Investigating the Use of Underwater Video for the Determination of Size, Stock Density, and Temporal Patterns of Habitat Usage of Grouper on Hard-Bottom Habitats

Investigating the use of underwater video for the determination of size, stock density, and temporal patterns of habitat usage of grouper on hard-bottom habitats

Project Number 08-FEG-12

Erin J. Burge1, Jim Atack2, Craig Andrews3

Report Date: 10 November 2009

1Corresponding author. Coastal Carolina University, Department of Marine Science, PO Box 261954, Conway, SC 29526, phone: (843) 349-6491, e-mail: [email protected]

2In Sea State Inc., 111 SW 20th St., Oak Island, NC 28465

3Over & Under Adventures Inc., 4956 Longbeach Rd # 14-149 Southport, NC 28461

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ABSTRACT

Accurate assessments of economically and ecologically important finfish populations are critical to single- and multi-species fishery management. As such, a diversity of data collection methodologies are advantageous for species of high economic value, both from a scientific desire to ensure the most sound population assessments, and from the perspective of public acceptance of scientific and management recommendations for the use of fishery resources. In this pilot project we investigated the use of a non-traditional and relatively inexpensive, collaborative method for enhancing fishery-independent datasets by collecting underwater video of grouper habitats. To our knowledge, a stationary video supplemental stock assessment for gag grouper (Mycteroperca microlepis) has not previously been attempted. Underwater video techniques were used to document the presence/absence, estimated size, density, behavioral patterns, and temporal habitat usage of gag grouper on shallow water, hard-bottom habitats on the continental shelf of North Carolina. A comparison between video findings and diver visual surveys of groupers at the same locations was also made. Survey dives (n = 57) were conducted from June 2008 – January 2009 and resulted in observations of 1813 scamp (M. phenax), 305 gag, 97 yellowmouth grouper (M. interstitialis) and 118 individuals of other serranid species in the total standard definition (SD) video footage analyzed (24.6 h). Comparing equal segments of each video (15 minute) resulted in observations of 760 scamp, 115 gag, 33 yellowmouth, 27 graysby (Cephalopholis cruentatus), 13 red grouper (Epinephelus morio), nine rock hind (E. adscensionis), two goliath grouper (E. itajara), and six unidentified serranids in 8.5 hours of video observation. Comparisons were made at multiple locations, using baited and unbaited camera deployments on ledge and live-bottom habitats. There were no significant differences in the numbers of gag and scamp detected for surveys in which bait was not used, nor were differences detected for scamp between the two habitat types. Gag grouper were more frequently observed on live-bottom habitats. With the necessity of accurate assessments for resource managers becoming more important, non-extractive survey techniques, similar to those employed in this program, should be considered for future applications. These video survey techniques were also valuable for observations of fish community structure and some behavioral traits, suggesting that the addition of similar video observation protocols to MARMAP (or similar) fishery-independent data collections would be very valuable for immediate assessments on critical species, and for long- term monitoring of trends in community structure.

2 INTRODUCTION

Accurate assessments of economically and ecologically important finfish populations are critical to single- and multi-species fishery management. As such, a diversity of data collection methodologies are advantageous for species of high economic value, both from a scientific desire to ensure the most sound population assessments, and from the perspective of public acceptance of scientific and management recommendations for the use of fishery resources. The latest gag grouper assessment and recommendations (SEDAR10, 2006) utilized data from both fishery- dependent and fishery-independent indices of abundance. These fishery-dependent datasets included commercial handline and longline fisheries, recreational headboat landings and MRFSS data from the recreational charter and private boat sectors. Fishery-independent data were developed from the SEAMAP reef fish video survey in the Gulf of Mexico and MARMAP cruises in North and South Carolina. Groupers (Family Serranidae, Subfamily Epinephilinae) play an important global role in hard-bottom ecosystems as high trophic level predators, and also support valuable commercial and recreational fisheries (Parrish, 1987). Groupers primarily live in habitats of complex topography and hard substrates (Chiappone et al., 2000; Smith, 1961) over a range of depths (1 to 300 m), and eat mainly fishes and crustaceans (Parrish, 1987). Certain characteristics of moderate to large species within the group that potentially negatively affect fisheries include slow growth, delayed reproduction, long life span, reduced spawning period, and commonly, protogynous sex reversal (reviewed in Coleman et al., 2000). Along the continental shelf of North Carolina gag and scamp grouper were the most commonly recorded moderate to large serranids from hard-bottom visual diver surveys in the 1970s (1975-80) and the early 1990s (1990-92) (Parker Jr. and Dixon, 1998), although they share space with other members of the snapper-grouper complex in this region (Grimes et al., 1982; Parker Jr., 1990; Quattrini and Ross, 2006; Quattrini et al., 2004). Both gag and scamp display reproductive aggregation behavior (Coleman et al., 1996) and appear to have limited home ranges (Heinisch and Fable Jr., 1999; Kiel, 2004). Kiel (2004) reported a tendency of gag to be site specific and to utilize a central core site as a result of numerous relocations of tagged gag on or near specific patch reefs. In this project we investigated the use of non-traditional and relatively inexpensive, collaborative methods for enhancing fishery-independent datasets by collecting underwater video data of gag grouper habitats without fish extraction. Underwater video techniques are useful for quantifying and observing fishes and were used in this study to estimate grouper sizes, densities, behavior, and temporal patterns of habitat usage on hard-bottom habitats near Cape Fear, North Carolina. Numerous previous studies have examined the use and efficacy of underwater video techniques (e. g.: Cappo et al., 2004; Gledhill et al., 1996; Harvey et al., 2007; Harvey et al., 2003; Pfister and Goulet, 1999). Underwater video techniques are practical because the recordings are a less intrusive, non-extractive method of data collection that reduces diver affects and observer bias that can arise with other collection methods (reviewed in Harvey et al., 2004). Video recordings are also valuable because they represent data on a permanent record that allows the opportunity to measure more variables from a given data set (Cappo et al., 2007) and to revisit historical data. The collection of video data also, to a large degree, removes the need for field deployment of scientific specialists, and provides an exciting “product” for use in communicating science to stakeholders and the general public (see attached video summary).

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The biology and behavior of fish species of interest are important for determining the underwater video techniques most appropriate for the survey methodology (Willis et al., 2000). This is especially true for baited underwater video techniques which are needed to offset biases introduced by changes in fish behavior (Willis et al., 2000). Baited video observation has been successfully used to document large, mobile species, including members of the snapper-grouper complex (Langlois, 2006; Rand et al., 2006) in the past. In contrast, Posey and Ambrose (1994) found that non-baited cameras may be less intrusive than baited camera systems since the absence of bait ensures that there will be no effective change in fish behavior regarding feeding. There are trade-offs to using non-baited video techniques including greater field time and more expensive equipment to ensure that statistically testable data is collected (Posey and Ambrose, 1994). This pilot project was designed to use underwater video data collection to document the presence/absence, estimated size, density, and temporal habitat usage of gag grouper (Mycteroperca microlepis) on shallow water, hard-bottom habitats on the continental shelf of North Carolina, and to compare the video findings to diver visual surveys of groupers at the same locations. Additional information was collected on other species of observed groupers, including primarily scamp (M. phenax) and yellowmouth grouper (M. interstitialis). Recent stock assessments for the Atlantic gag grouper indicated that the species is experiencing overfishing and noted that there is lack of fishery-independent abundance data for southern North Atlantic gag (SEDAR10 Review Workshop, 2007), indicating a need for additional monitoring of this species for future stock assessments and management recommendations.

