Invertebrates
November 7, 2008There are thousands of species of invertebrates in Narragansett Bay although, with several exceptions, they are not nearly as well studied as fish. Yet even some little known species, like comb jellies (Phylum Ctenophora) and copepods (Orders Calanoida and Cyclopoda) are of great ecological importance as consumers of phytoplankton or fish larvae, as food for larger species, or as competitors with other species. Invertebrates of importance to Narragansett Bay include crustaceans such as lobsters, crabs, shrimp and copepods; mollusks, including shellfish like clams and oysters as well as cephalopods such as squid; and a wide variety of benthic or sessile organisms such as sea stars and urchins (Class Echinoidea), corals and anemones (Class Anthozoa), and tunicates and sea squirts (Phylum Chordata). A variety of benthic worms (e.g., Class Polychaeta) are important as food for winter flounder and other demersal fish, while some of the mollusks (particularly blue mussels, oysters and slipper shells (Crepidula fornicata) serve an important role in the establishment of benthic habitat, forming extensive areas of structure on the bottom of the Bay. Several small shrimp species play important ecological roles-Palaemonetes spp. are abundant in salt marshes, while the sand shrimp Crangon septemspinosa has been identified as an important predator of winter flounder larvae.
The invertebrates of greatest fishery importance in Narragansett Bay are lobsters and quahogs. Lobsters are undoubtedly the Bay’s most valuable commercial fishery, although landings statistics don’t separate the Bay catch from that of other inshore waters. In 1999, the Rhode Island lobster fishery landed 3700 metric tons valued at more than $31 million; since then, the inshore lobster fishery has steadily declined, landing 1400 metric tons in 2005 with a landed value of $16 million. According to RIDEM (2006), a number of factors have been implicated in the decline, including oil spills, natural cycles, predation, pollution, disease and overfishing. In a 2007 report, the Atlantic States Marine Fisheries Commission stated that the Southern New England lobster stock “is in poor condition…the stock is considered depleted and overfishing is occurring.”
[reference/insert lobster graph from DEM stock report here]
While the landed value of quahogs is relatively small compared with that for lobsters, the quahog industry on Narragansett Bay is important in terms of employment. According to RIDEM, about 350 quahoggers were actively engaged in the fishery from 2000-2002 (RIDEM 2006); the species also supports an important recreational fishery. Again, fishery statistics don’t separate the Bay catch, but a majority of Rhode Island quahogs are harvested from Bay waters.
Like lobsters, quahogs have also suffered from harvest pressure. According to the National Marine Fisheries Service, Rhode Island quahoggers landed more than 300 metric tons in 2006, valued at roughly $3.5 million. This represents a decline from the landings high of more than 2,000 tons in the mid-1950’s (National Marine Fisheries Service 2008).