Pearl Dace - Margariscus margarita
State Rank Reason (see State Rank above)
Pearl dace are not abundant when they are collected at the relatively few sites in cool, small streams and ponds they are known to inhabit. This factor, as well as introduced northern pike invasions into their small prairie streams, has caused them to be designated as a Montana Species of Special Concern vulnerable to extinction in the state.
The pearl dace is a native of both the eastern and northern drainages within the Glaciated Plains ecoregion of Montana, and is an indicator species of the complete Coolwater Northern Glaciated Plains Fish Assemblage. Pearl dace are not abundant when they are collected at the relatively few sites in cool, small streams and ponds they are known to inhabit. This factor, as well as introduced northern pike invasions into their small prairie streams, has caused them to be designated as a Montana Species of Special Concern vulnerable to extinction in the state. Unlike most of the minnows, males establish and defend territories during the spawning season. Their diet includes a wide variety of plants and animals. Pearl dace grow to a maximum length of about 6 inches.
The pearl dace has a dark back, sides that are dusky-silver, and a white underside. Scattered dark lines give some individuals a speckled appearance. Young have a dusky midline band that fades on large specimens but may be distinct on the caudal peduncle. Breeding males are orange-red on the sides and below. A small, flaplike barbel is present in the groove of the upper lip just above each corner of the mouth, and is sometimes absent from one or both sides. A lateral line usually complete.
The pearl dace is at the southern end of it's range in northern Montana, but is considered abundant in other parts of its northeastern range.
Summary of Observations Submitted for Montana
Number of Observations:
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Map Help and Descriptions
(Records associated with a range of dates are excluded from time charts)
Do not migrate extensively, they tend to be residents of a series of permanent pools
Pearl dace prefer small cool streams, either clear or turbid (Brown 1971). They spawn in clear water at depths of 1 to 2 feet over a gravel or sand bottom (Brown 1971).
Pearl dace eat a variety of aquatic organisms including insects, crustaceans, worms, and small fish (Brown 1971).
Pearl dace are often associated with the Northern Redbelly Dace and Brassy Minnows in the Northern Glaciated Coolwater fish association (Stagliano 2005). Young of the year may be associated with a aqautic vegetation for security cover, while adults generally are water column feeder.
The species is sexually mature in two years and spawns during spring near the bottom (Brown 1971).
The management of this species should involve routine monitoring (once every 2 to 3 years) of existing populations, since there are only 12 documented in the state. The monitoring program should be designed to detect population trends, range expansion or losses and collect additional information on life history and ecology. This could be conducted while sampling for other species. The lack of proper monitoring of these populations could lead to their demise by virtue of not recognizing if and when they are in jeopardy of becoming extirpated by any artificial or natural entity.
Threats or Limiting Factors
Threats include: Introduced Species, especially Northern Pike, and loss of habitat from stock ponds, dams and diversions disrupting hydrologic regimes in the permanent pools of the prairie streams they inhabit.