Ecology of sharks and human attitudes towards shark conservation in the Galapagos Marine Reserve : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Albany, New Zealand

In this thesis, I used a multi-disciplinary approach to study both the spatial ecology of coastal sharks and human attitudes towards sharks at the Galapagos Marine Reserve (GMR). Benthic and pelagic baited remote underwater stereo-video systems recorded coastal shark assemblages that displayed high spatial variation, with the relative importance of environmental and biological drivers differing among shark species according to their mobility. Telemetry data (both acoustic and satellite) from tagged tiger sharks (Galeocerdo cuvier) showed a high degree of philopatry, with movements of adult tiger sharks concentrating at the most important nesting areas for sea turtles at the GMR. Using diver-operated stereo-video systems (DOVs) I demonstrated that non-instantaneous surveys yield estimates of shark densities that can almost double the ones obtained from instantaneous surveys. Furthermore, I proposed a new methodological approach to study attitudes towards sharks that proved to be reliable and informative, showing that attitudes were shaped by a range of psychological factors, such as aesthetics, and also by the socio-economic context of individual respondents. Strong correlations were found between attitudes and behavioural responses, such as tolerance or support for shark protection. In conclusion, I demonstrated that sharks at the GMR have species-specific and size-specific spatial requirements for particular habitats and food resources. Indeed, the presence of a predictable source of prey and suitable habitats at the GMR might reduce the spatial extent of the potential areas used by large and highly mobile shark species, such as tiger sharks, thereby enhancing the potential effectiveness of the GMR for their protection. I also propose the use of non-instantaneous DOV surveys to provide more accurate estimates of shark densities than underwater visual techniques. In addition, the multivariate methods used here for the first time to study human perspectives on sharks allowed me to identify specific attitudes and associated factors having the greatest influence on human behaviours towards shark conservation. In summary, with mounting anthropogenic pressures on shark populations, this thesis provides timely and critical information for the global objective of identifying effective strategies for the management and conservation of sharks to ensure their long-term survival

Reply to: Caution over the use of ecological big data for conservation

info:eu-repo/semantics/publishedVersio

Global Spatial Risk Assessment of Sharks Under the Footprint of Fisheries

Effective ocean management and conservation of highly migratory species depends on resolving overlap between animal movements and distributions and fishing effort. Yet, this information is lacking at a global scale. Here we show, using a big-data approach combining satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space use hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines (up to 76% and 64%, respectively) and were also associated with significant increases in fishing effort. We conclude that pelagic sharks have limited spatial refuge from current levels of high-seas fishing effort. Results demonstrate an urgent need for conservation and management measures at high-seas shark hotspots and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool for near-real time, dynamic management

Largest global shark biomass found in the northern Galápagos Islands of Darwin and Wolf

Overfishing has dramatically depleted sharks and other large predatory fishes worldwide except for a few remote and/or well-protected areas. The islands of Darwin and Wolf in the far north of the Galapagos Marine Reserve (GMR) are known for their large shark abundance, making them a global scuba diving and conservation hotspot. Here we report quantitative estimates of fish abundance at Darwin and Wolf over two consecutive years using stereo-video surveys, which reveal the largest reef fish biomass ever reported (17.5 t ${\mathrm{ha}}^{-1}$ ha − 1 on average), consisting largely of sharks. Despite this, the abundance of reef fishes around the GMR, such as groupers, has been severely reduced because of unsustainable fishing practices. Although Darwin and Wolf are within the GMR, they were not fully protected from fishing until March 2016. Given the ecological value and the economic importance of Darwin and Wolf for the dive tourism industry, the current protection should ensure the long-term conservation of this hotspot of unique global value

Summary of <i>R. typus</i> tracks at Darwin Island in 2013.

<p>Summary of <i>R. typus</i> tracks at Darwin Island in 2013.</p

Size-frequency distribution.

<p>Size measurements by laser photogrammetry (N = 47; dark grey bars and dotted line) and visual estimation (N = 35; light grey bars and dotted line) of the 82 whale sharks photo-identified at Darwin Island, Galapagos Marine Reserve, between 2011 and 2013.</p

Visual evidence of <i>R. typus</i> possible pregnancy.

<p>Image of two female whale sharks recorded at Darwin Island that displayed different signs of pregnancy (A) a 9.3 m TL female sighted on November 18^th 2013 with its belly not distended; (B) a 12 m TL female sighted on October 20^th 2012 with a clear distended belly, which is a sign of pregnancy (Ramírez-Macías et al. 2012b); (photo credit: David Acuña-Marrero).</p

Relationship between SST and sighting frequency of <i>R. typus</i>.

<p>Least square regression's result between SST and whale shark sightings per diver hour⁻¹ in the vicinity of Darwin's Arch from November 2007 to December 2013.</p

Location of the whale shark study area.

<p>A) Tracks of the four <i>R. typus</i> around Darwin Island with its bathymetry (10 m isobaths); B) Galapagos Archipelago's setting in the Eastern Tropical Pacific (Ecuador national territory in dark grey); C) Galapagos Islands with the Galapagos Marine Reserve boundaries that extends 40 nm from the islands (discontinued line).</p

Whale sharks dive profiles at Darwin Island.

<p>Plots showing dive profile and bottom depth of RT-01 (A), RT-02 (B), RT-03 (C: Nov 14^th, and D: Nov 15^th, the latter only showing her dive profile during the time she remained in the vicinity of the island (<1.3 nm)) and RT-04 (E: Nov 16^th, and F: Nov 17^th), respectively. Signal from RT-03 was lost from 13:33 PM to 14:32 PM on Nov 14^th (C). Note that bottom depth contour was obtained from skiff position, so sharks dive's and bottom depth's profiles relationship may not coincide exactly with the reality. For this reason shark dive profiles overlap with bottom depth in few occasions, especially at shallow areas (<30 m).</p