A video method for quantifying size distribution, density, and three-dimensional spatial structure of reef fish spawning aggregations

There 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 system to 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” were captured, and nose and tail of individual fish observed in the field of view of both cameras were digitized using image analysis 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 hydroacoustic survey and from direct measures of fish size using visual census techniques. We discovered a possible bias in length measures 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.

Behavior ecology of the Humboldt squid, Dosidicus gigas: insights from an animal-borne video and data logging system

Dosidicus gigas is a large pelagic cephalopod of the eastern Pacific that has recently undergone an unexpected, significant range expansion up the coast of North America. The impact that such a range expansion is expected to have on local fisheries and marine ecosystems has motivated a thorough study of this top predator, a squid whose lifestyle has been quite mysterious until recently. Unfortunately, Dosidicus spends daylight hours at depths prohibitive to making observations without significant artificial interference. Observations of this squid‟s natural behaviors have thus far been considerably limited by the bright illumination and loud noises of remotely-operated-vehicles, or else the presence of humans from boats or with SCUBA. However, recent technological innovations have allowed for observations to take place in the absence of humans, or significant human intrusion, through the use of animal-borne devices such as National Geographic‟s CRITTERCAM. Utilizing the advanced video recording and data logging technology of this device, this study seeks to characterize unknown components of Dosidicus gigas behavior at depth. Data from two successful CRITTERCAM deployments reveal an assortment of new observations concerning Dosidicus lifestyle. Tri-axial accelerometers enable a confident description of Dosidicus orientation during ascents, descents, and depth maintenance behavior - previously not possible with simple depth tags. Video documentation of intraspecific interactions between Dosidicus permits the identification of ten chromatic components, a previously undescribed basal chromatic behavior, and multiple distinct body postures. And finally, based on visualizations of spermatophore release by D. gigas and repetitive behavior patterns between squid pairs, this thesis proposes the existence of a new mating behavior in Dosidicus. This study intends to provide the first glimpse into the natural behavior of Dosidicus, establishing the groundwork for a comprehensive ethogram to be supported with data from future CRITTERCAM deployments. Cataloguing these behaviors will be useful in accounting for Dosidicus‟ current range expansion in the northeast Pacific, as well as to inform public interest in the impacts this expansion will have on local fisheries and marine ecosystems.

Progress toward a global genealogy of common carp (Cyprinus carpio L.) strains using mitochondrial nucleotide sequences data

As part of a study of genetic variation in the Vietnamese strains of the common carp (Cyprinus carpio L.) using direct DNA sequencing of mitochondrial control and ATPase6/8 gene regions, samples from a number of other countries were analyzed for comparison. Results show that the levels of sequence divergence in common carp is low on a global scale, with the Asian carp having the highest diversity while Koi and European carp are invariant. A genealogical analysis supports a close relationship among Vietnamese, Koi, Chinese Color and, to a lesser extent, European carp. Koi carp appear to have originated from a strain of Chinese red carp. There is considerable scope to extend this research through the analysis of additional samples of carp from around the world, especially from China, in order to generate a comprehensive global genealogy of common carp strains.

Video technology applied to the management of Bahrain's marine resources

Video technology has been used as a tool in research for many years. However, its widespread use as a fisheries management tool has been limited due to its relatively high cost. This is changing as video technology becomes a household commodity now widely available throughout the world.

Mitochondrial gene sequences useful for species identification of western North Atlantic Ocean sharks

Molecular-based approaches for shark species identification have been driven largely by issues specific to the fishery. In an effort to establish a more comprehensive identification data set, we investigated DNA sequence variation of a 1.4-kb region from the mitochondrial genome covering partial sequences from the 12S rDNA, 16S rDNA, and the complete valine tRNA from 35 shark species from the Atlantic fishery. Generally, within-species variability was low in relation to interspecific divergence because species haloptypes formed monophyletic groups. Phylogenetic analyses resolved ordinal relationships among Carcharhiniformes and Lamniformes, and revealed support for the families Sphyrnidae and Triakidae (within Carcharhiniformes) and Lamnidae and Alopidae (within Lamniformes). The combination of limited intraspecific variability and sufficient between-species divergence indicates that this locus is suitable for species identification.

