Wanted Dead or Alive? The Relative Value of Reef Sharks as a Fishery and an Ecotourism Asset in Palau

Over the last 20 years, ecotourism to view and interact with marine megafauna has become increasingly popular (Higham and Lück 2008). Examples of this type of tourism include turtle and whale watching, snorkelling with seals and shark diving (Jacobson and Robles 1992; Anderson and Ahmed 1993; Orams 2002; Kirkwood et al. 2003; Dearden et al. 2008; Dicken and Hosking 2009). The occurrence of many aggregations of megafauna along the coasts of regional areas remote from centres of population means that such tourism also provides significant flow-on effects and diversification to local economies where few alternative sources of income exist (Milne 1990; Garrod and Wilson 2004). Importantly, the development of a well-managed ecotourism industry based on megafauna provides the opportunity for local people to utilise natural resources in a sustainable manner over the long-term (Mau 2008). The economic value of tourism based on marine megafauna is enormous. In 2008, a study of whale watching estimated that this form of tourism was available in 119 countries, involved approximately 13 million participants and generated an income to operators and supporting businesses (hotels, restaurants and souvenirs) of over US$2.1 billion (O'Connor et al. 2009). This industry is estimated to have the potential to generate annual revenues of over US$2.5 billion (Cisneros-Montemayor et al. 2010). The development of whale watching has been paralleled by growth in tourism based on other types of marine megafauna. In particular, tourism to observe sharks and rays has become increasingly common. At the forefront of this relatively new market are industries that focus on whale sharks (Rhincodon typus) with estimates calculated in 2004 suggesting that these generated more than US$47.5 million worldwide, providing important revenues to developing countries such as Ecuador, Thailand and Mozambique (Graham 2004). Diving with other species of sharks has followed a similar trend of growing popularity. In 2005, it was estimated that approximately 500,000 divers were engaged in shark-diving activities worldwide (Topelko and Dearden 2005). An increasing range of opportunities for this type of tourism are available, including cage diving, shark feeding and drift diving with reef and oceanic sharks. Shark-diving tourism can be found in more than 40 countries (Carwardine and Watterson 2002), with new destinations and target species being established rapidly, due to the increasing recognition of the economic potential of this activity (Dicken and Hosking 2009; De la Cruz Modino et al. 2010)

The Socio-Economic Value of the Shark-Diving Industry in Fiji

Based on a survey of divers, dive operators, resort managers, estimates business revenues from shark diving and related expenditures by area; tax revenues; and economic benefit to local communities

Bycatch of lined seahorses (Hippocampus erectus) in a Gulf of Mexico shrimp trawl fishery

Bycatch studies have largely ignored population level effects on fish species of little commercial interest. Here we analyze bycatch of the lined seahorse (Hippocampus erectus) in the bait-shrimp trawl fishery in Hernando Beach, Florida, providing the first fisheries data for this species. Based on catch per unit of effort (CPUE), size, sex, and reproductive status of trawled H. erectus, 1) approximately 72,000 seahorses were caught annually by this fleet, from a population of unknown size, 2) trawling affected population cohorts differentially because of temporal and spatial variation in CPUE and population size, and 3) a greater proportion of females than males was removed in trawling. Our findings suggest that trawling may affect seahorse populations through direct mortality, social disruption, and habitat damage. However, the lack of specific abundance or catchability estimates for H. erectus means that the precise impact of trawling on this fish remains uncertain. This paper focuses attention on the need for research and monitoring of small fishes that are caught incidentally in nonselective gear

Marine Biodiversity and Ecosystem Health of Ilhas Selvagens, Portugal

In September 2015, National Geographic's Pristine Seas project, in conjunction with the Instituto Universitário-Portugal, The Waitt Institute, the University of Western Australia, and partners conducted a comprehensive assessment of the rarely surveyed Ilhas Selvagens to explore the marine environment, especially the poorly understood deep sea and open ocean areas, and quantify the biodiversity of the nearshore marine environment

True blue: Temporal and spatial stability of pelagic wildlife at a submarine canyon

