Industry Myth -Warm Water Kills Lobster

Hundreds of times I have been told that warm water kills lobster.  But is there any truth to this?  The answer is no in common industry practice.  The actual lethal temperature reported in studies is well above 30°C!  So, even in LFA 25 where they fish in "the warmest waters north of the Carolinas", it is not the temperature that is to blame for any mortality.

So why do so many lobsters die when the temperature goes up?  There are two factors at play here.  One is that as water warms up, it holds less oxygen.  Seawater at 1°C holds about 50% more oxygen than seawater at 20°.  Conversely, lobsters use more oxygen as the water temperature increases.  This is why so many in the industry report lobster being weakened or dead as water temperature rises.  The issue is really the lack of oxygen, not the water temperature.  

We have a customer in LFA 25 who upgraded his aeration system one summer and called me a few months later to excitedly exclaim that "for the first time, we are able to ship fall lobster!"  To my knowledge, he is the first one and perhaps the only to be exporting live 'fall lobster'.  The only change to his system was an upgrade from a conventional aeration system to an APS aeration system.  One of the lowest cost improvements that can be made to a lobster holding tank - yet, over and over again, we see it solve 80% of almost any chronic mortality issue. 

Thermal shock from rapid temperature changes is another one that is mostly a myth (or an excuse).  Lobsters are very capable of acclimating to a wide range of temperatures, but their circulatory system is greatly affected by water temperature.  Always better to change temperature in stages.  

After a lack of oxygen, the most common way lobsters suffer due to temperature is by being held in tanks that cannot keep them cold enough for torpor (like hibernation).  When holding lobster long term, keep the temperature cold enough and not fluctuating up and down.  Those who have APS temperature control systems do not see temperature fluctuations, nor the high energy costs that come with so many conventional chillers.

Finally, another common issue attributed to temperature is when the lobsters are outside (on deck, waiting to get on/off a truck, or between buildings at a plant) in the wind.  Warm wind can dry out the joints and cold wind can freeze the joints - both prone to causing dropped claws.