Beluga, Delphinapterus leucas, Group Sizes in Cook Inlet, Alaska, Based on Observer Counts and Aerial Video

Belugas, Delphinapterus leucas, groups were videotaped concurrent to observer counts during annual NMFS aerial surveys of Cook Inlet, Alaska, from 1994 to 2000. The videotapes provided permanent records of whale groups that could be examined and compared to group size estimates ade by aerial observers.Examination of the video recordings resulted in 275 counts of 79 whale groups. The McLaren formula was used to account for whales missed while they were underwater (average correction factor 2.03; SD=0.64). A correction for whales missed due to video resolution was developed by using a second, paired video camera that magnified images relative to the standard video. This analysis showed that some whales were missed either because their image size fell below the resolution of hte standard video recording or because two whales surfaced so close to each other that their images appeared to be one large whale. The correction method that resulted depended on knowing the average whale image size in the videotapes. Image sizes were measured for 2,775 whales from 275 different passes over whale groups. Corrected group sizes were calcualted as the product of the original count from video, the correction factor for whales missed underwater, and the correction factor for whales missed due to video resolution (averaged 1.17; SD=0.06). A regression formula was developed to estimate group sizes from aerial observer counts; independent variables were the aerial counts and an interaction term relative to encounter rate (whales per second during the counting of a group), which were regressed against the respective group sizes as calculated from the videotapes. Significant effects of encounter rate, either positive or negative, were found for several observers. This formula was used to estimate group size when video was not available. The estimated group sizes were used in the annual abundance estimates.

Establishing species–habitat associations for 4 eteline snappers with the use of a baited stereo-video camera system

With the use of a baited stereo-video camera system, this study semiquantitatively defined the habitat associations of 4 species of Lutjanidae: Opakapaka (Pristipomoides filamentosus), Kalekale (P. sieboldii), Onaga (Etelis coruscans), and Ehu (E. carbunculus). Fish abundance and length data from 6 locations in the main Hawaiian Islands were evaluated for species-specific and size-specific differences between regions and habitat types. Multibeam bathymetry and backscatter were used to classify habitats into 4 types on the basis of substrate (hard or soft) and slope (high or low). Depth was a major influence on bottomfish distributions. Opakapaka occurred at depths shallower than the depths at which other species were observed, and this species showed an ontogenetic shift to deeper water with increasing size. Opakapaka and Ehu had an overall preference for hard substrate with low slope (hard-low), and Onaga was found over both hard-low and hard-high habitats. No significant habitat preferences were recorded for Kalekale. Opakapaka, Kalekale, and Onaga exhibited size-related shifts with habitat type. A move into hard-high environments with increasing size was evident for Opakapaka and Kalekale. Onaga was seen predominantly in hard-low habitats at smaller sizes and in either hard-low or hard-high at larger sizes. These ontogenetic habitat shifts could be driven by reproductive triggers because they roughly coincided with the length at sexual maturity of each species. However, further studies are required to determine causality. No ontogenetic shifts were seen for Ehu, but only a limited number of juveniles were observed. Regional variations in abundance and length were also found and could be related to fishing pressure or large-scale habitat features.

Genetic characterization of three Ompok species using mitochondrial DNA sequences

Partial sequences of cytochrome b (Cyt b) and 16S ribosomal RNA (16S rRNA) mitochondrial genes were used for species identification and estimating phylogenetic relationship among three commercially important Ompok species viz. O. Pabda, O. pabo and O. bimaculatus. The sequence analysis of Cyt b (1118bp) and 16S rRNA (569 & 570bp) genes revealed that O. pabda, O. pabo & 0. bimaculatus were genetically distinct species and they exhibited identical phylogenetic relationship. The present study discussed usefulness of mtDNA genes (Cyt b & 16S rRNA) in resolving taxonomic ambiguity and estimating phylogenetics relationship.