MATERIALS AND METHODS

Study sites Video locations were chosen from a private database of known hard-bottom locations (J. Atack and C. Andrews, personal communication) and also included established MARMAP sampling sites in the depth range of 23 – 35 m (Figure 1). Sampling sites included previously visited and unvisited locations by the study authors. Factors used to select sites for each field day included recent local conditions, such as prevailing wind and wave forecasts, recent reports of bottom visibility, satellite imaging (SST composites and chlorophyll a 1 km resolution composites) and elapsed time since the last visit. In general, these sites were 48 – 65 km SE of Cape Fear (N 33° 50' 38" W 77° 57' 43") and included two representative bottom types (Figure 2). “Ledge” areas consisted of high-relief outcrops of limestone substrate, “live-bottom” areas of relatively low relief, extensive hard substrate heavily colonized by benthic fauna and flora (Blackwelder et al., 1982; Parker Jr., 1990; Sedberry and Van Dolah, 1984; Wenner et al., 1983). Live bottom areas generally had less than 1 m of sloping vertical relief, while ledge sites generally possessed greater than 1.5 - 2 m of topographic relief, and had numerous undercut ledges and areas of complex bathymetry (see attached video summary). Chosen sites were visited one to four times each during the period June 2008 – January 2009. At each of the sites a detailed log of dive personnel, water parameters, topographic descriptions, and diver observed fish counts were compiled (Figure 3).

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Video cameras and housings Video cameras used in this study consisted of a pair of Sony HDR-SR11 60GB High Definition (HD) Handycam® Camcorders (Sony Electronics, Inc., Kansas City, Missouri) (Table 1) fitted with 0.5× wide angle lenses. Underwater video housings were Light & Motion Stingray HD Underwater Video Housings for Sony cameras (Backscatter Underwater Photo and Video, Monterey, California) (Table 2). Each of the housing and camera units were mounted on a custom made stand constructed of drilled PVC tubing and marine starboard (Figure 4). Dive weights (1.8 – 6.8 kg [4 – 15 lb) attached under the stand were used to hold the camera in place at the dive locations and elevated the camera housing approximately 25 cm from the surroundings.

Camera deployments and diver visual surveys Upon arrival and anchoring at a suitable dive site, a pair of SCUBA divers descended using the anchor line and identified an appropriate location for setting up the camera. Conditions considered acceptable for filming included bottom visibility greater than 25 ft (estimated), appropriate structural habitat (ledge/live-bottom), and a secure anchorage to ensure equipment retrieval. While the camera operator chose a location and deployed the stand the second diver conducted a 2 minute visual census of all groupers visible from the camera location (Colvocoresses and Acosta, 2007). Each fish was assigned an estimated size category (< 12”, 12 – 18”, 18 – 24”, 24 – 30”, > 30”), and these data were recorded on dive slates and transferred to the dive log book (Figure 3) upon completion of the dive. The census diver would then assist in camera positioning and deployment by placing size and distance markers, and, when used, bait or chum. Size marker targets of measured lengths of floating PVC pipe (either 51 or 61 cm [20 or 24 in] length) were placed 6.1 m (20 ft) from the camera in order to give a known size marker for estimating lengths of distant fish (see attached video summary). On a few occasions the size marker was placed at a distance other than 6.1 m, and the diver signaled the distance during setup in the video. In some videos approximately 2-3 L of shrimp heads or lobster parts were used as a forage fish attractant. In some cases the bait was deployed as a frozen block accessible to feeding fish, and in other cases it was contained within a chum pot. After set-up the stationary video camera apparatus was left by the diver team for durations ranging from 18 to 90 min. At the end of the stationary video period a diver team would retrieve the equipment and return to the boat. In some cases a short swimming transect was conducted, however these were of variable length, swimming speed, and area, and were not used for data analysis.

Video data collection Video data from each dive were transferred from the Sony Handycam® HDR-SR11 and encoded in SD (standard definition) format on 4.7 Gb DVD discs for data collection and archival storage. These discs are compatible with home DVD players and computer DVD drives, and are viewable in standard video player software (e. g. Windows Media Player, Apple Quicktime). In order to generate the most usable information from each dive video the entire video clip was watched and all groupers were noted. Videos were observed separately by three individuals (E. J. Burge, B. M. Binder, L. E. Bohrer; Coastal Carolina University) who then met weekly to compare results within video clips and review the findings. Each grouper observed was recorded in a standardized data sheet constructed in Microsoft Excel 2003 (Figure 5). Data recorded

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included time code (H:MM:SS) (what time in the video the grouper was seen), grouper species, categorical size estimate, size estimate (inches), repeat likelihood code, and a note with information pertaining to behavior, other species of interest, or movements of divers. Categorical size estimates were assigned based on a scale 1 – 5, while repeat likelihood codes ranged from 0 – 5 (Table 3). Repeat likelihood codes were designed to account for recounting of the same fish within videos. Fish observations assigned codes 4 or 5 were presumed to represent fish that could be eliminated from the final data analysis. These variables were used as a measure for abundance and estimated size and densities. Habitat notes such as visibility, macroalgal cover, relief, and notable area characteristics were also recorded. After all grouper observations were compiled from all of the available video clips (n = 51; 6 dives did not result in collected video because of technical or field issues), each of the video clips was subjected to a decision tree and determined to meet criteria for inclusion in the study (Figure 6). Video clips meeting all criteria (n = 34) were used in the final analysis. Stated objectives of the project included conducting 48 surveys, with half of those being revisited monthly for the duration of the study. A smaller number of sites were able to be revisited than originally anticipated, and none with the frequency outlined in the original proposal. Effects due to Hurricane Bertha (mid – late July 2008), Tropical Strom Cristobal (late July 2008), which formed off of the Carolinas, and Tropical Storm Hanna (late August – early September 2008), which made landfall very close to the study locations, affected filming for approximately 12 weeks and disrupted the repetitive sampling originally proposed. Funded projects of longer duration (1 – 2 years) would be better able to accommodate these types of delays. Due to these unexpected circumstances each survey visit was considered as a unique site for analysis. Final video analysis consisted of collecting data as noted above for a 15 minute interval that began 3 minutes after the presence of divers in the area ceased. This was determined by divers leaving and not reappearing, cessation of audible breathing sounds, and no evidence of diver influence on fish behavior within view. Fish behavior appeared to return to normal within 1 minute of diver departure (personal observation). In the original request for funds a video interval of 10 minutes was suggested for data collection, with 10 minute periods before and after the data collection window (30 minutes video per site). Full viewings of all videos were conducted and this method of data collection was found to not be workable. In many cases the presence of divers lasted longer than 10 minutes at the beginning and video length was also highly variable. During the 15 minute interval, values designated MaxNgag and MaxNscamp were calculated. MaxN refers to the relative density of fishes based on the maximum number of individuals of each species visible at one time on the video, and has been used in other similar studies (Watson et al., 2005; Willis et al., 2000). This MaxN relative density value provides a conservative estimate, and most probably an underestimate, of the number of fish in the area.

