- Email: [email protected]
Spawning Habitat Selection by Rainbow Trout in the Pere Marquette River, Michigan
J. Great Lakes Res. 30(3):397–406 Internat. Assoc. Great Lakes Res., 2004
Spawning Habitat Selection by Rainbow Trout in the Pere Marquette River, Michigan R. Douglas Workman1,3,*, Daniel B. Hayes1, and Thomas G. Coon2 1Michigan
State University Department of Fisheries and Wildlife 13 Natural Resources Building East Lansing, Michigan 48824-1222 2Michigan
State University College of Agriculture and Natural Resources 101 Agriculture Hall East Lansing, Michigan 48824 ABSTRACT. We evaluated habitat features (i.e., substrate particle size, water depth, water velocity) at spawning redds and randomly selected reference locations (where spawning activity was not apparent) to determine importance of these features to rainbow trout (Oncorhynchus mykiss) spawning habitat use in the Pere Marquette River, Michigan, 1997 to 1999. Rainbow trout selected areas with small gravel, large gravel, and small cobble substrates for redd construction over areas with clay, silt, sand, and large cobble. Rainbow trout redds were located in areas where the stream velocity was significantly higher (F = 97.77, df = 630, p < 0.0001) than velocities that were recorded at reference sites, and redds were located in water that was significantly shallower than what was typically found in the study reaches (F = 113.84, df = 629, p < 0.0001). Water temperature did not affect selection of redd locations. Because rainbow trout spawn during spring in Michigan when water temperatures are cool, within-reach variation in water temperature may have minimal influence on choice of locations for redd construction. These microhabitat data provide an indication of rainbow trout spawning habitat utilization, and can be used to identify critical habitats that may serve as rainbow trout spawning sites, and provide guidance on targets for habitat improvement projects in the Pere Marquette River and elsewhere. INDEX WORDS:
Rainbow trout, spawning habitat selection, Pere Marquette River.
INTRODUCTION Microhabitat-scale features associated with redds (i.e., substrate particle sizes, redd depth, stream velocity above redds) of rainbow trout (Oncorhynchus mykiss) and other Pacific Coast salmonines, are well known (Cooper 1965, Kogl 1965, Smith 1973, Fukushima and Smoker 1998, Groves and Chandler 1999). However, information on spawning habitat use by Great Lakes rainbow trout is scarce. Substrate particle composition of redds varies among rainbow trout and other salmonines (Olsen 1968, Neilson and Banford 1983), however, redds of most salmonines share similarities related to sub-
strate particle composition. Substrate particles must be large enough and adequately sorted to accommodate alevin emergence; substrate must consist of a movable porous material such as gravel, so that a female can excavate the redd; and the redd must be located or shaped in a way that promotes the movement of oxygenated water through the redd (Cooper 1965, Sowden and Power 1985). In addition to substrate particle size composition, stream flow influences the reproductive success of rainbow trout by delivering oxygenated water to developing eggs (Vaux 1962, Silver et al. 1963), and thereby influences selection of spawning locations within streams. Rainbow trout and other Pacific Coast salmonines typically select stream reaches with faster-than-average water velocities, and are shallow with a high gradient
*Corresponding 3
author. E-mail: [email protected] Present Address: 2692 165th Avenue, Morley, MI 49336
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FIG. 1. 1999.
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Study site location and sample reaches in the Pere Marquette River, Michigan for 1997 through
(Smith 1973, Fukushima and Smoker 1998, Groves and Chandler 1999). Great Lakes rainbow trout are similarly influenced by stream flow in their selection of spawning habitat, but detailed documentation is lacking. The goal of our study was to gain a better understanding of the characteristics of habitat used by rainbow trout spawning in a tributary to Lake Michigan. We evaluated microhabitat-scale features associated with redds in relation to their availability within selected reaches of river. Identifying habitat features that are important to rainbow trout spawning site selection in a Great Lakes tributary can be used to identify other areas within the river that may be used by spawning rainbow trout. In addition, these important features could be incorporated into stream habitat improvement projects where habitat could be modified to enhance rainbow trout spawning.
METHODS Study Site Rainbow trout spawning habitat was evaluated throughout the Pere Marquette River (Fig. 1). The Pere Marquette River is located in west-central Michigan and the main stem of the river is approximately 154 km long (MDNR/IFR 1988). The river drains 1,955 km2 of watershed and is one of a few remaining large, free-flowing Great Lakes tributary streams in Michigan. The Pere Marquette River is primarily dominated by a cold-water fish community, and receives migratory rainbow trout during the fall, winter, and spring. Sample Reaches Sample reaches (1–2 km in length), where the bottom was readily observed and the stream was accessible through public access, boat launches, and
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Rainbow Trout Spawning Habitat Selection access permission from riparian landowners were identified within the Pere Marquette River (Fig. 1). Five study reaches were randomly selected and sampled in 1997 and 1998, and nine were randomly selected from a pool of 20 possible sites and sampled in 1999. We attempted to collect data from each site between 1000 and 1400 hr when daylight had the greatest intensity during April to optimize the visual detection of redds. Redds were identified by areas where there was evidence of excavated substrate free of debris, typically shaped with a conical depression in the center, and occasionally by the presence of spawning rainbow trout. Redds with fish tending them were recorded as active and apparently excavated sites were considered as suspected redds. Location of the redds within the river channel (river-left, mid-channel, and river-right), and run, riffle, and pool habitat types were noted (Hicks and Watson 1985). All redd measurements were taken in an area that was assumed to be the egg depositional zone (Chapman 1988), or approximately one-third of the distance between the deepest point of the redd depression, and the downstream edge of the redd. Stream temperature, mean column stream velocity, depth of water above each redd, and substrate particle size composition data were collected at each redd. Water temperature was measured using a Yellow Springs Instrument Company (YSI), Inc. meter at most redds. Mean column stream velocity and water depth