North Atlantic herring stocks have failed to recover despite a 25 year fishing ban. The haul of Peruvian anchovies have plummeted from 11 million tonnes in the late 60's to less than 100,000 tonnes today. These are some of the effects of the intrusion of capitalism into the hunter gatherer economy of fishing, on which humankind is dependent for a large proportion of its protein. However a highly significant article in the latest New Scientist (3 Feb), discusses the Allee effect, first described by Warder Allee 50 years ago, on many other species on land or in the sea, whose numbers may fall substantially. These effects explain why below a certain point, the species may just not be able to recover, because a minimum population density is necessary for successful reproduction as a result of a number of adaptive mechanisms. Some scientists suggest that Allee effects are relevant in the populations of many species. Essentially this is saying that populations cannot be expected simply to recover in a linear way if numbers fall, because of complex non-linear systems involving the interaction of individuals of that population. The Allee effect has been little studied up to now because of simplistic approaches to population prediction. If they are relevant, and on theoretical grounds, IMO they appear to be highly probable, we can expect far more population extinctions in the next hundred years, without the most carefully coordinated, essentially socialist, management of the land, seas, and total environment. Even so, many more species extinction than at present predicted, could be inevitable, with substantial reduction in the bio-diversity of the planet. Chris Burford London _______________________________________________ Crashlist website: http://website.lineone.net/~resource_base
