But this situation is a good case study of how scientists tend to choose their words carefully whenever certainty is concerned, but that this care is forsaken by mass media reports of the studies. The international commission charged with monitoring the status of the river dolphin used the phrase, "functionally extinct" to describe the baiji's plight. This followed a 6 week expedition at the end of 2006 to search for the dolphin. Another expedition in July made the same conclusion, and that two 'exhaustive' searched yielded no sightings was evidence to reinforce the original claim. "Functionally extinct" is a term that Wikipedia defines as
The population is no longer viable. There are no individuals able to reproduce, or the small population of breeding individuals will not be able to sustain itself due to inbreeding depression and genetic drift, leading to a loss of fitness.A good example of this is Lonesome George, the Galápagos Abingdon Island Tortoise, who is that species one known surviving individual, but is going strong as a 70 year old who can look forward to a 120 year lifespan.
Functionally extinct in the case of the baiji could mean isolation by dams or population dispersement in murky water or genetic inbreeding leading to loss of fitness. There is, in other words, a chance of slim to none that the species will recover to a sustainable population. If population biologists use the same criterion we use in biomedical science, slim means less than 5%. What concerns me is when public media (and bloggers outside their field) uncritically take 'very sure' to mean 'definitive.' That sets up situations like this one where those same media outlets (or worse, anti-science interest groups) can point to an outlier or other counterexample and say, "See, those scientists don't know what they are talking about!"
I still want an answer to my question above concerning the 50 year rule, but we all should question how it is that the practice and language of science can be better represented by the media.