Data analyses Statistical methods used for data analysis were conducted in R (v. 2.5.1; http://www.r- project.org/) and SigmaStat v. 3.11.0 (Systat Software, Inc., Chicago, Illinois). For these analyses the data were not assumed to be normally distributed, and as such, methods used in this report are non-parametric in nature. Alpha values considered significant were α ≤ 0.05. The Wilcoxon rank-sum test was used to test for differences in mean number of observed fish based on categorical variables such as habitat, bait, or sector of occurrence. Chi-Square tests (χ2) for independence were used to test for evidence of a relationship between two categorical variables.

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There are not any distributional assumptions placed on the χ2 test and hence it was appropriate in this setting. In order to obtain a linear model for the total count of fish based on a quantitative variable (visibility, depth, temperature), it was not possible to use simple linear regression due to the fact that the response variables were not continuous. For count data in this report, Poisson regression and Spearman’s r for nonparametric analyses were used for correlations. Spatial mapping of data used ArcMap v. 9.2 (ESRI Inc., Redlands, California) and shoreline data images from http://coastalgeospatial.noaa.gov/shoreline.html.

RESULTS

Inclusion of dives in data collection A total of 57 dives between 8 June 2008 and 3 January 2009 were conducted (Figure 7). Some locations corresponded to previous MARMAP sampling locations, although some visited MARMAP locations did not have the habitat complexity desirable for this study and no data was collected (see Figure 1). This project was originally planned to include monthly repeated visits to four sites (6 months project duration, 24 total surveys) in order to evaluate seasonal changes in grouper species, while the remaining 24 video surveys were planned to occur at unique sites. Repeated visits to representative sites were hampered due to weather and equipment problems, and after the exclusion of videos due to technical issues (Table 4) repetitive site visits were considered as independent surveys. Of the n = 57 dives conducted, deployment of the camera was deemed not worthwhile or technical difficulties precluded video collection for six sites. Of the 51 camera deployments, low visibility resulted in the exclusion of eight video clips from data analysis. Of the remaining 43 video clips, nine were excluded because they were too brief to allow for a data collection window of 15 minutes after the departure of divers. A 15 minute interval for video data collection balanced collecting larger numbers of grouper observations per video with including the largest number of total video clips. Reducing the observation interval window to 10 minutes would have resulted in the inclusion of one additional video clip (filmed 1 November 2008; dive number 20, Figure 7), but inclusion of this dive would have resulted in removal of 5 minutes of footage from all other videos, a loss of 2.8 h of total analyzed video time.

General video observations of groupers Observations of the 15 minute intervals from all 34 usable video clips (8.5 h) resulted in inclusive, potentially redundant counts of 760 scamp (Mycteroperca phenax), 115 gag (M. microlepis), 33 yellowmouth (M. interstitialis), 27 graysby (Cephalopholis cruentatus), 13 red grouper (Epinephelus morio), nine rock hind (E. adscensionis), two goliath grouper (E. itajara), and six unidentified serranids. Total counts uncorrected for variable lengths of video clips (24.6 h), and uncorrected for recounting of individuals were 1813 scamp, 305 gag, 97 yellowmouth grouper and 118 individuals of other serranid species.

Video count data and inferred minimum population sizes (MaxN) Because sample sizes for species other than scamp and gag were small, MaxN values were only calculated for these two species. These values were used to evaluate the absolute minimum number of fish present at the dive location. Sums of MaxNscamp (= 125) and MaxNgag (= 32)

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represented 18.4 and 27.8 % of all observed individuals of these species during the 15 minute video data collection intervals. For those fish of each species seen simultaneously on the screen of the stationary video at any given time during the 15 minute observation window, the MaxN inferred minimum population sizes by location ranged from 1 - 4 gag and 1 - 13 scamp. Observations outside of the 15 minute window indicate that gag grouper could be more abundant than these minimum population estimates, with MaxNgag more than twice as high as that recorded during the window, higher MaxN values were also obtained for videos viewed in high definition (see Discussion).

Diver point counts Diver point counts (2 minutes) also likely represent a non-redundant counting method as the diver is able to more accurately track, and not recount, moving fish within the field of view, compared to the stationary video camera. For the two primary species 402 scamp and 390 gag were observed by divers during the 2 minute intervals at all usable video locations (n = 34, 68 minutes total observation), which is slightly higher than the totals using the 15 minute video observations. Population sizes by location estimated from this counting method range between 1 – 40 scamp and 0 – 50 gag. No other species of groupers were noted during the diver point counts at the usable video sites, except for red grouper, which were occasionally observed on some dives, and were not expected to be abundant because of their different geographical distribution. Comparisons between the various counting techniques indicate that there is a significant degree of correlation (Spearman’s r for nonparametric analysis; Table 5) between the techniques, especially for scamp (Figure 8).

Relationships between physical parameters measured and grouper counts Visibility estimates for all usable videos were based on mean values determined by on-site divers and video observers (Figure 9). There was a significant positive correlation (Spearman’s rank correlation r = 0.637; p < 0.001) between the different estimated visibilities and as such these values were averaged to provide a reasonable estimation of visibility for each site. Total observed grouper numbers recorded during the 15 minute data collection interval did not differ (Poisson regression model, p = 0.7740) due to changes in visibility (Figure 10) once low visibility videos (< 25 ft) were excluded (data not shown). Habitat depth did not significantly affect grouper counts (Poisson regression model, p = 0.4050) for gag and scamp groupers over the sampled depth interval of 23 – 35 m (Figure 11). Water temperatures varied seasonally over the course of the study and a significant, negative correlation (Poisson regression, p < 0.001) existed between water temperatures (° C) and total numbers of observed gags and scamps (Figure 12).

Effect of baiting, geography, habitat type, and date of sampling on grouper counts Bait or chum (shrimp or lobster heads) was used as a forage fish attractant on 18 of 34 video collection dives. The gags and scamps observed in the 15 minute video counts did not differ significantly with the presence of bait (Wilcoxon test, p = 0.9037) and the range in numbers of fish for each treatment (baited, n = 18, range, 5 – 67 fish; unbaited, n = 16, range, 2 – 69 fish) were highly similar (Figure 13) with the baiting protocol used in this project. Data by location for gag and scamp were compared by segregating dive sites north and east of Frying Pan Tower from those south and west of this location. These sectors roughly correspond to the oceanographic break that occurs at Frying Pan Shoal and separates Long Bay

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from Onslow Bay. Comparison of grouper counts of gags and scamps in aggregate (video counts; Figure 14) were not significantly different between these sectors (Wilcoxon test, p = 0.8592). Numbers of fish varied substantially between sites regardless of the counting method used. Total inclusive video counts, which possibly represent an overestimate of fish in the immediate area, may be representative of a larger area than that seen in the video frame since the camera only records a portion of the sphere surrounding it. Fish recounts in the field of view may be offset by groupers in the immediate area that do not enter the field of view. Supporting evidence for this is drawn from the diver visual survey results which utilized 360° views and recorded similar numbers of gag and scamp in aggregate. MaxN values indicated minimum population sizes at each location and tended to be dominated by scamp (Figure 15). Diver point counts suggested that scamp and gag numbers were similar across all sites, although they varied substantially between sites (Figure 16). Counts of video observed groupers were tested to evaluate habitat usage by the most numerous grouper species. Individual dive videos were categorized as “ledge” (n = 18) or “live- bottom” (n = 16) habitats based on diver notes and video observations. Total observed gags and scamps in aggregate did not differ significantly between the habitat classifications (Wilcoxon test, p = 0.3598; Figure 17), however when considered separately by species, gag grouper were significantly more commonly associated with live-bottom habitats (χ2 test of independence, p < 0.001; Figure 18). This could be due to the fact that the live bottom areas offer less cover and gag would be more visible than in ledge locations that offer overhead cover. There were several instances where classification of the site was determined by the filming direction and the filming structure since the surrounding structure supported both habitat classifications. Total observed numbers of gag and scamp varied substantially from month to month (Figure 19), although there were large differences in the numbers of usable videos for different months. There was a general trend toward increasing numbers of both species into the winter months, with the maximum number of scamps recorded during November and December 2008 dives, and the maximum number of gags observed in early January 2009. As noted (Table 4) it was not possible to revisit sites on a consistent basis, and so trends in abundance at the same sites during the study period could not be evaluated.

Size distribution of major grouper species Each observed grouper was assigned an estimated size and estimated size category (Table 3) based on three independent video observers. Consensus estimates were reached by agreement between video observers. Size distributions differed significantly for the three most common species (Figure 20), respectively scamp, gag, and yellowmouth grouper (χ2 test of independence, p = 0.00049). Video observation only rarely identified fish < 12” (size category 1; 10 fish counted of 2215 total observations). The dominant estimated size category for scamp were group 3 (18 – 24”), group 4 (24 – 30”) for gag, and group 4 for yellowmouth grouper. Size categories for all three species were normally distributed (Kolmogorov-Smirnov test for normality; scamp, K-S Dist. = 0.343, p = 0.055; gag, K-S Dist. = 0.228, p > 0.200; yellowmouth, K-S Dist. = 0.191, p > 0.200). Size distributions for scamp and gag recorded by diver visual point counts (n = 34) differed from video observed size classes in that scamp were most commonly identified as group 2 (12 – 18”), while gag were most commonly identified as group 3 (18 – 24”) (Figure 21).

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TABLES AND FIGURES

TABLE 1. Technical specifications of Sony cameras (HDR-SR11 with 60 GB hard drive) used for video collection. Formats Supported HD: MPEG4 AVC/H.264; SD: MPEG2 Video Video Signal NTSC color, EIA standards Weights and Dimensions 83 × 76 × 138 mm Measurements Weight 650 g with Battery Lens Type Carl Zeiss® Vario-Sonnar® T 35mm Equivalent 49 - 588mm Aperture F 1.8 - 3.1 Digital Zoom 150x Filter Diameter 37 mm Optics/Lens Focal Distance 4.9 - 58.8 mm Focus Full range auto / Manual Shutter Speed Auto, 1/30 - 1/250 (Scene Selection Mode) Optical Zoom 12x Wide-angle Lens 0.5x Camera mounted Imaging Device 1/3" ClearVid™ CMOS sensor (with Exmor™ technology) General Processor BIONZ™ image processor Recording Media 60 GB Hard Disk Drive, Memory Stick Duo™ Media Battery Type InfoLITHIUM® with AccuPower™ Meter System (NP-FH60) Power Power Requirements 7.2V (battery pack); 8.4V (AC Adaptor) Power Consumption 4.5W/4.8W/4.9W Audio Audio Format Dolby® Digital 5.1

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TABLE 2. Technical specifications of Light & Motion Stingray HD Underwater Video Housing. Construction Marine-grade Aluminum, Anodized, Depth Rated 300 ft Weight 7 lb Dimensions 9.5 × 7.2 × 6" Multi-Camera Tray Compatible with Sony HD cameras 2.7" Monitor Back: AA battery powered Glass Zoom-Through front Ergonomic Non-Penetrating Electronic Camera Controls Self-Locking Rotating Latches Double O-ring Seals Monitor Back and Lenses Records Photos to Memory Stick Standard Features Ergonomic Grips Easy-Load Self-Locking Camera Tray Moisture/Leak alarm Color Correction filter Integrated Design for Battery Pods/Weight Brackets Quick Disconnect Mounts for Lights Record Indicator Light Power On/Off Record/Standby Zoom/Telephoto Auto-focus On/Off Depth Controls Auto-focus Lock Momentary Auto-focus Video/Photo Mode Manual Focus

TABLE 3. Data coding for categorical size estimates and likelihood of recount bins. Size Code Size Category Recount Code Recount Category 0 unknown 1 < 12" 1 not 2 12 - 18" 2 unlikely 3 18 - 24" 3 possible 4 24 - 30" 4 probable 5 > 30" 5 definite

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TABLE 4 Repeated site visits and outcomes of collected video. Site location2 Outcome Included in Reason for Dive #1 Revisits Latitude Longitude Date of visit study data exclusion3 1 33 27 77 40 8 Jun 2008 Yes 3 3 33 27 77 40 20 Jun 2008 Yes 18 33 32 77 25 1 Nov 2008 No Low visibility 2 33 29 77 25 20 Jun 2008 No Low visibility 33 33 27 77 39 23 Nov 2008 Yes 4 40 33 48 77 37 17 Dec 2008 No Low visibility 49 33 27 77 46 3 Jan 2009 Yes 4 33 46 77 31 12 Jul 2008 No No video 17 3 33 21 77 40 1 Nov 2008 No No video 48 33 17 77 46 3 Jan 2009 Yes 23 33 21 77 40 17 Aug 2008 Yes 38 3 33 30 77 15 24 Nov 2008 No Low visibility 47 33 17 77 47 30 Dec 2008 Yes 10 33 32 77 28 17 Aug 2008 No Video length 26 3 33 27 77 39 30 Aug 2008 Yes 34 33 46 77 31 23 Nov 2008 No Low visibility 9 33 50 77 16 17 Aug 2008 No Video length 29 3 33 24 77 31 16 Oct 2008 No Video length 44 33 22 77 38 30 Dec 2008 No Video length 1See Figure 7; 2Latitudes and longitudes are reported as DD MM and are rounded to the nearest minute; 3Low visibility was defined as estimated values less than 25 ft; No video indicates that survey divers did not collect video because of low visibility or camera/housing malfunctions; Video length refers to video surveys less than 18 min in total length; Blanks indicate that a survey was included in the final analysis

TABLE 5 Correlation analysis (Spearman’s r for non-parametric analysis) of counting techniques. Species Comparison Scamp Gag r p r p Video vs. MaxN 0.7590 < 0.0000 0.9544 < 0.0000 Diver vs. MaxN 0.5800 0.0003 0.0815 0.6465 Video vs. Diver 0.5291 0.0013 0.0814 0.9179

