Ecological geography as a framework for a transition towards responsible fishing

by

Daniel Pauly

Reg Watsonand

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 databasehttp://www.mscs.dal.ca/~myers/welcome.html

Many believe that addressing the issues raised by these worrying trends requires, among other things, a transition towards ecosystem-based 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.

Taxon (what) FAO Area (where)Country (who)

Taxon Distribution Database

Spatial ReferenceDatabase

Fishing AccessDatabase

Common spatial cells?

Assign catch to common cells

YES

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 …

This rule-based approach is gradually being refined …

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

Watson and Pauly (Nature, in press)

Global marine catches …

Watson and Pauly (Nature, in press)

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1970 1975 1980 1985 1990 1995 2000

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Uncorrected

Corrected

Corrected, no anchoveta

El Niño event

(a)El Niño events

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.