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Larval development and identification of the genus Triglops (Scorpaeniformes: Cottidae)Prior to Pietsch’s (1993) revision of the genus Triglops, identification of their larvae was difficult; six species co-occur in the eastern North Pacific Ocean and Bering Sea and three co-occur in the western North Atlantic Ocean. We examined larvae from collections of the Alaska Fisheries Science Center and Atlantic Reference Centre and used updated meristic data, pigment patterns, and morphological characters to identify larvae of Triglops forficatus, T. macellus, T. murrayi, T. nybelini, T. pingeli, and T. scepticus; larvae of T. metopias, T. dorothy, T. jordani, and T. xenostethus have yet to be identified and are thus not included in this paper. Larval Triglops are characterized by a high myomere count (42–54), heavy dorsolateral pigmentation on the gut, and a pointed snout. Among species co-occurring in the eastern North Pacific Ocean, T. forficatus, T. macellus, and T. pingeli larvae are distinguished from each other by meristic counts and presence or absence of a series of postanal ventral melanophores. Triglops scepticus is differentiated from other eastern North Pacific Ocean larvae by having 0–3 postanal ventral melanophores, a large eye, and a large body depth. Among species co-occurring in the western North Atlantic Ocean, T. murrayi and T. pingeli larvae are distinguished from each other by meristic counts (vertebrae, dorsal-fin rays, and anal-fin rays once formed), number of postanal ventral melanophores, and first appearance and size of head spines. Triglops nybelini is distinguished from T. murrayi and T. pingeli by a large eye, pigment on the lateral line and dorsal midline in flexion larvae, and a greater number of dorsal-fin rays and pectoral-fin rays once formed.
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Bathyraja panthera, a new species of skate (Rajidae: Arhynchobatinae) from the western Aleutian Islands, and resurrection of the subgenus Arctoraja IshiyamaWe provide morphological and molecular evidence to recognize a new species of skate from the North Pacific, Bathyraja panthera. We also resurrect the skate subgenus Arctoraja Ishiyama, confirming its monophyly and the validity of the subgenus. Arctoraja was previouslyrecognized as a distinct subgenus of Breviraja and later synonymized with Bathyraja (family Rajidae). Although the nominal species of Arctoraja have all been considered synonyms of Bathyraja parmifera by various authors, on the basis of morphometric, meristic, chondrological, and molecular data we recognize four species, including the new species. Species of Arctoraja are distributed across the North Pacific Ocean and adjacent seas from southern Japan to British Columbia. Bathyraja parmifera is abundant in the eastern Bering Sea, Aleutian Islands, and northern Gulf of Alaska; B. smirnovi is a western Pacific species found in the Sea of Okhotsk and Sea of Japan; B. simoterus is restricted to waters around the northern and eastern coasts of Hokkaido, Japan; and the new species B. panthera isrestricted to the western Aleutian Islands. Bathyraja panthera is diagnosed by its color pattern of light yellow blotches with black spotting on a greenish brown background, high thorn and vertebral counts, chondrological characters of the neurocranium and clasper, and a unique nucleotide sequence within the mitochondrial cytochrome oxidase gene. Furthermore, the species presently recognized as Bathyraja parmifera exhibits two haplotypes among specimens from Alaska, suggesting the possibility of a second, cryptic species.
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A guide to the deep-water sponges of the Aleutian Island ArchipelagoThe first dedicated collections of deep-water (>80 m) sponges from the central Aleutian Islands revealed a rich fauna including 28 novel species and geographical range extensions for 53 others. Based on these collections and the published literature, we now confirm the presence of 125 species (or subspecies)of deep-water sponges in the Aleutian Islands. Clearly the deep-water sponge fauna of the Aleutian Islands is extraordinarily rich and largely understudied. Submersible observations revealed that sponges, rather than deep-water corals, are the dominant feature shaping benthic habitats in the region and that they provide important refuge habitat for many species of fish and invertebrates including juvenile rockfish (Sebastes spp.) and king crabs (Lithodes sp). Examination of video footage collected along 127 km of the seafloor further indicate that there are likely hundreds of species still uncollected from the region, and many unknown to science. Furthermore, sponges are extremely fragile and easily damaged by contact with fishing gear. High rates of fishery bycatch clearly indicate a strong interaction between existing fisheries and sponge habitat. Bycatch in fisheries and fisheries-independent surveys can be a major source of information on the location of the sponge fauna, but current monitoring programs are greatly hampered by the inability of deck personnel to identify bycatch. This guide contains detailed species descriptions for 112 sponges collected in Alaska, principally in the central Aleutian Islands. It addresses bycatch identification challenges by providing fisheries observers and scientists with the information necessary to adequately identify sponge fauna. Using that identification data, areas of high abundance can be mapped and the locations of indicator species of vulnerable marine ecosystems can be determined. The guide is also designed for use by scientists making observations of the fauna in situ with submersibles, including remotely operated vehicles and autonomous underwater vehicles.