at the measured redds were recorded using a Price AA meter and wading rod. For reaches with high redd density, we sampled every fifth redd. We obtained stream discharge data from the U.S. Geological Survey gauge station, located in the river at Scottville (Fig. 1). Visual estimation of substrate particle size is a widely used method (Bovee and Cochnauer 1977, Price 1982, Orth and Maughan 1982, Ibbotson et al. 1994, Jones 1999), and was chosen for this study as a relatively quick and reliable method to detect coarse differences among particle sizes. Substrate particle-size composition was visually estimated using a modified Wentworth (1922) classification within a 1-m-diameter circular area that was centered on the egg depositional zone for each sample site. To avoid observer bias, particle-size estimates were conducted by only one person throughout this study (Wang et al. 1996, Bain et al.1985). The large (128–512 mm) and small cobble (64–128 mm) particle-size classes were combined during the 1997 sampling, but were differentiated during the 1998 and 1999 sampling. Smaller parti-
cle sizes such as clay (0.00024–0.004 mm) and silt (0.004–0.062 mm) were identified by the texture of particles, color (e.g., silt is dark and sand is light colored), and by how readily they suspended when disturbed (e.g., silt readily suspends, sand suspends somewhat, and clay was not readily suspended). Reference data from non-redd locations were collected within each site during 1998 and 1999, with approximately 10 reference locations per km of study reach. Reference locations were equally spaced from each other and alternated from river left (RL) to mid-channel (CH) to river right (RR) locations in a downstream direction. At each reference point, the same information was collected as at redd sites. Redd Characteristics Substrate particle size distributions were compared among years (1997, 1998, and 1999) and between reference and redd sites (1998 and 1999) using the Kolmogrov-Smirnov two-sample test statistic (Berry and Lindgren 1996). Vanderploeg and Scavia’s electivity index (Ei) was used to compare substrate at rainbow trout redds with the substrate at reference sites (Vanderploeg and Scavia 1979): 1 Wi = n Ei = 1 Wi + n
(1)
where, Wi =
ri / pi ri / pi
∑
and, ri = the proportion of observations of particle size i in the redd substrate composition pi = the proportion of observations of particle size i in the reference site substrate composition n = the number of particle size categories. The index ranges from +1 to –1. A positive value of Ei indicates a larger proportion of the substrate particle size in the redd than was found in the reference stream reaches. A negative value of Ei indicates a particle size was used less than was available in the stream reaches. A value of 0 indi-
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cates a particle size was used in proportion to availability within the stream reaches. A Mixed General Linear Model (GLM, Littell et al. 1996) was performed on stream velocity, water depth, and water temperature, to examine differences among years, channel locations, study reaches, and between sample locations (redd and reference sites). Least square means (Littell et al. 1996) were used to determine where significant differences occurred. The following model was used to evaluate stream velocity, water depth, or water temperature:
RESULTS We recorded rainbow trout redd and reference data from 15 April to 24 April 1997, 15 April to 23 April 1998, and 28 March to 17 April 1999. During 1997, we sampled 178 redds and no reference sites (Table 1), and during 1998, we sampled 75 redds and 99 reference sites. We sampled the greatest total number of sites during 1999, when we sampled 150 redds and 149 reference sites. Rainbow trout spawned primarily in riffles, and to some extent in runs (Table 1). We did not observe any redds in pool habitat (Table 1).
y = µ + αi + βj + ζl + γi,j + ιi,l + κj,l + ηk + e
Substrate Particle Size Rainbow trout did not appear to construct redds in areas with very large particle sizes. We did not observe any small boulders (256–512 mm) or larger particle sizes (> 512 mm) in redds. We observed large cobble in 6% of redds sampled in 1998 and 1999 (n = 219). Although large particle sizes were more frequently sampled (10% of the samples) in the 1998 and 1999 reference sites (n = 249), larger particles were not common within the study reaches. Rainbow trout also avoided smaller particles such as clay (0.00024 –0.004 mm) and silt (0.004–0.062 mm) occurring in redds. We did not observe clay or silt at any of the active and suspected redd sites, whereas silt was observed at an average of 3% (1999) and 0.8% (1998) in the reference samples. We observed clay at an average of 0.7% (1999) and 0% (1998) in the reference samples. We compared the substrate particle size distribution between active and suspected redds, reference sites, and sample years using the KolmogorovSmirnov test. Particle-size distribution of active and suspected redd locations were not significantly different for 1997 (D = 0.03, n1 = 141, n2 = 41, p > 0.27), 1998 (D = 0.02, n1 = 71, n2 = 15, p > 0.27), or 1999 (D = 0.04, n1 = 109, n2 = 43, p > 0.27). Thus, we combined the active and suspected redd data from each sample year for further analyses. The particle-size distributions of redd and reference sites were significantly different in 1998 (D = 0.41, n1 = 99, n2 = 88, p < 0.001) and 1999 (D = 0.36, n1 = 149, n2 = 152, p < 0.001). In 1998 and 1999, rainbow trout redds were associated with larger particle sizes than reference sites (Fig. 2), and none were associated with clay or silt. The 1998 and 1999 redd substrate data (when large cobble was differentiated from small cobble)
(2)
Where, y = stream velocity, water depth, or water temperature by year, channel location, and sample location µ = model intercept αi = year (fixed effect) βj = channel location (fixed effect) ζl = sample location, i.e., redd or non redd site (fixed effect) γi,j = interaction between year and channel location ιi,l = interaction between year and sample location κj,l = interaction between channel location and sample location ηk = study reach (random effect with mean zero and ) e = model error. A GLM was used to evaluate differences in stream flow from Scottville USGS gauging station among years. The Tukey-Kramer pairwise comparison was used to determine where significant differences occurred. The following model was used to evaluate stream flow: y = µ + αi + e
(3)
y = discharge recorded at the USGS gauging station in Scottville, Michigan µ = model intercept αi = year e = model error. All tests were conducted using α = 0.05.
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Rainbow Trout Spawning Habitat Selection TABLE 1. Redd and reference habitat characteristics (mean(standard deviation)) in the Pere Marquette River, Michigan 1997, 1998, and 1999.
