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Subsistence harvesting by a small community does not substantially compromise coral reef fish assemblages, Tyson Martin [et al.]

Subsistence harvesting by a small community does not substantially compromise coral reef fish assemblages, Tyson Martin [et al.]

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The functional backstop of reef fisheries

conservation

Aaron Macneil

1



∗ 1



Dalhousie University – 1355 Oxford St., P.O. Box 15000, Halifax, NS, B3H 4R2, Canada



Coral reef conservation has frequently focused on maintainence of biodiversity and the factors

that influece local and regional drivers of species ranges, with an eye to ensuring speicies do not

go extinct. Yet extinctions of reef fish species are rare or non-existent and the use of biodiversity

as a proxy for reef health is often ambiguous. Here I will revew a decade of reef fisheries research

by the SERF working group to show that clear trade-offs can be made between conservation and

exploitation. I outlinine how failures in sampling have re-enforeced the emphasis on biodiversity

and argue that utlimately what we want to conserve is a minimum level of function among

harvested reef fish communities, rather than biodiversity per se. As poorly-managed coral reef

fisheries are the primary source of protein for hundreds of millions of people world-wide, a

portfolio of function-based guidelines can help improve fisheries management among developing

nations where the majority of reef fisheries occur.







Speaker



159



Towards management for resilience:

Combined effects of natural disturbances

and fisheries activities on coral reef

ecosystem functioning.

M´elodie Dubois

1



∗ 1



, Joachim Claudet



1



´

Centre de recherches insulaires et observatoire de l’environnement (CRIOBE) – Ecole

Pratique des

´

Hautes Etudes

[EPHE], CNRS : USR3278 – Universit´e de Perpignan 52 Avenue Paul Alduy 66860

Perpignan Cedex, France



Worldwide, fisheries provide benefits to many countries, especially in tropical environments

where exploitation of reef marine resources provide to coastal communities valuable services such

as food and economic security, and contribute to their societal and cultural identity. However,

coral reef ecosystems evolves under several natural disturbance regimes which, combined with

increasing multiple human stressors, may cause irreversible shifts in community structure, and

thus in the delivery of ecosystem services.

These regime shifts had led to manage not just for the steady-state of the coral reef ecosystem but for its resilience. This approach supposes to move management actions towards the

preservation of key ecological processes that are responsible for the ecosystem dynamic rather

than to preserve an optimal ecosystem state. However, to date little is known about the whole

ecosystem structure and functioning of coral reefs, and even less about how feedbacks (social

and ecological) affect system dynamics.

With the objective to better understand complex interactions of the ecosystem dynamics we

developed a trophic model that assesses how acute combined effects of natural disturbances

(such as crown-of-thorns sea star outbreaks or cyclone events) and local fisheries dynamic in

coral reef trophic cascade.

Based on a case study in Moorea Island (French Polynesia), we present a dynamic and spatially

explicit trophic model that highlights fundamental ecosystem functions of an exploited coral

reef. In particular we show that, according to the way that communities use marine resource

through fishing, different key ecological processes are affected, having different consequences on

the coral reef resilience. These results can inform and guide robust resilience-based management.







Speaker



160



Where fishing meets function: the

intersection of spearfishing selectivity and

functional roles of herbivorous fishes on

Fijian coral reefs

Ryan Mcandrews

1



∗† 1,2,3



, Sebastian Ferse 1 , Sonia Bejarano



1



Leibniz Centre for Tropical Marine Research (ZMT) – Fahrenheitstr. 6, 28359 Bremen, Germany

2

University of Bremen – Bibliothekstr. 1, 28359 Bremen, Germany

3

New England Aquarium (NEAq) – 1 Central Wharf, Boston MA 02110, United States



Herbivorous coral reef fishes are simultaneously important to the health of coral reef ecosystems and as sources of protein for reef-side communities throughout the tropics. Reconciling

these two value systems is a major focus of fisheries management, but how the two might interact is not well understood. We employed a dual perspective, trait-based approach to examine

the intersection of ecological and social importance of herbivorous coral reef fishes in the Fiji

Islands. Consulting published literature, we built a matrix of functionally important traits to

classify the functional versatility and uniqueness of species observed using underwater visual

census and remote cameras at twelve sites across four islands. Surveys of the principal market

in Suva were conducted over a three-month period and revealed a large variety of herbivores,

chiefly caught by spearfishing. The available catch was dominated by a few species that did not

numerically dominate natural assemblages. Fishers’ selectivity for these species was confirmed

during interviews with fishers from the same twelve areas. Consistent physical and behavioural

traits underpinned the desirability and/or catchability of valuable and popular species. Additionally, some of the more popular and valuable species were identified from transect and

camera data as relatively rare and functionally unique, while some appeared to be functionally

redundant. With some fishes, traits that corresponded to functional importance also made them

desirable to fishers. The overlapping of such traits is likely resulting in the selection of functionally important species, which could in turn impede critical aspects of herbivorous fish functions.

Understanding what traits make a species a preferred target or functionally important could

prove useful to local communities in lessening the overlap between the two, by shifting fishing

selectivity from functionally unique to relatively redundant species and reducing the impact of

fisheries on ecosystem functioning.









Speaker

Corresponding author: ryan.mcandrews@my.jcu.edu.au



161



B2/ Marine Reserves as Tools for

Ecosystem-Based Fisheries

Management in the Indo-Pacific



162



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