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Age determination manual of the Alaska Fisheries Science Center Age and Growth ProgramThe Age and Growth Program at the Alaska Fisheries Science Center is tasked with providing age data in order to improve the basic understanding of the ecology and fisheries dynamics of Alaskan fish species. The primary focus of the Age and Growth Program is to estimate ages from otoliths and other calcified structures for age-structured modeling of commercially exploited stocks; however, the program has recently expanded its interests to include numerous studies on topics ranging from age estimate validation to the growth and life history of non-target species. Because so many applications rely upon age data and particularly upon assurances as to their accuracy and precision, the Age and Growth Program has developed this practical guide to document the age determination of key groundfish species from Alaskan waters. The main objective of this manual is to describe techniques specific to the age determination of commercially and ecologically important species studied by the Age and Growth Program. The manual also provides general background information on otolith morphology, dissection, and preparation, as well as descriptions of methods used to measure precision andaccuracy of age estimates. This manual is intended not only as a reference for age readers at the AFSC and other laboratories, but also to give insight into the quality of age estimates to scientists who routinely use such data.
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An atlas of reproductive development in rockfishes, genus SebastesThe genus Sebastes consists of over 100 fish species, all of which are viviparous and long-lived. Previous studies have presented schemes on the reproductive biology of a single targeted species of the genus Sebastes, but all appear to possess a similar reproductive biology asevidenced by this and other studies. This atlas stages major events during spermatogenesis, oogenesis, and embryogenesis, including atresia, in six species of Sebastes (S. alutus, S. elongatus, S. helvomaculatus, S. polyspinis, S. proriger, and S. zacentrus). Our study suggests that the male reproductive cycle of Sebastes is characterized by 11 phases of testicular development, with 10 stages of sperm development and 1 stage of spermatozoa atresia. Ovarian development was divided into 12 phases, with 10 stages of oocyte development, 1 stage of embryonic development, and 1 stage of oocyte atresia. Embryonic development up to parturition was divided into 33 stages following the research of Yamada and Kusakari (1991). Reproductive development of all six species examined followed the developmental classifications listed above which may apply to all species of Sebastes regardless of the number of broods produced annually. Multiple brooders vary in that not all ova are fertilized and progress to embryos; a proportion of ova are arrested at the pre-vitellogenic stage. Reproductive stage examples shown in this atlas use S. elongates for spermatic development, S. proriger for oocyte development, and S. alutus for embryological development, because opportunistic sampling only permitted complete analysis of each respective developmental phase for those species. The results of this study and the proposed reproductive phases complement the recommended scheme submitted by Brown-Peterson et al. (2011), who call for a standardization of terminology for describing reproductive development of fishes.
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Guide to the identification of larval and early juvenile pricklebacks (Perciformes: Zoarcoidei: Stichaeidae) in the northeastern Pacific Ocean and Bering SeaStichaeidae, commonly referred to as pricklebacks, are intertidal and subtidal fishes primarily of the North Pacific Ocean. Broad distribution in relatively inaccessible and undersampled habitats has contributed to a general lack of information about this family. In this study, descriptions of early life history stages are presented for 25 species representing 18 genera of stichaeid fishes from the northeastern Pacific Ocean, Bering Sea, and Arctic Ocean Basin. Six of these species also occur in the North Atlantic Ocean. Larval stages of 16 species are described for the first time. Additional information or illustrations intended to augment previous descriptions are provided for nine species. For most taxa, we present adult and larval distributions, descriptions of morphometric, meristic, and pigmentation characters, and species comparisons, and we provide illustrations for preflexion through postflexion or transformation stages. New counts of meristic features are reported for several species.
