The rainbow smelt is a small anadromous (migrating from salt water to fresh water to spawn) fish that spends its winter in estuaries like Great Bay. Each spring, smelt head upstream to spawn and were once so plentiful that farmers caught them by the barrelful. They had enough to eat, use as bait and spread on their fields as fertilizer.  Starting in the 1800s, smelt supported thriving commercial and recreational fisheries throughout New England.

Today, it would be difficult to fish for smelt and fill a single barrel. Catches have continued to drop off in New England since the 1980s even though commercial fishing no longer occurs.  And their range is shrinking. Smelt have disappeared from the southern end of their geographic range, which once extended to the Chesapeake Bay, and now are limited to estuaries and rivers north of Long Island Sound.

Many factors have contributed to the decline, including structural impediments to their spawning migration – dams and blocked culverts – and habitat degradation due to stormwater inputs such as toxic contaminants as well as excessive nutrients and sediment. Extremely high or low water flows can also disrupt their migration runs.

In 2004, the National Oceanic and Atmospheric Administration (NOAA) listed rainbow smelt as a federal Species of Concern. The State of New Hampshire also lists smelt as a Species of Special Concern.  As a result of these designations, the Maine Department of Natural Resources received a six-year grant from NOAA to develop and implement a regional conservation plan for rainbow smelt.

In collaboration with the New Hampshire Fish and Game Department and the Massachusetts Division of Marine Fisheries, the plan has now been completed. When examining the status of current smelt populations, the findings are not encouraging.

Once smelt reach their spawning grounds, water quality plays a major role in the hatching and survival of the eggs. In many rivers, pH levels, turbidity and an increase in nutrients can negatively impact water quality leading to declines in populations. Heavy metals can lead to egg mortality and impair development of young smelt.

So what does this mean for the future of smelt in the Great Bay estuary?

The study clearly documents that high algae growth – the direct result of too much nitrogen in the water – can lead to a considerable decrease in the survival of smelt embryos. This poses a significant risk to smelt in all of Great Bay’s rivers.  We know in the Winnicut – a river where smelt are rarely found today – algae growth is a major problem.  A small river with limited capacity, algae is appearing earlier in the season and increasing in abundance.

The decline in smelt populations is another disturbing sign that the health of the Great Bay estuary is in jeopardy.  Like other estuaries along the east coast, polluted stormwater runoff and excess nitrogen are having a negative impact on fisheries. The study also found that healthier smelt populations were found in more forested watersheds and poorer runs were associated with more developed watersheds. This is another reason why we must address the issue of urban sprawl and protect water quality.

Ice-fishing for smelt is a Great Bay tradition.  If we want our grandchildren to enjoy its pleasures, we need to take immediate action to clean up the estuary.

For more information about the Great Bay-Piscataqua Waterkeeper and my work to protect the Great Bay estuary, visit: http://www.clf.org/great-bay-waterkeeper/. You can also follow me on Facebook and Twitter.