Climate Change and Anthropogenic Influences Preamble
Christine M. Moffitt
Our understanding of the challenges for diadromous fishes has increased manyfold since our first symposium in 1986. In our first symposium, the discussion of anthropogenic influences mainly focused on factors controlling smolt physiology and differences between hatchery and wild fish stocks. Our concerns regarding human modifications of the environment were flow modification and migration barriers, although we discussed the risks of toxic compounds and changes in nutrient/trophic relationships in the freshwater or estuarine habitats. Stock harvest was considered as an appropriate concern within the marine environment. In 1986, we were absorbed in hypotheses of mechanistic relationships for single or limited factors. Many of us were young, and our science stayed in our biological comfort zone. We were optimistic that we could improve the survival and management of diadromous fishes by simply understanding the intrinsic life history components of these fishes.
During the 21 years between the two conferences, many factors contributed to a changed perspective. We now have many more sophisticated technical and molecular tools with which to interrogate and understand mechanistic genetic, physiological, and behavioral factors affecting fish stocks. Also revolutionary is the increased capability for us to model and approach synthetic multifactor aspects of stocks or environments through advanced statistical modeling and data analyses. Even scientists at remote sites have access to sophisticated computerassisted tools. Finally, we have changed the pace and methods for communication to allow for incorporation of real time and historical information in computer databases for use in adaptive management and decision analysis tools.
Today, we recognize the many changes in the physical environment of the world and its biota. In 1986, slightly more than 4.8 billion people were using global resources; today, the Earth is supporting 6.7 billion people. In 1986, scientists warned of global climate changes and UNESCO had convened work groups to address global challenges, but few of us suspected the amplification and threshold effects we would see with these changes, as well as potential interaction with fishing effects on the oceans. In years since our first conference, the Food and Agriculture Organization of the United Nations began discussions of the effects of overfishing, and the United Nations increased efforts to regulate high seas fishing. The U.S. government, among others, promoted buy backs of fishing fleets in efforts to reduce the overcapitalization that occurred decades before. At the same time, the growth in economics and industrialization across the world exploded demands and production of goods and food products and increased global consumption of fossil fuels. These effects of global economic development are felt throughout the world, and these effects have widespread influence on diadromous fish stocks. The introductions of xenobiotic chemicals have accumulated in the food chain, and trophic alterations from fishing down the food web have affected marine stocks throughout the world. With this section, we seek to explore some of these interrelationships with papers from scientists from the United States, Canada, France, England, Korea, Japan, Australia, and New Zealand.