Botcam: a Baited Camera System for Nonextractive Monitoring of Bottomfish Species 57
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56 Abstract—A stereo-video baited BotCam: a baited camera system for camera system (BotCam) has been de- veloped as a fishery-independent tool nonextractive monitoring of bottomfish species to monitor and study deepwater fish species and their habitat. During test- 1 3 ing, BotCam was deployed primar- Daniel Merritt (contact author) Michael Parke ily in water depths between 100 and Mary K. Donovan1 Kevin Wong3 300 m for an assessment of its use 2 4 in monitoring and studying Hawai- Christopher Kelley Jeffrey C. Drazen ian bottomfish species. Details of the Lynn Waterhouse2 video analyses and data from the pilot Email address for contact author: [email protected] study with BotCam in Hawai`i are 1 3 presented. Multibeam bathymetry and Joint Institute for Marine and NOAA Pacific Islands Fisheries Science Center backscatter data were used to delin- Atmospheric Research Coral Reef Ecosystem Division eate bottomfish habitat strata, and University of Hawai`i, and 2570 Dole St. a stratified random sampling design NOAA Pacific Islands Fisheries Science Center Honolulu, Hawaii 96822 was used for BotCam deployment loca- Coral Reef Ecosystem Division 4 Department of Oceanography, tions. Video data were analyzed to 1000 Pope Rd., MSB 312 University of Hawai`i assess relative fish abundance and Honolulu, Hawaii 96822 1000 Pope Rd., MSB to measure fish size composition. 2 Hawaii Undersea Research Laboratory (HURL) Honolulu, Hawaii 96822 Results corroborate published depth 1000 Pope Rd., MSB 303 ranges and zones of the target species, Honolulu, Hawaii 96822 as well as their habitat preferences. The results indicate that BotCam is a promising tool for monitoring and studying demersal fish populations associated with deepwater habitats to a depth of 300 m, at mesohabitat The ability to monitor stocks targeted communities, and habitat preferenc- scales. BotCam is a flexible, nonex- by a fishery in order to understand es. Baited camera systems have been tractive, and economical means to better understand deepwater eco- the effects of regulatory measures, used in a number of fisheries habitat systems and improve science-based such as spatial or temporal fishing studies (Ellis and DeMartini, 1995; ecosystem approaches to management. closures, is important to stakeholders. Gledhill et al., 1996; Priede and Mer- An understanding of species composi- rett, 1996; Francour et al., 1999; Wil- tion, age- and size-class distributions, lis et al., 2000; Cappo et al., 2003). habitat use, and other population Most of these studies involved deep- parameters is critical for developing water deployments (>1500 m) for the resource management programs and study of deep-sea scavengers or they for monitoring their effectiveness involved deployments in relatively (Jennings, 2001). However, acquisition shallow waters (<100 m) as a supple- of data for stock assessments within, ment to scuba surveys (Willis et al., and adjacent to, marine protected 2000; Watson et al., 2007). Currently, areas (MPAs) may be compromised there is a need to develop systems for by restrictions on extractive sampling use at intermediate depths. or fishery-dependent data. Further, In Hawai’i, the bottomfish fishery monitoring deepwater species is chal- targets snappers, groupers, and jacks lenging because of limitations (both that inhabit waters down to 400 m logistical and regulatory) on diving around the archipelago. The most im- in deep water; catch-and-release, or portant commercial species live below other nonlethal techniques typically 100 m and are often referred to as are used in shallow water. Because the “deep 7” (WPRFMC, 2007). Six of deepwater fisheries have developed these are snappers that include Etelis rapidly over the last few years, it is coruscans (flame snapper, onaga), Ete- important to develop reliable, non- lis carbunculus (ruby snapper, ehu), extractive, and fisheries-independent Pristipomoides zonatus (oblique-band- methods for stock assessment and ed snapper, gindai), Pristipomoides Manuscript submitted 19 March 2010. Manuscript accepted 25 October 2010. monitoring that will enable manag- sieboldii (lavender snapper, kalekale), Fish. Bull. 109:56–67 (2011). ers to assess fishery impacts, evaluate Pristipomoides filamentosus (pink MPAs, and implement ecosystem- snapper, opakapaka), and Aphareus The views and opinions expressed based management (Roberts, 2002). rutilans (silvermouth snapper, lehi). or implied in this article are those of the Camera systems provide a fisheries- The seventh species is an endemic author (or authors) and do not necessarily reflect the position of the National independent and nonextractive tool grouper called Epinephelus quer- Marine Fisheries Service, NOAA. for