Status of the Missouri-endemic Bluestripe Darter (Percina cymatotaenia).

Abstract: The state-endemic Bluestripe Darter, Percina cymatotaenia, occurs only in the Niangua and Gasconade river systems of central Missouri. Objectives' were to assess change in distribution and abundance between two time periods: 1976 to 1982 and 1994 to 2002. Fish community samples from within the range of P. cymatotaenia were analyzed." 40 from period 1 and 58 firm period 2. Data were averaged by 25-kin stream segment, for a total of 22 segments'. Average relative abundance of P cymatotaenia was greater in period 2 (0. 05 < P < 0.10) as was the average proportion of sites in which they were caught (0.01 < P < 0.025). The average relative abundance in period 1 was 1.7 P cymatotaenia per 100 benthic fish caught and in period 2 was 2.4 P. cymatotaenia per 100 benthic fish caught. They were caught in an average of 50% of the samples from period 1 and in an average of 73% of the samples from period 2. The upper Osage Fork showed decline over time, and the Woods Fork and upper Big Piney River showed depressed numbers in both time periods compared to pre-19 7 6 samples. These reaches' would be good candidates for further recovery efforts for P cymatotaenia.

Key Words: conservation, biodiversity, fishes, streams, Ozarks

Introduction

The Bluestripe Darter, Percina cymatotaenia, is endemic to rivers of central Missouri (Pflieger 1997). It is one of two species in the subgenus Odontopholis, the other of which is found in the Ohio River system in east-central Kentucky and Tennessee (Burr and Page 1993). These species are characterized by the presence of a caudal keel and elongated anal fin in breeding males which are hypothesized to facilitate the transfer of sperm from the male's genital opening to eggs buried in the substrate by the female (Page and Sabaj 1994). Pereina cymatotaenia is listed as imperiled (very vulnerable to extinction) both in the state and globally (Missouri Natural Heritage Program 2003).

Percina cymatotaenia is most common in the middle reaches of the Niangua, Osage Fork, Gasconade, Roubidoux, and Big Piney rivers (Pflieger 1997). It is not found in headwaters, and is naturally rare in the Niangua River below Bennett Spring and in the Gasconade River below the mouth of the Big Piney River. Gilbert (1888) described it as abundant in the Sac River system but, since then, only one individual has been collected there (in 1947). It has also been reported from the Maries River near Dixon (Meek 1891), but this location is so far up in the headwaters that it seems a mistake may have been made in the locality data. None have been collected from the Maries River system since then. Pflieger (1984), comparing his recently collected data with data from the 1940s and 1960s, warned that the remaining populations still seemed to be declining but at a slower rate compared to the tuna of the century. However, between the 1940s and the 1990s, Winston (2003) found an increase in the proportion of sites in which the species was collected.

In the present study, samples made from 1976 to 1982 were compared with samples made from 1994 to 2002. The objective was to use this data to assess the conservation status of P. cymatotaenia. The null hypothesis was no change in distribution or abundance between the two time periods.

Materials and Methods

Between 1976 and 1982, W. L. Pflieger made 40 samples within the range of P. cymatotaenia. He used a variety of seines but mostly a 1.8 m by 1.2 m, 3.2 mm mesh kick seine for sampling riffles and cover along the margins of pools and a 7.6 m by 2.4 m, 6.4 mm mesh drag seine for sampling pools and the deeper sections of riffles and runs. His goal, while sampling, was to catch most or all small fish species in a reach. He also sampled intensively enough so that P. cymatotaenia densities could be estimated (Pflieger 1984). He made 32 of his samples (80%) between February and May because he was also studying P. cymatotaenia reproduction.

Between 1994 and 1996, S. A. Bruenderman resampled 13 of Pflieger's sites. Bruenderman was trained by Pflieger and made three of the samples with him. Bruenderman sampled with a 1.8 m by 1.2 m, 6.4 mm mesh kick seine and a 4.6 m by 1.8 m, 6.4 mm mesh drag seine. She made 12 of the samples (92%) between June and August.

Between 2000 and 2002, M. R. Winston made 45 samples within the range of P. cymatotaenia. He located samples at randomly chosen access sites. Winston used a 1.8 m by 1.2 m, 3.2 mm mesh kick seine and a 4.6 m by 1.8 m, 3.2 mm mesh drag seine. His goal, while sampling, was to collect all small fish species (< 30 cm maximum length) in a reach. He sampled major habitat types (e.g., riffles, open water in pools, aquatic vegetation at the edge of pools) until he reached a plateau in the number of small species caught in each habitat. All were taken between June and September.

For analysis, Pflieger's samples (period 1) were compared with Bruenderman's and Winston's samples combined (period 2). Number of benthic fishes, number of P. cymatotaenia, relative abundance of P. cymatotaenia to benthic fishes, presence/absence of P. cymatotaenia, and number of benthic species were calculated for each sample. Values were averaged by 25-kin stream segment for a total of 22 segments (Table 1; Figure 1). This was necessary for three reasons: more samples were made in the later period; the spatial distribution of samples was uneven; and, Pflieger's sites were not always resampled. Wilcoxon signed rank tests (Sokal and Rohlf 1981) were used to test for a difference over time in average number of P. cymatomenia, average number of benthic fishes, average relative abundance, average presence/absence of P. cymatotaenia, and average number of benthic species in stream segments. Percina cymatotaenia have been categorized as benthic (Pflieger 1984); therefore the number of benthic fishes caught provides a better measure of effort for calculating relative abundance than does total number of fishes caught. Average number of benthic species caught was also used as a measure of effort.

