Monitoring Lobster Quality

Veronika Brzeski Latest News, Lobster, Science & Conservation

Lobsters go through a biological cycle with a focus on either growing or reproducing. When the lobster industry talks about “quality”, it often means where they are in that moult cycle.

Growth: To grow, a lobster needs to shed its hard carapace and replace it with a newer larger carapace. Once a lobster has moulted, it  absorbs sea water to rehydrate as quickly as possible which lowers the concentration of protein in the lobster’s hemolymph (or blood). The lobster then focuses on feeding and “filling” up that new shell and, as it does that, the protein level increases.

Reproduction: In most cases, lobsters mate after the female moults. Before that stage, the female release pheromones (chemicals) into the water to let nearby males know she is preparing to moult and mate. Her chosen mate will take the female into his cave and protect her while she is soft. After the moult, the male deposits sperm packets into the female to store for up to a year or more. The  female will then produce cement glands on her swimmerets to glue her eggs rather than focus energy on moulting. When ready, she releases her eggs and the stored sperm and attaches the eggs (all 5,000+ and up to 100,000), under her tail where they will stay for the next nine to eleven months. During this time she is called a berried lobster because the eggs look like small berries.

Protein samplingOnce a week, a lobster technician from the LFA 27 Management Board waits at the wharf to complete blood protein and moult stage samples. The process of sampling a lobster includes simple observations such as the sex, carapace length and a visual inspection for damage. The more complex aspects of the sample include drawing a hemolymph sample using needle and syringe, and estimating the concentration of total proteins in the liquid extracted using a device called a Brix refractometer. In general, a lobster with a reading of over 8% on the Brix index should withstand long distance travel or long term storage. As a large portion of our lobster is shipped or stored, we’d like to understand the process and the “seasonality” to ensure we land at peak “quality”.

molt stagingThe other sample that is collected is the tip of a swimmeret (also called a pleopod) since the process of moulting is first observed right there. That is also where the cement glands form, so either process can be monitored. A microscope is a necessary tool for this!

Since the start of our lobster season, our lobster technicians have sampled lobster in 13 ports. Average Brix values varied from 9.8% to 11.1% and very few lobster have entered the pre-moult stage. This comes as no surprise:

Our Spring fishery is aimed at landing high QUALITY lobster!

We are grateful to the Aquatic Science & Health Services in Charlottetown and Université Sainte-Anne’s Marine Research Centre for training and support!

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