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Atlas of abundance and distribution patterns of ichthyoplankton from the Northeast Pacific Ocean and Bering Sea ecosystems: based on research conducted by the Alaska Fisheries Science Center (1972–1996)This regional atlas summarizes and illustrates the distribution and abundance patterns of fish eggs and larvae of 102 taxa within 34 families found in the Northeast Pacific Ocean including the Bering Sea, Gulf of Alaska, and U.S. west coast ecosystems. Data were collected over a 20+ year period (1972–1996) by the Recruitment Processes Program of the Alaska Fisheries Science Center (AFSC).Ichthyoplankton catch records used in this atlas were generated from 11,379 tows taken during 100 cruises.For each taxon, general life history data are briefly summarized from the literature. Published information on distribution patterns of eggs and larvae are reviewed for the study area. Data from AFSC ichthyoplankton collections were combined to produce an average spatial distribution for each taxon. These data were also used to estimate mean abundance and percent occurrence by year and month, and relative abundance by larval length and season. Abundance from each tow was measured as catch per 10 m2 surface area. A larval distribution and abundance map was produced with a geographic information system using ArcInfo software. For taxa with identifiable pelagic eggs, distribution maps showing presence or absence of eggs are presented. Presenceor absence of adults in the study area is mapped based on recent literature and data from AFSC groundfish surveys.Distributional records for adults and early life history stages revealed several new range extensions. (PDF file contains 288 pages.)
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A taxonomic guide to the mysids of the South Atlantic Bight.Following the examination of extensive collections from the National Museum of Natural History (NMNH), the Southeastern Regional Taxonomic Center (SERTC), and other regional institutions, 18 species of the family Mysidae are recognized and described from the South Atlantic Bight(Cape Lookout, North Carolina to Cape Canaveral, Florida). This report includes synonymies of previous records, as well as new species distribution records. Previousregional accounts of Metamysidopsis munda and Metamysidopsis mexicana are attributed to Metamysidopsis swifti. New regional records are established for Amathimysis brattegardi, Heteromysis beetoni, and Siriella thompsonii. Two other species tentatively identified asAmathimysis sp. (nr. serrata) and Mysidopsis sp. (cf. mortenseni) may represent new taxa. Neobathymysis renoculata is included and discussed as a potential regional species. An illustrated key to the species currently known from the South Atlantic Bight is presented.Relevant taxonomic, distributional, and ecological information is also included for each species. (PDF file contains 45 pages.)
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The economic importance of marine angler expenditures in the United States.In 1998, the National Marine Fisheries Service (NMFS) began a series of marine angler expenditure surveys in thecoastal regions of the United States (U.S.) to evaluate marine recreational fishing expenditures and the financial impacts of these expenditures in each region and the U.S. as a whole. In this report, we use the previously estimated expenditure estimates to assess the total financial impactof anglers’ saltwater expenditures. Estimates are provided for sales, income, employment, and tax impacts for eachcoastal state in the U.S. Aggregate estimates are also provided for the entire U.S., excluding Alaska, Hawaii, and Texas. Direct, indirect, and induced effects associated with resident and non-resident angler expenditures were estimated using a regional input-output modeling systemcalled IMPLAN Pro. Nationwide, recreational saltwater fishing generated over $30.5 billion in sales in 2000, nearly $12.0 billion in income, and supported nearly350,000 jobs. Approximately 89 cents of every dollar spent by saltwater anglers was estimated to remain within the U.S. economy. At the state level, many of the goodsanglers purchased were imports, and, as such, as little as 44 cents of every dollar stayed in Rhode Island and as much as 80 cents of every dollar stayed in Georgia. In the Northeast, the highest impacts were generated in New Jersey, even though recreational fishing expenditures in Massachusetts and Maryland were considerably higher. In the Southeast, the highest impacts were generated in Florida, and on the Pacific Coast, the highest impacts weregenerated in California. Expenditures on boat maintenance/expenses generated more impacts than any other expenditure category in the U.S. Expenditures on rodsand reels was the single most important expense category in terms of generating impacts in most of the Northeast states.Expenditures on boat expenses generated the highest in most Southeast states, and expenditures for boat accessories produced the highest impacts in most Pacific Coast states.(PDF file contains 184 pages.)