Total number of redds Water depth above redd (m) Water temp above redd (°C) Velocity above redd (cm/s) Mean number redds/ha Percent of run/riffle/pool samples
178 0.43 (0.45) 8.5 (1.2) 73 (50) 30 15/85/0
Sample Year 1998 Redds 75 0.39 (0.40) 9.4 (0.2) 73 (44) 26 36/64/0
Total number of reference sites Water depth above ref site (m) Water temp above ref site (°C) Velocity above ref site (cm/s) Percent of run/riffle/pool samples
0 n/a n/a n/a n/a
Reference Sites 99 0.64 (0.71) 10.3 (1.4) 60 (73) 83/11/3
Site Metric
1997
1999 150 0.37 (0.47) 10.3 (2.5) 64 (48) 17 7/93/0
149 0.60 (0.77) 10.0 (2.3) 46 (64) 76/18/6
FIG. 2. The cumulative percent-frequency distribution of coverage of clay, silt, sand, small gravel, large gravel, small cobble, and large-cobble size classes within redd and reference sites in the Pere Marquette River, Michigan for 1997, 1998, and 1999.
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were not significantly different (D = 0.15, n1 = 88, n2 = 152, p = 0.186), and neither were the 1998 and 1999 reference data (D = 0.10, n1 = 99, n2 = 149, p > 0.27). The combined 1998 and 1999 redd particlesize distributions were not significantly different between run and riffle habitats (D = 0.08, n1 = 40, n2 = 198, p > 0.27). The combined 1998 and 1999 reference site particle size distributions were not significantly different among habitat types (D = 0.19, n1 = 195, n2 = 38, p = 0.22 for run vs. riffle; D = 0.11, n1 = 195,n2 = 15, p>0.27 for run vs. pool; D = 0.30, n 1 = 38, n 2 = 15, p > 0.27 for riffle vs. pool). We evaluated the combined 1998 and 1999 data for rainbow trout electivity of substrate particle size. Rainbow trout redds contained small gravel (1–8 mm), large gravel (8–64 mm), and small cobble disproportionately to their availability within stream reaches (Fig. 3). Although sand (0.065–1 mm) was frequently observed in the reference samples (Fig. 2), sand, large cobble, silt, and clay were found in low proportions within redds (Fig. 3). Velocity, Water Temperature, Water Depth Stream velocity was an important component of rainbow trout spawning site use. As illustrated
using the 1998 data (Fig. 4), reference velocities were significantly lower than redd velocities (F = 97.77, df = 630, p < 0.0001). Although redd velocities were significantly different among years (F = 15.01, df = 630, p < 0.0001), there was no significant interaction between redd and reference site velocities and years (F = 0.23, df = 630, p= 0.63) suggesting that rainbow trout consistently used sites with greater-than-average velocity regardless of the variability in reference conditions among years. The 1999 redd velocities were significantly lower than the 1997 (t = 4.57, df = 392, p < 0.0001) and the 1998 (t = 3.18, df = 392, p = 0.016) redd velocities (Fig. 5). The 1997 and 1998 mean redd velocities were 73 cm/s (Table 1) and were not significantly different (t = 1.67, df = 392, p = 0.22). Redd velocities varied less than velocities measured at reference sites (Table 1). Mean daily discharge recorded at Scottville, Michigan for April was significantly lower in 1999 than 1997 (t = 3.01, df = 91, p = 0.003) and 1998 (t = 4.87, df = 91, p < 0.0001). The 1997 and 1998 discharge data were not significantly different (t = –1.80, df = 91, p = 0.08) for April. Stream velocities for redds in the center of the channel were significantly greater than redds lo-
FIG. 3. Electivity values for rainbow trout spawning substrate particle sizes in the Pere Marquette River, Michigan for 1998 and 1999 combined.
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FIG. 4. Percent frequency of stream velocities recorded at rainbow trout redd and reference sites during 1998 in the Pere Marquette River, Michigan.
FIG. 5. Percent frequency of stream velocities recorded at rainbow trout redds during 1997, 1998, and 1999 in the Pere Marquette River, Michigan.
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FIG. 6. Percent frequency of water depths recorded at rainbow trout redd sites from 1997 to 1999, and from reference sites from 1998 to 1999 in the Pere Marquette River, Michigan. cated in river-left (t = 2.67, df = 389, p = 0.008) and river-right (t = 3.14, df = 389, p = 0.002) channel locations. However, velocities of reference samples were also higher (t = 3.91, df = 228, p = 0.0001; t = 4.44, df = 228, p < 0.001 respectively) in the center of the channel. Rainbow trout redds were located in significantly shallower water (F = 113.84, df = 629, p < 0.0001) than reference sites (Fig. 6). Rainbow trout constructed redds in water approximately 0.20 m shallower than was normally found within the study reaches (Table 1). The sample year did not appear to influence the depth of water above redds or reference sites (F = 1.92, df = 629, p = 0.15). Redd depth was not significantly different according to the location of the redd within the river channel (F = 2.65, df = 391, p = 0.07). Within-site variation in stream temperature was not an important component of rainbow trout selection of spawning habitat in the Pere Marquette River. Water temperature above the redd was not
significantly different between redd and reference sites (F = 1.16, df = 629, p = 0.28), but was significantly different among years 1997 (t = 11.78, df = 630, p < 0.0001), 1998 (t = 12.75, df = 630, p < 0.0001), and 1999 (t = 15.37, df = 630, p < 0.0001). DISCUSSION Velocity, Water Temperature, Water Depth Stream velocity appeared to influence the location where rainbow trout constructed redds. Rainbow trout constructed redds in locations with a higher stream velocity than average within each study reach. The stream velocities that we recorded at the redds in the Pere Marquette River were consistent with rainbow trout redd velocities as determined by Smith (1973) in Oregon streams. Smith found the average column velocities at redds to range from 63 to 70 cm/s, as compared with 64 to 73 cm/s in our study. Faster-moving water may as-
