January 28, 2010
Precautionary principle in the parks
Dear Editor,
The Jan. 21 West Marin Citizen article on the Marine Mammal Commission claimed, “even with the recent violation with DBOC clams in a harbor seal protected zone, the seals…according to NPS officials, remain unharmed.”
But DBOC bags were placed on one of the three pupping areas for over a month when the mother seals were in what amounts to their third trimester. Contrary to the article, that these pregnant seals were unable to rest in their preferred location could well have harmful consequences…such as greater stress on mothers, premature pupping, lower birth weights for pups, and thus higher chance of mortality.
But it is impossible to know the consequences of this disturbance for certain because, as the National Academy of Science noted, the research needed is functionally impossible to conduct. Such research would require intrusive lifetime monitoring of the disturbed individual seals and pups and comparing them to similarly monitored but undisturbed seals and pups…all the while keeping all other life variables the same. Such research is logistically almost impossible and would cost millions using sophisticated monitoring equipment, but if we want to have seals around in the future, we have to manage and protect them even in the absence of such research.
That is the “precautionary principle” followed by NPS, by the Marine Mammal Commission, and recognized in the National Academy of Sciences Report “visits to these areas (within 500 m of seal haulouts) by oyster farm workers can be expected to lead to the short-term disturbance of any seals… No studies have determined whether short-term responses to disturbance have long-term population consequences for harbor seals, but if the disturbance affects behavior during the breeding season, a precautionary approach to management would seek to reduce these types of disturbance.”
To put that Precautionary Principle in a human perspective, it is also impossible to know the consequences of conducting bomb squad exercises in Marin General’s maternity ward every day for over a month. But the fact that those mothers may make it through the exercises “unharmed” would not likely be used, as The Citizen article implies, to dismiss potential impacts. Similarly while an NPS official may have told The Citizen that it was not known whether DBOC’s bags harmed the pregnant seals, it is simply incorrect for The Citizen to translate that to an unequivocal statement that the seals “remain unharmed.”
In fact, for generations prior to DBOC’s placement of bags there, mother seals have used that nursery haulout, but did not use the haulout while the bags where there and have so far failed to return even though the bags have been removed. It is too early to tell whether DBOC has caused a permanent abandonment of one of the three pupping sites in the Estero, but it is critical that we find ways to eliminate such disturbances in the future even if we can’t prove the consequences.
Gordon Bennett, Sierra Club Marin Group Parks Chair