin Abstract—The feeding habits of red porgy (Pagrus pagrus) and gray trig- Feeding habits of 2 reef-associated fishes, gerfish (Balistes capriscus) were in- red porgy (Pagrus pagrus) and gray triggerfish vestigated by examining the gut con- tents of specimens collected during (Balistes capriscus), off the southeastern 2009–2011 from live bottom habitats off the southeastern United States. United States Red porgy had a diverse diet of 188 different taxa. Decapods, barnacles, Sarah F. Goldman (contact author) and bivalves were their main prey. Canonical correlation analysis indi- Dawn M. Glasgow cated that depth, season, and fish Michelle M. Falk length were statistically significant factors determining the degree of Email address for contact author: [email protected] variability in the diet of red porgy. Gray triggerfish also had a diverse South Carolina Department of Natural Resources diet, composed of 131 different prey P.O. Box 12559 taxa. Barnacles, gastropods, and Charleston, South Carolina 29422-2559 decapods were their main prey. Of the 4 explanatory variables, latitude was highly significant, and season, depth, and length were statistically significant. Red porgy and gray trig- There have been numerous calls and fisheries along the entire southeast- gerfish were observed to have a gen- mandates to adopt an ecosystem- ern U.S. Atlantic continental shelf, eralized feeding strategy of feeding opportunistically on a wide range of based approach to fisheries manage- often referred to as the South Atlan- prey. This study contains fundamen- ment (Link, 2002; Latour et al., 2003; tic Bight (SAB) (Bearden and McK- 2 tal trophic data on 2 important fish- NMFS, 2009). An ecosystem-based enzie ; Manooch, 1977; Antoni et al., ery species in the southeastern Unit- approach to fisheries management 2011), and both species are in the ed States. Most importantly, it pro- requires extensive knowledge of the snapper grouper complex managed vides fisheries managers with some dynamics of the ecosystem in ques- by the South Atlantic Fisheries Man- of the data necessary for the imple- tion, the trophic ecology of individual agement Council. Much of the fishery- mentation of an ecosystem-based ap- species, and the food web as a whole independent data used by managers proach to fisheries management. (Byron and Link, 2010), as well as for the snapper grouper complex are information on environmental and provided by the Marine Resources biological and economic factors. As Monitoring, Assessment, and Predic- fisheries managers move toward an tion program, which is a coopera- ecosystem-based approach to man- tive, long-term, fishery-independent agement, the data inputs for ecosys- monitoring survey. A recent report tem models, including diet informa- on analysis of data from this survey tion, must be acquired (Link et al., program revealed that red porgy and 2008; NMFS, 2009; SAFMC1). These gray triggerfish were the third and models require long-term monitoring fifth most commonly caught species of the food web and information on in chevron traps used in this survey, species interactions—data that are respectively (MARMAP3). lacking for most species in the south- 1 eastern United States (SAFMC ). 2 Bearden, C. M., and M. D. McKenzie. Red porgy (Pagrus pagrus) and 1969. An investigation of the offshore Manuscript submitted 23 April 2015. gray triggerfish (Balistes capriscus) demersal fish resources of South Caroli- Manuscript accepted 6 May 2016. support commercial and recreational na. South Carolina Wildl. Resour. Dep., Fish. Bull. 114:317–329 (2016). Tech. Rep. 2, 19 p. [Available at web- Online publication date: 26 May 2016. site.] doi: 10.7755/FB.114.3.5 3 MARMAP (Marine Resources Moni- 1 SAFMC (South Atlantic Fishery Man- toring, Assessment, and Prediction). The views and opinions expressed or agement Council). 2009. Fishery eco- 2014. Semi-annual progress report. system plan of the South Atlantic region. [Project report for the period 1 May–31 implied in this article are those of the Volume V: South Atlantic research pro- October 2014. Available from MAR- author (or authors) and do not necessarily grams and data needs, 177 p. SAFMC, MAP, South Carolina Dep. Nat. Resour., reflect the position of the National North Charleston, SC. [Available at 217 Fort Johnson Rd, Charleston, SC Marine Fisheries Service, NOAA. website.] 29412.] 