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Development of kelp rockfish, Sebastes atrovirens (Jordan and Gilbert 1880), and brown rockfish, S. auriculatus (Girard 1854), from birth to pelagic juvenile stage, with notes on early larval development of black-and-yellow rockfish, S. chrysomelas (Jordan and Gilbert 1880), reared in the laboratory (Pisces: Sebastidae).Larval kelp (Sebastes atrovirens), brown (S. auriculatus), and blackand-yellow (S. chrysomelas) rockfish were reared from known adults, to preflexion stage, nine days after birth for S. chrysomelas, to late postflexion stage for S. atrovirens, and to pelagic juvenile stage for S.auriculatus. Larval S. atrovirens and S. chrysomelaswere about 4.6 mm body length (BL) and S. auriculatus about 5.2 mm BL at birth. Both S. atrovirens and S. auriculatusunderwent notochord flexion at about 6–9 mm BL. Sebastes atrovirens transform to the pelagic juvenile stage at about 14–16 mm BL and S. auriculatus transformed at ca. 25 mm BL. Early larvae of all three species were characterized by melanistic pigment dorsally on the head, on the gut, on most of the ventral margin of the tail, and in a long series on the dorsal margin of the tail. Larval S. atrovirens and S. auriculatus developed a posterior bar on the tail during the flexion or postflexion stage. In S. atrovirens xanthic pigment resembled the melanistic pattern throughout larval development. Larval S. auriculatus lackedxanthophores except on the head until late preflexion stage, when a pattern much like the melanophore pattern gradually developed. Larval S. chrysomelas had extensive xanthic pigmentation dorsally, but none ventrally, in preflexion stage. All members of the Sebastes subgenusPteropodus (S. atrovirens, S. auriculatus, S. carnatus, S. caurinus, S. chrysomelas, S. dalli, S. maliger, S. nebulosus, S. rastrelliger) are morphologically similar and all share the basic melanistic pigment pattern describedhere. Although the three species reared in this study can be distinguished on the basis of xanthic pigmentation, itseems unlikely that it will be possible to reliably identify field-collected larvae to species using traditional morphological and melanistic pigmentation characters. (PDF file contains 36 pages.)
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Integration of technologies for understanding the functional relationship between reef habitat and fish growth and productionFunctional linkage between reef habitat quality and fish growth and production has remained elusive. Most current research is focused on correlative relationships between a general habitat type and presence/absence of a species,an index of species abundance, or species diversity. Such descriptive information largely ignores how reef attributesregulate reef fish abundance (density-dependent habitat selection), trophic interactions, and physiological performance (growth and condition). To determine thefunctional relationship between habitat quality, fish abundance, trophic interactions, and physiological performance, we are using an experimental reef system inthe northeastern Gulf of Mexico where we apply advanced sensor and biochemical technologies. Our study site controls for reef attributes (size, cavity space, and reefmosaics) and focuses on the processes that regulate gag grouper (Mycteroperca microlepis) abundance, behavior and performance (growth and condition), and the availability of their pelagic prey. We combine mobile and fixed-active (fisheries) acoustics, passive acoustics, video cameras,and advanced biochemical techniques. Fisheries acoustics quantifies the abundance of pelagic prey fishes associatedwith the reefs and their behavior. Passive acoustics and video allow direct observation of gag and prey fish behavior and the acoustic environment, and provide adirect visual for the interpretation of fixed fisheries acoustics measurements. New application of biochemical techniques, such as Electron Transport System (ETS) assay,allow the in situ measurement of metabolic expenditure of gag and relates this back to reef attributes, gag behavior, and prey fish availability. Here, we provide an overview of our integrated technological approach for understanding and quantifying the functional relationship between reef habitat quality and one element of production – gag grouper growth on shallow coastal reefs.