Funding: This research was funded through the Ian Potter Foundation and the First author.In coastal systems, marine-protected areas (MPAs) have been shown to increase the diversity, abundance, and biomass of wildlife assemblages as well as their resilience to climate change. The effectiveness of pelagic MPAs is less clear, with arguments against their establishment typically based on the highly mobile nature of pelagic taxa. We used mid-water stereo-baited remote underwater video systems (stereo-BRUVS) and spatial predictive models to characterize the pelagic wildlife assemblage at the head of the Perth Canyon, one of the largest submarine canyons in Australia, over a 7-yr period (2013–2019). The total number of unique taxa and mean values of taxonomic richness, abundance, fork length, and biomass demonstrated strong interannual stability, although mean taxonomic richness and abundance were significantly lower in 2018 relative to other years. Seasonal variability was absent in 2016, but in 2018, taxonomic richness and abundance were three times greater in the Austral spring than in the autumn. Some mobile megafauna were only recorded at the Perth Canyon Marine Park (PCMP) in the autumn, suggesting a seasonal component to their occurrence. The fine-scale distribution of pelagic taxa at the canyon head was largely stable over time, with many areas of higher relative probability of presence located outside protected zones. Despite a degree of variability that may relate to the effect of the El Niño Southern Oscillation on the Leeuwin Current, the PCMP assemblage demonstrates a relatively high degree of spatiotemporal stability. Stronger protection of the PCMP (IUCN II or higher) would potentially improve conservation outcomes for many species of pelagic wildlife.Publisher PDFPeer reviewe

Climate oscillation and the invasion of alien species influence the oceanic distribution of seabirds

Spatial and temporal distribution of seabird transiting and foraging at sea is an important consideration for marine conservation planning. Using at-sea observations of seabirds (n = 317), collected during the breeding season from 2012 to 2016, we built boosted regression tree (BRT) models to identify relationships between numerically dominant seabird species (red-footed booby, brown noddy, white tern, and wedge-tailed shearwater), geomorphology, oceanographic variability, and climate oscillation in the Chagos Archipelago. We documented positive relationships between red-footed booby and wedge-tailed shearwater abundance with the strength in the Indian Ocean Dipole, as represented by the Dipole Mode Index (6.7% and 23.7% contribution, respectively). The abundance of red-footed boobies, brown noddies, and white terns declined abruptly with greater distance to island (17.6%, 34.1%, and 41.1% contribution, respectively). We further quantified the effects of proximity to rat-free and rat-invaded islands on seabird distribution at sea and identified breaking point distribution thresholds. We detected areas of increased abundance at sea and habitat use-age under a scenario where rats are eradicated from invaded nearby islands and recolonized by seabirds. Following rat eradication, abundance at sea of red-footed booby, brown noddy, and white terns increased by 14%, 17%, and 3%, respectively, with no important increase detected for shearwaters. Our results have implication for seabird conservation and island restoration. Climate oscillations may cause shifts in seabird distribution, possibly through changes in regional productivity and prey distribution. Invasive species eradications and subsequent island recolonization can lead to greater access for seabirds to areas at sea, due to increased foraging or transiting through, potentially leading to distribution gains and increased competition. Our approach predicting distribution after successful eradications enables anticipatory threat mitigation in these areas, minimizing competition between colonies and thereby maximizing the risk of success and the conservation impact of eradication programs

The vertical distribution of fish on two offshore oil platforms

Knowledge of platform ecology is necessary to best inform decommissioning practice. Remotely operated vehicle (ROV) video is often collected during standard industry operations and may provide insight into the marine life associating with offshore platforms, however, the utility of this video for ecological assessments remains unclear. Archival ROV video surveys at the Wandoo oil platforms on Australia’s North West Shelf was evaluated for its utility, with only 4.9% of imagery usable for standardised ecological studies. Based on the subset of usable ROV video, the influence of depth and structural complexity on attributes of the fish assemblage on the Wandoo oil platforms was examined. Vertical ROV transects on three vertical shafts on the Wandoo platforms were stratified into 10 m depth strata from 0 to 50 m, with 111 fish taxa from 25 families identified and counted across all depth strata. At both platforms, taxonomic richness and abundance was significantly highest in shallow regions and declined with depth. Small reef fish were predominantly associated with structurally complex habitat in shallow regions (<22 m), whilst large demersal species dominated below 32 m. Future decommissioning policy in Australia should consider the vertical fish distributions and the importance of shallow sections of platforms. Finally, the dearth of usable video was due to the haphazard method of collection and it is recommended that future surveys should be conducted according to scientific standards to ensure greater utility of the video for both industry use and scientific research

