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Ground truthing dermal denticles to characterize shark assemblages on Palmyra Atoll, Erin Dillon [et al.]

Ground truthing dermal denticles to characterize shark assemblages on Palmyra Atoll, Erin Dillon [et al.]

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How does a shark’s paradise become a fish’s

nightmare? Ecology and behaviour of reef

sharks at Fakarava, one of the world’s

biggest aggregations.

Johann Mourier



∗† 1



, Laurent Ballesta 2 , Charlie Huveneers 3 , Yannis

Papastamatiou 4 , Serge Planes 5



1



Centre de Recherche Insulaire et Observatoire de l’Environnement (CRIOBE) – CNRS : USR3278,

Ecole Pratique des Hautes Etudes – Universite de Perpignan, 58 Av. Paul Alduy - 66860 Perpignan

cedex, France

2

Andromede Oceanology – Andromede Oceanology – 7 Place Cassan, 34280 Carnon-Plage, France

3

Flinders University – Room 140, Biology Building, Sturt Road, Bedford Park, SA, 5042 South

Australia, Australia

4

Florida International University – 3000 NE 151st st, North Miami, 33181, United States

5

Centre de Recherche Insulaire et Observatoire de l’Environnement (CRIOBE) – BP 1013 - 98 729,

Papetoai, Moorea, French Polynesia



The extent of the global human footprint limits our understanding of what are natural baselines in the marine environment. Remote near-pristine areas provide some baseline expectations

for biomass and suggest that predators dominate, producing an ‘inverted biomass pyramid’. The

southern pass of Fakarava atoll – a Biosphere Reserve in French Polynesia – hosts more than 500

reef sharks, 2-3 times the biomass/ha documented for any other reef shark aggregations. This

huge biomass of predators makes the trophic pyramid inverted. Bioenergetics models indicate

the sharks require ˜ 90 tons of fish/year while the total fish production in the pass is ˜ 17

tons/year. Sharks may overcome low local energy availability by feeding on fish spawning aggregations and other subsidies transiting into the pass which concentrate energy from other local

trophic pyramids. Using a combination of cutting edge technologies, ongoing research aims to

investigate the natural shark hunting behaviour, feeding ecology, movement patterns and social

behaviour in a unique pristine reef to better understand the role of sharks on the local ecosystem

and how such concentrations of predators are maintained. Altogether, our preliminary findings

have important conservation implications for maintaining a balanced and healthy ecosystem.









Speaker

Corresponding author: johann.mourier@gmail.com



310



Indo-Pacific Predatory Fish Out of Context:

Lionfish Invasion of Atlantic Coral Reefs

Mark Hixon

1



∗ 1



University of Hawaii – Department of Biology University of Hawaii Honolulu, HI 96822, United States



Lionfishes of the Pterois volitans/miles complex were introduced near Florida via the aquarium trade, likely during the 1980s, and are now found coastally along most of the US east coast,

the greater Caribbean region, and the coast of Brazil. Voracious generalized predators of small

reef fish, lionfish have severely reduced recruitment of many native species, including local extinctions, at multiple spatial scales. Native prey fishes do not evade lionfish, and lionfish are

seldom attacked by native predators, parasites, or interference competitors. There is evidence

that invasive lionfish out-compete native mesopredators. Lionfish have reached far greater densities on invaded coral reefs compared to their native range, and there is little evidence of density

dependence in their local population dynamics. Local control of the invasion is by lionfish derbies and targeted fisheries by means of spearfishing. There is recent evidence that the invasion

is starting to wane in the Bahamas, where the highest densities of lionfish previously occurred.

The causes of this apparent decline in lionfish abundance are presently unknown.







