Several players in the P.E.I. lobster industry took part in the International Conference and Workshop on the Lobster held in early June in Portland Maine.
Held every three to five years, the session brought together lobster biologists, oceanographers, lobster fishers and fisheries managers from 20 countries. The meeting was held in Charlottetown in 2007, marking the last time it was held in Canada.
Spencer Greenwood of the Lobster Science Centre at the Atlantic Veterinary College was part of a presentation on a potential biomarker of bacterial and microparasitic infection in the American lobster: Acute Phase Serum Amyloid Protein A (SAA). This acute phase protein is widely recognized as an important protein expressed early in the human immune response to infection, and has been used as a clinical diagnostic marker for immune activation in a variety of terrestrial and aquatic animal species.
Greenwood and his team say there’s a clear demonstration of the magnitude of SAA protein expression when it’s correlated with disease progression during pathogen challenge. They call this a significant step forward in demonstrating a biomarker for immune system activation in the American lobster, and it could potentially be applied to multiple crustacean species.
Greenwood was also involved in a presentation on next-generation sequencing technologies, such as RNA-Seq. He spoke of how this has enabled us to gain unprecedented amounts of information on lobster physiology and immune response at the molecular level.
Greenwood says multiple, antimicrobial peptide isoforms are differentially expressed during these infections, along with a suite of immune genes associated with important humoral immune cascades and acute phase response. The expression profile of immune genes identified in this study provides additional evidence for a H. americanus immune response tailored to the pathogen causing infection.
The combination of targeting hepatopancreatic gene expression and the use of pathogen challenges allows scientists to significantly increase knowledge of the immune molecule repertoire and timing of expression in specific immune molecules during bacterial and microparasitic pathogen infection.
Greenwood also participated in an international study that highlighted how an unbalanced sex ratio in the samples, combined with a few sex-linked markers, may lead to false interpretations of population structure, and thus to potentially erroneous management recommendations. The study argues that sex information is useful to control sex ratio in sampling, overcome “sex-ratio bias” that can lead to spurious genetic differentiation signals and fill knowledge gaps regarding sex determining systems.
Finally, Greenwood was part of a team looking at the joint effects of elevated temperature and partial pressure of CO2 (pCO2) on marine organisms. The experiments showed that larvae (stages I-III) and postlarvae (stage IV) reared at the temperature projected for the Northwest Atlantic by the year 2100 (19 °C) experienced significantly lower survival, developed twice as fast, and had significantly higher oxygen consumption rates, than those in 16 °C treatments. These preliminary results, in tandem with other measurements, provides insight into how postlarvae compensate for stress.
Andrea Battison and Jean Lavallée of CrustiPath and the Aquatic Sciences & Health Services in Charlottetown, talked about reference intervals for 25 hemolymph plasma biochemistry parameters when utilizing 551 hemolymph samples from apparently healthy male and female American lobsters (Homarus americanus). The samples were collected as part of the Atlantic Lobster Moult and Quality project in Lobster Fishing Areas 25 and 26A in Prince Edward Island between 2007 and 2010. A classification system (Brix molt category) representing four different stages of the molt cycle was devised retrospectively using available data on Brix value, pleopod score and carapace hardness.
The research showed energy-related indices, such as cholesterol, triglyceride, total protein and glucose, tended to have strong positive correlations to the Brix value and each other, especially in male lobsters. Correlations involving triglyceride were less marked in female lobsters. Enzyme activity was usually low. These intervals reflect lobster condition in a natural setting as lobsters were sampled on board fishing vessels within five minutes of commercial traps being hauled.
Melanie Griffin of the P.E.I. Fishermen’s Association talked about the Island experience with the lobster levy, marketing and quality. The structure of the Association ensures all core fishers are represented by one organization and this assisted in the communication and implementation of the voting that took place to solidify the lobster levy in P.E.I.