Enhanced pelagic biomass around coral atolls

T.B.L. was supported by the Marine Biodiversity Hub through the Australian Government’s National Environmental Research Program (NERP). P.H.B.-S. was supported by a Cusanuswerk doctoral fellowship, a Lesley & Charles Hilton-Brown Scholarship, University of St. Andrews, and a grant from the Fisheries Society of the British Isles. M.J.C. was supported by Australian Research Council grant FS110200057.Understanding the processes driving the distribution of mid-water prey such as euphausiids and lanternfish is important for effective management and conservation. In the vicinity of abrupt topographic features such as banks, seamounts and shelf-breaks, mid-water faunal biomass is often elevated, making these sites candidates for special protection. We investigated the spatial distribution of water column acoustic backscatter - a proxy for macrozoo - plankton and fish biomass - in the 9 km transition zone between the pelagos and coral atolls in the Chagos Archipelago (6° N, 72° E). The purpose was to determine the magnitude and distance over which bathymetry may enhance biomass in the mid-water, and thereby identify the scale over which static topographic features could influence the open ocean. Two distinct sound scattering layers were identified, from the surface to 180 m and from 300 to 600 m, during daytime. Both layers exhibited significant increases in backscatter near features. Close to features, the shallow layer backscatter was ca. 100 times higher and was driven partly by increasing numbers of larger individuals, evident as single target echoes. We determine the regional scale of influence of features on pelagic biomass enhancement to be ca. 1.8 km in the Chagos Archipelago, and suggest possible ecological explanations that may support it. Our approach determining the scale of influence of bathymetry should be applied during the process of marine reserve design, in order to improve protection of mid-water fauna associated with topographical features, such as seamounts and coral reefs.PostprintPeer reviewe

Isolation and no-entry marine reserves mitigate anthropogenic impacts on grey reef shark behavior

Reef sharks are vulnerable predators experiencing severe population declines mainly due to overexploitation. However, beyond direct exploitation, human activities can produce indirect or sub-lethal effects such as behavioral alterations. Such alterations are well known for terrestrial fauna but poorly documented for marine species. Using an extensive sampling of 367 stereo baited underwater videos systems, we show modifications in grey reef shark (Carcharhinus amblyrhynchos) occurrence and feeding behavior along a marked gradient of isolation from humans across the New Caledonian archipelago (South-Western Pacific). The probability of occurrence decreased by 68.9% between wilderness areas (more than 25 hours travel time from the capital city) and impacted areas while the few individuals occurring in impacted areas exhibited cautious behavior. We also show that only large no-entry reserves (above 150 km²) can protect the behavior of grey reef sharks found in the wilderness. Influencing the fitness, human linked behavioral alterations should be taken into account for management strategies to ensure the persistence of populations

Submerged carbonate banks aggregate pelagic megafauna in offshore tropical Australia

This research was undertaken for the Marine Biodiversity Hub, a collaborative partnership supported through funding from the Australian Government’s National Environmental Research Program (NERP). PB was the recipient of a scholarship for international fees during the course of this work. SN publishes with permission of the Chief Executive Officer, Geoscience Australia.The conservation of marine biodiversity is firmly embedded in national and international policy frameworks. However, the difficulties associated with conducting broad-scale surveys of oceanic environments restrict the evidence base available for applied management in pelagic waters. For example, the Oceanic Shoals Australian Marine Park (AMP) was established in 2012 in a part of Australia’s continental shelf where unique topographic features are thought to support significant levels of biodiversity, yet where our understanding of ecological processes remains limited. We deployed mid-water baited remote underwater video systems (mid-water BRUVS) in the Oceanic Shoals AMP to provide the first non-extractive baseline assessment of pelagic wildlife communities in the area. We used these observations and high-resolution multibeam swaths of the seafloor to explore potential relationships between prominent geomorphological features and the (i) composition, (ii) richness, and (iii) relative abundance of pelagic communities. We documented 32 vertebrate species across three sampling areas, ranging from small baitfish to large sharks and rays, and estimated that up to nearly twice as many taxa may occur within the region as a whole. This highlights the Oceanic Shoals AMP as a reservoir of biodiversity comparable to other documented offshore oceanic hotspots. Our results also confirm the AMP as a possible distant foraging destination for IUCN red listed sea turtles, and a potential breeding and/or nursing ground for a number of charismatic cetaceans. Model outputs indicate that both species richness and abundance increase in proximity to raised geomorphic structures such as submerged banks and pinnacles, highlighting the influence of submarine topography on megafauna distribution. By providing a foundational understanding of spatial patterns in pelagic wildlife communities throughout a little studied region, our work demonstrates how a combination of non-destructive sampling techniques and predictive models can provide new opportunities to support decision-making under data shortage.Publisher PDFPeer reviewe