It's down to one thing - the weather.
The boats just haven't been able to go out as it's not safe. In the lobster grounds that are open over in Canada they are experiencing winds over 100kph and snow, so much snow! There has been almost no fresh lobsters landed for the past four weeks. Although they are used to weather like this and prepared for it, there is a time that the lobstermen just can't get out and when the weather is like this, the lobsters don't climb into the pots either.
The Canadians store lobsters in deep water pounds to cover these periods but unfortunately, the worldwide demand over Valentines and Chinese New Year has exceeded expectations and they are fast running out of the stored lobsters. The tank houses (the companies who store the lobsters) are trying to control demand by increasing the prices. They are releasing a small amount of stock each day and increasing the price on a daily basis.
Until the fishermen start landing enough lobsters to meet demand the price will continue to increase and the availability decrease. This could be in 3-4 weeks and is purely dependant on the weather.