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Detecting fish aggregations from reef habitats mapped with high resolution side scan sonar imageryAs part of a multibeam and side scan sonar (SSS) benthic survey of the Marine Conservation District (MCD) south of St. Thomas, USVI and the seasonal closed areas in St. Croix—Lang Bank (LB) for red hind (Epinephelus guttatus) and the Mutton Snapper (MS) (Lutjanus analis) area—we extracted signals from water column targets that represent individualand aggregated fish over various benthic habitats encountered in the SSS imagery. The survey covered a total of 18 km2 throughout the federal jurisdiction fishery management areas. The complementary set of 28 habitat classification digital maps covered a total of 5,462.3 ha;MCDW (West) accounted for 45% of that area, and MCDE (East) 26%, LB 17%, and MS the remaining 13%. With the exceptionof MS, corals and gorgonians on consolidated habitats were significantly more abundant than submerged aquatic vegetation (SAV) on unconsolidated sediments or unconsolidated sediments. Continuous coral habitat was the most abundant consolidated habitat for both MCDW and MCDE (41% and 43% respectively). Consolidated habitats in LB and MS predominantly consisted of gorgonian plain habitat with 95% and 83% respectively. Coral limestone habitat was more abundant than coral patch habitat; it was found near the shelf break in MS, MCDW, and MCDE. Coral limestone and coral patch habitats only covered LB minimally. The high spatial resolution (0.15 m) of the acquired imagery allowed the detection of differing fish aggregation (FA) types. Thelargest FA densities were located at MCDW and MCDE over coral communities that occupy up to 70% of the bottom cover.Counts of unidentified swimming objects (USOs), likely representing individual fish, were similar among locations and occurred primarily over sand and shelf edge areas. Fish aggregation school sizes were significantly smaller at MS than the other three locations (MCDW, MCDE, and LB). This study shows the advantages of utilizing SSS in determining fish distributions and density.
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Designing marine fishery reserves using passive acoustic telemetryMarine Fishery Reserves (MFRs) are being adopted, in part, as a strategy to replenish depleted fish stocks and serve as a source for recruits to adjacent fisheries. By necessity, their design must consider the biological parameters of the species under consideration to ensure that the spawning stock is conserved while simultaneously providing propagules for dispersal. We describe how acoustic telemetry can be employed to design effective MFRs by elucidating important life-history parameters of the species under consideration, including home range, and ecological preferences, including habitat utilization. We then designed a reserve based on these parameters usingdata from two acoustic telemetry studies that examined two closely-linked subpopulations of queen conch (Strombusgigas) at Conch Reef in the Florida Keys. The union of the home ranges of the individual conch (aggregation home range:AgHR) within each subpopulation was used to construct a shape delineating the area within which a conch would be located with a high probability. Together with habitat utilization information acquired during both the spawning and non-spawning seasons, as well as landscape features(i.e., corridors), we designed a 66.5 ha MFR to conserve the conch population. Consideration was also given for further expansion of the population into suitable habitats.
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Acoustic signatures of the seafloor: Tools for predicting grouper habitatGroupers are important components of commercial and recreational fisheries. Current methods of diver-basedgrouper census surveys could potentially benefit from development of remotely sensed methods of seabed classification. The goal of the present study was to determine if areas of high grouper abundance have characteristic acoustic signatures. A commercial acoustic seabed mapping system, QTC View Series V, was used tosurvey an area near Carysfort Reef, Florida Keys. Acoustic data were clustered using QTC IMPACT software, resulting in three main acoustic classes covering 94% of the area surveyed. Diver-based data indicate that one of the acoustic classes corresponded to hard substrate and the other two represented sediment. A new measurement of seabed heterogeneity, designated acoustic variability, was also computed from the acoustic survey data in order to more fully characterize the acoustic response (i.e., the signature) of the seafloor.When compared with diver-based grouper census data, both acoustic classification and acoustic variability were significantly different at sites with and without groupers. Sites with groupers were characterized by hard bottom substrate and high acoustic variability. Thus, the acousticsignature of a site, as measured by acoustic classification or acoustic variability, is a potentially useful tool for stratifying diver sampling effort for grouper census.
