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Partially protected areas: a conservation middle ground?, April Hall [et al.]

Partially protected areas: a conservation middle ground?, April Hall [et al.]

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Relationships between Zooplankton

Production, Pelagic Fish Production and

Commercial Finfish Catch in Tropical

Shelves

Bruce Hodgson

2



∗ 2,1



Bruce.Hodgson@aurecongroup.com – 116 Military Road, Neutral Bay, Sydney, New South Wales,

Australia 2089, Australia

1

Aurecon Australasia, Advisory – 116 Military Road, Neutral Bay, Sydney, New South Wales,

Australia 2089, Australia



The purpose of this study was to review Ecopath model results for six tropical shelves

(Christensen and Pauly, 1993, Bulman, 2006) to investigate the role of zooplankton production

to pelagic fish production as a fundamental process to inform acceptable levels of fish catch in

these fishery areas, at the trophic ecosystem level. The investigation of the relationships between productions of pelagic fish with acceptable levels of catch was prompted by Allen’s 1971

paper on the ”Relation between Production and Biomass”. Zooplankton production transfers

to small pelagic fish, and from them to pelagic finfish production, was investigated using trophic

transfer efficiencies in the six tropical shelf fishery areas. These relationships were then used

at Heron Island to estimate the potential acceptable level of fish catch from measurements of

zooplankton biomass and estimates of production near Heron Island, in the southern area of the

Great Barrier Reef marine park.

The six tropical shelves were reviewed for the following productivity and fish catch relationships:

Estimating Trophic Transfer Efficiencies from zooplankton to fish;



Determining relationships between fish production and the commercial pelagic fish catches;

Considering the role of fish production in the various fishery areas in relation to acceptable

levels of fish catches;

Estimating pelagic fish production at Heron Island from the trophic transfer efficiencies and

potential fish catch from the tropical shelf relationships between fish production and catch.



The close-fitting relationships between the tropical shelf zooplankton production, pelagic fish

production and fish catch data suggests that the fish catches across all these areas are strongly





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related to the productivity of the fisheries. This suggests that fish catches are at acceptable levels

because they keep pace with the available production inputs from zooplankton production, into

the fishery.

Subject to further investigation, the potential benefits of this approach for fishery management

could include consideration of production based fish catches as acceptable levels in marine parks

and surrounding areas, with protection of appropriate areas (eg. spawing areas) that generate

the fish production supporting the fish catch.



173



Science inventory of the Austral Islands’

marine environment and project of large

marine reserve by the population of the 5

Austral islands

Donatien Tanret

1



∗ 1



, Tihoti Tanepau



2



The Pew Charitable Trusts – Tahiti Gare maritime, French Polynesia

2

School of Tubuai – Tubuai, French Polynesia



A detailed scientific inventory of the Austral Islands’ marine environment has been conducted in 2015 by IRCP, CRIOBE and The Pew Charitable Trusts, with thirty experts and four

field expeditions.

With a total ocean area of about 1 million square kilometers, the Austral archipelago differs

from other island strings in French Polynesia. The diversity of island topographies, the varied

characteristics of the Austral climate between a tropical zone and a temperate one, and the

Australs’ relative isolation has led to a remarkable diversity of life well preserved and a high

number of endemic species, especially among mollusks, fish, coral, and algae. It makes this a

valuable site to observe the impacts of a changing climate. The island of Rapa is a hot spot of

marine biodiversity, with 112 coral species out of the 170 in all of French Polynesia, 250 species

of mollusks and 383 species of coastal fish-10 percent of which are endemic to the island.

In the 1980s, Rapa was able to fix their coastal fish decline through a coastal rahui covering 30% of the coast. This traditional temporary ban on the use of a resource or a territory was

widely used in the Polynesian Triangle. But now, local fishermen are experiencing a collapse of

their pelagic resources because of industrial fishing of which they are not responsible. Therefore,

they want to create a pelagic rahui in the waters of their archipelago. They called this proposal

the ” big rahui of Austral islands ”.

After an extensive series of consultations and a participatory and collaborative process, the 5

municipalities and the population of the 5 Austral islands have proposed a large marine reserve

in the waters of their archipelago. The proposed zoning foresees 5 coastal fishing areas of 20

nautical miles around each island, with boats smaller than 10 meter long. And a large 1 million

km2 no take marine reserve up to the limit of the EEZ where no fishing could occur. This would

help protecting the Austral fishing resources for the 1600 Austral artisanal fishermen relying on

them for their subsistence.







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174



The role of marine protected areas in the

replenishment of local fisheries

Hugo Harrison



∗ 1



, Michael Bode 1 , David Williamson 2 , Michael

Berumen 3,4 , Geoff Jones 5



1



ARC Centre of Excellence for Coral Reef Studies (CoralCoE) – ARC Centre of Excellence for Coral

Reef StudiesJames Cook University TownsvilleQueensland 4811 Australia, Australia

2

Australian Research Council Centre of Excellence for Coral Reef Studies (ARC CoE for Coral Reef

Studies) – 1 James Cook Drive, James Cook University, Townsville, QLD 4811, Australia

3

King Abdullah University of Science and Technology (KAUST) – Thuwal, Saudi Arabia

4

Woods Hole Oceanographic Institution (WHOI) – 266 Woods Hole Road Woods Hole, MA

02543-1050, United States

5

ARC Centre of Excellence for Coral Reef Studies and James Cook University (CoralCoE and JCU) –

ARC Centre of Excellence for Coral Reef Studies Marine Biology and Aquaculture, College of Science

and Engineering, James Cook University Townsville Queensland 4811 Australia, Australia



The precarious state of many coastal marine ecosystems has prompted the use of marine

protected areas (MPAs) as a tool for management and conservation. However, the effectiveness

of MPA networks is contingent upon our understanding of the processes that affect population

dynamics. Since coral reefs are a naturally patchy and fragmented environment, the degree of

connectivity between discrete populations is critical to the persistence of populations and by

extension, the subsistence of local fisheries. We compared observed patterns of larval dispersal

over successive years for two exploited species of coral reef fish in the Keppel Islands, Great

Barrier Reef. We combine parentage analysis with emergent analytical tools in graph theory

to determine the consistency of larval export from a small network of no-take MPAs to nearby

fished areas. Further, we test the old adage that bigger, older and fatter fish make the greatest

contribution to the replenishment of fished population, and provide empirical evidence for the

relationship between fish size and local recruitment success. Our findings give unprecedented

insight into the mechanisms shaping connectivity patterns in coral reef fish and the role of

no-take MPAs in the replenishment of local fisheries.







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