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TABLE 6 Relative frequency of occurrence for all observed fish and elasmobranch species from all videos. This listing is not limited to videos deemed useful for grouper observation, nor is it limited to the 15 minute interval of analysis used for grouper counts. Frequency of Occurence1 Common Name Species2 Family gray triggerfish Balistes capriscus Balistidae amberjack Seriola dumerili Carangidae almaco jack Seriola rivoliana Carangidae tomtate Haemulon aurolineatum Haemulidae white grunt Haemulon plumieri Haemulidae hogfish Lachnolaimus maximus Labridae Most frequent Spanish hogfish Bodianus rufus Labridae vermillion snapper Rhomboplites aurorubens Lutjanidae blue angelfish Holacanthus bermudensis Pomacanthidae gag Mycteroperca microlepis Serranidae scamp Mycteroperca phenax Serranidae knobbed porgy Calamus nodosus Sparidae spottail pinfish Diplodus holbrookii Sparidae scads* Decapterus spp. Carangidae spadefish Chaetodipterus faber Ephippidae spotfin hogfish Bodianus pulchellus Labridae bicolor damselfish Stegastes partitus Pomacentridae Frequent black sea bass Centropristis striata Serranidae graysby Cephalophis cruentatus Serranidae sheepshead Archosargus probatocephalus Sparidae jolthead porgy Calamus bajonado Sparidae saucereye porgy Calamus calamus Sparidae red porgy Pagrus pagrus Sparidae ocean surgeonfish Acanthurus bahianus Acanthuridae doctorfish Acanthurus chirurgus Acanthuridae blue tang Acanthurus coeruleus Acanthuridae trumpetfish Aulostomus maculatus Aulostomidae sand tiger shark Carcharias taurus Carcharhinidae foureye butterflyfish Chaetodon capistratus Chaetodontidae spotfin butterflyfish Chaetodon ocellatus Chaetodontidae reef butterflyfish Chaetodon sedentarius Chaetodontidae banded butterflyfish Chaetodon striatus Chaetodontidae squirrelfish Holocentrus adscensionis Holocentridae Less frequent Bermuda/yellow chub Kyphosus sectatrix/incisor Kyphosidae planehead filefish Stephanolepis hispudus Monacanthidae spotted goatfish Pseudupeneus maculatus Mullidae queen angelfish Holacanthus ciliaris Pomacanthidae red lionfish Pterois volitans Scorpaenidae bank sea bass Centropristis ocyurus Serranidae rock hind Epinephelus adscensionis Serranidae yellow goatfish Mulloidichthys martinicus Mullidae red grouper Epinephelus morio Serranidae yellowmouth grouper Mycteroperca interstitialis Serranidae great barracuda Sphyraena barracuda Sphyraenidae bandtail puffer Sphoeroides spengleri Tetraodontidae queen triggerfish Balistes vetula Balistidae African pompano Alectis ciliaris Carangidae carcharinid sharks* Carcharhinus spp. Carcharhinidae stingrays* Dasyatis spp. Dasyatidae remoras* Echeneis spp. Echeneidae cornetfish Fistularia tabacaria Fistularidae smooth butterfly ray Gymnura micrura Gymnuridae porkfish Anistotremus virginicus Haemulidae blackbar soldierfish Myripristis jacobus Holocentridae bluehead wrasse Thalassoma bifasciatum Labridae tautog Tautoga onitis Labridae red snapper Lutjanus campechanus Lutjanidae gray snapper Lutjanus griseus Lutjanidae orangespotted filefish Cantherhines pullus Monacanthidae moray eels* Gymnothorax spp. Muraenidae Least frequent spotted eagle ray Aetobatus narinari Myliobatidae scrawled cowfish Acanthostracion quadricornis Ostraciidae trunkfish Lactophyrs trigonus Ostraciidae southern flounder Paralichthys lethostigma Paralichthyidae rock beauty Holacanthus tricolor Pomacanthidae gray angelfish Pomacanthus arcuatus Pomacanthidae French angelfish Pomacanthus paru Pomacanthidae cobia Rachycentron canadum Rachycentridae parrotfishes* Scarus spp. Scaridae jackknife fish Equetus lanceolatus Sciaenidae king mackerel Scomberomorus cavalla Scombridae spotted scorpionfish Scorpaena plumieri Scorpaenidae goliath grouper Epinephelus itajara Serranidae greater soapfish Rypticus saponaceus Serranidae red hind Epinephelus guttatus Serranidae speckled hind Epinephelus drummondhayi Serranidae tiger grouper Mycteroperca tigris Serranidae 1Categories were assigned based on the prelimiary estimates of the frequency of observation of each species among all videos; most frequent: species present 50-100%, frequent: species present 25-50%, less frequent: species present 10-25%, least frequent: species present uniquely-10%; 2 Based on classifications presented by fishbase.org; *Identification to species was not possible or ambiguous.

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Figure 1: MARMAP sampling locations (+) and dives completed for this study (open and closed circles).

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(a)

(b)

Figure 2: Underwater video frame captures of representative hard-bottom habitats. Video stills are not as clear as video footage viewed in real time. (a) Ledge habitat greater than 2 m in relief is visible in the foreground and background. (b) Representative live-bottom habitat with extensive macroalgal and benthic invertebrate cover.

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Figure 3: Example of a survey dive logbook entry. Physical data was accessed from the National Data Buoy Center, Station 41013 (33°26'11" N 77°44'35" W) Frying Pan Shoals, NC, for the date and time that most closely matched the actual dive time based on hourly updates (http://www.ndbc.noaa.gov/ station_page.php?station=41013).

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Figure 4: Views of the Light & Motion Stingray HD Underwater Video Housing, (a) forward, lateral (b) rear monitor (c) and custom made stand for field deployment. Photos (a) and (b) from www.backscatter.com.

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Figure 5: Example of data entry system for observations.

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Field Camera deployed at site, n = 57 No Yes

No video Camera worked, video collected, n = 51 Yes No

Est. visibility > No video 25 ft, n = 43

No Yes Lab

Video excluded Video length > from analysis 18 min, n = 34 Yes No

Video included in Video final analysis excluded from analysis

Figure 6: Decision tree applied to all site videos to determine inclusion in final data analysis. The large boxes indicated Field and Lab refer to where the decision on data collection occurred. Of the n = 57 dives conducted, deployment of the camera was deemed not worthwhile for six sites (n = 51). Of the 51 camera deployments low visibility resulted in the exclusion of eight video clips (n = 43). Of the remaining 43 video clips, nine were excluded because they were to brief to allow for a data collection window of 15 minutes after the departure of divers.

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Figure 7: All survey dive locations. See the Appendix data for information on dates corresponding to each dive number.

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(a) (b) 70 50

60 40 50 30 40 20 30 10 20

10 0 Total observed gag, 15 min 15 gag, Total observed Total scamp, observed 15 min 0 0 2 4 6 8 10 12 14 012345 MaxNscamp MaxNgag (c) (d) 50 35

30 40 25 30 20

20 15

10 10 5 0

0 min gag, 2 point count Diver Diver point count scamp, 2 min 2 scamp, point count Diver

02468101214012345 MaxNscamp MaxNgag

Figure 8: A comparison of counting methods for the two most abundant grouper species observed, scamp and gag. a) and b) compare total observed individuals with the maximum number of fish of that species visible simultaneously (MaxN) during the 15 minute interval. c) and d) compare the diver point counts to MaxN values.

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Visibility estimated from video (m) estimated from video Visibility 6

4 4 6 8 10121416182022 Visibility estimated by divers (m)

Figure 9: Comparison of visibility estimates (feet converted to meters) made by divers on-site (n = 2-4) and from video clips analyzed by others (n = 3). A high correlation (Spearman’s rank correlation r = 0.637; p < 0.001) was found between the different observations. Visibility was one parameter which affected whether a video was included for the analysis (see Figure 6), such that only distances greater than 25 ft were considered adequate for video data collection.

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0 Total groupers observed, 15 min Total groupers observed,

6 8 10 12 14 16 18 Estimated visibility (m)

Figure 10: Estimated visibility (m), calculated as the mean of estimates taken from video observers and diver participants, compared to the count of observed groupers during the 15 minute video interval. A Poisson regression model found insufficient evidence of a relationship between visibility and number of visible fish (p = 0.7740).

