The critical species that have been identified as important in the Piscataqua Region include soft-shell clams, American oysters, Eastern brook trout, diadromous fish, shorebirds, salt marsh breeding birds, and eelgrass. Robust populations of these species are good indicators of estuarine, marsh, and watershed health. So let’s dig a little deeper into these species and their importance.
For the latest data on the abundance of these species please refer to the State of Our Estuaries Report.
Soft-shell clam beds are primarily found in the Hampton-Seabrook Harbor, although they exist in the Great Bay Estuary. Soft shell clams are an important economic, recreational, cultural and natural resource for the Seacoast region. Recreational shellfishing in Hampton-Seabrook Harbor is estimated to contribute more than $3 million a year to the New Hampshire economy. Predators (primarily green crabs), diseases, and recreational harvest pressures have caused the clam populations to decline. Periodically, harvesting is limited by the presence of red tide toxins and high bacteria counts.
Oysters are a keystone species in the Great Bay Estuary because they provide many benefits. As filter feeders, they take in the water around them, filter out some of the pollutants and sediments and then release cleaner water. When healthy, an oyster can filter up to 20 gallons of water a day. They play a key role in nutrient cycling taking up nitrogen into their shells and tissue. Harvesting and aquaculture farming of oysters provide economic benefits to local communities and businesses. Oyster shell reefs also create important habitat for other creatures in the estuary. Oyster populations have declined significantly from 1993 to today. There was 1,100 acres of oysters in the bay in 1993 and now there is only 100 acres. Disease, overharvest and poor water clarity and quality are likely to blame.
Eastern brook trout
Eastern brook trout is the New Hampshire state fish and requires high quality, coldwater streams for spawning and juvenile growth. They are the only trout native to streams and rivers of the eastern United States and are an excellent indicator of the health of the watersheds they live in. Development impacts in the headwater and first-order streams increase water temperatures and degrade water quality, resulting in conditions that do not support native Eastern brook trout. Improving stream connectivity, protecting low order streams and their buffers, limiting impervious surfaces (pavement, roofs & roads) and removing pollutants from stormwater runoff will improve the habitat and future survival of this critical species.
Major rivers of the Piscataqua Region historically had very large populations of migratory fi sh including Atlantic salmon, river herring, American shad, and American eels. Today, only river herring and American eels still return regularly in substantial numbers to the rivers and are the focus of current migratory fish restoration efforts. River herring are migratory fish, which means they travel from the ocean upstream to the freshwater streams, marshes and ponds to reproduce. Herring are eaten by other species and therefore sustain important commercial and recreational fisheries and other wildlife. Herring returns are in decline due to a number of factors such as water quality and habitat degradation, barriers to stream and river connectivity caused by dams and road crossings, as well as overharvest. The construction of dams and road-crossing culverts has fragmented and blocked the vast majority of the freshwater stream habitat historically used by diadromous fish.
Shorebirds & Salt Marsh Breeding Birds
The Hampton-Seabrook Estuary – and to a lesser extent Great Bay and the smaller coastal marshes– are critical stopover sites for migratory shorebirds in spring and fall. During these periods, birds roost and feed on tidal flats, eelgrass leaves and seeds and marshes. These birds get critical nutrients and rest for their long journeys to their wintering grounds. The saltmarsh sparrow is a species of special concern in Maine and New Hampshire. Saltmarsh sparrows require tidal wetland habitat that is dominated by the high salt salt marsh grass called Spartina patens for nesting and foraging. A NH Audubon study in 2007 counted more than 800 Salt Marsh sparrow nests in the Hampton-Seabrook estuary. Ninety percent of the bird’s breeding range is in the Northeast. Preserving the existing habitat and restoring degraded saltmarsh will benefit the saltmarsh sparrow.
Eelgrass (Zostera marina)
Eelgrass (Zostera marina) is a rooted vascular plant that can form dense sub-tidal meadows in estuary waters. Eelgrass beds provide valuable habitat for estuarine species, especially juvenile commercial fish and shellfish species like stripers and lobsters are a critical component of the estuarine food web, and reflect the overall health of estuarine water quality. Eelgrass filters nutrients and suspended particles from water and stabilizes sediments. Eelgrass beds are in decline in Great Bay Estuary.