Speaker



311



Insights into genetic chaos among tuna

species in the Western and Central Pacific

Ocean

Giulia Anderson ∗ 1 , Amandine Marie 1 , Monal Lal 1,2 , Janice Natasha 1 ,

Roselene Dayal 1,3 , Caroline Sanchez 4 , Francois Roupsard 4 , John

Hampton 4 , Graham Pilling 4 , Neville Smith 4 , Ciro Rico 1,5

1



University of the South Pacific (USP) – University of the South Pacific Laucala Bay Dr. Suva, Fiji

Islands, Fiji

2

Tropical Aquaculture, Faculty of Science, Health, Education and Engineering – University of the

Sunshine Coast, Maroochydore DC, Queensland 4558, Australia

3

School of Sciences, College of Engineering, Science and Technology – Fiji National University, Nabua

Campus, Fiji

4

Oceanic Fisheries Programme (OFP) Pacific Community – 95 Promenade Roger Laroque, BP D5,

98848 Noum´ea, New Caledonia

5

Estaci´

on Biol´

ogica de Do˜

nana, Consejo Superior de Investigaciones Cient´ıficas (EBD, CSIC),

c/Am´erico Vespucio s/n, – Sevilla 41092, Spain



Ignoring stock structure in fisheries management may result in localized overexploitation.

Genetic evidence suggests that tuna stocks, as currently defined, are not biologically relevant,

yet tunas are still managed as single interbreeding populations within ocean basins, or large

parts thereof. We used genome-wide single nucleotide polymorphisms to establish whether the

distribution of neutral genetic diversity among tuna stocks supports the traditional assumption

of panmixia. We found significant heterozygous deficits and genetic heterogeneity in albacore,

bigeye, skipjack and yellowfin tunas at unprecedented small geographical and temporal scales

in the Western and Central Pacific Ocean (WCPO). Differentiation occurred among locations

within a single year and among years in the same location, suggesting the existence of tuna

metapopulations within an ocean basin. Five main conclusions follow from our study: (i) the

neutral genetic diversity in tuna populations in the WCPO is patchily and chaotically distributed; (ii) the significant heterozygous deficits observed are most likely due to admixture

and/or migration; (iii) the tuna spatial structure observed is compatible with metapopulation

theory; (iv) the extremely small N e/N ratios obtained can be explained by mechanisms related

to chaotic genetic patchiness; and (v) our results confirm recent studies suggesting complex

biological, ecological and oceanographic processes shaping tunas’ population structure, and no

panmixia in the Pacific Ocean. These unprecedented findings underscore the need to understand the drivers of chaotic genetic structure, and its potential consequences for management

of a fishery that represents up to 8% of global marine capture fish products.







Speaker



312



Life history aspects and taxonomy of

deep-sea chondrichthyans in the

Southwestern Indian Ocean

Paul Clerkin

1



∗ 1



, David Ebert



1



Pacific Shark Research Center (PSRC) – 8272 Moss Landing Rd, Moss Landing, CA 95039, United

States



Chondrichthyans were collected and examined during two surveys (2012, 2014) of Southwestern Indian Ocean seamounts in order to: 1) survey the species in this region, 2) document and

describe taxonomically the species encountered, and 3) to collect and assess life history characteristics of these species. Specimens were incidentally taken as bycatch during deep-sea trawling

operations targeting Orange Rough (Hoplostethus atlanticus) and Alfonsino (Beryx decadactylus) from 46 sites along seamounts of the Madagascar Ridge and the Southwestern Indian Ocean

Ridge at depths between 500m and 1,500m. Over 4,000 sharks were encountered comprising four

orders, seven families, 14 genera and 31 species. To date, six new species (Bythaelurus bachi,

B. naylori, Etmopterus alphus, and three Chimaera species) have been described, with several

more potential new species currently under investigation. In addition, the information gathered from these surveys was crucial in clarifying the taxonomic status of several genera and

species. Reproductive and maturity data including sex, length, maturity stage, oviducal gland

development, egg width, and number of eggs were recorded and analyzed in JMP and MATLAB. Using a non-metric multidimensional scaling analysis in PRIMER, species abundance and

diversity, are compared between sites and depth to investigate habitat use. The expeditions

were an international collaboration between the Pacific Shark Research Center, Moss Landing Marine Laboratories, Hollings Marine Laboratory, College of Charleston, Southern Indian

Ocean Deepsea Fishers Association, Sealord Corporation, New Zealand, and the Mauritius Ministry of Fisheries. This project was funded, in part, by NSF grant: DEB 1132229, Discovery

Communications, and Save Our Seas Foundation.







Speaker



313



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