NC Sea Grant 08-FEG-12 Final Report 20091110

8/14/2019 NC Sea Grant 08-FEG-12 Final Report 20091110

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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 Atack

2, Craig Andrews

3

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 20

thSt., Oak Island, NC 28465

3Over & Under Adventures Inc., 4956 Longbeach Rd # 14-149 Southport, NC 28461
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


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Final Report 08-FEG-12

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ABSTRACT

Accurate assessments of economically and ecologically important finfish populations arecritical 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 acceptanceof scientific and management recommendations for the use of fishery resources. In this pilotproject 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 habitatson the continentalshelf 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 additionof 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.


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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 acceptanceof 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 datasetsincluded 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 MARMAPcruises 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 commercialand 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 (1to 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 includeslow 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 mostcommonly 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 homeranges (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 incommunicating 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 moreexpensive 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 thepresence/absence, estimated size, density, and temporal habitat usage of gag grouper

(Mycteroperca microlepis) on shallow water, hard-bottom habitatson the continental shelf of

North Carolina, and to compare the video findings to diver visual surveys of groupers at thesame locations. Additional information was collected on other species of observed groupers,

including primarily scamp (M. phenax) and yellowmouth grouper (M. interstitialis). Recentstock 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 southernNorth 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 previouslyvisited 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 ofCape 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 undercutledges 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 HighDefinition (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 acustom 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 thesurroundings.

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 thecamera 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 areviewable 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 tocompare 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 withinformation 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 representfish 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 (Figure6). 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 originallyanticipated, 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), whichformed 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 12weeks 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 diverinfluence 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 videointerval 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 thepresence 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 ofeach 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 0.05. The

Wilcoxon rank-sum test was used to test for differences in mean number of observed fish basedon categorical variables such as habitat, bait, or sector of occurrence. Chi-Square tests (

2) 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 2test and hence it was appropriate in

this setting. In order to obtain a linear model for the total count of fish based on a quantitativevariable (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 Spearmans rfor nonparametric analyses were used for correlations. Spatial

mapping of data used ArcMap v. 9.2 (ESRI Inc., Redlands, California) and shoreline data imagesfrom 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 visitedMARMAP 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 visitsto 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 43video 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 datacollection 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; divenumber 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 redgrouper (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 yellowmouthgrouper 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 wereonly 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 screenof 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 thatrecorded 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 videoobservations. 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 pointcounts 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 geographicaldistribution. Comparisons between the various counting techniques indicate that there is a

significant degree of correlation (Spearmans rfor 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-sitedivers and video observers (Figure 9). There was a significant positive correlation (Spearmans

rank correlation r= 0.637;p < 0.001) between the different estimated visibilities and as suchthese 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 lowvisibility 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 differsignificantly 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 eastof 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 viewmay 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 valuesindicated 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 andscamps 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 weresignificantly more commonly associated with live-bottom habitats (2

test of independence,p 0.200; yellowmouth,

K-S Dist. = 0.191,p > 0.200). Size distributions for scamp and gag recorded by diver visualpoint 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

Formats Supported HD: MPEG4 AVC/H.264; SD: MPEG2Video Signal NTSC color, EIA standards

Dimensions 83 76 138 mm

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

Focal Distance 4.9 - 58.8 mm

Focus Full range auto / Manual

Shutter Speed Auto, 1/30 - 1/250 (Scene Selection Mode)

Optical Zoom 12xWide-angle Lens 0.5x Camera mounted

Imaging Device 1/3" ClearVid CMOS sensor (with Exmor technology)

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 Requirements 7.2V (battery pack); 8.4V (AC Adaptor)

Power Consumption 4.5W/4.8W/4.9W

Audio Audio Format Dolby Digital 5.1

General

Power

Optics/Lens

TABLE 1. Technical specifications of Sony cameras (HDR-SR11 with 60 GB hard drive) used for video

collection.

Video

Weights and

Measurements

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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

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

Auto-focus Lock

Momentary Auto-focus

Video/Photo Mode

Manual Focus

TABLE 2. Technical specifications of Light & Motion Stingray HD

Underwater Video Housing.

Standard Features

Depth Controls

Size Code Size Category Recount Code Recount Category

0 unknown

1 < 12" 1 not

2 12 - 18" 2 unlikely3 18 - 24" 3 possible

4 24 - 30" 4 probable

5 > 30" 5 definite

TABLE 3. Data coding for categorical size estimates and likelihood of recount bins.

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Latitude Longitude

Included in

study data

Reason for

exclusion3

1 33 27 77 40 8 Jun 2008 Yes3 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

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 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 Yes38 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 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 33 24 77 31 16 Oct 2008 No Video length

44 33 22 77 38 30 Dec 2008 No Video length1See 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

Outcome

Date of visitDive #1

3

3

Site location2

Revisits

4

3

3

3

TABLE 4 Repeated site visits and outcomes of collected video.

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

TABLE 5 Correlation analysis (Spearmans r for non-parametric

analysis) of counting techniques.

Species

Scamp GagComparison

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Frequency of Occurence1 Common Name Species

2 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

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

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 Aulostomidaesand 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

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 Carangidaecarcharinid 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

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 Rachycentridaeparrotfishes* 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 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%;2Based on classifications presented by

fishbase.org; *Identification to species was not possible or ambiguous.

TABLE 6 Species richness and 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.

Less frequent

Least frequent

Frequent

Most frequent

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

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(b)

(a)

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 (3326'11" N 7744'35" 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).

16
http://www.ndbc.noaa.gov/http://www.ndbc.noaa.gov/station_page.php?station=41013http://www.ndbc.noaa.gov/station_page.php?station=41013http://www.ndbc.noaa.gov/


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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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http://www.backscatter.com/http://www.backscatter.com/


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Figure 5: Example of data entry system for observations.

