Percina vigil

Introduction

This paper will outline a monitoring plan for the Saddleback Darter, Percina vigil. This darter species is widespread, occurring from the Escambia River drainage west to the Mississippi River basin and as far north as the Wabash River historically. Some populations have been reported in the Tennessee River drainage. The Saddleback Darter is aptly named as it has 5 saddle-like patterns on its dorsum, with the first occurring near the first dorsal fin and the fifth near the caudal penduncle. Adults can attain a maximum size of about 3 inches or 7.8 centimeters. Percina vigil typically occurs over sand and gravel runs of creeks and small to medium sized rivers and is sometimes found in very shallow water. This darter’s diet consists of invertebrates such as caddisfly larvae, beetles, mayflies, and stoneflies. The Saddleback Darter deposits eggs over sand and gravel shoals during the spring. Based on length-frequency data, this species has an average lifespan between 2 and 3 years. Currently the Saddleback Darter is listed by the IUCN as least concern, and there does not appear to be any specific monitoring plan for the species throughout its range. While widespread threats do not seem apparent and populations appear stable, monitoring of the species could uncover any potential future threats for the species. ^[1] Since the Saddleback Darter occurs in the Mississippi River drainage, it could suffer from increased levels of nitrogen and other nutrients. Poor agriculture practices remain a problem throughout the Mississippi alluvial plain, and with every weather event there is the possibility for fertilizers, pesticides, and other chemicals to enter the watershed. Thus, monitoring of this species could prove important to understand changes of water quality within its range.^[2]

Geographic distribution

The Saddleback Darter has a widespread but sporadic distribution throughout its range. It commonly occurs in low gradient streams from the Mississippi River drainage in southeast Indiana and Missouri southward to the Gulf Slope in the Escambia River Drainage. This fish is most common in the Gulf Slope region of its range.^[3] The fish has also been recorded in the Tennessee River drainages such as the Hatchie River. The Saddleback Darter was once found in the Wabash River, however it has been extirpated. This raises interest as to what contributed to the extirpation of this darter. Anthropogenic factors, especially siltation and excess nutrients, are likely to blame for the loss of this fish from the river. The Wabash River flows through the Corn Belt, a major agricultural area of the United States. This puts the river at great risk for increased nutrients from fertilizers and siltation from frequent disturbance of the soil. This reduction in water quality has likely been what extirpated the Saddleback Darter from the watershed, along with several other fish species.^[4]

Ecology

Percina vigil typically inhabits large creeks and rivers, but is occasionally found in small streams as well. These fish are closely associated with shoal habitats where they prefer sand or gravel substrates. The Saddleback Darter is a lowland area darter occurring in temperate areas, thus the water temperature generally ranges from a low of 40°F to a high of around 80°F. The Saddleback Darter also co-occurs with the Snail Darter in the Lower Paint Rock River in Alabama.^{[5] [6]} Percina vigil feeds on invertebrates including river snails, hydropsychid caddisfly larvae, midge larvae, and small mayfly nymphs such as baetids. This fish is likely a prey item for almost any piscivorous fish that occur within the darter’s range. Likely predators include Largemouth Bass, Smallmouth Bass, and other large piscivores. Human induced changes to the waterways they occur in could cause their decline in the future. Since they have an affinity for swift water such as that found in shoals, the creation of impoundments causes the loss of their particular microhabitat. ^[7]

Life History

The Saddleback Darter spawns over gravel shoals as early as late winter, though it can continue into April. Maximum tubercle development in males was documented to occur in February in an Alabama population. There is evidence to support the hypothesis that these fish may have more than a single clutch in a reproductive season. Clutches from females of 41-55mm consisted of anywhere from 40 to 400 eggs. Sexual maturity is reached within one year, and following this males are usually slightly larger than females of the same age class. The average lifespan of Percina vigil is usually 2 years, with few specimens making it through their third winter. Reproduction is another aspect of the fish’s status that could be negatively impacted by creating impoundments. Building dams to create lakes and hydroelectric power facilities causes a loss of shoal habitat needed for Percina vigil to spawn.^[8]

Current Management

Game fish such as Bass, Crappie, and other panfish receive a lot of attention and have been the center of fisheries research and management for many years. However, they only comprise a small percentage of all the fish in a given ecosystem. Thus there is little known about several non-game species of fish, such as Percina vigil. The Saddleback Darter along with many fish in this category do not have any active management and their populations are usually poorly reported. ^[9] This was a downfall of fisheries research because until recent years, these fish have not been appreciated for the potentially vital role they play in their native range. There has been a fair amount of research conducted on the Saddleback Darter in the past four decades. However, there was not enough monitoring performed on these fish before they were extripated from the Wabash River section of their range. Thus, this extirpation shows just how important monitoring of this and other non-game species is. ^[10]

Management Recommendations

Monitoring Percina vigil populations throughout its range would be highly recommended as they have already disappeared from the Wabash River watershed where they once occurred. A good estimate for populations could be recorded with the use of seining. Streams to be sampled could be selected by analyzing historical records. Once individual streams are selected, choosing specific sampling sites could be done by seeking out preferred habitat of the fish. In this case an example would be looking to find that populations have been found in the Hatchie River. Then sampling would occur within any shoals which were composed of a sand or gravel substrate. The seine hauls would be taken by starting several feet downstream and taking a few hauls while working up stream. This would ensure that accurate data was being collected as the most used habitat types were being looked at in all historical watersheds. Sampling should take place once a year in order to understand any obvious changes within individual populations. With an understanding of the Saddleback Darter’s habitat requirements and the disappearance of it from part of its range, caution should be exercised in order to keep this fish from being further extirpated or going extinct. Limiting impoundments within watersheds that Percina vigil occurs in would help preserve their habitat. Another action that should be taken to protect this fish and the ecosystem as a whole is encouraging the proper streamside management, especially in areas of high agricultural land use. This would reduce sedimentation and eutrophication to preserve Percina vigil and our aquatic resources as a whole.

References