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[Tuna
Ecology and Biology]
Ecosystem
Research
Up to the 1980s, fisheries have to a large extent focused on obtaining
information on the exploited resources in a ‘single-species’ management style.
The concept of ecosystem-based management of fisheries emerged in the 1982 UN
convention on the Law of the Sea. In the last two decades, emphasis was put on
ecosystem resources interaction, and the fact that these interaction are
sometimes more important than the impact of the fisheries.
However, adequately assessing the status of an ecosystem would require
assessments and monitoring of all major species. Fisheries data are not
available for most non-target species, scientific surveys are expensive and
time-consuming, and ongoing monitoring may be logistically impossible. The best
option seems to be the development of models that represent the principal
elements of the ecosystem and description of biomass flows between them, based
on the best available information on who eats who.
Fisheries research has lately focused on ecosystem modeling as a result of FAO,
UNEP and EU incentives as well as Agenda 21 from Rio de Janeiro 1992 Earth
Summit. This has led to the development of numerous modeling tools. They have
not as yet proved themselves as management tools, but are paving the way to
future implementation of ecosystem-based management of fisheries.
The Oceanic Fisheries Programme of the SPC is developing 2 projects to address
the ecosystem issues:
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The UNDP/GEF project: Food web study of the western and central
Pacific Ocean tuna ecosystem
In February 2000 a five-year UNDP GEF Strategic Action
Programme for International Waters of the Pacific Island Region was signed to
focus on the threat of the unsustainable exploitation of living and non-living
resources in this region. The project identifies the Westren Pacific Warm Pool
Ecosystem is the defining feature of the region, with boundaries that coincide
with western and central Pacific Ocean tuna fishery. This project has two main
components: oceanic and coastal and the Food web study is part of the first one.
The oceanic component focuses on the management and conservation of tuna stocks
in the western central Pacific and its objective is “to enable conservation and
sustainable yield of ocean living resources”. The oceanic component is to be
implemented by the Forum Fisheries Agency (FFA) and the Oceanic Fisheries
Programme (OFP) of the Secretariat of the Pacific Community (SPC).
Biological research on the Warm Pool Ecosystem, and more specifically the food
web study  of this
area are an important part of Activity 3.5 of this UNDP/GEF project: “Improved
scientific advice relating to regional tuna stocks, non-target species and the
oceanic ecosystem available to support management decision-making”.
[more...]
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The PFRP project: Trophic structure and tuna movement in the cold tongue-warm
pool pelagic ecosystem of the equatorial Pacific
The project “Trophic structure and tuna movement in the cold tongue-warm
pool pelagic ecosystem of the equatorial Pacific” was submitted to the Pelagic
Fisheries Research Programme of the University of Hawaii who funded this
three-year project starting in January 2003.
The objectives of this project are based on recent modeling that suggests that
tuna productivity in the western and central Pacific Ocean is tied to upwelling
along the equator in  the
central and eastern Pacific (Lehodey, P. 2001. The pelagic ecosystem in the
tropical Pacific Ocean: dynamic spatial modelling and biological consequences of
ENSO. Progress in Oceanography 49: 439-468). The project proposes to test this
hypothesis by combining diet analysis, stable isotopic compositions, food-web
modeling, and stable isotope markers to trace tuna movements and trophic-level
variation in the equatorial Pacific.
[more...]
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