On September 25, our neighbours and industry competitors south of the border marked their 9th annual National Lobster Day.
The special day devoted to homarus americanus was started by the Maine Lobster Marketing Collaborative (MLMC) to honour the individuals who sustain the state’s iconic lobster fishery.
To the north, in this neck of the woods, the unofficial Lobster Day in Canada is probably the last Monday of November when one of the largest lobster fisheries in the world opens in lobster fishing areas (LFAs) 33–34, off Southwest Nova Scotia. The fishery in neighbouring LFA 35 is already up and running.
Needless to say, anticipation for the 2024–25 fall/winter lobster season is high. However, as with any industry, where there is hope, there are also concerns. And one of the predominant worries for Canadian and American lobster fishermen over the last few years has been the trend of warming ocean temperatures.
Both the National Oceanic and Atmospheric Administration (NOAA) and Department of Fisheries and Oceans (DFO) has had the North Atlantic warming phenomenon on their radars for quite some time now. In fact, as Navigator readers already know, the Gulf of Maine is warming faster than nearly any other ocean surface on the planet and it is critical to understand how the effects of climate change will impact the sustainability of the species and the fishery it supports.
There are fears that, as waters warm, lobsters are moving north, following the cooler ocean temperatures, resulting in detrimental economic outcomes for harvesters and processors.
However, a recent study might just be able to pour some cold water on the warming theory.
According to a study by researchers at William and Mary’s Batten School of Coastal and Marine Sciences, the American lobster may be more resilient to the effects of climate change than expected.
For the first time, experiments performed at the Virginia Institute of Marine Science (VIMS) documented how female American lobsters groom their offspring, providing evidence that these behaviors are not significantly impacted by temperature and acidity levels forecasted for Maine’s coastal waters by the end of the century.
“Brood grooming by female lobsters has been anecdotally observed, but it had not been quantitatively recorded before,” said Abigail Sisti, who is completing her Ph.D. in Marine Science at the Batten School and is lead author on the study.
“In other crustaceans, these behaviors can have a significant impact on the survival of their offspring. Because the environment supporting the lobster fishery is rapidly changing, we wanted to understand how it might impact the way they care for their offspring.”
Female American lobsters can produce thousands of eggs that they hold under their tails for long periods of time, between five to 12 months, as the embryos develop. In other crustaceans, grooming behaviors help clear out parasites, remove dead eggs and facilitate the flow of water carrying oxygen and nutrients through the densely packed egg masses.
In this study, the researchers were testing whether increases in water temperatures and acidity had an impact on grooming behaviors and embryo survival.
The researchers partnered with officials from Maine’s Department of Marine Resources to secure lobsters from commercial operations for use in the study. The female lobsters needed to be at a marketable size with intact legs, which are frequently lost in the wild or when they are caught. In total, they observed the behavior of 24 lobsters for five months, or until the embryos matured.
The researchers then reviewed dozens of hours of recordings from underwater cameras and documenting the frequency and type of grooming behaviors as well as the overall survival of the embryos.
Lobsters in experimental groups experienced temperature increases of four degrees Celsius and acidification levels of -0.5 pH from present conditions. Oxygen levels remained constant for all animals to isolate the effects of temperature and acidity.
They expected to observe several different grooming behaviors and hypothesized that grooming would increase in response to environmental stressors.
“We did observe a number of grooming behaviors that increased in frequency during embryo development. However, neither water temperature nor acidification at the levels in our experiments caused significant behavioral changes or impacted embryo survival. This is encouraging because it shows lobsters may be reproductively resilient to forecasted environmental changes,” the scientists explained.
The researchers are optimistic about the results of the study for the future of the fishery. However, they caution there are still many other variables to consider.
“While this study focused primarily on maternal behavior, future studies will explore other factors like how the embryos themselves are affected over time by different stressors. We also want to explore how these factors are impacting the overall wellbeing of egg bearing female lobsters as well as conditions that exist in microenvironments frequented by lobsters,” Sisti stated.
The variables in the study were determined using forecasts for open ocean conditions. However, wild lobsters often prefer specific habitats like rock crevices and sand mounds that provide cover from predators. There, the conditions may differ dramatically from those in open water.
“In our experiments, control temperatures were akin to spring and summertime conditions in the Gulf of Maine, which may have accelerated embryo development. We recommend future experiments explore behavioral changes during wintertime conditions.”
While questions remain, these are positive findings for lobsters and the all-important, multi-million-dollar fishery on both sides of the border. As a result, collaboration and cooperation between harvesters and scientists is now more important than ever.
