Rainbow Smelt

Common name: Rainbow smelt, Atlantic smelt

 

Scientific name: Osmerus mordax

 

Fun Fact: Its Latin name, Osmerus, comes from the Greek word meaning “odor”. Freshly caught smelt have a scent reminiscent of cucumber or watermelon!

 

Similar species: Capelin, Atlantic silverside

 

Range: Note: Rainbow Smelt can either be anadromous or landlocked in freshwater. This page will focus mainly on the anadromous form. 

 

Rainbow smelt are native to Atlantic coastal drainages from Labrador south to New Jersey and Pacific coastal drainages in Canada and Alaska. They live in estuaries and offshore waters, and spawn in shallow freshwater streams each spring. Their range is naturally limited by small falls and rapids, since they are unable to jump very far. 

 

On the Atlantic coast, the species’ historical range is from the Chesapeake Bay to Labrador, but has contracted since the 1950s. Sea-run smelt now range from Massachusetts to Newfoundland, and are relatively abundant in Maine.

 

Native freshwater populations exist in a number of inland lakes and ponds throughout the northeast, but the majority of landlocked smelt are the result of either intentional or unintentional introduction in inland waters across the country. The most notable example is of the Great Lakes. After they were introduced into Michigan’s Crystal Lake as a food source for stocked salmon in 1912, they quickly spread to Lake Michigan and beyond, and now support a thriving fishery in the Great Lakes.

 

Identification: Rainbow smelt are the smallest of Maine’s native sea-run fish. They are mostly a dark blue green color with bright silver sides and iridescent purple, pink, and blue reflections that shimmer colorfully in the water. They have a long, slender body with a pointed head and a large, elongated, pointed mouth. Their large mouth contains numerous strong conical teeth on their jaws and tongue that they use to catch and hold their prey. They have a small adipose fin located between their single dorsal fin and deeply forked tail fin. Rainbow smelt rarely grow over 13 inches with the average adult measuring between 7 and 9 inches. They generally weigh between 1 and 6 ounces. 

 

Life history: Adult rainbow smelt move into coastal rivers and streams to spawn during the early spring, shortly after ice-out in the lower reaches of streams or along shorelines. Spawning usually starts in late March to early May and lasts 2-3 weeks. Coastal populations move into freshwater rivers to spawn at the first barrier above the head of tide, since smelt are unable to jump more than 6 inches. Spawning takes place only at night, when several males and one female swim side by side near the bottom, simultaneously shedding eggs and milt into the water. Many of the males will die shortly after spawning, though they may spawn in several places in a single season. 

 

Over the course of a few days, female rainbow smelt lay roughly between 20,000 and 80,000 eggs depending on their size. They prefer well oxygenated riffle habitat for spawning, as the eggs survive best in fast moving water and on aquatic vegetation. After being laid, the eggs sink to the bottom of the stream and adhere to sticks, pebbles, and plants with a stalk-like protrusion. They often create thick mats of eggs (small white clusters of dots), which can be easily spotted if you know where to look. However, if they are unable to get far enough upstream, they may not reproduce successfully since salt water can kill their eggs. 

 

After about 2-3 weeks, depending on water temperature, the eggs hatch into larvae which are about a quarter of an inch long. For the first three to four days, smelt larvae are attracted to light, vigorously wriggling up to the surface of the stream, where currents gradually drift them downstream to the brackish waters of estuaries. As they mature, they become more salt-tolerant, and many eventually move out into the ocean bays for part of the year. Rainbow smelt are relatively a short lived species, with most individuals reaching maturity in their second year. They can live up to 6 years, but most smelt in Maine waters are about three years old. At maturity, smelt generally reach a length of 7 to 9 inches, and a weight of 1 to 6 ounces.

 

Behavior and diet: Smelt can be found in the mid-water column, where they travel in schools. In salt water, rainbow smelt are rarely found far from shore. Patterns of movement are dependent on water temperature and change with the seasons. In the winter, smelt are caught by anglers through the ice as they move in and out with the tides in search of food. Young smelt eat zooplankton and adult smelt eat mostly small crustaceans, fish, and marine worms.

 

Ecological importance: Under favorable conditions, smelt populations can become extremely abundant and provide an important source of forage for larger predatory fish such as striped bass, white perch, bluefish, and Atlantic salmon. Rainbow smelt are also a favorite of fish-eating birds like ospreys, bald eagles, and great blue herons, as well as marine mammals like seals, otters, and mink. Smelt contain high amounts of oil and fat, and help seabirds like cormorants and mergansers maintain their body temperatures in cold seas.

 

They are routinely stocked in freshwater lakes as food for landlocked salmon and trout fisheries. However, they can also have a negative impact due to their abundance, outcompeting other small fish for food, though this is mainly a problem in areas where they are non-native. 

