I've been banging on about the benefits of omega-3 fatty acids for human health for a long time in internet years - more than a decade. Research papers on the subject were sparse in those early days but they have become common now. A new one notes that omega-3 is a psychoactive substance that helps us be mellow.

In a study of 106 healthy volunteers, researchers found that participants who had lower blood levels of omega-3 polyunsaturated fatty acids were more likely to report mild or moderate symptoms of depression, a more negative outlook and be more impulsive. Conversely, those with higher blood levels of omega-3s were found to be more agreeable.

"A number of previous studies have linked low levels of omega-3 to clinically significant conditions such as major depressive disorder, bipolar disorder, schizophrenia, substance abuse and attention deficit disorder," said Sarah Conklin, Ph.D., a postdoctoral scholar with the Cardiovascular Behavioral Medicine Program in the department of psychiatry at the University of Pittsburgh School of Medicine. "However, few studies have shown that these relationships also occur in healthy adults. This study opens the door for future research looking at what effect increasing omega-3 intake, whether by eating omega-3 rich foods like salmon, or taking fish-oil supplements, has on people's mood."

A post last year discussed a study that showed that omega-3 fatty acid consumption by infants "raises baby IQ dramatically". These mind and mood effects are in addition to previous work showing benefits for hearts and bones, reducing problems with heart disease and rheumatoid arthritis. Hurray for omega-3!

I've also been banging on about sensible sources of omega-3, pointing out again and again that one of the best and easiest to get sources of these nutrients is from beef and dairy products that have been raised the old fashioned way eating grass and weeds in a meadow as opposed to scarfing twinkies (grain) in a feedlot. You can get healthy foods without risking being dosed with mercury and other pollutants common in fishes.

One of the issues for producers of pastured products is that over the years of increasing use of grain finishing in confined animal feeding operations the genetics of domestic livestock have drifted toward animals that perform better in these conditions. Breeders pay close attention since feedlot operators pressure them to deliver animals that fit their system by paying more for such animals, or more accurately, discounting those that don't fit as well. US producers of pastured products have been going to other nations such as New Zealand that do not use much grain to find sires that have been selected for grazing performance rather than grain performance.

Everything we do affects genetics. From the very beginning of agriculture humans have altered the genetics of food and fiber plants by their choices about which to harvest. Every predator does this. When a cow eats one plant rather than another - preferring its smell, taste or texture - it participates in a Darwinian system of genetic drift. Agriculture institutionalized such choices since it wasn't just harvest time selection it was also sowing time selection. Some of this was inadvertent rather than conscious choosing, but the effects are identical.

We have been doing the same thing to fisheries.

In most commercial fisheries, fish are removed on the basis of size. There are minimum, not maximum, size limits. But Conover and Munch’s results show that this approach may have results that are exactly the opposite of what is intended. Within only four generations, taking out larger fish produced a smaller and less fertile population that also converted food into flesh less efficiently. In contrast, catching smaller fish increased the average size of fourth-generation fish to nearly double that of fish in populations where only the larger fish had been taken. In the short term, catching the largest fish gave the highest yield and mean weight of fish. But this effect was temporary. After four generations, removing the smaller individuals gave nearly twice the yield of the populations from which larger individuals had been harvested. One reason for this greater productivity was that the larger adults had a greater reproductive potential. Another was that, as expected, removing small individuals selected for fast growth.

Additional evidence is accumulating—from modeling, lab experiments, and studies of wild populations—that the heavy exploitation of fish stocks is indeed causing them to undergo genetic change. Richard Law, an evolutionary biologist at the University of York in the U.K., believes that the effect of evolution on yield has the potential to be quite large (3). Some simple calculations, he says, on the life history of the Northeast Arctic cod suggest that selection due to fishing mortality could halve the yield of the fishery, with the exact reduction in yield depending on the levels of fishing mortality applied on the spawning and feeding grounds. These results should certainly give commercial fisheries managers something to think about.

This isn't really news but it is formal research that supports practitioner wisdom and earlier studies on related issues. There has been some work on lobsters, for example, that supported old ideas that the biggest and oldest lobsters should be freed if caught since they are worth more as breeding stock than as supper. But it's hard to do such management on a large scale, especially in the oceans since it is a commons of sorts with open access rather than well defined or even definable interests. Efforts to institute property rights using transferable harvesting permits with limits defined by regulators have had some success, but scientists are pessimistic about longer term prospects.

Given the accumulating evidence of the obvious, it is difficult to be optimistic. Each harvest introduces tiny, hard-to-reverse genetic changes into a population. By ignoring these changes, we run the risk of reducing productivity in ways that will not be easily reversed in the future. It is a debt we are running up, a Darwinian debt that we owe to future generations of fishermen.

For decades it has been a struggle merely to bring the massive overexploitation of fisheries under control. Today’s struggle involves trying to rebuild fish stocks, and that is difficult enough to do. Changing to maximum-size restrictions would involve something of a sea change in attitudes in fisheries management. And yet this alone is probably not enough. Scientists such as Andy Rosenberg of the University of New Hampshire, a member of the U.S. Commission on Ocean Policy, believe it is necessary to work on multiple fronts if we are to recover the huge losses induced by the overexploitation of the past. We need to protect fish of all ages, we must safeguard genetic diversity, and we must conserve functioning marine ecosystems.

Whatever the science reveals, action is hard to achieve in a world of competing priorities. How on earth does one manage stocks for the day after tomorrow, when managing them for tomorrow is difficult enough? Politicians, who are ultimately faced with making the decisions about how we manage our resources, are caught between good long-term management and harsh short-term realities for their constituents. With politicians, as with fish, it is survival of the fittest. It is a shame that fish cannot vote.

She has a point. Politics isn't a promising way to manage systems . . . any system. There are those who think it should just be given up as a bad job and refuse to consume wild fishes. Farmed fishes have issues as well, especially predator species that are fed prey fishes caught in the wild. Perhaps worse, some farmed fishes are fed grain products. Such farms are confined fish feeding operations and have all of the negatives of feedlots for other land living livestock including a reduction in quality, especially a drop in omega-3 fatty acids. The twinkie diet strikes again! There would also be a genetic drift in farmed fishes just as there has been with cattle.

Any way I look at it I end up preferring to get my omega-3s from grass based meat and dairy systems. It's the least harmful type of agricultural system - less harmful than hunting wild stocks and less harmful than field and row crop based food systems - and it's the most healthful. Say cheese:-)