Rainbow Trout Spawning Habitat Selection sist embryo development by providing well-mixed, oxygenated water (Stuart 1953, Sowden and Power 1985). Delivery of oxygenated water to the redd is also affected by water depth. Water velocity must be fast enough to penetrate the interstices of the redd and deliver oxygenated water, and the water must remain deep enough to cover the redd until fry emerge from the redd (Semko 1954, Smith 1973). Rainbow trout exhibited a preference for substrate particles that were larger than sand and smaller than large cobble. Sowden and Power (1985) indicated that the spawning substrate must be coarse yet small enough that the fish can move it. Although rainbow trout consistently constructed redds in locations with stream velocities that were higher than average, stream velocity at the redds and river discharge recorded at Scottville varied annually. The annual variation may be attributed to large-scale influences that affect stream flow (e.g., annual differences in precipitation). Despite this variability, rainbow trout consistently chose sites with higher water velocity relative to what was available each year. Water depth influenced the location of rainbow trout redds. As indicated by the disproportionate number of redds located in riffles (Table 1), rainbow trout constructed redds in water that was shallower than the average depth within study reaches. Rainbow trout in our study constructed redds in water depths that were consistent with a Pacific Coast rainbow trout spawning study (Smith 1973). The influence of water temperature on the selection of rainbow trout redd locations was not evident in our Pere Marquette River data. Because rainbow trout spawn during the spring in Michigan when water temperatures are cool, within-reach variation in water temperature may have had a minimal influence on the choice of locations for redd construction. However, several investigators (Geist 1999, Baxter and Hauer 2000) have observed that largescale differences in groundwater input can influence which reaches are selected for spawning in general. Although the spawning period of several other fish species (e.g., Catostomus spp., Moxostoma, spp.) in the Pere Marquette River overlaps that of rainbow trout, we are not aware of any evidence of interspecific competition for spawning sites. Substrate Particle Size Using visual estimation of particle size, our data indicated rainbow trout utilized coarse substrate
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particles (e.g., small gravel, large gravel, and small cobble) to construct redds. Although a pebble-count approach (Kondolf and Li 1992) may have provided greater accuracy in distinguishing among particle size classes, visual estimation has been found to be sufficiently accurate for many fisheries applications (Wang et al. 1996). Although we did not explore the vertical distribution of substrate particles within redds, we feel that visual estimates of surficial substrate composition are likely to be most useful in surveying extensive areas within a watershed to determine likely spawning habitat. We identified substrate particle composition, stream velocity, and water depth features that characterize rainbow trout redds in the Pere Marquette River. Identifying these spawning habitat features serves as a quantitative description of rainbow trout spawning habitat preference within a Great Lakes tributary. Stream habitat improvement projects are regularly conducted within the Pere Marquette watershed (Pere Marquette Watershed Council, Dick Schwikert, Baldwin, MI) as well as elsewhere throughout the Great Lakes region. Habitat improvement projects are often streambank stabilization efforts to minimize the amount of fine sediments entering the river. These habitat improvement projects may create opportunities to monitor effects of stream-bank stabilization by identifying spawning locations and redd densities prior to the improvement project and evaluating changes to spawning habitat following the work. Our results could be used to evaluate the project in terms of improving or creating additional rainbow trout spawning habitat. Our data also have management implications for other Great Lakes tributaries that support rainbow trout reproduction. Should suitable spawning habitat be limited within another Great Lakes tributary, these features could be used as a measure to evaluate other locations within the river where habitat may be suitable or modified to accommodate rainbow trout reproduction. ACKNOWLEDGMENTS The authors thank the Michigan Department of Natural Resources, the Great Lakes Fishery Commission, Michigan State University Department of Fisheries and Wildlife, and the Michigan Agricultural Experiment Station for providing the funds to make this research possible.
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Bain, M.B., Finn, J.T., and Booke, H.E. 1985. Quantifying stream substrate for habitat analysis studies, Management briefs. N. Am. J. Fish. Manage. 5:499–506. Baxter, C.V., and Hauer, F.R. 2000. Geomorphology, hyporheic exchange, and selection of spawning habitat by bull trout (Salvelinus confluentus). Can. J. Fish. Aquat. Sci. 57:1470–1481. Berry, D.A., and Lindgren, B.W. 1996. Statistics Theory and Methods, 2 nd edition. Belmont, California: Wadsworth Publishing Company. Bovee, K.D., and Cochnauer, T. 1977. Development and evaluation of weighted criteria-probability of use curves for instream flow assessments: fisheries. FWS/OBS-77/63. U.S. Fish and Wildlife Service, Fort Collins, Colorado. Chapman, D.W. 1988. Critical review of variables used to define effects of fines in redds of large salmonids. Trans. Am. Fish. Soc. 117:1–21. Cooper, A.C. 1965. The effect of transported stream sediment on the survival of sockeye and pink salmon eggs and alevin. International Pacific Salmon Fisheries Commission, Bulletin 18. Fukushima, M., and Smoker, W.W. 1998. Spawning habitat segregation of sympatric sockeye and pink salmon. Trans. Am. Fish. Soc. 127:253–260. Geist, D.R. 1999. Redd site selection and spawning habitat use by fall Chinook salmon, Hanford Reach, Columbia River. U.S. Department of Energy/Bonneville Power Administration #62611-14 Lib #I110. Groves, P.A., and Chandler, J.A. 1999. Spawning habitat used by fall Chinook salmon in the Snake River. N. Am. J. Fish. Manage. 19:912–922. Hicks, B.J., and Watson, R.R.N. 1985. Seasonal changes in abundance of brown trout (Salmo trutta) and rainbow trout (S. gairdnerii) assessed by drift diving in the Rangitikei River, New Zealand. New Zealand J. Mar. and Freshwater Res. 19:1–10. Ibbotson, A., Armitage, P., Beaumont, W., Ladle, M., and Welton, S. 1994. Spatial and temporal distribution of fish in a small lowland stream. Fish. Mgmt. and Ecol. 1:143–156. Jones, E.B.D., Helfman, G.S., Harper, J.O., and Bolstad, P.V. 1999. Effects of riparian forest removal on fish assemblages in southern Appalachian streams. Consv. Bio. 13(6):1454–1465. Kogl, D.R. 1965. Springs and ground-water as factors affecting survival of chum salmon in a sub-arctic stream. M.S. thesis, Univ. of Alaska, College, AK. Kondolf, G.M., and Li, S. 1992. The pebble count technique for quantifying surface bed material size in instream flow studies. Rivers 3(2):80–87. Littell, R.C., Milliken, G.A., Stroup, W.W., and Wolfinger, R.D. 1996. SAS system for mixed models. Cary, North Carolina: SAS Institute, Inc. MDNR/IFR (Michigan Department of Natural Resources Institute for Fisheries Research). 1998. Streambed
