Document Type

Honors Thesis

Publication Date

Spring 5-2018


The American lobster is Maine’s most valuable export commodity. Hard-shell lobster commands the highest price because they survive shipping to overseas markets, but much of Maine’s summer production comes as perishable, low-value, softshell lobster. Lobster processors would like to know whether they can enhance profitability by holding over low-quality lobsters to increase their hardness instead of the standard process of receiving and shipping lobsters in under 48 hours. In a collaborative experiment with Ready Seafood Co. (Portland, Maine), we conducted week-long trials to evaluate the joint effects of temperature and feeding on shell hardness and hemolymph protein levels, an indicator of lobster health. Lobster were hand graded into four shell hardness categories used in the trade. Hemolymph total protein levels were quantified on the Brix percentage scale with a refractometer. Over the duration of 7-day trials, an average of 33.5% of lobster improved in grade and the average survival rate was 85%. Hemolymph protein levels improved significantly with higher shell grade but declined over the duration of the trials. We found no significant effect of temperature or feeding treatment on shell grade, survival, or hemolymph protein levels. We estimate that with an 85% survival rate and a 33.5% improvement in shell grade over 7 days, at the highest observed market price differential between A and B grade lobster, Ready Seafood Co. would lose over $10,000. The company would realize a profit, however, if it improved survival rate by a few percent, and with a survival rate of 100%, would gain more than $72,000 in profits. Therefore, by holding over lobster there is much potential to enhance the value of Maine’s lobster industry.