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Deep reef fish surveys by submersible on Alderdice, McGrail, and Sonnier Banks in the Northwestern Gulf of MexicoSubmersible surveys at numerous reefs and banks in the northwestern Gulf of Mexico (NWGOM) were conducted as part of the Sustainable Seas Expedition (SSE) during July/August2002 to identify reef fish communities, characterize benthic habitats, and identify deep coral reef ecosystems. To identify the spatial extent of hard bottom reefcommunities, the Flower Garden Banks National Marine Sanctuary (FGBNMS) and the U.S. Geological Survey (USGS)mapped approximately 2000 km2 of the Northwestern Gulf of Mexico (NWGOM) continental shelf during June 2002 withhigh-resolution multibeam bathymetry. Previous investigations conducted on the features of interest (with the exceptions of East and West Flower Garden and SonnierBanks, accessible by SCUBA) had not been conducted since the 1970s and 1980s, and did not have the use of high-resolution maps to target survey sites. The base maps were instrumental in navigating submersibles to specific features at each study site during the Sustainable SeasExpedition (SSE)—a submersible effort culminating from a partnership between the National Atmospheric and OceanicAdministration (NOAA) and the National Geographic Society (NGS). We report the initial findings of our submersible surveys, including habitat and reef fish diversity atMcGrail, Alderdice, and Sonnier Banks. A total of 120 species and 40,724 individuals were identified from video surveys at the three banks. Planktivorous fishes constituted over 87% by number for the three banks, ranging from 81.4% at Sonnier Banks to 94.3% at Alderdice Bank,indicating a direct link to pelagic prey communities, particularly in the deep reef zones. High numbers of groupers, snappers, jacks, and other fishery specieswere observed on all three features. These sites were nominated as Habitat Areas of Particular Concern (HAPC) bythe Gulf of Mexico Fishery Council in March 2004. Data obtained during this project will contribute to benthic habitat characterization and assessment of the associatedfish communities through future SCUBA, ROV, and submersible missions, and allow comparisons to other deep reefecosystems found throughout the Gulf of Mexico and western Atlantic Ocean.
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Deepwater reef fishes and multibeam bathymetry of the Tortugas South Ecological Reserve, Florida Keys National Marine Sanctuary, FloridaThe Tortugas South Ecological Reserve, located along the margin of the southwest Florida carbonate platform, is part of the largest no-take marine reserve in the U.S. Established in July 2001, the reserve is approximately206 km2 in area, and ranges in depths from 30 m at Riley’s Hump to over 600 m at the southern edge of the reserve. Geological and biological information for the Tortugas South Reserve is lacking, and critical for management of the area. Bathymetric surveys were conducted with a Simrad EM 3000 multibeam echosounder at Riley’s Hump and Miller’s Ledge, located in the northern and central part of the reserve. Resulting data were used to produce basemaps to obtain geological ground truth and visual surveys ofbiological communities, including reef fishes. Visual surveys were conducted using SCUBA and the Phantom S2 Remotely Operated Vehicle (ROV) at Riley’s Hump. Visual surveys were conducted using the ROV and the Deepworker 2000 research submersible along Miller’s Ledge, withinand outside of the reserve. A total of 108 fishes were recorded during SCUBA, ROV, and submersible observations. Replicate survey transects resulted in over 50 fishesdocumented at Miller’s Ledge, and eight of the top ten most abundant species were planktivores. Many species of groupers, including scamp (Mycteroperca phenax), red grouper (Epinephelus morio), snowy grouper (E. niveatus), speckled hind (E. drummondhayi), and Warsaw grouper (E.nigritus), are present in the sanctuary. Numerous aggregations of scamp and a bicolor phase of the Warsaw grouper were observed, indicating the importance of Miller’s Ledge as a potential spawning location for both commercially important and rare deep reef species, and as a potential source of larval recruits for the Florida Keys and other deep reef ecosystems of Florida
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Nassau grouper (Epinephelus striatus) spawning aggregations: hydroacoustic surveys and geostatistical analysisWith the near extinction of many spawning aggregations of large grouper and snapper throughout the Caribbean, Gulf of Mexico, and tropical Atlantic, we need to provide baselinesfor their conservation. Thus, there is a critical need to develop techniques for rapidly assessing the remaining known(and unknown) aggregations. To this end we used mobile hydroacoustic surveys to estimate the density, spatial extent, and total abundance of a Nassau grouper spawning aggregation at Little Cayman Island, Cayman Islands, BWI.Hydroacoustic estimates of abundance, density, and spatial extent were similar on two sampling