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article imageOp-Ed: The codfish numbers game — Less codswallop, more science, please

By Paul Wallis     Dec 11, 2011 in Environment
Sydney - One of the most important fisheries projects in history, the restoration of the famous North American cod fisheries, is getting fishier by the second, thanks to confusing reports of both sparse and plentiful fish populations.
The New York Times:
GLOUCESTER, Mass. — Federal regulators are considering the unthinkable in New England: severely restricting — maybe even shutting down — cod fishing in the Gulf of Maine, from north of Cape Cod clear up to Canada. New data suggest that the status of the humble fish that has sustained the region for centuries is much worse than previously thought.
Fishermen insist that there are plenty of cod and that the real problem is fuzzy science. They say the data are grossly inconsistent, pointing to a 2008 federal report that concluded that Gulf of Maine cod, though historically overfished, were well on the way to recovery.
The one undisputed fact is that fishing boats are in fact catching lots of cod. Some boats are trying to buy up licenses.
Meanwhile, this bit of information:
But researchers now say the survey might have sharply overestimated the number of young cod; the new data suggest the spawning population is at only about 20 percent of the rebuilding target. The estimates are based on a mathematical model that uses data from a number of sources, including catch records and research trawlers that fish in the gulf several times a year.
This is an ecologically critical project for the world's fisheries. If successful, a working method for rehabilitating the world’s hideously overfished oceans could be considered viable. Fish provide a lot of the world’s protein, and without effective operations to re-establish the natural populations at working levels, the oceans could become a large desert. Guessing is not an option.
Fish with an audit trail
There are some problems with using mathematical models. While theoretically forming a reasonable base for assumptions, the ocean populations of fish are flexible and subject to various environmental issues, events and local situations on a continuous basis. Populations have significant thresholds. Big populations can handle these thresholds, small populations can't. You'd need some damn good numbers to cover all these issues.
There is, in fact, another way of checking on the cod numbers- Checking their environmental supports. These fish actually have an audit trail. The only sure thing is that big populations of fish need environmental supports. If those supports aren't there, neither are the fish.
1. Check their food chain- To survive, predators like cod can crash in numbers if their prey species are scarce. Adult breeding age cod can take mackerel, for example. If mackerel numbers are up or down, the breeding cod are under more or less stress. Young cod have smaller prey, which can also be assessed for their ability to support a new generation of cod.
2. Check environmental threats- Jellyfish plagues can affect fry numbers, trashing the breeding population stats. Parasites can also affect adult cod numbers. Diseases can also produce various effects.
3. Check water temperature variations and water quality- The Grand Banks have two currents affecting them- the warm Gulf Stream and the cold Labrador currents. Variations in water temperature are both seasonal and annual. A bad breeding year would probably coincide with a temperature variation and perhaps also allow in other environmental hazards like invasive species. Water quality issues may include acidity, salinity, pollution or microorganism contamination.
Good catches, unfortunately, can be purely local or can be a result of efficient fishing. While some of the numbers obviously do point to lots of fish, if those numbers are purely local or one-off catches, the numbers are still blurry.
Fish may congregate in good areas and carry out their own version of “over-fishing”, wiping out a resource locally.
The audit trail approach will also establish the ability of the fishing grounds to support high populations or not. This actually can be done systematically, too, so there’s a reasonable chance of monitoring the health of fishing ground on an ongoing basis as well.
This is so important. The early European and American accounts of cod fishing in these waters are fascinating. You can see the writers struggling to describe some of the most productive fishing grounds on Earth. They ran out of superlatives. Environmentalists, fishermen and governments ran out of superlatives trying to describe the fish population crash.
So let's lose the adjectives and get down to some hard numbers. These waters are still historically important, perhaps never more so. If the cod fishing grounds can be restored in the middle of the busiest part of the Atlantic, so can the rest of the world’s fisheries. Getting this right is critical. Attempts to manage the cod in the North Sea failed, and took big fishing industries to oblivion with them. This may be the best, but close to last, chance to ensure the cod of North America survive. Getting the numbers right is the only game in town. Accurate counts are the only shot at proving the success or failure of the conservation efforts.
This opinion article was written by an independent writer. The opinions and views expressed herein are those of the author and are not necessarily intended to reflect those of
More about codfish numbers north america, codfish conservation, codfish ecology, audit trail for predator ecosystems
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