Ecological Geography as Framework for a Transition Toward Responsible Fishing by hellais

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									Ecological geography as a framework for a transition towards responsible fishing
by

Daniel Pauly Reg Watson
and

Villy Christensen Iceland-FAO Conference on Responsible Fisheries in the Marine Ecosystem Reykjavík, Iceland, 24-28 September 2001

The fisheries of the North Atlantic are in deep trouble, as illustrated here by trends in biomass (blue) and fishing mortality (red) from single-species assessments.

Trends from R.M. Myers’ online database http://www.mscs .dal.ca/~myers/w elcome.html

Many believe that addressing the issues raised by these worrying trends requires, among other things, a transition towards ecosystembased management. This itself will require :
• A definition of ecosystems ‘on the ground’, and hence, • A return to the use of maps as tool for conceptualizing and presenting data.

An early map …

Distribution of plaice in the North Sea, modified from Garstang (1909)

The FAO system of 18 statistical areas is useful, but too coarse for ecological work …

The system of LME identified by K. Sherman and collaborators is perhaps more useful …

Oceanic ‘biomes’ can also serve for global ecosystem classification

Modified from Longhurst (1998)

… especially as the biogeochemical provinces in the coastal biome largely overlap with LMEs …

The approach developed by the Sea Around Us Project for mapping fisheries (catches) uses:
• Catches by FAO area; • Distribution maps for all fish species or groups (> 1,000) included in the FAO global catch statistics, and in national databases; and • Rules regulating countries’ access to the EEZ.

This rule-based approach is gradually being refined …
Taxon (what) Country (who) FAO Area (where)

Taxon Distribution Database

Fishing Access Database

Spatial Reference Database

Common spatial cells?

YES
Assign catch to common cells

Over 95% of the global marine catch has been assigned to ½ degree spatial cells so far, and we are now improving the underlying databases …

… and has already generated interesting results …
(note high values off Chinese coast)

Watson and Pauly (Nature, in press)

Global marine catches …
(a)
90 85 80
El Niño events

Global catch (t ·10 6)

75 70 65 60 55 50 45 40 1970
El Niño event

Uncorrected Corrected Corrected, no anchoveta

1975

1980

1985

1990

1995

2000

Watson and Pauly (Nature, in press)

We can also zoom onto the North Atlantic and show a catch map, e.g., for the 1990s.

More interesting, however, are biomass maps for the North Atlantic. Here is the approach we used:
• Re-express biomass of 18 ‘Ecopath’ models in half degree cells using ‘Ecospace;’ • Estimate parameters of a statistical model for predicting observed biomass by half degree cells from physical (e.g., depth) and biological (e.g., catch) properties of cells; • Predict biomasses in entire North Atlantic from properties of all (about 20,000) cells.

The resulting biomass maps are illustrated here for predatory fish (TL=3.75) in the 1950s …

… in the 1970s …

… and in 1999 …

… and conversely for fishing intensity (catch/biomass) in the 1950s …

… in the 1970s …

… and in 1999.

Reality check: our maps, jointly, generate the same trends as the single-species assessments shown at the beginning.

The reason for the quickly worsening situation of the North Atlantic ecosystems is on this map, where areas with no fishing whatsoever are shown in green …

Acknowledgements…
• Thanks to the Pew Charitable Trusts, Philadelphia;

• Fisheries Centre, Faculty of Graduate Studies, UBC; • Members of the Sea Around Us Project;

and many others.


								
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