Physiological effects of post-harvest commercial practices on the lobster, Homarus americanus

Garland, John James

Abstract

The lobster, Homarus americanus (Milne Edwards) is a commercially-important species harvested in Canada and exported live to international markets. Landed condition and post-harvest handling practices play a significant role in the ability of an exporter of live lobster to provide customers with a premium product. A set of standardized quality handling, storage and shipping parameters does not exist, an absence that can lead to quality degradation or premature mortality that impacts both the reputation of the H. americanus stakeholders as well as being a potential waste of a limited natural resource. Studies on physiological risk factors for storage, emersion tolerance and cardioventilatory responses to immersion temperature change were conducted to assess their impact on the maintenance of quality in the supply chains of live H. americanus.

Based on survival analysis during long term storage, it was found that storage risk factor predictive success was season-dependent, with haemolymph lactate positively correlated with long-term storage mortality in spring-caught lobsters, but not with winter-caught ones. Haemolymph total protein, haemocyanin and refractive index were positivelycorrelated with long term storage mortality in winter-caught lobsters but not spring-caught ones.

The immediate pre-harvest acclimation temperature affected the lobsters’ response to emersion. Haemolymph pH and lactate levels during emersion revealed that the standard 3 °C environmental air temperature, used for commercial live shipments, causes a delay in the onset of anaerobic metabolism in 7.5 °C, but not 2.5 °C pre-acclimated lobsters.

Although H. americanus is reportedly sensitive to changes in environmental temperatures less than 0.5 °C, it was found that acute changes in immersed water temperature of 5 °C did not elicit an overall change in cardioventilatory activity. Complete haemolymph temperature change occurred within 30 minutes of immersed, acute environmental temperature change, notably faster than was observed in the absence of cardioventilatory activity, indicating the effectiveness of the cardioventilatory activities in H. americanus as a heat exchange system.

The current findings, along with existing relevant research findings in the literature, were used to create a template for model commercial post-harvest practices for H. americanus. The template consists of a food quality and safety control program based on the globally-accepted HACCP principles of inductive reasoning that stress proactive versus reactive processes. The current research findings provide critical control points that can be applied throughout the post-harvest distribution chain from first landing to delivery to the end consumer. These critical control points are identified with suggested parameters to use as guidelines for the H. americanus live trade in an effort to improve the consistency of quality and reduce the risks that can lead to product and / or quality loss as a result of incorrect practices.

Citation

Garland, J. J. (2014). Physiological effects of post-harvest commercial practices on the lobster, Homarus americanus. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4222184

• Thesis Type: Thesis
• Deposit Date: Feb 26, 2020
• Publicly Available Date: Feb 23, 2023
• Keywords: Biological sciences
• Public URL: https://hull-repository.worktribe.com/output/4222184
• Additional Information: School of Biological, Biomedical and Environmental Sciences, The University of Hull
• Award Date: Dec 1, 2014