While Bank Transfer Day helped to boost membership to record numbers, the industry could see an exodus of some of its more profitable members in 2013 if credit unions are not capitalizing on those relationships.

Dave Colby, chief economist at CUNA Mutual Group, shared that insight in the March "Credit Union Trends Report." According to the data, initial estimates showed there were 94.8 million members in January, the latest month tracked. That figure is up 2.2 million since January 2010.

The failed attempt by Bank of America last year to levy a $5 monthly debit card usage fee helped credit unions boost their memberships by 1.2 million, the data showed. Positive momentum continued as credit unions added another 272,000 in January. That month's gain was 172,000 above the average January results for the previous four years.