Baited Remote Underwater Video Systems Research Articles

Multiple lines of evidence highlight the dire straits of yellowfin tuna in the Indian Ocean.

Yellowfin tuna (Thunnus albacares) are highly valued pelagic fisheries target species. Regional fisheries management organizations (RFMOs) are the principal mechanism that manage yellowfin tuna fisheries. Determining changes in population abundances is crucial for effective conservation and management. We use multiple methods for monitoring biomass trends and evaluating the status of yellowfin tuna in each ocean basin and show how additional, multiple lines of evidence can enhance our understanding of the conservation and exploitation status of this species. Our analysis of regional biomass trajectories and Catch-MSY++ assessments corroborate the findings of the most recent RFMO stock assessments suggesting yellowfin tuna in the Indian Ocean are in critical condition, while the Eastern Pacific yellowfin tuna population shows the lowest levels of exploitation. These results are supported by fisheries-independent data from baited remote underwater video systems (BRUVS), showing that the Indian Ocean yellowfin tuna population is the least common, least abundant, and smallest across all oceans. Our findings support previous claims of systematic and widespread overfishing of yellowfin tuna in the Indian Ocean and thus confirm calls to reduce current fishing levels to ensure the long-term viability of the species.

Observations of Multiple Young-of-the-Year to Juvenile White Sharks (Carcharodon carcharias) within South-West Australian Waters and Its Implications for a Potential Nursery Area(s)

The white shark (Carcharodon carcharias) is a globally distributed top predator. Due to its ecological importance, increasing knowledge through continued research can enhance management measures. One such facet of biological knowledge is the identification of shark nursery areas, as protection of these regions is critical to species survival. Presently, there are two known C. carcharias nursery areas in association with the Eastern Australian subpopulation; however, a nursery area associated with the Southern-Western Australian C. carcharias subpopulation has yet to be identified. Herein, we report opportunistic laser photogrammetry, stereo-photogrammetry, and baited remote underwater video systems (BRUVS) data that resulted in the identification of sixteen young-of-the-year (YOY)-juvenile C. carcharias from two separate regions (i.e., Salisbury Island and Daw Island) in South-West Australia. Additionally, anecdotal bycatch data associated with two YOY C. carcharias (i.e., 1.40 and 1.70 m total length) from another location within the Great Australian Bight are reported. While it is premature to conclude that these sites represent discrete or an expansive interconnected nursery area, the sightings success in this study is indicative that future research may want to consider implementing a study during a similar time period (i.e., February–March) while using a similar attractant methodology (i.e., bottom-set BRUVS baited with squid [Sepioteuthis australis]) to help elucidate the unique life-history characteristics of this C. carcharias subpopulation.

Predatory fish exploitation and relative abundance in a data‐poor region from the Caribbean coast of Colombia, inferred from artisanal fishery interview surveys and baited remote underwater video systems

Abstract Artisanal fisheries are socially and economically important along the Caribbean coast of Colombia. These fisheries remain poorly characterized, making it difficult to estimate their potential impact, especially on non‐targeted catch such as elasmobranchs. A rapid assessment framework was used to investigate the exploitation, use, and relative abundance of elasmobranchs and predatory teleosts in a region along the Caribbean coast of Colombia. In‐person structured interview surveys (n = 188) were conducted during the autumn of 2016 at eight fishing towns around Cartagena and the islands of the Natural National Park (NNP) Corales del Rosario and San Bernardo. Baited remote underwater video systems (BRUVS) (n = 200) deployed at four reefs were used to assess the relative abundance of elasmobranchs and other predatory teleosts. Fishers reported capturing eight shark and five ray taxa. Although 99% of fishers indicated that they did not target sharks, 83% reported keeping the catches to sell, eat, or both. Similarly, 81% of fishers did not target rays, but 90% reported retaining catches. Most fishers (84%) perceived a decline of sharks in the coastal waters since they started fishing, compared with 41% reporting batoid declines. BRUVS data support the perceptions of elasmobranch declines. Elasmobranch abundances were very low and no difference was detected between protected and unprotected reefs. Results were similar for teleost taxa, but there were higher abundances inside one marine protected area (MPA) that had high enforcement. Taken together, the data suggest considerable degradation of not only elasmobranch populations but also predatory fish populations of coral reef habitats in a region of the Colombian Caribbean. Furthermore, artisanal fishers continue to exploit coral reef resources inside MPAs unless there is strong enforcement. Enforcement can be difficult with limited resources, and therefore community‐based conservation methods may be more effective. Engagement with the local fishing community may help to reduce existing tensions and improve compliance.