gradient data for the mainstem Pere Marquette River. University of Michigan, Ann Arbor, MI. Neilson, J.D., and Banford, C.E. 1983. Chinook salmon (Oncorhynchus tshawytscha) spawner characteristics in relation to redd physical features. Can. J. Zoo. 61: 97–110. Olsen, J.C. 1968. Physical environment and egg development in mainland beach area and island beach area of Ilimana Lake. In Further Studies of Alaska Sockeye Salmon, ed. R.L. Burgner, pp. 169–197. University of Washington Publication of Fisheries News. Series 3. Seattle, WA. Orth, D.J., and Maughan, O.E. 1982. Evaluation of the incremental flow methodology for recommending instream flows for fishes. Trans. Am. Fish. Soc. 111: 413–445. Price, D.G. 1982. A fishery resource sampling methodology for small streams. In Acquisition and utilization of aquatic habitat inventory information., pp. 54–91. Publication of the Western Division of the American Fisheries Society, Bethesda, Maryland. Semko, R.S. 1954. The stocks of west Kamchatka salmon and their commercial utilization. Izv. Tikhookean. Nauchno-Issled. Inst. Rbn. Khoz. Okeanogr. 41:3–109 (Translated from Russian; Fish. Res. Board Can. Translations Series 288). Silver, S.J., Warren, C.E., and Doudoroff, P. 1963. Dissolved oxygen requirements of developing steelhead trout and Chinook salmon embryos at different water velocities. Trans. Am. Fish. Soc. 92(4):327–343. Smith, A.K. 1973. Development and application of spawning velocity and depth criteria for Oregon salmonids. Trans. Am. Fish. Soc. 102:312–316. Sowden, T.K., and Power, G. 1985. Prediction of rainbow trout embryo survival in relation to groundwater seepage and particle size of spawning substrates. Trans. Am. Fish. Soc. 114:804–812. Stuart, T.A. 1953. Water currents through permeable gravels and their significance to spawning salmonids. Nature 172:407–408. Vanderploeg, H.A., and Scavia, D. 1979. Two electivity indicies for feeding with special reference to zooplankton grazing. J. Fish. Res. Board Can. 36:363–365. Vaux, W.G. 1962. Interchange of stream and intergravel water in a salmon spawning riffle. U. S. Fish and Wildlife Service Special Scientific Report-Fisheries No. 405, Washington, D. C. Wang, L., Simonson, T.D., and Lyons, J. 1996. Accuracy and precision of selected stream habitat estimates. N. Am. J. Fish. Manage. 16:340–347. Wentworth, C.K. 1922. A scale of grade and class terms for clastic sediments. J. Geo. 30:377–392. Submitted: 25 February 2003 Accepted: 18 June 2004 Editorial handling: John Janssen
Spawning Habitat Selection by Rainbow Trout in the Pere Marquette River, Michigan R. Douglas Workman1,3,*, Daniel B. Hayes1, and Thomas G. Coon2 1Michigan
State University Department of Fisheries and Wildlife 13 Natural Resources Building East Lansing, Michigan 48824-1222 2Michigan
State University College of Agriculture and Natural Resources 101 Agriculture Hall East Lansing, Michigan 48824 ABSTRACT. We evaluated habitat features (i.e., substrate particle size, water depth, water velocity) at spawning redds and randomly selected reference locations (where spawning activity was not apparent) to determine importance of these features to rainbow trout (Oncorhynchus mykiss) spawning habitat use in the Pere Marquette River, Michigan, 1997 to 1999. Rainbow trout selected areas with small gravel, large gravel, and small cobble substrates for redd construction over areas with clay, silt, sand, and large cobble. Rainbow trout redds were located in areas where the stream velocity was significantly higher (F = 97.77, df = 630, p < 0.0001) than velocities that were recorded at reference sites, and redds were located in water that was significantly shallower than what was typically found in the study reaches (F = 113.84, df = 629, p < 0.0001). Water temperature did not affect selection of redd locations. Because rainbow trout spawn during spring in Michigan when water temperatures are cool, within-reach variation in water temperature may have minimal influence on choice of locations for redd construction. These microhabitat data provide an indication of rainbow trout spawning habitat utilization, and can be used to identify critical habitats that may serve as rainbow trout spawning sites, and provide guidance on targets for habitat improvement projects in the Pere Marquette River and elsewhere. INDEX WORDS:
Rainbow trout, spawning habitat selection, Pere Marquette River.
INTRODUCTION Microhabitat-scale features associated with redds (i.e., substrate particle sizes, redd depth, stream velocity above redds) of rainbow trout (Oncorhynchus mykiss) and other Pacific Coast salmonines, are well known (Cooper 1965, Kogl 1965, Smith 1973, Fukushima and Smoker 1998, Groves and Chandler 1999). However, information on spawning habitat use by Great Lakes rainbow trout is scarce. Substrate particle composition of redds varies among rainbow trout and other salmonines (Olsen 1968, Neilson and Banford 1983), however, redds of most salmonines share similarities related to sub-
strate particle composition. Substrate particles must be large enough and adequately sorted to accommodate alevin emergence; substrate must consist of a movable porous material such as gravel, so that a female can excavate the redd; and the redd must be located or shaped in a way that promotes the movement of oxygenated water through the redd (Cooper 1965, Sowden and Power 1985). In addition to substrate particle size composition, stream flow influences the reproductive success of rainbow trout by delivering oxygenated water to developing eggs (Vaux 1962, Silver et al. 1963), and thereby influences selection of spawning locations within streams. Rainbow trout and other Pacific Coast salmonines typically select stream reaches with faster-than-average water velocities, and are shallow with a high gradient
*Corresponding 3
author. E-mail: [email protected] Present Address: 2692 165th Avenue, Morley, MI 49336
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FIG. 1. 1999.
