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原文传递 Report of the Scientific Research Program under the International Dolphin Conservation Program Act

题名：	Report of the Scientific Research Program under the International Dolphin Conservation Program Act
作者：	empty
关键词：	Fisheries##Dolphins##Marine mammals##Abundance##Ecosystems##Stress##Legislation##Pacific Ocean##Fishery effects##Environments##Stock assessments##International Dolphin Conservation Program Act##
摘要：	The tropical waters of the Pacific Ocean west of Mexico and Central America, an area known as the eastern tropical Pacific (ETP), support one of the world's largest fisheries for yellowfin tuna with between 100,000 and 300,000 metric tons caught each year. A primary basis for this fishery's success is an ecological association in the region between tunas and dolphins in which large yellowfin tuna regularly swim together with several species of dolphins. In the 1950s, a fishery method was developed whereby fishermen look for the surface-schooling dolphins to locate the tuna and use speed boats to herd these dolphins into large purse-seine nets. Because of the strong association, the co-schooling tunas followed and were also captured. This method rapidly became the predominant tuna fishing method in the ETP although many dolphins would die in the nets before they could be released. Since the fishery began, an estimated six million dolphins have been killed, resulting in three stocks of dolphins being declared 'depleted' under the Marine Mammal Protection Act (MMPA): the northeastern offshore spotted dolphin, the eastern spinner dolphin, and the coastal spotted dolphin. In the last decade, however, technological and procedural improvements and the increasing skills of captains and crews have reduced reported mortality to very low levels relative to dolphin population sizes; currently ship-board observers report fewer than 3,000 dolphins killed per year. With this dramatic reduction in mortality, indications of the initial stages of a recovery of the affected populations to near pre-exploitation abundance levels would be expected. However, despite considerable scientific effort by fishery scientists, there is little evidence of recovery, and concerns remain that the practice of chasing and encircling dolphins somehow is adversely affecting the ability of these depleted stocks to recover.
总页数：	104
报告类型：	科技报告