318 Fishery Bulletin 114(3) Previous studies regarding the trophic habits of red Materials and methods porgy and gray triggerfish in the SAB were limited in scope or are dated and, therefore, may not reflect possi- Collections ble recent dietary shifts that result from natural or an- thropogenic disturbances. There has been, for example, Red porgy and gray triggerfish were collected during only one published study on the feeding habits of red seasonal cruises (May–October) from 2009 through porgy in the southeast (Manooch, 1977). Although that 2011 in the SAB (Fig. 1) with hook-and-line fishing. study was very comprehensive and had a large sample The hooks were baited with cut squid (Illex sp.) and cut size (n=779), it was completed more than 40 years ago. round scad (Decapterus sp.). Sampling was conducted Additionally, we found a report from 1984 (SCWMRD4) during the day and night while the research vessel was on feeding of red porgy in the SAB in which diet by anchored or drifted over hard-bottom reef habitat. Ten size class and calculated diet overlap were examined specimens of each species were targeted in each of 16 in relation with other common reef fishes. Information sampling zones. Each sampling zone consisted of 1 of 2 on the food habits of gray triggerfish is also limited, depth zones (20–50 m or >50 m) and 1 of 8 latitudinal and the few studies that have been undertaken have zones (1° from 27°N through 34°N). focused on their feeding behavior on artificial reefs All specimens were weighed to the nearest gram, (Blitch, 2000; Kauppert, 2002) and on their interactions and total length (TL) was measured in millimeters. The with sand dollars (Frazer et al., 1991; Kurz, 1995). digestive tract (gut) was excised from the esophagus Ecological dynamics and processes can be influenced to the anus and individually labeled. Intestines were by changing environmental conditions and anthropo- included because both species consume prey with some genic disturbances (Byron and Link, 2010), such as anatomical features that are particularly resistant to fishing. It is likely that intense fishing pressure has an digestion, and gray triggerfish lack a distinct stomach. impact on predator–prey relationships, and when these Guts were fixed in 10% formalin for at least 14 days relationships are altered the food web can become un- and then rinsed with freshwater. After rinsing, gut con- stable (Holling, 1973). Therefore, it is reasonable to tents were scraped into individual jars containing 70% postulate that intense fishing pressure over the last ethanol and stored for identification. several decades not only has affected predatory fish Identification of gut contents species, such as red porgy and gray triggerfish, directly but has also altered other ecological interactions. An Gut contents were sorted by taxa, enumerated, and additional change in the trophic dynamics of fish spe- weighed (wet weight to the nearest 0.001 g) with a cies of the U.S. southeastern waters has been the ac- Sartorius5 balance, model BP211D (Sartorius AG, Goet- cidental introduction of piscivorous lionfishes (Pterois tingen, Germany). Prey items were identified to the spp.) (Whitfield et al., 2002; Meister et al., 2005) The lowest possible taxon. Multiple fragments of individual scale of the ecological impact of lionfishes is uncertain organisms were counted as single individuals, unless as its range expands, but studies have indicated that the number could be estimated by counting structures, lionfish predation has caused a reduction in prey com- such as eyes, claws. Colonial organisms (i.e., bryozoans munities and, therefore, a decrease of prey for native and tunicates) were counted as one individual. Fishes predators (Albins and Hixon, 2008; Morris and Akins, were identified according to the identification guide 2009). of Carpenter (2002a, 2000b), decapods were identi- This article provides descriptions of the current fied by using Williams (1984), bivalves and gastropods feeding habits of red porgy and gray triggerfish col- were identified by using Abbott (1968), zooplankters lected from natural, live bottom habitats in the SAB. were identified by using Johnson and Allen (2005) and This study is the first one on feeding habits of gray Boltovsky (1999), echinoderms were identified by us- triggerfish on natural reefs off the Carolinas and ing Hendler et al. (1995), and isopods were identified Georgia. The primary objectives of this study were 1) by using Schultz (1969). Voucher specimens from the to qualitatively and quantitatively describe the diet Southeastern Regional Taxonomic Laboratory of the of red porgy and gray triggerfish; 2) to determine South Carolina Department of Natural Resources were whether prey consumption differs significantly among used to confirm some identifications. seasons, depth zones, and latitudes; 3) to describe on- togenetic shifts in diet; 4) to determine the feeding Diet analyses strategy of each species; and 5) to provide data on diet to managers that use ecosystem-based models for fish- Description of general diet To quantify feeding habits, eries management. the relative contribution of food items to the total diet was determined by using 3 traditional indices: percent 4 SCWMRD (South Carolina Wildlife and Marine Resources frequency of occurrence (%F), percent composition by Department). 1984. Final report: South Atlantic OCS number (%N), and percent composition by weight (%W). 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.