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FieldCamera deployed at site, n = 57

No Yes

Camera worked, videocollected, n = 51

Figure 6: Decision tree applied to all site videos to determine inclusion in final data analysis. The large boxesindicated 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.

Yes No

No video

Est. visibility >

25 ft, n = 43

No video

Lab No Yes

Video excludedfrom analysis

Video length >18 min, n = 34

Yes No

Video included in

final analysis

Video

excluded from

analysis

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

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MaxNscamp

0 2 4 6 8 10 12 14

Totalobservedscam

p,15min

0

10

20

30

40

50

60

70

MaxNgag

0 1 2 3 4 5

Totalobservedgag,15min

0

10

20

30

40

50

MaxNscamp

0 2 4 6 8 10 12 14

Diverpointcountscamp,2min

0

10

20

30

40

50

MaxNgag

0 1 2 3 4 5

D

iverpointcountgag,2min

0

5

10

15

20

25

30

35

(c)

(a) (b)

(d)

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 by divers (m)

4 6 8 10 12 14 16 18 20 22

Visibility

estimatedfromv

ideo(m)

4

6

8

10

12

14

16

18

20

22

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 (Spearmans rank correlation r= 0.637;p < 0.001) wasfound 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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Estimated visibility (m)

6 8 10 12 14 16 18

Total

groupersobserved,15min

0

20

40

60

80

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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Dive depth (m)

20 22 24 26 28 30 32 34 36 38

Total

groupersobserved,

15min

0

10

20

30

40

50

60

70

80

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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Bottom water temperature ( C)

12 14 16 18 20 22 24 26 28

Tota

lgroupersobserved,15min

0

20

40

60

80

Figure 12: Relationship between grouper counts for scamp and gag based on bottom water temperatures. Bottomwater 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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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 percentilesand filled circles are outliers.

Totalgroupersobserved(15min)

0

20

40

60

80

Unbaited Baited

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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 areproportional 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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Figure 17: Box plots illustrating the distribution of groupers observed in the 15 minute video interval on twoqualitative 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.

Habitat type

Total

groupersobserved,

15min

0

20

40

60

80

Live-bottom(1.5 m relief)

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Figure 18: In aggregate total observed fish did not differ between habitats (Wilcoxon rank-sum test,p = 0.3598),

however a 2 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).

Species

Scamp Gag

Totalfisho

bserved,15min(meanSD

)

0

10

20

30

40

50

LedgeLive-bottom

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Study Month

Jun Jul Aug Sep Oct Nov Dec Jan

Totalob

servedfish,15min(meanSD)

0

10

20

30

40

50

60

Scamp

Gag

n = 2 n = 5n = 0 n = 0 n = 4 n = 10 n = 8 n = 5

Figure 19: Distribution of groupers by species and sampling months. Bars represent mean SD for each speciesfrom 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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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 2 test of independence provided significant evidence of a relationship between

size of the individual and species of grouper (p = 0.00049).

Size Category (in)


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Size category (in)

< 12" 12 - 18" 18 - 24" 24 - 30" > 30"

Diverpointcounts,

2min

0

20

40

60

80

100

120

140

160

180

200

Scamp

Gag

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 apartfrom 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) Scampand 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)

(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)

(c)

(d)

(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, beingunidentified. 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 habitatson the continental

shelf of North Carolina. Other important objectives included comparing video findings to divervisual 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 ofthis 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 VanDolah, 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, suchas gag and scamp groupers. Extractive methods like angling, trawling and trapping provide

accurate size, weight, and age measurements, and can have reduced post-survey laboratoryanalyses (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), butgenerally 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. Forexample 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 doesincrease 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 additionaltraining 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 thecollected 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 madeup 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, likely because divers were not instructed to identify yellowmouth as a

separate species. The highest MaxNyellowmouth recorded was two (data not shown).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

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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 tochallenge, 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 ispossible 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 haveeliminated 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 moreaccurate 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 recountingfish, 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, andsubsequently 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 estimatesof 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 fishviewed 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 whenviewing 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 moreapparent 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 15minute 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 thedepth 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

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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 thisgeneral 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 thecamera 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 thatthe 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 methodsfor gag grouper specifically. These observations are anecdotal, but could be evaluated

scientifically in another project. Scamp grouper tended to be much more inquisitive and weremore 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 arenot 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, andwere 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 groupersby 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 orlive-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 asignificant 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 ininvasive 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 Institutes Video Annotation andReference 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

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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 areas 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 fishextraction and presents an opportunity to expand stock assessments into other areas, including

behavior and multi-species interactions. Conservative biomass estimates suggest that thegroupers 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 lbgrouper).

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 wereheavily involved in collecting data from videos as part of an honors thesis and as an independent

research project. One of these students completed her degree and is pursuing graduate work infisheries 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 Aults

(University of Miami, Rosenstiel School of Marine and Atmospheric Science) multi-agency reeffish 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 otherswho 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 Carolinaseafood.

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, andfisheries 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

41
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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). Studentpresentations 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 topublications 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 - SCWildlife 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 SeaGrant, 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 KevinBeasley 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, Grays Reef National Marine Sanctuary), Dr. Rob Young (Coastal CarolinaUniversity, Department of Marine Science), Dr. John Walter (NOAA Fisheries, SEFSC) and

John Foster (NOAA Fisheries, Office of Science and Technology) assisted in problematic

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species identifications, and Christopher Neil Ferguson (Coastal Carolina University, Kimbel

Library) assisted with literature research.

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Documents

NC Sea Grant 08-FEG-12 Final Report 20091110