As the weather gets chilly, many living things in coastal waters are ramping down. Many species have migrated south like some marine mammals and sea birds.
Others like lobsters are finding their way into deeper water where the temperatures stay constant, or deep into the mud like shellfish. In many ways, the coast becomes less active as activities like fishing recreation slow down. But, there is still a lot of life in that water to pay attention to – even in the winter.
With changes in the climate, the warmer part of the year has crept later and later. This means that the conditions favorable for the growth of living things have also extended later into the year. That can mean some species staying around longer, or never leaving at all, and other species showing up that we haven’t seen here before. What we might not expect is for these species to show up at this time of year.
But, one nasty one has caused concern to local managers. ASP? Pseudo-nitzchia? These names are likely not familiar to most people living along the coast. That’s because pseudo-nitzchia has only been spotted in the area over the last five or so years. It is a family of tiny marine plankton called diatoms, which are single-celled organisms that photosynthesize inside a tiny glass-like greenhouse made of silica. Pseudo-nitzchia diatoms look like tiny pins that are as nasty as they look. It is also nasty because it reproduces quickly. Shellfish are filter feeders and gulp in large quantities of these tiny creatures, concentrating them in their tissues. That’s when it becomes a problem for a person eating those shellfish. That’s because Pseudo-nitzchia produces an acid called domoic acid (DA) that can cause amnesic shellfish poisoning (ASP). “Amnesic” sounds like amnesia because ASP can lead to a neurological disorder that includes memory loss and in some severe cases, death.
Pseudo-nitzchia is a somewhat silent invader because it shows up in cooler weather. This is unlike the more familiar phenomenon known as “red tide” that occurs in the summer. Red tide is another name for a Harmful Algal Bloom (HAB) where certain types of toxic marine algae grow like crazy under certain conditions. In some parts of the world, these blooms are very visible and look like tomato soup in the water, which is why more people are aware of this kind of “bloom”. Here in Maine, we don’t always see HABs, but, like pseudo-nitzchia, these algae make shellfish unsafe to eat.
While you might not eat buckets of steamers as frequently in November as you would in July, harvesters are still out there gathering them and a fresh supply is available at several local seafood shops. Quahogs, or hard shell clams, are also still being harvested for a few weeks until the winter closure goes into effect to protect them before we get a deep freeze. The winter quahog closure is a local conservation measure that the town of Brunswick has been utilizing for several years to protect the quahog resource.
Now that ASP has been detected, the question is how we address it. Because it is a fast-growing species that can spread quickly, there have been efforts to try to control it at a small scale before it gets to be a bigger problem. To that end, there have been a series of targeted temporary closures in Brunswick. This has obviously limited the ability of harvesters to dig in those areas, but the purpose of that is to prevent a statewide closure that could shut down harvesting statewide and could be quite detrimental to the industry.
Most relevant to the public, perhaps, is the ability to eat these shellfish and to do so safely. There are multiple efforts to do that. The responsibility for the testing of shellfish falls to the state’s Department of Marine Resources (DMR). They test for any number of contaminants and toxins that could impact consumers on a regular basis, including ASP. You can learn more about the DMR’s Shellfish Sanitation Program and sign up to get alerts about closures on their website (www.maine.gov/dmr/shellfish-sanitation-management/).
The testing is rigorous because the impacts are serious. But, the result is that people can feel quite safe and comfortable eating the delicious seafood that is permitted to come to the market. So, fingers crossed that ASP won’t spread and we will have plenty of shellfish to eat. After all, some of the traditional New England Thanksgiving feasts included shellfish.
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