Managing Food Webs: Field Testing Systems Ecology

Systems ecology. Born of nuclear weapons production and the Cold War, forging science and engineering into an explanatory alloy of great power. Unprecedented insights into dynamics of tropical, tundra, desert, deep marine, and many other biomes were generated by systems ecologists. In systems dominated by humans, probably the most progress was made in terrestrial agroecology. Urban ecosystems turned out to be such a stew of economics, sociology, and biology that the tools of systems ecology provided few breakthroughs. Similarly, fisheries management, traditionally conducted on the basis of population biology, was a weak spot in the ecosystems armor.

But. Fisheries ecology, perhaps via aquacultural multidisciplinary bridge building, has made serious systems headway in the past couple of decades. Massive academic efforts have been thrown at characterizing and parameterizing a wide range of aquatic tropic webs around the world. An enormously successful estuarine restoration project (the Delaware Estuary Enhancement Program, http://www.pseg.com/info/environment/estuary.jsp) put a consortium of regulators, academics, consulting scientists, and other local and environmental stakeholders into play to institute a systems-driven impact offset of great overall value. And recently the Atlantic States Marine Fisheries Commission voted a deep reduction in the allowed harvest north Atlantic menhaden stocks.

Menhaden.  A schooling fish species not too small, not too large, just right to serve as a primary food source for predators ranging from barracuda to whales. And whose population behavior puts massive schools of lipid- and protein-rich fish not too deep, not too shallow, just at the right depth of the ocean to be the base of food chains yielding everything from commercially harvested mackerels, tuna and billfish to dolphins, porpoises, and squids. Really, really important component of the Atlantic marine ecosystem.

And a really important source of industrial materials as well. Massively harvested for processing into commercial fish bait, fish oil and protein meal and other useful materials. Valuable.

But vulnerable. A debated but substantive proportion of the annual menhaden production is being diverted from ecosystem to industry. How much to cut that diversion and how intensively to regulate the fishery were serious matters of debate. Remarkably, there was little debate, even among diverse stakeholders, over the need for some diversion.

Thus, the vote. The council voted heavily in favor of a 20% catch restriction and additional monitoring and population evaluation.

Score one for systems ecology. A field holding up on skinny legs in a world built on sturdy plinths of heavily funded subcellular engineering and molecular biochemistry. For a sustainable world, we need all our scientific tools, applied rationally, cogently, effectively. The wisdom and the will and the logistics and the politics involved in doing so are not going to be easy to come by. But maybe this menhaden decision is a sign that thing could shift in our direction. Let’s hope so!