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Study site location and sample reaches in the Pere Marquette River, Michigan for 1997 through
(Smith 1973, Fukushima and Smoker 1998, Groves and Chandler 1999). Great Lakes rainbow trout are similarly influenced by stream flow in their selection of spawning habitat, but detailed documentation is lacking. The goal of our study was to gain a better understanding of the characteristics of habitat used by rainbow trout spawning in a tributary to Lake Michigan. We evaluated microhabitat-scale features associated with redds in relation to their availability within selected reaches of river. Identifying habitat features that are important to rainbow trout spawning site selection in a Great Lakes tributary can be used to identify other areas within the river that may be used by spawning rainbow trout. In addition, these important features could be incorporated into stream habitat improvement projects where habitat could be modified to enhance rainbow trout spawning.
METHODS Study Site Rainbow trout spawning habitat was evaluated throughout the Pere Marquette River (Fig. 1). The Pere Marquette River is located in west-central Michigan and the main stem of the river is approximately 154 km long (MDNR/IFR 1988). The river drains 1,955 km2 of watershed and is one of a few remaining large, free-flowing Great Lakes tributary streams in Michigan. The Pere Marquette River is primarily dominated by a cold-water fish community, and receives migratory rainbow trout during the fall, winter, and spring. Sample Reaches Sample reaches (1–2 km in length), where the bottom was readily observed and the stream was accessible through public access, boat launches, and
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Rainbow Trout Spawning Habitat Selection access permission from riparian landowners were identified within the Pere Marquette River (Fig. 1). Five study reaches were randomly selected and sampled in 1997 and 1998, and nine were randomly selected from a pool of 20 possible sites and sampled in 1999. We attempted to collect data from each site between 1000 and 1400 hr when daylight had the greatest intensity during April to optimize the visual detection of redds. Redds were identified by areas where there was evidence of excavated substrate free of debris, typically shaped with a conical depression in the center, and occasionally by the presence of spawning rainbow trout. Redds with fish tending them were recorded as active and apparently excavated sites were considered as suspected redds. Location of the redds within the river channel (river-left, mid-channel, and river-right), and run, riffle, and pool habitat types were noted (Hicks and Watson 1985). All redd measurements were taken in an area that was assumed to be the egg depositional zone (Chapman 1988), or approximately one-third of the distance between the deepest point of the redd depression, and the downstream edge of the redd. Stream temperature, mean column stream velocity, depth of water above each redd, and substrate particle size composition data were collected at each redd. Water temperature was measured using a Yellow Springs Instrument Company (YSI), Inc. meter at most redds. Mean column stream velocity and water depth at the measured redds were recorded using a Price AA meter and wading rod. For reaches with high redd density, we sampled every fifth redd. We obtained stream discharge data from the U.S. Geological Survey gauge station, located in the river at Scottville (Fig. 1). Visual estimation of substrate particle size is a widely used method (Bovee and Cochnauer 1977, Price 1982, Orth and Maughan 1982, Ibbotson et al. 1994, Jones 1999), and was chosen for this study as a relatively quick and reliable method to detect coarse differences among particle sizes. Substrate particle-size composition was visually estimated using a modified Wentworth (1922) classification within a 1-m-diameter circular area that was centered on the egg depositional zone for each sample site. To avoid observer bias, particle-size estimates were conducted by only one person throughout this study (Wang et al. 1996, Bain et al.1985). The large (128–512 mm) and small cobble (64–128 mm) particle-size classes were combined during the 1997 sampling, but were differentiated during the 1998 and 1999 sampling. Smaller parti-
cle sizes such as clay (0.00024–0.004 mm) and silt (0.004–0.062 mm) were identified by the texture of particles, color (e.g., silt is dark and sand is light colored), and by how readily they suspended when disturbed (e.g., silt readily suspends, sand suspends somewhat, and clay was not readily suspended). Reference data from non-redd locations were collected within each site during 1998 and 1999, with approximately 10 reference locations per km of study reach. Reference locations were equally spaced from each other and alternated from river left (RL) to mid-channel (CH) to river right (RR) locations in a downstream direction. At each reference point, the same information was collected as at redd sites. Redd Characteristics Substrate particle size distributions were compared among years (1997, 1998, and 1999) and between reference and redd sites (1998 and 1999) using the Kolmogrov-Smirnov two-sample test statistic (Berry and Lindgren 1996). Vanderploeg and Scavia’s electivity index (Ei) was used to compare substrate at rainbow trout redds with the substrate at reference sites (Vanderploeg and Scavia 1979): 1 Wi = n Ei = 1 Wi + n
(1)
where, Wi =
ri / pi ri / pi
∑
and, ri = the proportion of observations of particle size i in the redd substrate composition pi = the proportion of observations of particle size i in the reference site substrate composition n = the number of particle size categories. The index ranges from +1 to –1. A positive value of Ei indicates a larger proportion of the substrate particle size in the redd than was found in the reference stream reaches. A negative value of Ei indicates a particle size was used less than was available in the stream reaches. A value of 0 indi-
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cates a particle size was used in proportion to availability within the stream reaches. A Mixed General Linear Model (GLM, Littell et al. 1996) was performed on stream velocity, water depth, and water temperature, to examine differences among years, channel locations, study reaches, and between sample locations (redd and reference sites). Least square means (Littell et al. 1996) were used to determine where significant differences occurred. The following model was used to evaluate stream velocity, water depth, or water temperature:
RESULTS We recorded rainbow trout redd and reference data from 15 April to 24 April 1997, 15 April to 23 April 1998, and 28 March to 17 April 1999. During 1997, we sampled 178 redds and no reference sites (Table 1), and during 1998, we sampled 75 redds and 99 reference sites. We sampled the greatest total number of sites during 1999, when we sampled 150 redds and 149 reference sites. Rainbow trout spawned primarily in riffles, and to some extent in runs (Table 1). We did not observe any redds in pool habitat (Table 1).
y = µ + αi + βj + ζl + γi,j + ιi,l + κj,l + ηk + e
Substrate Particle Size Rainbow trout did not appear to construct redds in areas with very large particle sizes. We did not observe any small boulders (256–512 mm) or larger particle sizes (> 512 mm) in redds. We observed large cobble in 6% of redds sampled in 1998 and 1999 (n = 219). Although large particle sizes were more frequently sampled (10% of the samples) in the 1998 and 1999 reference sites (n = 249), larger particles were not common within the study reaches. Rainbow trout also avoided smaller particles such as clay (0.00024 –0.004 mm) and silt (0.004–0.062 mm) occurring in redds. We did not observe clay or silt at any of the active and suspected redd sites, whereas silt was observed at an average of 3% (1999) and 0.8% (1998) in the reference samples. We observed clay at an average of 0.7% (1999) and 0% (1998) in the reference samples. We compared the substrate particle size distribution between active and suspected redds, reference sites, and sample years using the KolmogorovSmirnov test. Particle-size distribution of active and suspected redd locations were not significantly different for 1997 (D = 0.03, n1 = 141, n2 = 41, p > 0.27), 1998 (D = 0.02, n1 = 71, n2 = 15, p > 0.27), or 1999 (D = 0.04, n1 = 109, n2 = 43, p > 0.27). Thus, we combined the active and suspected redd data from each sample year for further analyses. The particle-size distributions of redd and reference sites were significantly different in 1998 (D = 0.41, n1 = 99, n2 = 88, p < 0.001) and 1999 (D = 0.36, n1 = 149, n2 = 152, p < 0.001). In 1998 and 1999, rainbow trout redds were associated with larger particle sizes than reference sites (Fig. 2), and none were associated with clay or silt. The 1998 and 1999 redd substrate data (when large cobble was differentiated from small cobble)
(2)
Where, y = stream velocity, water depth, or water temperature by year, channel location, and sample location µ = model intercept αi = year (fixed effect) βj = channel location (fixed effect) ζl = sample location, i.e., redd or non redd site (fixed effect) γi,j = interaction between year and channel location ιi,l = interaction between year and sample location κj,l = interaction between channel location and sample location ηk = study reach (random effect with mean zero and ) e = model error. A GLM was used to evaluate differences in stream flow from Scottville USGS gauging station among years. The Tukey-Kramer pairwise comparison was used to determine where significant differences occurred. The following model was used to evaluate stream flow: y = µ + αi + e
(3)
y = discharge recorded at the USGS gauging station in Scottville, Michigan µ = model intercept αi = year e = model error. All tests were conducted using α = 0.05.
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Rainbow Trout Spawning Habitat Selection TABLE 1. Redd and reference habitat characteristics (mean(standard deviation)) in the Pere Marquette River, Michigan 1997, 1998, and 1999.
Total number of redds Water depth above redd (m) Water temp above redd (°C) Velocity above redd (cm/s) Mean number redds/ha Percent of run/riffle/pool samples
178 0.43 (0.45) 8.5 (1.2) 73 (50) 30 15/85/0
Sample Year 1998 Redds 75 0.39 (0.40) 9.4 (0.2) 73 (44) 26 36/64/0
Total number of reference sites Water depth above ref site (m) Water temp above ref site (°C) Velocity above ref site (cm/s) Percent of run/riffle/pool samples
0 n/a n/a n/a n/a
Reference Sites 99 0.64 (0.71) 10.3 (1.4) 60 (73) 83/11/3
Site Metric
1997
1999 150 0.37 (0.47) 10.3 (2.5) 64 (48) 17 7/93/0
149 0.60 (0.77) 10.0 (2.3) 46 (64) 76/18/6
FIG. 2. The cumulative percent-frequency distribution of coverage of clay, silt, sand, small gravel, large gravel, small cobble, and large-cobble size classes within redd and reference sites in the Pere Marquette River, Michigan for 1997, 1998, and 1999.
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were not significantly different (D = 0.15, n1 = 88, n2 = 152, p = 0.186), and neither were the 1998 and 1999 reference data (D = 0.10, n1 = 99, n2 = 149, p > 0.27). The combined 1998 and 1999 redd particlesize distributions were not significantly different between run and riffle habitats (D = 0.08, n1 = 40, n2 = 198, p > 0.27). The combined 1998 and 1999 reference site particle size distributions were not significantly different among habitat types (D = 0.19, n1 = 195, n2 = 38, p = 0.22 for run vs. riffle; D = 0.11, n1 = 195,n2 = 15, p>0.27 for run vs. pool; D = 0.30, n 1 = 38, n 2 = 15, p > 0.27 for riffle vs. pool). We evaluated the combined 1998 and 1999 data for rainbow trout electivity of substrate particle size. Rainbow trout redds contained small gravel (1–8 mm), large gravel (8–64 mm), and small cobble disproportionately to their availability within stream reaches (Fig. 3). Although sand (0.065–1 mm) was frequently observed in the reference samples (Fig. 2), sand, large cobble, silt, and clay were found in low proportions within redds (Fig. 3). Velocity, Water Temperature, Water Depth Stream velocity was an important component of rainbow trout spawning site use. As illustrated
using the 1998 data (Fig. 4), reference velocities were significantly lower than redd velocities (F = 97.77, df = 630, p < 0.0001). Although redd velocities were significantly different among years (F = 15.01, df = 630, p < 0.0001), there was no significant interaction between redd and reference site velocities and years (F = 0.23, df = 630, p= 0.63) suggesting that rainbow trout consistently used sites with greater-than-average velocity regardless of the variability in reference conditions among years. The 1999 redd velocities were significantly lower than the 1997 (t = 4.57, df = 392, p < 0.0001) and the 1998 (t = 3.18, df = 392, p = 0.016) redd velocities (Fig. 5). The 1997 and 1998 mean redd velocities were 73 cm/s (Table 1) and were not significantly different (t = 1.67, df = 392, p = 0.22). Redd velocities varied less than velocities measured at reference sites (Table 1). Mean daily discharge recorded at Scottville, Michigan for April was significantly lower in 1999 than 1997 (t = 3.01, df = 91, p = 0.003) and 1998 (t = 4.87, df = 91, p < 0.0001). The 1997 and 1998 discharge data were not significantly different (t = –1.80, df = 91, p = 0.08) for April. Stream velocities for redds in the center of the channel were significantly greater than redds lo-
FIG. 3. Electivity values for rainbow trout spawning substrate particle sizes in the Pere Marquette River, Michigan for 1998 and 1999 combined.