 

Cultural importance: Historically, people in New England valued rainbow smelt as an easy-to-catch, abundant source of fresh protein after the long winter, laying the foundation for a thriving recreational smelt fishery. Smelt fishing is an age-old tradition in downeast Maine. Local fishermen and women recall catching smelt on the West Branch of the Pleasant River in abundance all the way up to Route 1 before the tide gates were installed at the mouth of the river in 1941.

 

Fishing for smelt through the ice is a rite of passage for many Mainers, and recreational fishing for rainbow smelt continues to be a popular pastime in Massachusetts, New Hampshire, and Maine. The commercial fishery for rainbow smelt is one of the oldest in New England, and for many years it was among the most valuable. While populations have recently dwindled, parts of eastern Maine still have strong commercial fisheries.

 

Frying is one of the most popular methods for cooking smelt, and it is around this that Downeast Salmon Federation bases its annual smelt fry fundraiser.

 

Threats: Rainbow smelt were so plentiful a hundred years ago that farmers caught them by the barrelful and had enough to eat, use as bait, and even spread on their fields as fertilizer. Yet, in recent decades, their numbers have experienced alarming declines. Populations south of Massachusetts no longer appear viable, and in the north, a once thriving recreational winter smelt fishery is becoming a thing of memory.

 

Given the smelts’ small size and inability to clear barriers, access to spawning habitat has been reduced by dams and culverts at the head of tide. Spawning habitat has also been altered by stream bank modifications which can lead to changes in flow and sedimentation. Soils eroding into streams result in greater turbidity, or suspended silts, which can inhibit light and temperature stability, coat the gravel beds where eggs are laid making adhesion difficult, bury eggs, and clog the gills of larvae. Increased nutrient loads in coastal rivers may cause algae to grow on smelt eggs, and excess runoff from roadways degrades water quality. Climate change also plays a significant role; changes in ocean temperatures, the timing and duration of ice formation in the estuaries, and shifts in Gulf of Maine fish communities may also play a role in the decline of smelt populations in the northeast. 

 

Restoration efforts: The state governments of Maine, Massachusetts, and New Hampshire are working together to understand the rainbow smelt’s current status and threats, and to plan a regional conservation effort for the species. A regional conservation plan for Rainbow smelt in the Gulf of Maine was published in 2012, with a focus on collecting the data needed to monitor the current population and get a better understanding of the causes of its decline. Scientific research by the three-state collaborative focuses on the status of the smelt population and the condition of spawning areas in streams, which may be a key factor in the rainbow smelt’s decline. 

 

You don’t have to be a scientist to get involved in smelt conservation. The Gulf of Maine Research Institute’s Ecosystem Investigation Network has an ongoing citizen science project which aims to collect data on where and when smelt are spawning. Volunteers can collect data both at night and during the day, which will help determine where the smelt are choosing to spawn, even if there are no fish to be found. 

 

If field observation is not your idea of fun, consider simply learning about your local smelt run or advocating for restoring riparian buffers, reducing the use of fertilizers and road salt/sand near streams, and fixing or removing road stream crossings and dams. Even small actions can add up to improve water quality and access to habitat for these fish! 

 

Fishery: Smelt have been fished commercially since the nineteenth century; harvest peaked in 1966 at 360,000 pounds, with the majority being landed from Maine waters. Unfortunately, recreational anglers have noted declining catches over the last three decades, and the smelt was listed as a federal Species of Concern in 2004.

 

In Maine today, where populations are still relatively healthy, rainbow smelt are a prized food fish that are harvested in three distinct fisheries. During the spring months, as they move into streams to spawn, fishermen use dip nets to capture them. The fall season supports a riverine and coastal bay hook and line fishery. A lightweight spinning rod and reel is considered the equipment of choice for smelt. And in winter, anglers fish for smelt through the ice, using mobile shanties or shacks to protect themselves from the winter cold. This manner of fishing has proven to be very popular on many of the state's tidal rivers and saltwater bays.

 

Depending on where in Maine you fish, different regulations may apply. Check with Maine DMR for updated information before heading out!

 

Sources:

 

https://www.maine.gov/ifw/fish-wildlife/fisheries/species-information/rainbow-smelt.html

https://www.maine.gov/dmr/fisheries/recreational/anglers-guide/do-you-know-your-catch

https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=796

https://www.wildlife.nh.gov/fishing-new-hampshire/fish-species-nh/rainbow-smelt

https://www.mass.gov/info-details/learn-about-rainbow-smelt

https://seagrant.umaine.edu/wp-content/uploads/sites/467/2019/03/2011-rainbow-smelt-poster.pdf

https://www.nrcm.org/nrcm-creature-feature/rainbow-smelt/

https://www.maine.gov/dmr/science/species-information/smelt

https://seagrant.umaine.edu/maine-seafood-guide/smelt/

https://www.maine.gov/dmr/sites/maine.gov.dmr/files/docs/pamphlet.pdf

https://investigate.gmri.org/project/smelt_spawning