Survey of Nautilus pompilius Linnaeus, 1758 (Cephalopoda) from Siquijor Island and Dalaguete–Alcoy in the Philippines Using Baited Traps and Baited Remote Underwater Video Systems (BRUVS)

Survey of Nautilus pompilius Linnaeus, 1758 (Cephalopoda) from Siquijor Island and Dalaguete–Alcoy in the Philippines Using Baited Traps and Baited Remote Underwater Video Systems (BRUVS)

Environmental DNA reveals fine‐scale habitat associations for sedentary and resident marine species across a coastal mosaic of soft‐ and hard‐bottom habitats

AbstractAccurate knowledge on spatiotemporal distributions of marine species and their association with surrounding habitats is crucial to inform adaptive management actions responding to coastal degradation across the globe. Here, we investigate the potential use of environmental DNA (eDNA) to detect species–habitat associations in a patchy coastal area of the Baltic Sea. We directly compare species‐specific qPCR analysis of eDNA with baited remote underwater video systems (BRUVS), two non‐invasive methods widely used to monitor marine habitats. Four focal species (cod Gadus morhua, flounder Platichthys flesus, plaice Pleuronectes platessa, and goldsinny wrasse Ctenolabrus rupestris) were selected based on contrasting habitat associations (reef‐ vs. sand‐associated species), as well as differential levels of mobility and residency, to investigate whether these factors affected the detection of species–habitat associations from eDNA. To this end, a species‐specific qPCR assay for goldsinny wrasse is developed and made available herein. In addition, potential correlations between eDNA signals and abundance counts (MaxN) from videos were assessed. Results from Bayesian multilevel models revealed strong evidence for a sand association for sedentary flounder (98% posterior probability) and a reef association for highly resident wrasse (99% posterior probability) using eDNA, in agreement with BRUVS. However, contrary to BRUVS, eDNA sampling did not detect habitat associations for cod or plaice. We found a positive correlation between eDNA detection and MaxN for wrasse (posterior probability 95%), but not for the remaining species and explanatory power of all relationships was generally limited. Our results indicate that eDNA sampling can detect species–habitat associations on a fine spatial scale, yet this ability likely depends on the mobility and residency of the target organism, with associations for sedentary or resident species most likely to be detected. Combined sampling with conventional non‐invasive methods is advised to improve detection of habitat associations for mobile and transient species, or for species with low eDNA concentrations.

Seascape connectivity of temperate fishes between estuarine nursery areas and open coastal reefs

