MARINE MAMMAL COMMISSION - Annual Report for 1998 



(1) to provide a succinct summary of what is 

 known about the types and levels of potentially 

 harmful persistent contaminants that have been 

 found in marine mammals throughout the 

 world, and the known and potential effects of 

 those contaminants on marine mammal health 

 and population dynamics; 



(2) to identify and rank by relative importance the 

 critical gaps in knowledge concerning the 

 presence, levels, sources, fates, and effects of 

 organochlorines, toxic elements, and other 

 persistent contaminants in marine mammals; 



(3) to determine and describe the types of research 

 and monitoring programs, including new and 

 innovative approaches, that would be required 

 to resolve the most critical uncertainties as 

 quickly as possible; and 



(4) to assess how ongoing and planned research and 

 monitoring programs might be restructured or 

 augmented to better meet the identified informa- 

 tion needs. 



• a combination of laboratory and field studies likely 

 will be required to document adverse effects and 

 determine how to mitigate them. Some effects 

 probably can be inferred from in vitro studies; 

 others probably can be inferred from in vivo 

 studies of rodents and other laboratory animals; 

 still others may be inferred from postmortem 

 examination of marine mammals found dead on 

 beaches, killed for subsistence purposes, or taken 

 incidentally in fisheries or as a result of other 

 human activities. In some instances, detailed field 

 studies or controlled studies with captive animals 

 may be required; and 



• cellular and biochemical markers have been found 

 to be useful indicators of contaminant exposure and 

 effects in humans, laboratory animals, and certain 

 other organisms including some marine mammals. 

 More effort is required to identify such biomarkers 

 and determine how they may be used to infer and 

 monitor the exposure levels and effects of various 

 chemical contaminants in marine mammals. 



The workshop involved plenary presentations and 

 discussions and smaller working group meetings to 

 address four topic areas: endocrinology and reproduc- 

 tion; immunotoxicity, pathology, and disease; risk 

 assessment; and likely future trends. Although the 

 workshop report had not been completed by the end 

 of 1998, the following findings were evident: 



• there is good reason to be concerned that, in some 

 parts of the world, the survival and productivity of 

 marine mammals are being affected by chemical 

 contaminants; 



• new chemicals and chemical combinations being 

 developed for use as pesticides, herbicides, fertiliz- 

 ers, etc., could be hazardous to marine mammals 

 and other marine organisms and should be careful- 

 ly evaluated before they are marketed; 



• the effects of many contaminants may vary depend- 

 ing on exposure level; the species, age, sex, and 

 general condition of the affected animals; and the 

 presence of other contaminants. Effects may 

 include toxicity, endocrine disruption, immunosup- 

 pression, and reproductive failure. In some cases, 

 there may be no physiological or other response 

 until a threshold level is reached. Studies to 

 assess possible effects must factor in all the rele- 

 vant variables; 



The final workshop report is expected to be com- 

 pleted early in 1999. It will be distributed to the 

 workshop participants and to relevant government 

 agencies, laboratories, and scientists throughout the 

 world. It will be reviewed by the Commission, in 

 consultation with its Committee of Scientific Advisors, 

 to identify and recommend to the responsible regulato- 

 ry agencies actions necessary to assess chemical 

 contaminants and to ensure that they are not jeopardiz- 

 ing marine mammals or the ecosystems of which they 

 are a part. 



Effects of Noise 



Many species of marine mammals use sound to 

 communicate, sense their environment, navigate, and 

 capture prey. Both natural and anthropogenic sounds 

 may mask the sounds used for such purposes and 

 interfere with these and other vital fiinctions. If the 

 interference occurs frequently or for long periods of 

 time, it may cause animals to abandon or avoid 

 important feeding, breeding, or resting areas and alter 

 migratory routes. This can make animals more 

 vulnerable to predation and disease and cause them to 

 concentrate in undisturbed areas, which in mm may 



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