Guagas Lake - Courtesy of Nelson Cloud

Freshwater mussels are an important part of a healthy aquatic ecosystem. As benthic organisms, they play a vital role in the composition of aquatic food webs, nutrient cycling and energy flow. They also help maintain water quality as filter feeders. Freshwater mussels are considered to be the most threatened taxonomic group in North America. Although some rivers in New Brunswick have been surveyed for freshwater mussels, very few surveys have been done in the Miramichi River watershed. Little is thus known about which species are present, and their abundance and distribution. Particularly due to limited access, the Northwest Miramichi River has never been surveyed prior to this project, but areas on the Southwest Miramichi River have been surveyed in the past by freshwater mussel specialist Ms. Kate Bredin. Ms. Bredin also has a special interest in a rare freshwater mussel species, the Brook Floater, which she has discovered in the Miramichi River and therefore increases the importance of continuing such surveys in the watershed in order to understand the status of this species.

Brook Floater found on the Taxis River

The Brook Floater (Alasmidonta varicosea) has recently been assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and has a National General Status Rank of "special concern" in New Brunswick. With the discovery of this mussel in the Southwest Miramichi, further freshwater mussel surveys in the Miramichi River would help delineate the extent of this rare species in the Miramichi watershed. Brook Floaters are declining throughout their range in the US due to pollution and alteration of river habitats (ie. dams). With the knowledge that this species existing in the Miramichi River makes this river even more important and significant ecosystem.

Miramichi Results for 2008-2010

North Pole Stream below Palasaides

MREAC has conducted three field seasons (2008, 2009 & 2010) of Freshwater Mussel Surveys for the Miramichi River watershed, completing 45 sites on 22 tributaries. This project was funded by the Wildlife Trust Fund. Freshwater mussel specialist Ms. Kate Bredin was consulted for advice, guidance and training for this project, as well as Ms. Mary Sollows who is another expert working for the New Brunswick Museum. During MREAC's three year effort of surveys, four species of freshwater mussels were found; Eastern Pearlshell, Eastern Elliptio, Eastern Floater and the rare Brook Floater. However, a fifth species, Eastern Lampmussel, is known to inhabit the Southwest Miramichi River as it was found by Mr. Bredin during her early work.

The Eastern Pearlshell (Margaritifera margaritifera) is the most abundant freshwater mussel species in the Miramichi River watershed with 13,448 specimens counted at 39 of the 45 sites surveyed. This species has a diverse range of habitats as it was found in the rough, rocky headwaters of the South Branch of the Southwest Miramichi, to the calm, slow flow of the Barnaby River. The Miramichi River is world renowned for its Atlantic salmon fishing and also very popular for trout fishing. Both of these fish species are common hosts for the Eastern Pearlshell’s larval stage. Also, with limited industrial impacts the water quality and mussel habitat conditions on most of the Miramichi River is very good.

The second most common freshwater mussel MREAC discovered during this project was the Eastern Elliptio (Elliptio complanata), discovering 683 specimens at 11 of the 45 sites surveyed. This mussel species is not as rugged as the Eastern Pearlshell and therefore was not found in the rocky, headwater sites. Most of the sites where this species was found were on the Barnaby River, which was one of the two focal rivers during 2010-11.

A lake species, Eastern Floater (Pyganodon cataracta), was discovered at two sites. Guagus Lake was home to 57 of these mussel species, and Napan River during a slow, sandy stretch had resulted in the discovery of one live specimen, bringing the total to 58 Eastern Floater found during this project.

The Brook Floater (Alasmidonta varicosa) was discovered during the second and third year of sampling, found at three sites with a total number of five live specimens recorded. Even with a concentrated focus on the Taxis and Barnaby Rivers, this species continues to demonstrate its rarity and how critical freshwater mussel surveys are in order to understand and protect the Brook Floater and their habitat. Miramichi River is becoming a more important link to the survival of this freshwater mussel species.

There is one other species of freshwater mussels that can be found on the Miramichi River, the Eastern Lampmussel (Lampsilis radiata). This species was not discovered by MREAC during the three years of surveying, however, it was found during Ms. Bredin's survey efforts on the Southwest Miramichi River. With this species included, the Miramichi River watershed is home to five known freshwater mussel species.

Data collected during this project was shared with the NB Museum in order to keep a record of freshwater mussel populations throughout New Brunswick. It was also shared with COSEWIC in order to be part of future status assessments for the Brook Floater, and possibility for the Eastern Pearlshell which is currently being investigated as a possible "special concern" species. This species is the most abundant in the Miramichi River watershed; conversely other watersheds have been seeing a decline in their Eastern Pearlshell population.

Map illistrates the freshwater musself survey sites completed by MREAC (2008, 2009 & 2010), along with Ms. Bredin’s sites (2002 & 2006). This map demonstrates the distribution of freshwater mussels on the Miramichi to date.

	Freshwater Mussel Surveys on the Miramichi, 2010 & Overview of Past Three Years
	Freshwater Mussel Surveys on the Miramichi, 2009
	Freshwater Mussel Surveys on the Miramichi, 2008