Abstract While estuaries are considered valuable nurseries for many harvested fish species, little quantitative data exist about the spatial scales over which estuaries supply individuals to coastal reefs and how this influences coastal metapopulations. Quantifying this connectivity between estuaries and coastal reefs will assist the sustainable management of fisheries and key fish habitat. This information is particularly pertinent considering estuaries world‐wide are experiencing degradation and habitat loss. We examine how the relative abundance and body length of three exploited fishes (Chrysophrys auratus, Pseudocaranx georgianus and Nemadactylus douglasii) varied in relation to the proximity and size of the nearest estuary, predicting that estuarine dependent species (i.e. C. auratus) would be smaller and more abundant on reefs close to large estuaries. As a network of ‘no‐take’ marine reserves exist across the study area, we also assessed for reserve effects and if these were influenced by the proximity and size of estuaries. Fish assemblages were surveyed using baited remote underwater video systems deployed on 629 rocky reefs across 417 km of coastline in south‐eastern Australia. As predicted, C. auratus were smaller and more abundant on reefs adjacent to estuaries (<8.5 km), which is consistent with the species being heavily reliant on estuaries as nursery habitats. Neither the length nor abundance of N. douglasii and P. georgianus were influenced by the proximity or size of estuaries. Marine reserves consistently had higher abundances and larger C. auratus, regardless of their proximity to estuaries. However, reserve effects were more variable for both N. douglasii and P. georgianus. Synthesis and applications. Our results suggest that the dispersal of subadult Chrysophrys auratus from estuarine nurseries to coastal reefs occurs across relatively small spatial scales, highlighting that conserving the ecological functioning of estuaries is paramount to sustaining recruitment to nearby coastal fisheries. Estuary size and proximity had little influence on populations of both Nemadactylus douglasii and Pseudocaranx georgianus as these species are not greatly dependent on estuaries. We also found that the proximity to estuaries did not enhance reserve effects, instead these effects were consistent across the study area.

Temporal stability in a protected and isolated fish community within marine parks surrounding Lord Howe Island

Remote oceanic islands often display high levels of biodiversity and endemism, making them important locations for marine parks aimed at conserving biodiversity. To determine whether marine parks are reaching conservation objectives requires consistent assessments of their effectiveness through time. Lord Howe Island and Balls Pyramid are World Heritage listed remote oceanic islands in the Tasman Sea that support a diverse assemblage of fishes including many endemic and protected species. To conserve the region’s unique marine biodiversity, state and Commonwealth marine parks including no-take zones and partially protected zones open to line fishing were established. After approximately 5, 9 and 13 years of protection of shelf habitat we tested for changes in the marine park’s fish assemblage across management zones through time using baited remote underwater video systems (BRUVs). We detected no difference in total fish abundance, diversity, or assemblage composition between management zone types. The relative abundance of targeted carangids, yellowtail kingfish and silver trevally were 2 and 1.6 times greater in no-take zones than partially protected zones respectively, however, the substantial variation in their abundances among locations and sites meant that these differences were not statistically significant. No clear difference in the relative abundance of endemic, near-endemic and protected species were observed between management zone types. Generally, the abundance and diversity of fishes varied most among locations, sites and sampling years. The overall lack of difference in the fish assemblage between management zone types and its stability through time suggests current anthropogenic threats are relatively minor, and the marine park’s condition is reasonably healthy. Future surveys of the marine park’s fish assemblage will be valuable to test for body-size differences between zone types and to monitor trends in condition, particularly in response to possible changes in the number, frequency and intensity of anthropogenic threats.

Ensuring the Sustainability of Coastal Small-Scale Fisheries at Pitcairn Island (South Pacific) Within a Large Scale No-Take MPA

The Pitcairn Islands, located in the central South Pacific, contain near-pristine marine ecosystems which support unique fish assemblages, together with both endemic and threatened species. Pitcairn itself is the only inhabited island in the group and, before this study, the environmental impact of local fisheries was unclear, with little data to inform conservation and management. In 2014–2015 coastal fish populations were assessed using a mixed methods approach: a newly introduced system of fishers’ catch monitoring and Baited Remote Underwater Video Systems (BRUVS). Thirty-nine BRUVS deployments recorded 88 species in total, with small-bodied herbivores (e.g., Kyphosus pacificus) and mesopredators (e.g., Xanthichthys mento) dominating a “bottom heavy” assemblage. Several large pelagic predators were recorded, but reef-associated predators were rare with only one shark observed. Pitcairn’s top predator assemblage was relatively impoverished compared to global “pristine” sites, including other islands within the Pitcairn group. Top predator scarcity may be explained by local artisanal fisheries, which have historically targeted sharks and other large reef carnivores, and these taxa may not have recovered despite subsequent declines in fishing pressure. The dominant small-bodied species may have proliferated as a result of diminished top predator populations. Subsequent to BRUVS sampling, a local fisheries officer post was created to collate catch data from coastal fishers. Regular returns were obtained from over half of the active fishers (representing approximately 80% of catches), with K. pacificus also dominating catches and the small grouper Epinephelus fasciatus frequently targeted. Thirty fish species were represented in the recorded catch over a 12 month period. Results were shared with the local community, providing a basis for the cooperative design of a Fisheries Management Plan. This plan ensured traditional fisheries could continue in a sustainable manner within Coastal Conservation Zones around each of the four Pitcairn Islands, established within the large, no-take Marine Protected Area designated in 2016, covering the entire Pitcairn Exclusive Economic Zone. Monitoring of Pitcairn’s artisanal fisheries should be continued beyond this one-off study in order to inform adjustment of the Fisheries Management Plan, as the ongoing island fishery may still have consequences for long-term sustainability, particularly for pelagic species caught in coastal waters which remain a significant data gap.

