zaterdag 29 december 2012

Mapping marine economics (4): Fishers are not alone anymore

One of the major attractions of Scheveningen (if you can pronounce that you've successfully adapted to Dutch culture) is a 360 degrees painting by the Dutch painter Hendrik Willem Mesdag. It depicts the North Sea coast near Scheveningen in the nineteenth century, long before its neighbouring city, The Hague, absorbed this coastal fishing village in one big agglomeration. Mesdag created an illusion that worked surprisingly well: there appears to be depth in the painting and you feel like standing on a dune watching over the beach, or looking down on the village with its neat little houses, or the villas where rich city folk spent their free time. What is also striking is the dominance of fishing, together with transport, in the coastal zone. You see some sunbathers, but they are easily outnumbered by fishers and other workers in the fishery, such as the horsemen towing the bomschuiten (flat-bottomed fishing vessels, a bit like the pink).

How different is it nowadays. International trade has mushroomed. We have largely replaced sails and steam engines by combustion engines running on oil and gas, scattering drilling platforms all over the North Sea to get to the stuff. Wind is making a come-back as wind turbines are forming entire forests in the open sea. Meanwhile, fishing has become something to limit rather than promote: in Mesdag's days the British scientist Thomas Henry Huxley called fishery resources "inexhaustible", but for numerous stocks we have actually found those limits and are now concerned about crossing them. And we're not only concerned for edible species, but also for marine life in general: enter marine protected areas.

So many uses, so many users, so little resource
Like the North Sea, many marine and coastal ecosystems have many different uses, many different users, and many different ways to meet the users' needs. Mangrove forests provide coastal protection, a nursery ground for wild fish, a source of juvenile shrimp for extensive shrimp farming systems, and a fascinating ecosystem to float through for tourists. Likewise, other coastal ecosystems like mudflats and coral reefs provide a variety of goods and services to a variety of users. And none of these biomes are limitless.

Given this variety of uses it is not surprising that policy makers need to make many tradeoffs. How far are we willing to limit fishing for an extra gigawatt of wind energy? How do we trade off port capacity against tourism? Does the income generated by an extra hectare of intensive shrimp aquaculture offset the loss in biodiversity and coastal protection?

All these examples are tradeoffs between uses, but also within one and the same use policy makers have to make difficult choices. What is worse, a small flood every year or a big flood every ten years? How do we rebuild fish stocks if local communities depend so much on fishing that they cannot miss a single year of it?

Note that simply putting a price tag on services may not be enough: the average per hectare value of a mangrove forest may be low when the forest is large, but once we have cut most of it the last few remaining hectares will be much more valuable. Moreover, aggregating monetary values over all stakeholders and over time may give you a single figure (the net present value), but this simplicity obscures problems of poverty and income distribution. So we may need to consider the entire tradeoff.

Tradeoff analyses and bioeconomic modelling
I have done tradeoff analyses of dairy farming and biodiversity conservation in my PhD thesis, and I recently submitted a paper with a former MSc student of ours, Matteo Zavalloni, and fisheries ecologist Paul van Zwieten where we analyze the tradeoff between shrimp aquaculture and mangrove conservation in a coastal area in Viet Nam. Both analyses are spatially explicit, i.e. we analyze not only how much of something can or should be done, but also where. The "where" question is quite important as many uses of marine areas (shipping, fishing, aquaculture) have a spatial dimension.

So this will be one of my major focus points: developing tools to make quantitative tradeoff analyses of coastal and marine ecosystems. I'm very much a bioeconomic modeller. I guess it's the geek in me: I've always been terrible at practical technical stuff (the holes my house's walls and the crappy paint jobs on my window panes bear witness to that), but I enjoy the patient development of a complicated quantitative model, or an insightful analytical model. I also enjoy the interdisciplinary nature of this work: you need to collaborate intensively with other scientists, mainly ecologists, to do it right.

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