Fish Populations and Habitat Assessment on the Oculina Bank

195 Abstract—A portion of the Oculina Assessment of fish populations and habitat Bank located off eastern Florida is a marine protected area (MPA) pre- on Oculina Bank, a deep-sea coral marine served for its dense populations of the ivory tree coral (Oculina varicosa), protected area off eastern Florida which provides important habitat for fish. Surveys of fish assemblages Stacey L. Harter (contact author)1 and benthic habitat were conducted 1 inside and outside the MPA in 2003 Marta M. Ribera and 2005 by using remotely operated Andrew N. Shepard2 vehicle video transects and digital 3 still imagery. Fish species composi- John K. Reed tion, biodiversity, and grouper densi- Email address for contact author: [email protected] ties were used to determine whether 1 National Marine Fisheries Service O. varicosa forms an essential habitat Southeast Fisheries Science Center compared to other structure-forming 3500 Delwood Beach Rd. habitats and to examine the effective- Panama City, Florida 32408 ness of the MPA. Multivariate analy- 2 NOAA Undersea Research Center ses indicated no differences in fish University of North Carolina at Wilmington assemblages or biodiversity among 5600 Marvin Moss Lane hardbottom habitat types and grou- Wilmington, North Carolina 28409 per densities were highest among the most complex habitats; however the 3 Harbor Branch Oceanographic Institute higher densities were not exclusive to Florida Atlantic University coral habitat. Therefore, we conclude 5600 U.S. 1 North that O. varicosa was functionally Ft. Pierce, Florida 34946 equivalent to other hardbottom habitats. Even though fish assemblages were not different among management areas, biodiversity and grouper densities were higher inside the MPA compared to outside. The percentage Like shallow tropical coral reefs, deep- al., 1998; Bohnsack, 1998; Guenette of intact coral was also higher inside sea coral habitats support important et al., 1998). the MPA. These results provide initial ecosystem functions, for example, One of the world’s first deep-sea evidence demonstrating effectiveness as hotspots for biodiversity and bio- coral ecosystems to be designated a of the MPA for restoring reef fish and mass production (Husebo et al., 2002; marine protected area is located ap- their habitat. This is the first study Jonsson et al., 2004; George et al., proximately 37 km off Florida’s east to compare reef fish populations on O. 2007) and as important fish habitat coast in depths of 60–120 m. This varicosa with other structure-form- (Gilmore and Jones, 1992; Fosså et area is known as the Oculina Bank, ing reef habitats and also the first al., 2002; Ross and Quattrini, 2007). a series of reefs and high-relief bio- to examine the effectiveness of the MPA for restoring fish populations Like their shallow-water counter- herms (thickets of live coral, capping and live reef cover. parts, deep-sea coral ecosystems are mounds of sediment and coral rubble, affected by human activities. As har- built upon an underlying lithified vests have declined in shallow eco- base structure) constructed by the systems, fishing pressure has moved scleractinian ivory tree coral (Ocu- further offshore (Watling and Norse, lina varicosa). This species lives in 1998; Koslow et al., 2000; Roberts, water depths of 49 to 152 m without 2002), thus raising interest in deep- zooxanthellae and may form extensive sea coral ecosystem protection. With thickets 1 m tall, which over thou- the passage of the Magnuson-Ste- sands of years have built up mounds vens Fishery Management and Con- and ridges extending as much as 200 servation Act of 1996, an ecosystem m laterally and 35 m above the sur- approach to fishery management in rounding seafloor (Reed, 1980). These the United States has been encour- O. varicosa bioherms are known to aged by linking the preservation of exist only off the east coast of Florida essential fish habitat with protection from Ft. Pierce to St. Augustine, a Manuscript submitted 26 March 2008. Manuscript accepted 14 November 2008. of fishery resources. Reauthoriza- stretch of almost 150 km along the Fish. Bull 107:195–206 (2009). tion of the Act in 2006 mandated the edge of the Florida-Hatteras slope conservation and studies of deep-sea and beneath the western edge of the The views and opinions expressed coral ecosystems. These mandates are Gulf Stream. Surface water currents or implied in this article are those expected to lead to the increasing use may exceed 150 cm/sec and bottom of the author and do not necessarily reflect the position of the National of marine protected areas (MPAs) as currents may exceed 50 cm/sec (Reed, Marine Fisheries Service, NOAA. a fishery management tool (Allison et 2002a). Intact, live O. varicosa sup- 196 Fishery Bulletin 107(2) ports a diverse and dense assemblage of invertebrates to protect the fragile coral. Within the OHAPC, the and fishes (Avent et al., 1977; Reed, 2002a, 2002b; Koe- 315 km² (92 nm²) Oculina Experimental Closed Area nig et al., 2005), and it may serve as spawning grounds (OECA) (Fig. 1) was designated in 1994 in response to for a number of economically important or threatened the rapidly diminishing grouper (Mycteroperca and Epi- reef fish species (Gilmore and Jones, 1992; Koenig et nephelus spp.) populations and excludes all bottom fish- al., 2005). ing, including fishing with hook-and-line gear, in order A portion of the Oculina Bank known as the Oculina to assess the use of a MPA for recovering over-fished Habitat Area of Particular Concern (OHAPC) first re- reef fish populations, especially those of grouper. ceived protection in 1984 (Koenig et al., 2005; Reed et Management requirements to protect many deep-sea al., 2005). Current management regulations established coral ecosystems have been delayed owing to the dif- by the South Atlantic Fishery Management Council ficulty in quantifying, monitoring, and restoring dam- include a 1029 km² (300 nm²) OHAPC (Fig. 1), within aged reefs (Pyle, 2000). Despite efforts to understand which bottom-fishing gear such as trawls, dredges, long- and protect the Oculina Bank, extensive damage to lines, traps, and anchors are not permitted, in order the fragile coral had already occurred from fishing gear prior to the implementation of management regulations (Koenig et al., 2000; Reed et al., 2007). When the first management action was taken in 1984, only about 30% of the reef sys- tem was afforded protection (Reed et al., 2005). Fishing, including shrimp trawling, was allowed to continue in the northern section of the Oculina Bank until the OHAPC was expanded in 2000. Decades of shrimp trawling and scallop dredging before protection had reduced most of the 150- km stretch of healthy reefs to coral rubble (Reed et al., 2007). Remotely operated vehicle (ROV) transects and multi-beam mapping surveys since 2000, however, have indicated that Jeff’s Reef and Chapman’s Reef, both located in the southern portion of the OECA, still contain a large amount of intact live O. varicosa (Fig. 1) (Reed et al., 2005). Over-fishing has significantly diminished populations of reef fishes, especially those of groupers (Koenig et al., 2000, 2005). Historical observa- tions made during the 1970s and 1980s indicate that O. varicosa reefs were once dominated by large groupers, but later surveys found grouper populations greatly diminished and the reefs dominated by small, non-fishery species like small sea basses (Serranus and Centropristis spp.), butterflyfishes (Chaetodon spp.), and damselfishes (Chromis spp.) (Koenig et al., 2005). A current topic of discussion regard- Figure 1 ing deep water corals is whether they Remotely operated vehicle (ROV) transects overlain on the multi- serve as essential habitat for some fish beam map of the Oculina marine protected area (MPA) off east- species or whether any type of 3-di- ern Florida. Location of the OHAPC and OECA (OHAPC=areas where all bottom gear except hook and line are restricted, i.e., mensional structure (e.g., rock ledges) excluding the OECA, and OECA=inside the MPA where all is important. Auster (2005) proposed bottom gear, including hook and line fishing, are restricted) are that examination of the distribution of shown along with Chapman’s and Jeff’s Reefs. ROV transects fish in relation to all available habitats were conducted during April–May 2003 and October 2005. is one method to assess the “essential” Harter et al.: Assessment of fish populations and habitat on Oculina Bank 197 role of deep water corals. Several studies have concluded habitat classification and that of SEAMAP is that we that deep water corals were no more important to fishes distinguished between live and dead coral. Pavement than other reef structures (Auster, 2005; Tissot et al., habitat was fairly flat rock pavement often with small 2006) suggesting an opportunistic fish association with cracks or crevices present. Rubble habitat consisted of deep corals. Ross and Quattrini (2007), however, found small coral fragments exhibiting little to no relief. Rock that deep reef habitats along the southeast United outcrop habitat was small rock outcrops approximately States slope contain a unique and possibly obligate 0.3–0.9 m relief, occasionally 1.2–1.8 m relief. O. vari- assemblage of fish. No previous studies have examined cosa existed mostly as small individual heads (about whether O. varicosa supports a distinct assemblage of 0.3–0.9 m relief), but occasionally as larger mounds fish compared to other structure-forming, hardbottom and thickets. habitats. In 2014, the South Atlantic Fishery Management Collection methods Council will re-evaluate the effectiveness of the OECA. To aid the Council in making future management deci- The Phantom Spectrum II ROV (National Undersea sions, our goals for this project were to (1) compare fish Research Center, University of North Carolina at Wilm- assemblage composition, biodiversity, and grouper densi- ington) was used to conduct video and digital still tran- ties among hardbottom reef habitat types to examine sects to estimate fish densities and characterize habitat.

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