Increased connectivity and depth improve the effectiveness of marine reserves.

Marine reserves are a key tool for the conservation of marine biodiversity, yet only ~2.5% of the world's oceans are protected. The integration of marine reserves into connected networks representing all habitats has been encouraged by international agreements, yet the benefits of this design has not been tested empirically. Australia has one of the largest systems of marine reserves, providing a rare opportunity to assess how connectivity influences conservation success. An Australia‐wide dataset was collected using baited remote underwater video systems deployed across a depth range from 0 to 100 m to assess the effectiveness of marine reserves for protecting teleosts subject to commercial and recreational fishing. A meta‐analytical comparison of 73 fished species within 91 marine reserves found that, on average, marine reserves had 28% greater abundance and 53% greater biomass of fished species compared to adjacent areas open to fishing. However, benefits of protection were not observed across all reserves (heterogeneity), so full subsets generalized additive modelling was used to consider factors that influence marine reserve effectiveness, including distance‐based and ecological metrics of connectivity among reserves. Our results suggest that increased connectivity and depth improve the aforementioned marine reserve benefits and that these factors should be considered to optimize such benefits over time. We provide important guidance on factors to consider when implementing marine reserves for the purpose of increasing the abundance and size of fished species, given the expected increase in coverage globally. We show that marine reserves that are highly protected (no‐take) and designed to optimize connectivity, size and depth range can provide an effective conservation strategy for fished species in temperate and tropical waters within an overarching marine biodiversity conservation framework.

A comparison of the fauna in eelgrass and erosion control structures in a warm temperate Southern African estuary

Estuaries are important coastal systems offering nursery and foraging grounds for many species. With the increasing threat from climate change and sea-level rise, the armouring of coastlines, to withstand coastal erosion, has become common practice. The transformation of soft sediment habitats to hard, artificial habitats can lead to changes in species diversity, composition and distribution. As there is limited information regarding the ecological impacts of using Reno mattresses (wire mattresses filled with rocks) to combat erosion, this study investigated the faunistic differences of these structures compared to natural eelgrass (Zostera capensis) habitat in the Keurbooms estuary, South Africa. Benthic macroinvertebrate and fish abundances and assemblages were assessed seasonally from winter 2018 to spring 2019. Macroinvertebrates were assessed using standard core and suction sampling whereas the non-destructive method of mini Baited Remote Underwater Video Systems (BRUVs) was used to sample fish. Fish assemblages differed significantly between habitats and across seasons with greater abundances and diversity at the artificial structures compared to eelgrass habitat. Invertebrate taxa displayed some overlap between habitats, however, three higher taxonomic groups were only recorded within Reno mattress habitat with only one taxon unique to the eelgrass habitat. This study provides new information on the ecological efficacy of Reno mattress structures used in coastal management which can inform future coastal erosion control practices.

Isolated reefs support stable fish communities with high abundances of regionally fished species.

