- Taxon: Fish
- Range: Mississippi and Louisiana
- Status: Threatened species
The pearl darter, a small fish native to the Pascagoula River system of Mississippi and the Pearl River system of Mississippi and Louisiana, was listed as a threatened species by the Service in October 2017. Pearl darters continue to survive in the Pascagoula River system but have not been seen in the Pearl River system for more than 40 years.
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The pearl darter is a small bottom dwelling freshwater fish measuring about two and a half inches in length. It has a blunt snout, a horizontal mouth, and large eyes situated high on its head. The common name, pearl darter, is derived from iridescent patches on its gill covers resembling the coloration of a pearl.
The pearl darter is found in free-flowing, low-gradient streams and rivers with pools and scour holes associated with channel bends and runs. Coarse sand and gravel substrates and woody debris supply habitat for its prey. Pearl darters can also be found in streams and rivers with bottom substrates composed of sand, silt, loose clay, and gravel, with organic matter in the form of coarse and fine particulates and snag material. Their occurrences within these habitats may be seasonal, with spawning occurring in upstream reaches, and growth and recruitment in downstream reaches. Downstream drift of larvae or movement of juveniles, and the upstream migration of spawning adults requires perennial, uninterrupted, and interconnected stream to river channel habitat.
The natural diet of the pearl darter is unknown, however like other species within the genus they probably feed on midges, small crustaceans, mayflies, and caddisflies. Food availability is affected by adequate flow, channel stability, and water quality.
The pearl darter is historically known from rivers and streams within the Pascagoula River system in Mississippi and the Pearl River system in Mississippi and Louisiana. Within the Pearl River system in Mississippi the species was historically found in high abundances in the lower Strong River.
Pearl darters continue to survive in the Pascagoula River system in Mississippi but have not been seen in the Pearl River system for more than 40 years.
The primary threat to the pearl darter is water quality degradation caused by pollution in association with land-surface, storm water, and effluent runoff from urban and rural areas. In addition, the pearl darter’s localized distribution, apparent low population numbers, and possibly, low genetic diversity, all make it more vulnerable to catastrophic events such as drought, storms, and oil or chemical spills. These threats are compounded by the species’ naturally low numbers and short life span.
A recovery plan is being drafted for the species.
Partnerships, Research, and Projects
Plans for the pearl darter’s recovery includes reintroduction into the Pearl River system. The Service, the University of Southern Mississippi, and the Mississippi Department of Wildlife, Fisheries, and Parks have worked to regularly monitor for the presence of the pearl darter and other bottom-dwelling fish in both the Pearl and Pascagoula river systems. Methods and facilities for propagating the species have also been developed, tested, and proven at the Pvt. John Allen National Fish Hatchery in Tupelo, Mississippi.
How you can help
A number of actions can help conserve the pearl darter including:
- Don’t dump chemicals into streams and rivers.
- Do report spills to state environmental protection agencies.
- During timber harvest, construction or other projects, implement certified best management practices for sediment and erosion control.
- Start a watershed group or assist in stream and water quality monitoring efforts.
- Plant trees and other native woody vegetation along stream banks to help restore and preserve water quality.
Subject matter experts
Matthew Wagner, Fish and Wildlife Biologist, Mississippi Ecological Services Field Office, firstname.lastname@example.org, 601-321-1130
Designated critical habitat
The Service is proposing to designate 517 river miles of critical habitat for the pearl darter in two separate units in Mississippi within Clarke, Covington, Forrest, George, Greene, Lauderdale, Jackson, Jones, Newton, Perry, Simpson, Stone, and Wayne Counties. The proposed critical habitat does not include riparian areas, only instream habitat (stream and river channels) within the ordinary high water line.
Unit one, the Pascagoula River Unit, is 487 river miles of occupied critical habitat. Unit two, the Strong River Unit, is 30 river miles of unoccupied critical habitat and is being included in order to allow for the reintroduction of the pearl darter into this major tributary of the Pearl River system in Simpson County, Mississippi. Strong River was historically occupied by the species, prior to 1973.