Conserve Wildlife Blog

Posts Tagged ‘freshwater mussels’

New Jersey’s Field Guide to Freshwater Mussels is Here!

Wednesday, December 2nd, 2015

By Michael Davenport, GIS Program Manager

Freshwater mussels are distant relatives of marine mussels with a life cycle which includes a larval stage where they hitch a ride on fish as a parasite. There are a dozen species native to New Jersey and some species are known to live for over 100 years. This is an often overlooked group of species which deserves greater attention since many species are imperiled and because they are indicator species of water quality.

Conserve Wildlife Foundation of New Jersey (CWF) has partnered with the NJ Endangered and Nongame Species Program to create and release our latest Story Map, “Freshwater Mussels of New Jersey.”


This Story Map is a web-based field guide to New Jersey’s freshwater mussel species. The field guide explores the diversity of this group of species, how to identify them, their life history, threats and conservation measures, as well as providing range maps for each species. This is the only freshwater mussel field guide specific to the state of New Jersey and developed by state biologists.

Photos and interactive range maps are available for all 12 of New Jersey’s native species as well as several non-native species found within the state. Several short videos are also included which demonstrate different methods of surveying for freshwater mussels.

Funding for the creation of this Story Map was provided in part through a New Jersey Division of Fish & Wildlife grant.

Photos From the Field

Monday, September 9th, 2013

By Michael Davenport, Marine Species & GIS Programs Manager

Left: a killifish with attached glochidia.  Right: a crayfish taking shelter within a mussel shell.  © Mike Davenport

Left: a killifish with attached glochidia. Right: a crayfish taking shelter within a mussel shell. © Mike Davenport

The images above were taken during a recent survey of the Raritan River in Somerset County.  The image on the left is a Banded Killifish with the larval stage of freshwater mussels attached (the small black dots on the side of the fish are the larval mussels, known as glochidia).  Glochidia are parasites of fish, and some other aquatic animals, which will drop-off at the end of their larval stage, and then complete their life cycle in the bottom of the river, stream, or lake as the adult mussels most people are familiar with.  The host fish not only provides a meal for the glochidia, but also enables mussels to travel further than they can as an adult.

The image on the right is a crayfish which took shelter within the old shell of a freshwater mussel, in this case an Eastern Elliptio.  Other freshwater invertebrates may reside within old mussel shells, such as snails and aquatic insects.

To learn more about freshwater mussels in New Jersey, visit our Freshwater Mussel site.

Witness to a New Species’ Invasion

Wednesday, June 19th, 2013

By Michael Davenport, Marine Species & GIS Programs Manager

In 2010, a non-native freshwater mussel species was discovered in Hunterdon County, NJ – the Chinese pond mussel (Sinanodonta woodiana, previously referred to as Anodonta woodiana).  Not only was it the first time found in New Jersey, but it was the first documented occurrence within the entire US.

A Chinese pond mussel.  Photo by Mike Davenport.

A Chinese pond mussel. Photo by Mike Davenport.

The Chinese pond mussel is native to eastern Asia.  It is a large freshwater mussel, reaching a size of almost 1-foot across; which makes it the largest species now in New Jersey.  New Jersey is home to 12 native species of freshwater mussel – you can learn more about their distribution on Conserve Wildlife Foundation’s freshwater mussel page.  Additional non-native freshwater mollusks include the Asian clam and paper pondshell.

The Chinese pond mussels discovered in New Jersey have thus far only been found within the ponds of an abandoned fish farm and an adjacent stream.  They were most likely introduced by accident as “hitchhikers” on the Asian carp being farmed within the ponds (young mussels, known as glochidia, are parasites on fish and a few other aquatic vertebrates).  The non-native mussels thrived within the ponds.

Non-native mussels are a threat to native mussels because they compete with them for space and food.  Out of 12 native species in New Jersey, 9 of those are classified as Endangered, Threatened, or Special Concern.  The addition of the new potential threat of another invasive species is a great concern for the recovery of those 9 species.

The ponds where the mussels were found were treated with the chemical rotenone, which eradicated the non-native carp as well as most of the mussels.  A survey by staff from the NJ Endangered & Non-game Species Program and CWF earlier this year, however, confirmed that the mussels are still within the ponds, although their numbers have been greatly reduced.  The mussels could no longer be found in portions of the stream downstream of the ponds where they had been found in 2010.  This is significant because the stream drains into the Delaware River.  If the mussels were able to expand their distribution into the Delaware, opportunities to control their spread and establishment in the river would be much more difficult if not impossible.

Although most experts aren’t certain of the full potential magnitude of a Chinese pond mussel invasion, we’re in a position right now to stop it in its tracks.  Further monitoring and perhaps further chemical treatments will be necessary to keep yet another invasive species from becoming established in New Jersey.