Anthropogenic impacts at isolated and inaccessible reefs are often minimal, offering rare opportunities to observe fish assemblages in a relatively undisturbed state. The remote Rowley Shoals are regarded as one of the healthiest reef systems in the Indian Ocean with demonstrated resilience to natural disturbance, no permanent human population nearby, low visitation rates, and large protected areas where fishing prohibitions are enforced. We used baited remote underwater video systems (BRUVS) to quantify fish assemblages and the relative abundance of regionally fished species within the lagoon, on the slope and in the mesophotic habitat at the Rowley Shoals at three times spanning 14 years and compared abundances of regionally fished species and the length distributions of predatory species to other isolated reefs in the northeast Indian Ocean. Fish assemblage composition and the relative abundance of regionally fished species were remarkably stable through time. We recorded high abundances of regionally fished species relative to other isolated reefs, including globally threatened humphead Maori wrasse (Cheilinus undulatus) and bumphead parrotfish (Bolbometopon muricatum). Length distributions of fish differed among habitats at the Rowley Shoals, suggesting differences in ontogenetic shifts among species. The Cocos (Keeling) Islands typically had larger‐bodied predatory species than at the Rowley Shoals. Differences in geomorphology, lagoonal habitats, and fishing history likely contribute to the differences among remote reefs. Rowley Shoals is a rare example of a reef system demonstrating ecological stability in reef fish assemblages during a time of unprecedented degradation of coral reefs.

The influence of shark behavior and environmental conditions on baited remote underwater video survey results

Baited remote underwater video systems (BRUVS) have become an important and frequently used tool by resource managers to monitor relative abundances for a variety of marine species. As with any abundance survey method, fundamental assumptions of the technique are that counts derived from videos accurately reflect true changes to abundances, while being robust to changes in density-independent factors. We tested these assumptions using a newly developed spatially-explicit individual-based simulation model for two of the most commonly used video survey metrics of relative abundance; MaxN and MeanCount. Simulating a 1-km2 area over a 60-min BRUV deployment targeting elasmobranch species, we evaluated how resulting estimates of each metric were influenced by swimming speed, relative directness of movement patterns, relative attraction strength to bait, bait plume size, and camera visibility range while shark density was held constant. By simulating both standard (120°) and full-spherical (FS; 360°) fields of view (FOV), we were also able to explore if newly developed FS cameras could help reduce the impact of these density-independent factors. Results from both generalized linear models and visual inspection of simulations indicated that density as well as non-density-related factors were highly significant in predicting camera counts, regardless of the camera's FOV or count metric used. Collectively, these findings illustrate that video survey metrics are sensitive to factors unrelated to changes in density, and researchers should carefully consider their potential influence on survey results as well as potential management decisions based on these data.

Can bait improve the efficiency of underwater video monitoring of fish in headwater streams? A case study from the Rondegat River, South Africa

The use of action cameras for underwater video sampling provides a non-harmful alternative for monitoring endangered and threatened fish populations in clear headwater streams. Here, we examine the use of baited remote underwater video systems (BRUVS) for the monitoring of vulnerable species in the clear headwater streams of the Cederberg Wilderness Area, South Africa. We tested whether baits (bread and Marmite™) increased the number of individuals recorded in comparison to un-baited BRUVS. Overall, baiting cameras increased the number of individuals recorded, with bread outperforming Marmite™. Numbers recorded varied notably among species and sites. We conclude that BRUVS are a useful monitoring tool, but caution that monitoring programmes should first determine the effectiveness of a range of baits to attract each species expected at the study sites.

Moray eels are more common on coral reefs subject to higher human pressure in the greater Caribbean

SummaryProximity and size of the nearest market (‘market gravity’) have been shown to have strong negative effects on coral reef fish communities that can be mitigated by the establishment of closed areas. However, moray eels are functionally unique predators that are generally not subject to targeted fishing and should therefore not directly be affected by these factors. We used baited remote underwater video systems to investigate associations between morays and anthropogenic, habitat, and ecological factors in the Caribbean region. Market gravity had a positive effect on morays, while the opposite pattern was observed in a predator group subject to exploitation (sharks). Environmental DNA analyses corroborated the positive effect of market gravity on morays. We hypothesize that the observed pattern could be the indirect result of the depletion of moray competitors and predators near humans.

