The Importance of Thinking Big:

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The Importance of Thinking Big

• Addressing large-scale and global change issues
  through marine and fisheries biological research

Daniel Pauly Fisheries Centre University of
British Columbia Vancouver, Canada
A presentation originally created for
presentation at Woods Hole, Mass., Feb. 2, 2001
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This contribution

• Was originally created for an event connected
  with Black History Month (February), over a year
  ago
• Thus, it is both dated, and has a very personal
  feel
• Nevertheless, it may appeal to Aqualink members
  in that it describes how a young scientist (yes,
  I was once young!) broadened his vision, and
  ended up leading a project (see
  www.fisheries.ubc.ca/project/saup) with a global
  scope
• The slides have not been updated visit our web
  site for the follow up to this presentation.
• So here we go

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This also being a report of how one scientist
grew with age

• The object of my first paper (1973) had a length
  of 30 cm

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A benthos washing machine
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This also being a report of how one scientist
grew with age

• The object of my first paper (1973) had a length
  of 30 cm
• The study area of my Ms thesis (1974) was a one
  km2 lagoon in Ghana, West Africa

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On the ecology of a small West-African lagoon
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This also being a report of how one scientist
grew with age

• The object of my first paper (1973) had a length
  of 30 cm
• The study area of my Ms thesis (1974) was a one
  km2 lagoon in Ghana, West Africa
• The survey area during my first job, in
  Indonesia, (1975-1976) was 106 km2

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The Sunda Shelf, Indonesia
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This also being a report of how one scientist
grew with age

• The object of my first paper (1973) had a length
  of 30 cm
• The study area of my Ms thesis (1974) was a one
  km2 lagoon in Ghana, West Africa
• The survey area during my first job, in
  Indonesia, (1975-1976) was 106 km2
• And I now work on the global ocean (3.6108 km2).
• Definitely a change of scale.

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But why such broadening of scale?

• In the 1970s, the idea was that the fisheries of
  developing countries should well develop, and
  then be managed using analytic models such as
  were then applied to the management of North
  Atlantic fisheries

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Developing Fisheries in Developing Countries?
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But why such broadening of scale?

• In the 1970s, the idea was that the fisheries of
  developing countries should well develop, and
  then be managed using analytic models such as
  were then applied to the management of North
  Atlantic fisheries
• Hence, one needed to know the growth and natural
  mortality of key species

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Moreover, hundreds of species were showing up in
catches, and they could not be aged and sampled
as can be done, e.g. in New England

• Hence the need to develop length-based method for
  the estimation of growth
• And the need to develop a predictive model for
  estimating natural mortality from easy-to
  estimate parameters
• And, as well, the need to ensure that available
  estimates of these parameters did not disappear
  in the gray literature.
• These then led to the development of.

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Electronic Length-Frequency Analysis (ELEFAN),
widely used in developing countries
(see www.fisat2000.org for updates)
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A widely-used empirical model for estimating M
(natural mortality) from growth parameters and
mean environmental temperature
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See www.fishbase.org to learn why
We get over 750,000 hits permonth.
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One neat aspect of FishBase, incidentally, is
that its high quality standards generate equality
among its contributors, wherever they are from.
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But then, all of this assumes single-species
management works.

• Yet every species the fisheries exploit is
  embedded in an ecosystem, both as predator and
  prey,
• and thus the mutual impacts of fisheries
  exploiting different species must be considered.
• Hence the need for ecosystem-based management.

No fish is an island
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Fisheries form part of complex ecosystems
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Fortunately, the franchise for a neat ecosystem
modeling approach (Ecopath) was available.

• And so Ecopath was made accessible ( taught) to
  a vast number of colleagues (2300 registered
  users in 120 countries, see www.ecopath.org)
• Which resulted not only in a better understanding
  of the concept of trophic levels (TL), but also
  in many estimates of TL

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Trophic level the concept
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Top predators
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Prey fish
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Trophic level
? 10
Zooplankton
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? 10
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Phytoplankton
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So it became possible to estimate TLs for the
worlds fisheries, using two sources of data

• The TL for species of species groups in FishBase
• And the global FAO database of fisheries catches.
  

• The equation used TLi1 DCij? TLj for
  (groups of) species i with prey j and
• ?TLk Yik ? TLi / Yi given catches (Y) by year
  (k)
• simple stuff.

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This led to two rather visible contributions on

• Primary production required to sustain global
  fisheries (Pauly and Christensen, Nature, 1995)

• Fishing down marine food webs (Pauly et al.,
  Science, 1998)

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PPR to Sustain Global Fisheries
Non-tropical shelves 35
Tropical shelves 35
Rivers/ lakes 24
Terrestrial average 35-40
Open ocean 2
Coastal/reefs 8
Upwelling 25
Nature 1995, 374
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Global fishing down the food web
Marine
Freshwater
Science March 1998, 279
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(No Transcript)
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And, because one shouldnt quit when on a roll,
we are working on

• Harmonizing global ecosystem classifications, to
  accelerate the transition to ecosystem-based
  management
• Mapping the world catch, using rule-based
  approaches (not coloring crayons!)
• Comparing the present state of ecosystem on
  ocean-wide scale with their state 50 years ago.

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This, for example isimportant, but lacks finesse
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But then, catches by FAO area are not much
better..
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Here are catches by half degree squares. Better.
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And this will allow us to start

• Evaluating the cost of rebuilding some or our
  depleted marine ecosystems, or of not doing so
• Inferring where changing fisheries operations
  will conflict with conservation of biodiversity
• Interfacing with predicted scenarios from global
  circulation models, and hence join the community
  that attempts to deal with the changes that
  global warming will cause.

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I will stop here any more growth would be too
much

• Thanks to Ambrose Jearld, for having me invited
  to speak here, and to all those who helped me
  have something to say Villy Christensen, Reg
  Watson and my other friends at UBC, Prof. G.
  Hempel in Germany (for supporting me as an unruly
  student), Jack Marr for hiring me as an ICLARM
  postdoc (against sound contrary advice) and all
  these wonderful colleagues on five continents
• My recent research is supported by the Pew
  Charitable Trusts, Philadelphia, and National
  Science and Engineering Council of Canada.