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Total groupers observed, 15 min Total groupers observed, 10

0 20 22 24 26 28 30 32 34 36 38 Dive depth (m)

Figure 11: Total counts of scamp and gag groupers during the 15 minute video interval compared to the depth at which the video was recorded. Based on Poisson regression methods to predict presence of fish, there is insufficient evidence of a relationship between depth and the number of visible fish (p = 0.4050).

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0 Total groupers observed, 15 min Total groupers observed,

12 14 16 18 20 22 24 26 28 Bottom water temperature (° C)

Figure 12: Relationship between grouper counts for scamp and gag based on bottom water temperatures. Bottom water temperatures were recorded by the dive computers of diver participants in the study. A significant negative correlation between total counts and temperature was observed (Poisson regression, p < 0.001).

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0 Total groupers observed (15 min) Total groupers observed

Unbaited Baited Figure 13: Box plots illustrating the effects of the presence of bait or chum (2 - 3 L of shrimp shells or lobster parts) on counts of total observed groupers. A Wilcoxon test showed insignificant evidence of a difference in the average number of fish between locations with and without bait (p = 0.9037). The boundary of the box closest to zero indicates the 25th percentile, a line within the box marks the median, and the boundary of the box farthest from zero indicates the 75th percentile. Whiskers (error bars) above and below the box indicate the 90th and 10th percentiles and filled circles are outliers.

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Figure 14: GIS plot of the spatial distribution of scamp and gag recorded from 15 minute video surveys. Scamp significantly outnumbered observations of gag grouper (Wilcoxon test for scamp vs. gag, p < 0.001). Scale bars are proportional by size to 33 fish.

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Figure 15: GIS plot of the spatial distribution of scamp and gag as MaxN estimates of population abundance (Wilcoxon test for scamp vs. gag, p < 0.001). Scale bars are proportional by size to 6.5 fish.

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Figure 16: GIS plot of the spatial distribution of scamp and gag as diver point count estimates of population abundance (2 min). Scamp and gag numbers are not significantly different (Wilcoxon test for scamp vs. gag, p = 0.3199). Scale bars are proportional by size to 26 fish.

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0 Total groupers observed, 15 min Total groupers observed,

Live-bottom Ledge (<1 m relief) (>1.5 m relief) Habitat type

Figure 17: Box plots illustrating the distribution of groupers observed in the 15 minute video interval on two qualitative habitat types. Habitat categories are based on descriptions in (Blackwelder et al., 1982; Grimes et al., 1982; Parker Jr. and Dixon, 1998; Sedberry and Van Dolah, 1984). A Wilcoxon rank-sum test for differences between median values indicated that there was no relationship between total observed scamps and gags and habitat type (p = 0.3598). The boundary of the box closest to zero indicates the 25th percentile, a line within the box marks the median, and the boundary of the box farthest from zero indicates the 75th percentile. Whiskers (error bars) above and below the box indicate the 90th and 10th percentiles and filled circles are outliers.

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50 Ledge Live-bottom

20 ***

10 Total 15 min (meanfish observed, ± SD) 0 Scamp Gag Species Figure 18: In aggregate total observed fish did not differ between habitats (Wilcoxon rank-sum test, p = 0.3598), however a χ2 test of independence provided significant evidence of a relationship between gag and habitat (ledge or live-bottom) (***p < 0.001), suggesting that gag groupers were more frequently observed over live-bottom habitats. Habitat categories are based on descriptions from several studies (Blackwelder et al., 1982; Grimes et al., 1982; Parker Jr. and Dixon, 1998; Sedberry and Van Dolah, 1984).

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60 Scamp Gag 50

10 Total observed fish, 15 min (mean ±Total observed SD) 0 Jun Jul Aug Sep Oct Nov Dec Jan n = 2 n = 0 n = 5 n = 0 n = 4 n = 10 n = 8 n = 5 Study Month

Figure 19: Distribution of groupers by species and sampling months. Bars represent mean ± SD for each species from all usable dives conducted during that month. Usable dive numbers are indicated as n = x. Attempted trips in July and September did not result in usable video due to poor visibility.

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3.5 Gag Scamp 3.0 Yellowmouth

2.5

2.0

1.5

1.0

0.5 log10 (Total observed fish, 15 min) log10 (Total observed

0.0 <12" 12"-<18" 18"-<24" 24"-<30" >30" Size Category (in) Figure 20: Individual observed grouper were speciated and assigned to an estimated size category (Table 3) based on video observation. The three most numerous species observed were scamp (n = 1813), gag (n = 305), and yellowmouth (n = 97) groupers. A χ2 test of independence provided significant evidence of a relationship between size of the individual and species of grouper (p = 0.00049).

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200 Scamp 180 Gag

160

140

120

100

Diver point counts, 2 Diver min 40

0 < 12" 12 - 18" 18 - 24" 24 - 30" > 30" Size category (in)

Figure 21: Size category distribution of scamp and gag recorded from diver visual point counts of 2 minute during each dive (n = 34).

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(a)

(b)

Figure 22: Video frame captures illustrating difficulties associated with grouper species identification and recount frequency. Video stills are not as clear as video footage viewed in real time. Frames were taken six minutes apart from a dive conducted 23 November 2008 and show co-occurring scamp and yellowmouth grouper. A 24” length estimation marker (vertical bar in the center of frame) is visible. (a) Two scamp grouper are visible on the far right (top, light fish) and (bottom, dark fish) and an adult yellowmouth grouper is visible on the bottom center. (b) Scamp and yellowmouth are visible in the left top of the frame. Comparing (a) and (b) it is not clear whether the yellowmouth groupers, seen minutes apart on the same video, are the same fish.

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(a)

(b)

Figure 23a: Near simultaneous (< 1 s due to differences in viewer software) video screen captures illustrating (a) standard definition (SD; .mpg encoding) and (b) high definition (HD; .m2ts encoding) resolution differences. Video stills are not as clear as video footage viewed in real time. Relative image width is also different between SD and HD video players. Data collection utilized SD DVDs and resulted in some fish, especially distant ones, being unidentified. HD video collection results in higher fish counts, especially at the edge of visibility due to crisper silhouettes of fish. This figure is best viewed at higher magnification (200% or higher).

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(c)

(d)

Figure 23b: Near simultaneous (< 1 s due to differences in viewer software) video screen captures illustrating (c) standard definition (SD; .mpg encoding) and (d) high definition (HD; .m2ts encoding) resolution differences. Video stills are not as clear as video footage viewed in real time. Relative image width is also different between SD and HD video players. Data collection utilized SD DVDs and resulted in some fish, especially distant ones, being unidentified. Arrows in (c) indicate gag grouper counted from SD video. Arrows in (d) indicate total gag present. HD video collection results in higher fish counts, especially at the edge of visibility due to crisper silhouettes of fish. This figure is best viewed at higher magnification (200% or higher).