The Use of Baited Remote Underwater Video Systems (BRUVS) to Noninvasively Characterize a White Shark (Carcharodon carcharias) Nursery Area off Eastern Long Island, New York

AbstractUnderstanding if a discrete region fits three key criteria for shark nursery area designation is of utmost importance. Such a designation within United States territorial waters could result in the implementation of an Essential Fish Habitat (EFH) classification, a determination facilitating species protection. In this study, baited remote underwater video systems (BRUVS) were used to determine if they could effectively confirm a previously identified white shark (Carcharodon carcharias) nursery area south of Montauk, New York, so that the technique may be applied in other potential nursery areas. During experimentation, 1,348.32 h of video data were collected between Region A (Block Island Sound; 674.16 h), outside of the previously identified nursery area, and Region B (Atlantic Ocean; 674.16 h), within the identified nursery area. From the video data, 35 sightings of C. carcharias were recorded, with 31 unique individuals identified. Data associated with Region B fit all three nursery area criteria: (a) young-of-the-year (YOY) and juvenile sharks were more commonly found in this region over Region A (p < 0.001), (b) several YOY and juvenile sharks (n = 4) were resighted in this region within a given year (e.g., average resighting duration: 10.5 days), and (c) YOY and juvenile sharks exhibited repeated use of this region over multiple years. We conclude that BRUVS can be used for fine-scale analyses to help designate a discrete area(s) as a shark nursery, even in turbid New York waters. Therefore, using BRUVS to identify shark nursery areas is a viable and noninvasive approach that can contribute to species conservation.

What eats a cauliflower coral? An assessment of predation on the endangered temperate soft coral,

Temperate soft corals are found in many estuaries around the world and often form large habitats in these environments, yet the functional ecology of soft corals is poorly understood. To understand the functional role of a soft coral in temperate ecosystems, we examined the role of the endangered Dendronepthya australis cauliflower coral as habitat for fishes and invertebrates, and whether associated species used the soft coral as a food source. Using Bayesian stable isotope mixing models of δ13C and δ15N values of soft corals and a suite of potential invertebrate consumers, we found that five of eight soft-coral-associated invertebrates were all likely to be feeding almost exclusively on the soft corals. In situ feeding experiments conducted using baited remote underwater video systems (BRUVS) with soft coral cuttings as ‘bait’ did not identify any larger species as consumers. Fish assemblages studied using remote underwater video systems (RUVS) were diverse in the soft coral habitat and overlapped with assemblages of both sediment and seagrass environments. These results highlighted that these soft corals have a valuable trophic role in estuarine food webs through trophic transfer of nutrients via invertebrate consumers, and that soft coral habitats are used by commercially and recreationally important fishes.

Anthropogenic pressures on reef-associated sharks in jurisdictions with and without directed shark fishing

Shark populations have declined across the Caribbean region, with negative associations between shark abundance and human population density, open access to fishing, and proximity to large markets (‘market gravity’). This decline is frequently attributed to fishing mortality, which increases in areas closer to humans and outside marine reserves. Although it is difficult to disentangle the effects of fishing mortality from other anthropogenic pressures on sharks, comparing shark abundance and diversity in jurisdictions with near zero fishing mortality versus prevalent shark fishing can demonstrate the role of overfishing. We used baited remote underwater video systems to compare shark abundance and diversity on coral reefs in 2 Caribbean nations with contrasting levels of shark exploitation: Belize (shark fishing) and The Bahamas (shark sanctuary). The abundance of targeted shark species and diversity were significantly higher in The Bahamas than in Belize. Caribbean reef and nurse shark abundance in Belize were best predicted by fishing-related factors (marine reserves, market gravity, their interaction). In The Bahamas, abiotic factors (depth, sea surface temperature) best predicted nurse shark abundance, while depth, market gravity, and its interaction with marine reserves predicted Caribbean reef shark abundance. These results indicate that fishing mortality reduces shark abundance and diversity in Belize, while lower fishing mortality in The Bahamas has greatly reduced but not eliminated human impacts on sharks. Future work should elucidate the indirect effects of humans to develop holistic shark conservation plans. We suggest minimizing shark fishing through multinational management plans to improve shark abundance and diversity, especially on reefs near densely populated areas.

