I could be wrong, but my impression was that the club often had modest attendance.
This is what's written on their franchise's Wiki article (no source given, so I dunno if it's accurate):
"The Whalers were never as successful in the NHL as they had been in the WHA, yet they attracted a decent fan base over the years, most living outside of Hartford which contributed to low attendance at home games many seasons."
"Hartford was the smallest American market in the NHL and was located on the traditional dividing line between the home territories for Boston and New York area teams. This limited the team's marketability. Additionally, for most of the Whalers' tenure as an NHL team, the Hartford Civic Center was one of the smallest arenas in the league. At its maximum, it seated just 15,635 for hockey. The team averaged over 14,000 fans only twice in its 15 years at the Civic Center. They averaged only 13,867 from 1980 to 1997."
I mean, an average of almost 14,000 isn't bad considering the team's struggles... would the Canucks have had attendance that high in the 80s?