occasions. The locationand approximate spatial extent of the Nassau grouper spawning aggregation near the shelf-break was corroborated by diver visual observations. Hydroacoustic density estimates were, overall, three-times higher than the average density observed by divers; however, we note that in some instances diver-estimated densities in localizedareas were similar to hydroacoustic density estimates. The resolution of the hydroacoustic transects and geostatisticalinterpolation may have resulted in over-estimates in fish abundance, but still provided reasonable estimates of total spatial extent of the aggregation. Limitations in bottom time for scuba and visibility resulted in poor coverage of the entire Nassau grouper aggregation and low estimatesof abundance when compared to hydroacoustic estimates. Although the majority of fish in the aggregation werewell off bottom, fish that were sometimes in close proximity to the seafloor were not detected by the hydroacoustic survey. We conclude that diver observations offish spawning aggregations are critical to interpretations of hydroacoustic surveys, and that hydroacoustic surveys provide a more accurate estimate of overall fish abundance and spatial extent than diver observations. Thus, hydroacoustics is an emerging technology that, when coupledwith diver observations, provides a comprehensive survey method for monitoring spawning aggregations of fish.
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A video method for quantifying size distribution, density, and three-dimensional spatial structure of reef fish spawning aggregationsThere is a clear need to develop fisheries independent methods to quantify individual sizes, density, and three dimensional characteristics of reef fish spawning aggregations for use in population assessments and to provide critical baseline data on reproductive life history of exploited populations. We designed, constructed, calibrated, and applied an underwater stereo-video systemto estimate individual sizes and three dimensional (3D) positions of Nassau grouper (Epinephelus striatus) at a spawning aggregation site located on a reef promontory on the western edge of Little Cayman Island, Cayman Islands, BWI, on 23 January 2003. The system consists of two free-running camcorders mounted on a meter-long bar and supported by a SCUBA diver. Paired video “stills” werecaptured, and nose and tail of individual fish observed in the field of view of both cameras were digitized using imageanalysis software. Conversion of these two dimensional screen coordinates to 3D coordinates was achieved through a matrix inversion algorithm and calibration data. Our estimate of mean total length (58.5 cm, n = 29) was in close agreement with estimated lengths from a hydroacousticsurvey and from direct measures of fish size using visual census techniques. We discovered a possible bias in lengthmeasures using the video method, most likely arising from some fish orientations that were not perpendicular with respect to the optical axis of the camera system. We observed 40 individuals occupying a volume of 33.3 m3, resulting in a concentration of 1.2 individuals m–3 with a mean (SD) nearest neighbor distance of 70.0 (29.7) cm. We promote the use of roving diver stereo-videography as a method to assess the size distribution, density, and 3D spatial structure of fish spawning aggregations.
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Emerging technologies for reef fisheries research and managementThis publication of the NOAA Professional Paper NMFS Seriesis the product of a special symposium on “Emerging Technologies for Reef Fisheries Research and Management” held during the 56th annual Gulf and Caribbean Fisheries Institute meeting in Tortola, British Virgin Islands, November 2003. The purpose of this collection is to highlight the diversity of questions and issues in reeffisheries management that are benefiting from applications of technology. Topics cover a wide variety of questions and issues from the study of individual behavior, distribution and abundance of groups and populations, and associations between habitats and fish and shellfish species.
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Emerging technologies for reef fisheries research and management [held during the 56th annual Gulf and Caribbean Fisheries Institute meeting in Tortola, British Virgin Islands, November 2003]This publication of the NOAA Professional Paper NMFS Seriesis the product of a special symposium on “Emerging Technologies for Reef Fisheries Research and Management” held during the 56th annual Gulf and Caribbean Fisheries Institute meeting in Tortola, British Virgin Islands, November 2003. The purpose of this collection is to highlight the diversity of questions and issues in reeffisheries management that are benefiting from applications of technology. Topics cover a wide variety of questions and issues from the study of individual behavior, distribution and abundance of groups and populations, and associations between habitats and fish and shellfish species.(PDF files contains 124 pages.)