Results

Greater numbers of benthic fishes were caught in the period 1 (0.001 <P < 0.005). The average number of benthic fishes caught in period 1 was 226 and in period 2 was 94.

There was no significant difference in the number of P. cymatotaenia caught (P > 0.10). The average number caught in period 1 was 2.6 and in period 2 was 1.9 (Table 1).

Relative abundance was marginally greater in period 2 (0.05 < P < 0.10). The average relative abundance in period 1 was 1.7 and in period 2 was 2.4 P cymatotaenia per 100 benthic fish caught. This result was due to the large difference in number of benthic fishes caught compared to the small difference in number of P. cymatotaenia caught.

The difference in the average proportion of sites in which P. cymatotaenia were caught was significant (0.01 < P < 0.025). They were caught in an average of 50% of the samples from period 1 and in an average of 73% of the samples from period 2 (Table 1).

There was no significant difference in the number of benthic species caught (P > 0.10). The average number of benthic species caught was 8.7 in both time periods.

Discussion

The data show a significant increase in relative abundance and occurrence (proportion of sites in which they were caught) of P. cymatotaenia. Relative abundance increased by 41%, and occurrence increased by 46%. In a related study, between the 1940s and 1990s, P. cymatotaenia was found to have increased in occurrence by 138% (Winston 2003), indicating that the increase has been ongoing since 1940.

The results of the presence/absence analysis should be more robust than the results of the total number and relative abundance analyses. The season in which most samples were taken and the effort put into sampling differed between time periods. Percina cymatotaenia is not known to make regular migrations, and they can be collected with seines at all times of the year where they are known to occur (Pflieger 1984). Effort was most likely greater in the earlier time period as shown by the greater number of benthic fishes caught. One would expect that the number of species caught would increase with the number of fish caught; however, this was not the case. A similar number of benthic species was caught in both time periods. This suggests that a plateau was reached in the number of species caught with effort in both time periods. Therefore, the presence/ absence analysis should not be biased by season. Total number and relative abundance would seem to be more sensitive to small differences in decisions made by the samplers in the field such as the time spent sampling in different habitats, as well as seasonal and water-level differences. Although calculating abundance of P. cymatotaenia relative to number of benthic fishes was better than to number of all fishes, an even better metric would have been number of benthic fishes collected in cover in pools with little water velocity, but this was not available for many of the samples.

Pflieger (1984) warned that the main area of decline of P cymatotaenia was in the upper reaches of its range. This problem seems to have worsened since his study. Pflieger (1984) noted locations of decline in the Woods Fork and upper Big Piney River. In period 2, the species showed little evidence of recovery in these reaches. One sample was made in the Woods Fork and four were made in the upper Big Piney River; and, only one P. cymatotaenia was collected total. Pflieger (1984) did not mention the upper Osage Fork; probably because he caught 10 P cymatotaenia in two samples there. In period 2, the species showed a strong decline in this reach. Only one individual was caught in nine samples. In an analysis of land use and land cover, Blanc (2001) rated the upper Osage Fork as one of the more impacted subbasins in the Gasconade drainage, with a relatively high percentage area of urban and cropland in the watershed, a high percentage area of gravel bars in the river channel, and low riparian quality. Pflieger (1984) noted the urbanization of the Woods Fork and upper Big Piney River watersheds. The data suggest that these reaches merit special concern relating to their land use and management.

Table 1. Numbers of Percina cymatotaenia caught. Multiple numbers in
a stream segment in a time period represent multiple samples. Numbers
are listed from downstream to upstream within a segment/period. Stream
segments are mapped in Figure 1.

                           Time Period

Stream Segment        1976-1982    1994-2002

Niangua River 1       0            1
Niangua River 2       0,0          3,3
Niangua River 3       7            1,4
Niangua River 4       18,3         1,0,1
Niangua River 5       1,0          1,0
Osage Fork 1          0            1,1
Osage Fork 2          0            1
Osage Fork 3          0            1,0,0
Osage Fork 4          2            0,0,0,0
Osage Fork 5          8            0,0,1,0,0
Gasconade River 1 *                0,0,0
Gasconade River 2     0            1
Gasconade River 3 *   0
Gasconade River 4 *
Gasconade River 5     3            2,1
Gasconade River 6     0            5
Gasconade River 7     3,3          1,0
Gasconade River 8     4,1          9
Gasconade River 9     3            1,5,5
Gasconade River 10    13,0         1,2,0
Woods Fork 1 *        0            0
Whetstone Creek 1     7,4          4,0
Roubidoux Creek 1     7,1,0,0      1,0,3,0
Big Piney River 1 *   0            0
Big Piney River 2     0            1,10
Big Piney River 3 *
Big Piney River 4     1,0,17,0,0   2,2
Big Piney River 5 *                0
Big Piney River 6     0,0          0,0,1,0

* Data not included in statistical analyses.

Acknowledgements

The authors would like to thank D. Novinger and M. Wallendorf for help with statistics and with the writing of the manuscript.

References

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Pflieger, W. L. 1984. Distribution, status, and life history of the bluestripe darter, Percina cymatotaenia, Missouri Department of Conservation Aquatic Series 18, Jefferson City, MO.

Pflieger, W. L. 1997. Fishes of Missouri. Missouri Department of Conservation, Jefferson City, MO.

Sokal, R. R., and F, J. Rohlf. 1981. Biometry, second edition. W. H. Freeman and Co., New York, NY.

Winston, M. R. 2003. Distribution changes of small fishes in streams of Missouri from the 1940s to the 1990s. Missouri Department of Conservation, Jefferson City, MO.

Matthew R. Winston and Ryan P. Tilley

Missouri Department of Conservation

1110 S. College Ave.

Columbia, MO 65201