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Gigantothermy in whale sharks – tracking the behavioural strategies of a homeothermic ectotherm, Mark Meekan [et al.]

Gigantothermy in whale sharks – tracking the behavioural strategies of a homeothermic ectotherm, Mark Meekan [et al.]

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How effective are front-line community

programs in addressing the threats to

marine species and habitats? A case study

from the world’s largest manta ray hunting

community.

Sarah Lewis



∗ 1,2,3



, Shawn Heinrichs



1,2,4



, Mochamad Iqbal Herwata Putra



2



1



2



Manta Trust – Catemwood House Corscombe Dorchester Dorset DT2 0NT, United Kingdom

Misool Foundation – Misool Baseftin, Perum KPR, Pepabri, Kelurahan Malaingkedi, Sorong, Papua

Barat, Indonesia

3

Sea Sanctuaries Trust – London, UK, United Kingdom

4

Blue Sphere Foundation – New York, United States



There are a lot of questions, and a rise in skepticism surrounding the efficacy of communitybased conservation programs, but as human behavior is the primary driver of global species and

habitat decline surely the societal factors of conservation need to be addressed as a priority.

There are numerous examples of well-intentioned conservation initiatives faltering when they

fail to engage communities in the conservation process. On the other hand, there are also many

cases of community-based conservation initiatives failing when communities are not approached

in the right manner.

In this presentation we discuss a case study from Lamakera Indonesia, the worlds’ largest manta

ray hunting community, with a megafauna hunting tradition going back over 400 years. In 2014

we initiated a program to help Lamakera transition from the unsustainable hunting of manta

rays, whale sharks and other vulnerable marine megafauna to sustainable fisheries and other

alternative livelihoods. In 2016 we expanded the program to include other communities in the

Savu Sea region who were also having a negative impact on the marine megafauna and marine

environment. In the 3 years since the programs inception, there has been a lot of learning,

disappointing setbacks, and exciting successes. Our program has demonstrated that we have

not only affected positive change in the community where we have had our primary focus, but

through a deliberated expansion of our activities to communities in the surrounding region,

there has been a wide-scale and enthusiastic adoption of our conservation messages. As a result,

community driven conservation activities are arising throughout the region, ultimately leading

to significant increases in the protections of manta rays and other threatened marine species and

habitats.

Our experience in Lamakera is demonstrating that even the most difficult communities – a

village nearly completely dependent upon unsustainable fisheries, driven by both destructive

economics and outdated traditions – positive and lasting change can be achieved. We will show





Speaker



291



that environmental protection and long-term economic and cultural wellbeing can go hand in

hand.



292



Incremental analysis of vertebral centra in

wild and captive-bred bull sharks

(Carcharhinus leucas) through

micro-computed tomography

Fabienne Ziadi-Kuenzli



∗† 2,1



, Momoko Sakurai 2 , Katsunori Tachihara‡



3



2



Graduate School of Engineering and Science, University of the Ryukyus – Senbaru 1, Nishihara,

Okinawa 901-0213, Japan

1

Physics and Biology Unit, Okinawa Institute of Science and Technology Graduate University – Onna,

Okinawa 904-0495, Japan

3

Laboratory of Fisheries Biology and Coral Reef Studies, Faculty of Science, University of the Ryukyus

– Senbaru 1, Nishihara, Okinawa 901-2013, Japan



Age determination in tropical elasmobranchs is routinely performed using whole and sectioned vertebral centra. Seasonal variation in calcification rates results in visible bands or rings

which are used as proxies for annual growth. Here, we assessed band deposition in vertebrae of

young bull sharks from a natural riverine habitat at Iriomote Island (n=42), and captive-bred

bull sharks from Churaumi Aquarium at Okinawa Island (n=6) using high-resolution computed

tomography. From reconstructed images of scanned centra, we find that the birth ring is represented by a distinct, thin band in the corpus calcareum. Opaque bands (‘winter bands’)

were comparatively thicker and more prominent, but not present in neonate (0+) centra. All

centra possessed a pre-birth mark, which may correspond with the time of placenta formation

and attachment of placenta in bull shark embryo. Edge analysis and seasonal change in width

of the summer increment in neonate centra was consistent with an annual formation of one

growth band (opaque). Morphometric analysis of pre-birth ring, birth ring, and first year ring

(radia length measured from vertebra focus along the corpus calcareum) showed no significant

differences between wild and captive-bred individuals, indicating that captivity had no marked

influence on growth performance on pups. Overall, CT imaging as a fast, non-destructive and

cutting-edge technology is a powerful tool to visualize band characteristics in elasmobranchs and

to locate growth bands through unlimited virtual sectioning.







Speaker

Corresponding author: fabienne.ziadi@oist.jp



Corresponding author: ktachiha@sci.u-ryukyu.ac.jp





293



Long-term biological monitoring and stable

isotope analysis of Aetobatus narutobiei in

Ariake Bay, Japan: Feeding ecology and

foraging impact on bivalve fisheries

Atsuko Yamaguchi



1



∗† 1



, Mao Watanabe 1 , Yu Umezawa 1 , Keisuke

Furumitsu 1



Nagasaki University (NU) – 1-14 Bunkyo, Nagasaki, 852-8521, Japan



The Naru eagle ray, Aetobatus narutobiei, inhabits areas ranging from the coastal areas of

Japan to the South China Sea. Population has increased since the 1990s in the southwestern

coastal areas of Japan, such as Ariake Bay. A. narutobiei feeds on commercially important

farmed bivalves and is considered responsible for the decrease in bivalve catches in the bay. To

reduce predation pressure on bivalves, a predator control program was initiated in 2001.At the

same time, we studied the life history, behavior, seasonal migrations, and population structure

of A. narutobiei. Detailed information on the feeding ecology of this species and its impact on

bivalve fisheries remains limited, because the occurrence of this species, along with its movement

patterns and food sources, vary annually. Therefore, for the past 16 years, we have monitored

the control program and studied the biology of this species. Long-term monitoring showed a

decrease in disk width and a decline in catch per unit effort. Stomach content analysis showed

mostly bivalves, but the species composition varied throughout the monitoring period. However,

Anadara kagoshimensis has remained the most important prey throughout the study. In the

beginning of the survey, the pen shells, Atrina spp. and the Japanese carpet shell, Ruditapes

philippinarum, was an important prey item for A. narutobiei, but after their abundance declined,

the proportion of the Pacific oyster, Crassostrea gigas, in the diet increased. Isotope analysis

(δ13C and δ15N) of muscle tissue samples suggested that A. kagoshimensis accounts for the

largest proportion of A. narutobiei diet. Moreover, comparative analysis of the stable isotopes

in A. kagoshimensis collected from cultured and natural areas showed that A. narutobiei feeds

predominantly on wild, non-targeted clams. This study demonstrates the possibility of using

stable isotope analysis as a tool to determine both the feeding ecology and foraging impact of a

predator species on bivalve cultures.









Speaker

Corresponding author: y-atsuko@nagasaki-u.ac.jp



294



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