premise: Between March and June, scientific observers say, up to 300,000 seals are killed. In Canada, seal-hunting means jobs, but opponents say it is vicious and endangers the species, also threatened by global warming.
hypothesis: Between August and December, up to 350,000 seals are killed.
reason: There is no way of knowing, based on the information provided, whether or not this many seals are killed in this time period. However, the number is close enough to the number stated that it COULD be real.