Shrimp is one of New England’s signature dishes.
Unfortunately, the Gulf of Maine or Northern Shrimp (Pandalus borealis) is a cold water species and New England is at the southernmost point of its range.
They are present from the Arctic to northern New England and are a species that is so dependent on temperature that we could use them as an indicator to detect climate change.
Since 2014, northern shrimp fishing has been banned in the United States. The stock in our area has declined to the point where they no longer breed. It’s not overfishing; it is directly due to the temperature of the water. They simply moved north into colder Canadian waters.
Let’s do a little biology lesson on the northern shrimp. Shrimps are a crustacean related to lobsters and crabs. Like other crustaceans, they have an exoskeleton and must molt to grow. They are pink/red and have fin-like pleopods under their tails that allow them to get away from predators quickly and swim long distances.
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In fact, these small animals are diurnal; they spend the night between two waters and sink to the bottom the next day their food, the plankton, which does the same. They also spend the summer in the deep waters of the central basins of the Gulf of Maine where they moult and migrate inshore during the winter where they spawn.
This allows the eggs to hatch in an area with high plankton content so that the larvae have food to eat. Northern shrimp only spawn at around 2-3 degrees Celsius.
Thus, the warming of the Gulf of Maine has not allowed successful spawning for many years. In recent years, the coast here has averaged 4-6 degrees Celsius.
Northern shrimp grow to about 3 to 4 inches and live along the muddy bottom and dwell in the middle of the food chain in the Gulf of Maine. They eat both plant and animal plankton and are in turn eaten by cod, spiny dogfish, whiting and other important food fish.
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This is where it gets interesting. Shrimp are short-lived crustaceans that typically only live five years. They hatch from the eggs and mature at around 2.5 years as males, at which time they spawn. Then, around 3 and a half years old, they begin to become a female and live for another two years.
Their total lifespan is about five years. Weird but true.
In 2007, when there was a strong northern shrimp fishery in the Gulf of Maine, scientists were researching net modifications that would catch shrimp but not finfish bycatch. Since shrimp fisheries around the world have some of the highest bycatch of any fishery, this was a global priority.
At that time, the University of New Hampshire’s Northeast Consortium helped fund Dr. Pingguo’s research. He and David Goethel developed a trawl, named “The Topless Trawl”, which dramatically reduced bycatch in the northern shrimp fishery. It has proven to be so effective in reducing bycatch that it received an honorable mention in the World Wide Fund for Nature’s ‘Smart Gear’ competition. He has also helped local fishermen preserve groundfish stocks while fishing for shrimp. The crew loved the net because all they had to do was shovel the shrimp into boxes to sell, and the shrimp catches increased. An easy day on the ocean for them. Although they no longer fish shrimp in the United States, the net continued to be modified by Canadians.
Now you can say, wait, I saw baby shrimp in the tidal pools! You may have seen what looks like a shrimp either an amphipod or even an invader of our shores, a European rockpool shrimp (Palaemon elegans). Although amphipods are abundant and resemble baby shrimp, their adult size can be less than an inch and their lifespan is very short.
Recently, I spotted some very shrimp-like animals about 2 inches in length. This is the rockpool shrimp, another invasive species that recently arrived from Europe, first spotted in the Gulf of Maine in 2010. These seem to be doing very well and could be disrupting the estuarine food chain. Time will tell us. In this day of fast moving ships all over the world, we will inevitably see more and more invasive species. Although these invasive species can permanently alter the ecosystem, this is also how evolution continues. In the ocean, evolution seems to be happening faster and faster.
Keep your eyes peeled as you hunt the tidal pools, focus on these tiny animals, you may be amazed at how many different animals you will see.
Ellen Goethel is a marine biologist and owner of Explore the Ocean World at 367 Ocean Blvd. in Hampton Beach.