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DISCUSSION

Primary objectives of this pilot project included using underwater stationary video surveys to document the presence/absence, estimated size, density, and temporal habitat usage of gag grouper (Mycteroperca microlepis) on shallow water, hard-bottom habitats on the continental shelf of North Carolina. Other important objectives included comparing video findings to diver visual surveys of groupers to investigate the use of underwater videos to augment fishery- independent surveys. As a pilot project, this study demonstrated that underwater stationary video techniques can record large numbers of groupers in a non-extractive way. The addition of this technique to MARMAP (or similar) fishery-independent surveys has the potential to be very valuable. For example, video numbers could be compared to extractive methods for grouper species at appropriate sampling locations and/or intervals (see discussion in Sedberry and Van Dolah, 1984). Video observation of fishes for this project had both unique advantages and disadvantages when compared to a more traditional population assessment for large, mobile bottom fish, such as gag and scamp groupers. Extractive methods like angling, trawling and trapping provide accurate size, weight, and age measurements, and can have reduced post-survey laboratory analyses (Willis et al., 2000). Video surveys involve substantial field time, along with a large amount of post-survey laboratory time to analyze videos (depending on fish density), but generally need less personnel than other methods. More often than not, the greatest limitations with video surveys include low water visibility (Cappo et al., 2007). Nevertheless, video surveys can simplify data collection, and require fewer personnel and fewer hours in the field. For example data collection in the form of video camera deployment and retrieval can be accomplished quite easily with a minimum of training for qualified SCUBA divers, and decreases the need for scientific specialists on hand. The use of non-specialists however does increase the likelihood that sampling protocols may not be closely adhered to and that data collection methods could change unexpectedly. These problems can be minimized by additional training in quality data collection. Data analysis of collected videos requires a significant time investment post-collection. On average, video observation and data recording in this study took three times the length of the collected video and it was desirable to have multiple observers for each video segment that would meet to compare findings. Experience in fish identification and size estimation was also very important. Both underwater and on video, it was sometimes difficult to differentiate individuals of different grouper species from each other. This was especially true for small, demersal groupers, including graysby, rock hind, red hind, speckled hind, juvenile goliath grouper and juvenile red grouper, because they utilized cover more frequently than larger fish. Identifications were also sometimes problematic for large scamp and yellowmouth groupers, which have similar body shapes and habits, and they utilize social and behavioral color changes (Gilmore and Jones, 1992). Similar difficulties in species identification between gag and black groupers (M. bonaci) have been reported previously (Chih, 2006). Yellowmouth groupers made up 4.3 % (33 yellowmouth/760 scamp) of the total number of scamp seen on video, and they always co-occurred in videos (Figure 22), but no yellowmouth groupers were recorded by the diver point count methods, potentially due to incorrect identifications, or behavioral differences of this species that resulted in diver avoidance. The highest MaxNyellowmouth recorded was two (data not shown).

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A minimum visibility of 6.1 m (25 ft) was necessary for video data collection to be feasible. It is unlikely that this variable is a consideration when using extractive fishing methods such as hook and line, trawl, or trapping capture for the same species of groupers, although the effects of visibility on CPUE are probably relevant. Size estimations made in this study may be open to challenge, but they were completed with multiple, experienced observers to decrease size estimation biases. Previous work by others has shown that fish observers can routinely over- and underestimate certain size classes of fish (Bell et al., 1985; Edgar et al., 2004; Harvey et al., 2004), including the common size classes used here for categorizing grouper populations. It is possible to accurately size fish in situ, although these techniques were not applied in this specific project. For example, laser measurements aimed from the film housing by a swimming diver can be used for sizing, as can stereo-video apparatus for stationary video. Other authors have eliminated diver or video estimation biases by deploying calibrated stereo-video systems that allow automated sizing of fish (Dunbrack, 2006; Harvey et al., 2003; Harvey et al., 2002; Harvey et al., 2001; Harvey, 2003; van Rooij and Videler, 1996). Stereo-video techniques support more accurate and precise data collection of fish size, but increase costs due to the need for multiple cameras, and require more specialized scientific support for calibration and successful operation of stereo-video camera systems. With the video techniques and data collection methods used in this study it was not possible to avoid recounting fish. Substantial efforts were made to account for the problem of recounting fish, however, the use of a recount likelihood coding system (see Table 3 and Figure 5) was problematic and attempts to integrate this system into data analysis were eventually discarded. Primarily this was due to the large differences between video observers in their relative assignments of the recount categories, and a lack of agreement about how best to apply these categorizations. Additionally, because data was collected on each video in its entirety, and subsequently a subset of each usable video (15 min) was extracted for further analysis, the recount data assignments were no longer valid for each individual fish. Therefore, a decision was made to incorporate MaxN values into the analyses to provide more conservative estimates of grouper population densities. These MaxN values represent the minimum number of fish that were present at any given site on video, because MaxN was calculated by only considering fish viewed simultaneously on a given video. Our observations suggest that gag grouper were undercounted with this technique because of their more solitary behaviors, smaller social group sizes and larger territories (Coleman et al., 1996; Collins, 1987; Gilmore and Jones, 1992; Kiel, 2004). In discussions between the authors it was discovered that the video encoding step (see Materials and Methods/Video data collection) used for transferring the large (> 3 Gb) files also influenced the recorded abundance of gag grouper. The enhanced resolution available when viewing high-definition (HD) footage increased the number of fish seen (personal observations) for some, but not all, videos, compared to those viewed in standard-definition (SD), and resulted in fish being uncounted that were far from the camera (Figure 23). This problem was more apparent for gag because of their recorded behavioral patterns, propensity to remain distant from the camera, and difficulty speciating distant fish by their silhouettes. Reviewing HD footage resulted in increased MaxNscamp, from 1 – 13 to 1 – 16, and MaxNgag from 1 – 4 to 1 – 5 in the 15 minute intervals. This was discovered by watching footage extracted from the cameras in the native HD (.mt2s) format and comparing fish counts against footage from the same intervals and recorded in SD (.mpg) on DVD. Undercounting was especially apparent in videos that were collected with the camera oriented away from vertical structure, out into open water where the

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depth of field was substantially larger. Videos that were oriented into or obliquely toward structure did not have these same issues (personal observations). Since this pilot program was to primarily address the viability of video data collection for supplemental stock assessments, HD versus SD resolutions should be addressed in future video protocols. Gag numbers were generally expected to increase toward the end of the study as inshore water temperatures decreased and fish moved to deeper temperature refugia nearer to the shelf edge and reproductively mature individuals began to make offshore spawning migrations (McGovern et al., 1998; Sedberry et al., 2006). The video data collected seem to support this general pattern of migration (Figure 18), and support other studies that have documented these movement patterns. Behavioral differences between gag and scamp were apparent throughout the study. Both species tended to be initially curious about the presence of divers and the camera station, however gag tended to not approach closely and after an initial inspection they were not repeatedly seen. It appeared that larger gag grouper (> 30”) were more reluctant to approach divers and the filming area with any frequency. The swimming transects suggested that the variation seen between diver point surveys and stationary video counts of gag grouper at the same locations were primarily due to reactions of fish to the presence of divers. Transect line video data collections may be a viable option for incorporation in future data collection methods for gag grouper specifically. These observations are anecdotal, but could be evaluated scientifically in another project. Scamp grouper tended to be much more inquisitive and were more gregarious in view of the camera. Anecdotal diver observations indicated that size 1 and 2 gag displayed similar behavior to scamp, in contrast to larger (size 3+) gag. Whitfield et al. (2007) estimated grouper numbers (per hectare [ha-1]) for North Carolina hard-bottom habitats (30 – 45 m) using diver visual surveys and reported gag abundances of 18 ha-1, scamp of 60 ha-1, and yellowmouth grouper at 8 ha-1. Densities recorded in this study are not directly comparable to those values, due to the differing area of hard-bottom “sampled” in each video survey. Some camera stations were oriented into structure, providing a relatively limited area of observation, while other stations were filmed shooting away from structure, and were essentially only limited by visibility. Future work in this area should focus on accurately measuring surveyed areas of observation to allow the calculation of relative densities of groupers by location and time from video surveys. Habitat classifications used in this study were based on diver notes, personal observations (E. J. Burge) and video observations about the area in view. It was frequently the case that a survey location contained areas that could be defined as ledge or live-bottom habitat, depending on the field of view of the camera. Given this it would be desirable in future surveys to develop a rapid, objective habitat classification scheme. The diversity of fish species observed using video techniques in this study was large (Table 6). It should be noted that due to the different behavioral patterns of each fish species, occurrences in the data set may not be an accurate representation of abundance for every species (MacNeil et al., 2008). For purposes of this report other species outside the commercially important groupers were not considered, however the video record collected represents a significant opportunity for datamining estimates of fish diversity, species richness, and potentially, estimating biomass. Work is underway to examine the fish community in addition to the grouper data collected in this study and may be of interest considering recent changes in invasive species introductions (Hare and Whitfield, 2003; Whitfield et al., 2002), fishing efforts (Miller, 2007), regulations (Federal Register, 2009) and climate change (Parker Jr. and Dixon, 1998) associated with North Carolina hard-bottom habitats. The videos themselves will be assessed for inclusion in the Monterey Bay Aquarium Research Institute’s Video Annotation and

