A study by veterinary scientists in the September 2012 issue of Marine Policy shows that the conditions under which the Canadian seal hunt occurs are such that it is impossible to assure the humane treatment of the seals. By implication, only a ban can succeed in addressing the EU concern about animal welfare.
Here is the abstract:
The Canadian seal hunt is the world's largest commercial slaughter of marine mammals and, as such, has been the subject of veterinary scrutiny for half a century. In that time, veterinary experts have made multiple recommendations to improve welfare at the seal hunt, some of which have been included in Canadian sealing regulations. Yet analysis of video material and studies on the outcomes of the hunt suggest that the potential for suffering during the hunt continues, and may, in fact, be increasing. In the past decade, numerous countries have taken action to prohibit their trade in products of commercial seal hunts in response to public concerns about the welfare of the seals. With these actions now being examined at the World Trade Organization, it is important to determine if these concerns are warranted. This paper reviews relevant veterinary science, exploring the intrinsic elements of commercial sealing and unique physical adaptations of seals that prevent effective and consistent application of humane slaughter methods at the seal hunt. The review of available data indicates that generally accepted principles of humane slaughter cannot be carried out effectively or consistently in the commercial seal hunt.This is a link to the study:
http://www.sciencedirect.com/science/article/pii/S0308597X12001662