Postprandial changes in plasma free amino acid levels obtained simultaneously from the hepatic portal vein and the dorsal aorta in rainbow trout (Oncorhynchus mykiss).
Distribution Th e species’ range encompasses Europe, North America, and Green land (1) (Fig.1). Non-anadromous forms occur in Europe in a few land-locked locations in Norway and Sweden, and throughout the Neva/Lake Ladoga system and Karelia regions of Russia. In North America non-anadromous forms occurred throughout most of the species’ historical range, as far west as Lake Ontario, and remain common throughout Newfoundland, Labrador and northern Quebec. Over the last 150 years anadromous stocks have become extinct in many rivers. Native stocks are no longer present in the Elbe and the Rhine, two of Europe’s largest rivers, or in many rivers draining into the Baltic and in southern England, France and Spain, which previously had abundant salmon runs (1), and have become extinct in many rivers in the US and southern Canada (1, 2, 3). Th e species has been introduced in a number of locations, both within its range and elsewhere (1) but its native range has contracted and fragmented. Most remaining stocks, particularly in the southern part of its range and in the Baltic Sea region, are depressed and many no longer self-sustaining; detailed information, however, is lacking for most river systems where the species still occurs.