SYMPOSIUM SUMMARY 



309 



trophic level and one at a low trophic level. 



For the purpose for which we convened this 

 symposium conservation I do not think 

 that we need detailed knowledge of the factors 

 which regulate populations. Such knowledge 

 is, of course, of immense biological interest 

 and will ultimately be needed for effective 

 long-term management. However, it does not 

 have immediate or even medium-term rele- 

 vance to the urgent problems of conservation 

 that we now face. What we do need to do is to 

 set up some long-term studies of a few care- 

 fully selected species preferably long-lived 

 species so that we can trace the effect of en- 

 vironmental fluctuations on their perfor- 

 mance for a long period. 



Vulnerability of the 

 Resource 



We already understand a number of factors 

 that make some of these bird populations par- 

 ticularly vulnerable to the kind of human ac- 

 tivities which we can envisage in the next 

 decade or two. Most of the breeding birds con- 

 centrate on islands where they are vulnerable 

 to predators and to human disturbance. Many 

 of them concentrate in flocks on human fish- 

 ing grounds and over other areas of the conti- 

 nental shelf which are likely to be the focus of 

 human activity in the near future. In particu- 

 lar, some of the birds are known to concen- 

 trate in the passes through the Aleutian Is- 

 lands, where they will be particularly vulner- 

 able to future oil spills. In all these ways the 

 birds are concentrated in areas where they are 

 likely to receive disproportionate impacts 

 from human activity and exploitation. 



One point that has been barely mentioned in 

 this symposium is the effect of molting on the 

 vulnerability of some of these populations. 

 The eiders, for example, concentrate on molt- 

 ing grounds in the Arctic. The exact location 

 of these molting grounds may not be fully 

 known, but we certainly know that the birds 

 molt somewhere in an area where they will be 

 vulnerable to oil spills (and also to human 

 hunting if the people who move to the Arctic 

 choose to hunt them). Nor are eiders the only 

 species that are flightless when they molt. 

 Some alcids and loons are also flightless for 

 short periods and, hence, particularly vulner- 

 able to oil spills during molt. 



Past Damage to 

 the Resource 



In the speech opening the symposium, As- 

 sistant Secretary Reed referred to this bio- 

 logical resource as still relatively unspoiled. 

 While "relatively" may be an appropriate 

 word, we do have spectacular evidence of 

 changes and damage to these bird popula- 

 tions. The use of the Aleutian Islands for fox 

 farming seems to me a quite horrifying situa- 

 tion. We know also that the early whalers and 

 sealers exploited seabird populations. Al- 

 though I know of little specific information 

 about the effects of such exploitation on birds 

 in the northern North Pacific, D. G. Ainley in 

 his survey of historical records from the 

 Farallon Islands has shown very clearly the 

 massive effects of human exploitation of 

 birds, starting early in the 19th century. In 

 our area of discussion alone, one species (the 

 spectacled cormorant) is extinct and another 

 (the short-tailed albatross) became virtually 

 extinct and is still very rare. I believe that one 

 or two southern hemisphere species, which 

 must have been substantial elements in the 

 northern summer bird population, have also 

 been seriously depleted as a result of human 

 activity on their breeding grounds. 



Several speakers emphasized the impor- 

 tance of long-term fluctuations in bird popula- 

 tions resulting from natural causes, including 

 some examples from the North Pacific. Other 

 types of human activity must also have had 

 some indirect effects on the birds. For 

 example, whaling and sealing in the 19th cen- 

 tury must have provided large amounts of 

 food for scavenging birds and eliminated im- 

 portant competitors for the larger fish-eating 

 birds. A similar experiment is now in progress 

 as the predatory fish are being overfished. 



Major Threats to the 

 Bird Populations 



We now know enough about the distribu- 

 tion and ecology of the seabirds to identify 

 the major threats to them that are likely to be 

 posed by the projected increase in human ac- 

 tivity in the coming decades. The relative im- 

 portance of these threats clearly varies from 

 species to species and from area to area. How- 