Highly diverse mesophotic reef fish communities in Raja Ampat, West Papua

Mesophotic coral ecosystems (MCEs; reefs 30–150 m depth) are poorly studied, with existing research heavily geographically biased away from the most species-rich reef regions. Yet, MCEs are of high interest because of their unique species and potential to act as refuges from the impacts of fishing. Using baited remote underwater video systems, we surveyed reef fish communities from 2 to 85 m depths throughout the Raja Ampat archipelago in West Papua, Indonesia—an area considered the heart of the Coral Triangle where coral reef biodiversity is greatest. We sought to provide the first assessment of fish communities across this depth gradient in the region and identify whether human population density and market access differently affected fish abundance based on depth. Here we show that—similar to shallow reefs—Raja Ampat MCEs are exceptionally diverse, with 152 fish species recorded at depths greater than 40 m. We found that fish community structures were highly depth driven, with declines in fish abundance at increased depth. In contrast to previous studies elsewhere in the world, we found that the proportion of planktivores declined across the shallow reef to MCE depth gradient. While greater human population density correlated with lower Epinephelidae and Lutjanidae abundance (two key fisheries families), we did not find evidence that MCEs provide a depth refuge from fishing. Surprisingly, we also found that fish abundance declined at greater distances from the major regional market—likely caused by historical fisheries pressure in more remote areas. These results both expand upon and contrast some previously established MCE-depth patterns and human impact patterns on fish communities, suggesting that regional context and historical pressures matters. Our findings highlight the need for future MCE studies within the Coral Triangle region.

Wild observation of putative dynamic decapod mimicry by a cuttlefish (Sepia cf. smithi)

Stereo baited remote underwater video systems (BRUVS) are widely used to document diversity, abundance, and biomass of marine wildlife and record unusual behaviours. We observed a cuttlefish appearing to mimic decapod morphology and locomotion during a non-targeted BRUVS study on Australia’s Northwest Shelf. While the pharaoh cuttlefish Sepia pharaonis (Ehrenberg, 1831) is putatively thought to mimic the appearance of a hermit crab in a laboratory setting, our observation is the first wild record of decapod mimicry by a cuttlefish, tentatively identified as Sepia smithi (Hoyle, 1885). In situ observations increase our understanding of how cuttlefish behave in their natural environment while interacting with other species and provide opportunities to further our understanding of the source and breadth of these mimicry.

A baited remote underwater video system (BRUVS) assessment of elasmobranch diversity and abundance on the eastern Caicos Bank (Turks and Caicos Islands); an environment in transition

The present study was undertaken to assess the diversity and abundance of elasmobranch fishes in coral reef and sand flat environments on the eastern Caicos Bank, with a view to informing marine spatial planning as the island of South Caicos and its environs transition to a tourism-based economy. Using baited remote underwater video systems (BRUVS), the nurse shark Ginglymostoma cirratum, Caribbean reef shark Carcharhinus perezi, spotted eagle ray Aetobatus narinari, southern stingray Hypanus americanus, lemon shark Negaprion brevirostris, tiger shark Galeocerdo cuvier, blacknose shark Carcharhinus acronotus, and great hammerhead shark Sphyrna mokarran were observed to use these waters, with G. cirratum and C. perezi being particularly abundant. Species diversity and overall abundance was greater in the reef environment than on the sand flats, but G. cirratum was equally abundant in both environments. Furthermore, even reef-associated species such as C. perezi were occasionally encountered on the flats a considerable distance from the reef. This indicates that although marine conservation efforts in the Turks and Caicos Islands should continue to focus on coral reef areas, less dramatic environments such as sand flats should not be ignored.