monitoring fish stocks, associated nus (Hawaiian grouper, hapu`upu`u) Merritt et al.: BotCam: a baited camera system for nonextractive monitoring of bottomfish species 57 (Randall, 2007). Most of these species are long-lived, Materials and methods slow-growing, and are assumed to have a low annual natural mortality rate and limited reproductive capacity Baited stereo-video camera system (Haight et al., 1993a). These characteristics make these bottomfish stocks especially susceptible to overfishing BotCam was designed as a fully autonomous baited and habitat destruction (Ralston et al.1). stereo-video camera system (Merritt, 2005). Most of The Hawaiian bottomfish fishing is primarily con- the components are housed in an aluminum frame (1.2 ducted by jigging hooks and lines on motorized reels. m wide × 0.5 m deep × 0.45 m tall) designed to protect All of the deep 7 species eat a variety of fish and in- the cameras and maintain fixed camera positions to vertebrate species opportunistically. For example, E. one another for accurate length measurements (Fig. 1). coruscans are known to feed on species within the water The system consists of two ultralow-light video cameras column near the bottom, whereas E. carbunculus targets (Monochrome Navigator, Remote Ocean Systems, San species on the bottom. All target species are caught Diego, CA), the video capture electronics and system con- by using both fish, such as mackerel (Decapterus spp.) troller (Viperfish Deep, Deep Development Corporation, and invertebrates (such as squid) as bait. Fishing ves- Sumas, WA), a temperature and pressure recorder (SBE sels that anchor will often use a palu bag containing a 39TP, Seabird Electronics Inc., Bellvue, WA), a custom- mixture of baits. built battery pack and relay used to trigger a delayed Although the entire range of depths used by the bait release-system (BWR, Sexton Photographics LLC, Hawai`i deepwater bottomfish assemblage has not been Salem, OR), and syntactic foam blocks for positive buoy- determined, the Western Pacific Regional Fishery Man- ancy (Flotation Technologies, Biddeford, ME). The frame agement Council (WPRFMC) has defined the deepwater also allows for the attachment of oceanographic instru- bottomfish essential fish habitat as all depths between ments such as current meters, temperature and depth 100 and 400 m, and adult habitat areas of particular recorders, and hydrophones. The system is moored to the concern as slopes and escarpments between 40 and 280 bottom by anchor weights attached to an anchor line and m depth (WPRFMC, 1998). Low light levels at these is designed to float above the bottom and to record video depths complicate the use of cameras. However, sur- by pointing horizontally down-current with a nominal veys with submersibles and remotely operated vehicles downward angle of 15°. This orientation improves the (ROVs) indicate that ambient lighting is preferable to view of the benthic habitat without sacrificing the field artificial area lights or strobes because the artificial of view. Each camera provides an 80° diagonal field of lights may repel or attract target species (Ralston et view in water. Because of the depth of targeted deploy- al., 1986; Ryer et al., 2009). ments, motions of the floating system are not affected To address the need for a nonextractive, fishery-in- by surface waves and the platform moves only by means dependent method for monitoring Hawaiian bottomfish of the currents, which are generally driven by tides, stocks, a baited stereo-video camera system (BotCam) and are therefore stable on the order of several min- has been developed by the National Oceanic and Atmo- utes. BotCam does often rotate and change the field of spheric Administration’s Pacific Islands Fisheries Sci- view relative to the substratum over the duration of a ence Center (PIFSC) in collaboration with the Hawai`i deployment. This floating design was chosen to address Undersea Research Laboratory. BotCam is designed to a couple of concerns. First, the target species are known survey the distribution, relative abundance, and size to school in the water column several meters above the composition of bottomfish, and associated biological and bottom. Second, the habitat of these target species is physical characteristics of their habitat. found on extremely steep and rocky slopes and setting A pilot study was designed to test BotCam as a tool a system directly on the bottom would be problematic in making stock assessments. The main purpose of the for both the deployment and recovery of the system. An study was to determine whether, from an operational extension arm attached to the frame can carry both a perspective, BotCam can consistently and reliably col- stereo-video synchronizing (SVS) device and a bait can- lect the same types of data collected by other baited