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FIG. 4. Percent frequency of stream velocities recorded at rainbow trout redd and reference sites during 1998 in the Pere Marquette River, Michigan.
FIG. 5. Percent frequency of stream velocities recorded at rainbow trout redds during 1997, 1998, and 1999 in the Pere Marquette River, Michigan.
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FIG. 6. Percent frequency of water depths recorded at rainbow trout redd sites from 1997 to 1999, and from reference sites from 1998 to 1999 in the Pere Marquette River, Michigan. cated in river-left (t = 2.67, df = 389, p = 0.008) and river-right (t = 3.14, df = 389, p = 0.002) channel locations. However, velocities of reference samples were also higher (t = 3.91, df = 228, p = 0.0001; t = 4.44, df = 228, p < 0.001 respectively) in the center of the channel. Rainbow trout redds were located in significantly shallower water (F = 113.84, df = 629, p < 0.0001) than reference sites (Fig. 6). Rainbow trout constructed redds in water approximately 0.20 m shallower than was normally found within the study reaches (Table 1). The sample year did not appear to influence the depth of water above redds or reference sites (F = 1.92, df = 629, p = 0.15). Redd depth was not significantly different according to the location of the redd within the river channel (F = 2.65, df = 391, p = 0.07). Within-site variation in stream temperature was not an important component of rainbow trout selection of spawning habitat in the Pere Marquette River. Water temperature above the redd was not
significantly different between redd and reference sites (F = 1.16, df = 629, p = 0.28), but was significantly different among years 1997 (t = 11.78, df = 630, p < 0.0001), 1998 (t = 12.75, df = 630, p < 0.0001), and 1999 (t = 15.37, df = 630, p < 0.0001). DISCUSSION Velocity, Water Temperature, Water Depth Stream velocity appeared to influence the location where rainbow trout constructed redds. Rainbow trout constructed redds in locations with a higher stream velocity than average within each study reach. The stream velocities that we recorded at the redds in the Pere Marquette River were consistent with rainbow trout redd velocities as determined by Smith (1973) in Oregon streams. Smith found the average column velocities at redds to range from 63 to 70 cm/s, as compared with 64 to 73 cm/s in our study. Faster-moving water may as-
Rainbow Trout Spawning Habitat Selection sist embryo development by providing well-mixed, oxygenated water (Stuart 1953, Sowden and Power 1985). Delivery of oxygenated water to the redd is also affected by water depth. Water velocity must be fast enough to penetrate the interstices of the redd and deliver oxygenated water, and the water must remain deep enough to cover the redd until fry emerge from the redd (Semko 1954, Smith 1973). Rainbow trout exhibited a preference for substrate particles that were larger than sand and smaller than large cobble. Sowden and Power (1985) indicated that the spawning substrate must be coarse yet small enough that the fish can move it. Although rainbow trout consistently constructed redds in locations with stream velocities that were higher than average, stream velocity at the redds and river discharge recorded at Scottville varied annually. The annual variation may be attributed to large-scale influences that affect stream flow (e.g., annual differences in precipitation). Despite this variability, rainbow trout consistently chose sites with higher water velocity relative to what was available each year. Water depth influenced the location of rainbow trout redds. As indicated by the disproportionate number of redds located in riffles (Table 1), rainbow trout constructed redds in water that was shallower than the average depth within study reaches. Rainbow trout in our study constructed redds in water depths that were consistent with a Pacific Coast rainbow trout spawning study (Smith 1973). The influence of water temperature on the selection of rainbow trout redd locations was not evident in our Pere Marquette River data. Because rainbow trout spawn during the spring in Michigan when water temperatures are cool, within-reach variation in water temperature may have had a minimal influence on the choice of locations for redd construction. However, several investigators (Geist 1999, Baxter and Hauer 2000) have observed that largescale differences in groundwater input can influence which reaches are selected for spawning in general. Although the spawning period of several other fish species (e.g., Catostomus spp., Moxostoma, spp.) in the Pere Marquette River overlaps that of rainbow trout, we are not aware of any evidence of interspecific competition for spawning sites. Substrate Particle Size Using visual estimation of particle size, our data indicated rainbow trout utilized coarse substrate
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particles (e.g., small gravel, large gravel, and small cobble) to construct redds. Although a pebble-count approach (Kondolf and Li 1992) may have provided greater accuracy in distinguishing among particle size classes, visual estimation has been found to be sufficiently accurate for many fisheries applications (Wang et al. 1996). Although we did not explore the vertical distribution of substrate particles within redds, we feel that visual estimates of surficial substrate composition are likely to be most useful in surveying extensive areas within a watershed to determine likely spawning habitat. We identified substrate particle composition, stream velocity, and water depth features that characterize rainbow trout redds in the Pere Marquette River. Identifying these spawning habitat features serves as a quantitative description of rainbow trout spawning habitat preference within a Great Lakes tributary. Stream habitat improvement projects are regularly conducted within the Pere Marquette watershed (Pere Marquette Watershed Council, Dick Schwikert, Baldwin, MI) as well as elsewhere throughout the Great Lakes region. Habitat improvement projects are often streambank stabilization efforts to minimize the amount of fine sediments entering the river. These habitat improvement projects may create opportunities to monitor effects of stream-bank stabilization by identifying spawning locations and redd densities prior to the improvement project and evaluating changes to spawning habitat following the work. Our results could be used to evaluate the project in terms of improving or creating additional rainbow trout spawning habitat. Our data also have management implications for other Great Lakes tributaries that support rainbow trout reproduction. Should suitable spawning habitat be limited within another Great Lakes tributary, these features could be used as a measure to evaluate other locations within the river where habitat may be suitable or modified to accommodate rainbow trout reproduction. ACKNOWLEDGMENTS The authors thank the Michigan Department of Natural Resources, the Great Lakes Fishery Commission, Michigan State University Department of Fisheries and Wildlife, and the Michigan Agricultural Experiment Station for providing the funds to make this research possible.
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