First, I think it's important to understand what St. Marys Bay is. It's a shallow, warm coastal bay that acts as a lobster moulting and breeding ground. During the warm summer months, lobsters gather there in incredibly dense concentrations. What it means is that when fishing takes place out of season, the catchability of traps in that area is considered by many to be 10:1, compared to fishing during the commercial season.
Even though we've seen a 65% decline in landings within St. Marys Bay over the last three years, compared to a 6% decline across the wider fishing area, which is attributed generally to seasonable variability, the landings don't account for all the damage that's taking place by out-of-season fishing. Also, it is never appropriate to fish in a lobster breeding ground during the closed season, because the lobsters are soft-shelled at that time and really susceptible to damage.
I've heard the defence that Americans fish year-round for lobster, but I think if you spoke to any American fisherman they would talk to you about the incredible strength of the lobster resource in Atlantic Canada, and fishing them during the season when it's most sustainable to do so is really at the core of that.
As for lobster fisheries taking place at different times throughout Atlantic Canada, they take place because of a change in the environmental conditions. Lobster fishermen across the region harvest lobster when it's most sustainable and when it's most profitable.