AN INTRODUCTION TO RIVER DOLPHIN SPECIES - Biology, Evolution and Conservation of River Dolphins Within South America and Asia - page 4

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B
Figure 1. Two images (a & b) of Neophocaena phocaenoides asiaeorientalis (copyright Dr. Wang).
numbers. The confluence can be a highly productive area with elevated nutrient
concentrations and abundant dolphin prey. Observations by scientists support that the finless
porpoise swims alone, in small groups, or even in larger groups of up to fifty individuals.
Unfortunately, its numbers have dropped considerably to the current estimate of
approximately 1,200 individuals and the species is listed as endangered by the International
Union for the Conservation of Nature and Natural Resources (IUCN). The finless porpoise is
affected by sand digging, sand-transport ships, fishing, pollution, bridges and dam
construction. In the present topic, Li et al.,(chapter 18) discuss how the population density