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Reference System (MBARI VARS; http://www.mbari.org/vars/). This research tool is a software interface and database system for describing, cataloging, retrieving, and viewing data associated with video collections. Cataloging of the videos collected in this study is likely to provide future added value. This study demonstrated that underwater stationary video surveys for gag grouper can be a valuable addition to fishery-independent datasets, and development of a scientifically rationale protocol to implement these techniques is recommended.

IMPACTS AND BENFITS

The methods explored in this project indicate that video data collection is a viable supplemental assessment for groupers. With a fish species such as the gag grouper that has a high economic value, it is reasonable to consider alternative methods of data collection that are as accurate, current, specific and conclusive as possible. Implementation of a similar study, perhaps in conjunction with existing fishery-independent surveys like MARMAP could be valuable for use in SEDAR stock assessments for members of the snapper-grouper complex. Presently, most fishery-independent data on gag grouper are collected at sea by specialists. This pilot project outlines a methodology that augments traditional sampling methods without fish extraction and presents an opportunity to expand stock assessments into other areas, including behavior and multi-species interactions. Conservative biomass estimates suggest that the groupers observed in this project represented approximately 15,592 lb of fish counted but not removed from local populations ((1813 scamp × 6 lb/scamp) + (305 gag × 12 lb/gag) + (97 yellowmouth grouper × 6 lb/yellowmouth) + (118 other serranids× 4 lb/serranid) = 15,592 lb grouper). Student training has also been a benefit of this project. Seven Coastal Carolina University marine science undergraduates participated in various aspects of the project. Two students were heavily involved in collecting data from videos as part of an honor’s thesis and as an independent research project. One of these students completed her degree and is pursuing graduate work in fisheries ecology at the University of North Carolina Wilmington. The other member of the video review team is currently participating in a 6 month internship with Dr. Jerrald Ault’s (University of Miami, Rosenstiel School of Marine and Atmospheric Science) multi-agency reef fish visual census monitoring in the Florida Keys. Three current CCU undergraduates are datamining the videos to examine reef fish diversity for independent projects, and two other students participated as volunteer divers. The video clips have generated interest and excitement among local fishermen and others who have seen excerpts of footage. Brunswick Catch (http://www.brunswickcatch.com/), an association of commercial fishermen, seafood dealers and restaurant owners, has expressed an interest in using some of the footage as a marketing tool highlighting local North Carolina seafood.

EXTENSION OF RESULTS

Formal outreach has been limited as research results have only been recently synthesized. A peer-reviewed manuscript on the findings of this project is planned, and presentation of results to academic audiences, including NC DMF, the snapper-grouper advisory panel of SAFMC, and

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fisheries managers is welcomed. Dr. Burge is scheduled to present general interest seminars on the project to community groups early in 2010 for the Jackson Center for Ethics at Coastal Carolina University (“Empty Waters: The Ethics of Marine Conservation,” 4 March 2010, Conway, SC) and the Grand Strand (SC) Shell Club (8 April 2010, Murrells Inlet, SC). Student presentations are anticipated for the 2010 Celebration of Inquiry (11-12 February 2010), a research symposium of undergraduate projects. To achieve an outreach program directed to the recreational and commercial sector of non- scientific audiences, preparation of a less technical version of the final report can be submitted to publications and on-line fishing forums that have agreed to review the project for publication consideration and posting. These include NC Sportsman Magazine, SC Sportsman Magazine, NC Wildlife Resources Commission - Wildlife in NC Magazine, South Carolina DNR - SC Wildlife Magazine, NC Waterman.com, NC Fisheries Association.com, NC CCA.com, The Hull Truth.com, Spearboard.com, Charleston Diving.com, NC Divers.com, Scuba Board.com, Frying Pan Tower.com, Charlotte NC Offshore Fishing Club.com and Ocean Isle Fishing Center.com. There will also be a final report e-mail attachment sent out to over 75 NC coastal charter captains.

STUDENTS

Student Role Program* Degree Benjamin M. Binder Video data analysis; volunteer diver Undergraduate, Marine Science in progress Lauren E. Bohrer Video data analysis Undergraduate, Marine Science BS Zachery D. Hart Fish identification Undergraduate, Marine Science in progress Dana E. Putman Fish identification Undergraduate, Marine Science in progress Amanda C. Wood Fish identification Undergraduate, Marine Science in progress Brandon M. Toms Volunteer diver Undergraduate, Marine Science in progress Mark A. Nevin Volunteer diver Undergraduate, Marine Science in progress Emma K. Wear GIS plots Graduate, Coastal Marine and Wetland Studies MS *All students are from Coastal Carolina University

ACKNOWLEDGEMENTS

The authors acknowledge and thank the North Carolina General Assembly and NC Sea Grant, Fishery Resource Grant program for financial support of this project under grant 08-FEG- 12. We also acknowledge and thank M. Scott Baker, Jr., (Sea Grant Fisheries Specialist, University of North Carolina Wilmington) for being our project mentor. The following individuals contributed to this project as volunteer divers: Travis Amstuz, Alan Beasley, Bob Bellman, Ben Binder, Matt Chappell, Frederick Farzanegan, Bobby Mayfield, Mark Nevin Leslie Scoggins, and Brandon Toms. Assistance in video data analysis was provided by Ben M. Binder (Coastal Carolina University) and Lauren E. Bohrer (Coastal Carolina University). Dr. Keshav Jaggannathan (Coastal Carolina University, Department of Mathematics and Statistics) was instrumental in data analysis by conducting the statistical tests. Danny Hughes and Kevin Beasley assisted with the production of the video summary, and Emma Wear (Coastal Carolina University, Coastal Marine and Wetland Studies) constructed the GIS plots. Dr. George Sedberry (NOAA, Gray’s Reef National Marine Sanctuary), Dr. Rob Young (Coastal Carolina University, Department of Marine Science), Dr. John Walter (NOAA Fisheries, SEFSC) and

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John Foster (NOAA Fisheries, Office of Science and Technology) assisted in problematic species identifications, and Christopher Neil Ferguson (Coastal Carolina University, Kimbel Library) assisted with literature research.

LITERATURE CITED

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