Thursday, January 21, 2010

Human Impacts on Marine Ecosystems

The magnitude of human impacts on marine ecosystems can at times be difficult to grasp. Undoubtedly humans are impacting our oceans and the biology they support. While scientists and society have acknowledged the threats posed by climate change and ocean acidification the range of activities which degrade the productivity and resilience of marine ecosystems are poorly understood.

Here is a thought provoking email from Bill McMillan on the subject:

Bill Bakke recently sent out an excellent quote from the book The Unnatural History of the Sea (the email and quote below).
Attached is a review of the book. Also attached is a news article about the increasing acidity of the upper 300' of the North Pacific.

Regarding the latter, back in 1999 or early 2000s the sky on the Skagit was continually obscured with a brownish haze that I subsequently learned was from dust storms raging across the deserts of northern China and Mongolia. This means that northern Puget Sound is in direct line with the prevailing air flows from northern Asia much of the year. In the past 4-5 years, in particular, the metal roof on the north side of our house has gone from silver to pervasive orange of rust. The roofs facing the south, west, and east on our home and all the outbuildings have not been similarly affected with little change the past 11 years. My suspicion has been it is related not only to the northerly direction (as we know moss grows on north side of trees), but that it has been greatly exacerbated by the recent increased industrial pollutants from China carried here by the prevailing winds (whatever pollutants that are carried include some that are particularly active in the shade and coolness on the north side houses, but presumably are also particularly active in the cooler and wetter areas of forested landscapes). In the case of pollutants carried from Asia that may be driving the acidity of the North Pacific (our own pollutants driving the acidification of East Coast forests and seascapes), this is likely one of the components contributing to the particularly noticeable decline in steelhead, and more recently Fraser sockeye, in the Georgia Strait/Puget Sound region. But it is not alone.

Anadromous fishery managers often call to their defense a convenient black hole represented by so-called "ocean conditions" that no one has control over as natural events beyond their ability to alter. But is this really the case? Are the oceans what we have made of them -- from little regulated harvests of bait fish and bottom fish; to scouring of the ocean floor with trawlers leaving devastated swaths in their wake; to broken away drift nets that continuously remain fishing for years to come; to massive releases of hatchery reared fish with little savvy in the wild attracting easy living for predator populations and resulting stresses on wild fish productivity due to both the increased predators and competition for limited available food; to coasts lined with salmon farms as factories for disease, proliferation of sea lice, and dependency on greater poundage of native fishes to feed those in the pens than the pens themselves produce; to lack of clean air and clean water standards for those nations without them and otherwise insufficient, or too little enforced, for those that do have them.

Do we need to better break down the terminology? There are legitimately cyclic conditions at sea that have a basis in what we broadly call nature. But both the highs and the lows of these cyclic conditions that result in swinging alterations in ocean productivity are in a continual declining trend due to the human caused factors listed above. Some of these human caused factors are directly related to fisheries management itself, and/or to the environmental standards fishery managers sometimes have significant opportunity to enforce, or in their ability to generate data from which to indicate the changes that have to occur in how we as humans operate. Then again there are some factors that fishery managers of one nation ultimately have no control whose source is another nation thousands of miles away. Although the latter we can't do much about beyond the goal of greater international cooperations through the agreed problem of climate change that we have all induced, there remain the other components of human conditions on the oceans we do have control over at the more localized scales of management in Washington, Oregon, British Columbia, and Alaska.


No comments: