Niagara Power Project FERC No. 2216
USE OF
BUCKHORN MARSH AND GRAND ISLAND TRIBUTARIES BY
NORTHERN
PIKE FOR SPAWNING AND AS A NURSERY
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Prepared for: New York Power Authority
Prepared by: New York Power Authority and Gomez and Sullivan Enigeers, P.C.
August 2005
___________________________________________________
Copyright © 2005 New York Power Authority
A fish study was conducted for the New York Power Authority during 2003 in Buckhorn Marsh Restoration Project (BMRP), Woods Creek, Gun Creek, Spicer Creek, and Big Six Mile Creek as part of the process for relicensing the Niagara Power Project. BMRP includes two distinct portions of the former Burnt Ship Creek channel: 1) Burnt Ship Creek - from the mouth of the creek to a weir located near I-190 (west weir) and 2) Buckhorn Marsh impoundment - from the west weir to a weir located about 1,720 feet farther east and on the west bank of Woods Creek. The objectives were to: 1) determine whether northern pike, largemouth bass, and yellow perch used BMRP for spawning and as a nursery, and if so, estimate how many used it and establish whether they traversed either of the two weirs in BMRP; 2) compare the use of BMRP by northern pike for spawning and as a nursery with that of Woods Creek, Gun Creek, Spicer Creek, and Big Six Mile Creek; 3) determine the relative abundance and composition of all fish species in BMRP and Woods Creek; and 4) evaluate the need to increase fish passage into or out of BMRP as an approach for promoting its use by northern pike for spawning and as a nursery while maintaining BMRP goals for wildlife species.
Based on the data collected during 2003, the following inferences and conclusions are reasonable:
· BMRP is used by northern pike and largemouth bass for spawning and as a nursery and by yellow perch as a nursery.
· Within BMRP, Buckhorn Marsh impoundment is used more extensively than Burnt Ship Creek by yearling and older northern pike for spawning and by YOY northern pike as a nursery but less extensively than Burnt Ship Creek by YOY largemouth bass as a nursery.
· Within BMRP, Buckhorn Marsh impoundment was not used by yellow perch, and Burnt Ship Creek was lightly used by yellow perch YOY as a nursery.
· Northern pike do not migrate out of Buckhorn Marsh impoundment and rarely migrate into it.
· Largemouth bass and yellow perch do not migrate into or out of Buckhorn Marsh impoundment.
· Migration of northern pike, largemouth bass, and yellow perch into Burnt Ship Creek from the Niagara River and out of Burnt Ship Creek to the Niagara River is limited by dense cattail stands.
· Migration of northern pike and largemouth bass into Burnt Ship Creek from Buckhorn Marsh impoundment is limited by water elevations below the top of the weir separating Burnt Ship Creek and Buckhorn Marsh impoundment.
· Fewer yearling and older northern pike use Buckhorn Marsh impoundment than Woods Creek and Gun Creek but more used Buckhorn Marsh impoundment than Burnt Ship Creek, Big Six Mile Creek, and Spicer Creek.
· The species composition and relative abundance of fish in Buckhorn Marsh impoundment and in Burnt Ship Creek differ from those of fish in Woods Creek and appear to reflect limited access from the Niagara River and lower water quality.
· Increasing fish passage into Buckhorn Marsh impoundment is not needed to promote its use by northern pike for spawning and as a nursery if the objective is to maintain a self-sustaining population; doing so might increase competition among northern pike.
· Increasing passage of northern pike out of Buckhorn Marsh impoundment after spawning may be needed to reduce population density if the objective is to maintain a self-sustaining population in the impoundment with good growth rates.
· If the objective is to use Buckhorn Marsh impoundment as seasonal spawning and nursery habitat for northern pike, then increasing fish passage into and out of the impoundment annually would be needed.
· Increasing fish passage into or out of Buckhorn Marsh impoundment would likely involve lowering the stoplog height of at least one weir during the spring and summer.
· Lowering the stoplog height of either weir would lower the water level in Buckhorn Marsh impoundment and make it more susceptible to daily changes in the water level of the Niagara River, which would not help maintain BMRP goals for wildlife species or improve the spawning and nursery habitat of the impoundment.
A fish study was conducted for the New York Power Authority during 2003 in Buckhorn Marsh Restoration Project (BMRP), Woods Creek, Gun Creek, Spicer Creek, and Big Six Mile Creek as part of the process for relicensing the Niagara Power Project. BMRP includes two distinct portions of the former Burnt Ship Creek channel: 1) Burnt Ship Creek - from the mouth of the creek to a weir located near I-190 (the west weir) and 2) Buckhorn Marsh impoundment - from the west weir to a weir located about 1,720 feet farther east and on the west bank of Woods Creek (the east weir). The objectives were to: 1) determine whether northern pike, largemouth bass, and yellow perch used BMRP for spawning and as a nursery, and if so, estimate how many used it and establish whether they traversed either of the two weirs in BMRP; 2) compare the use of BMRP by northern pike for spawning and as a nursery with that of Woods Creek, Gun Creek, Spicer Creek, and Big Six Mile Creek; 3) determine the relative abundance and composition of all fish species in BMRP and Woods Creek; and 4) evaluate the need to increase fish passage into or out of BMRP as an approach for promoting its use by northern pike for spawning and as a nursery while maintaining BMRP goals for wildlife species.
From the last week in March through the first week in July, fyke netting and electrofishing were conducted to catch yearling and older fish. From June through September, seining was conducted to catch young-of-the-year (YOY). A PIT tag was implanted in healthy yearling and older northern pike, largemouth bass, and yellow perch before the fish were released. Partial fin clips were applied to healthy YOY and to some yearling and older northern pike, largemouth bass, and yellow perch that were not tagged.
BMRP is used by northern pike and largemouth bass for spawning and as a nursery and by yellow perch as a nursery. Within BMRP, Buckhorn Marsh impoundment was used more extensively than Burnt Ship Creek by YOY and by yearling and older northern pike but less extensively than Burnt Ship Creek by YOY largemouth bass. In Buckhorn Marsh impoundment, fyke netting caught 190 yearling and older northern pike. Of those, 72 were tagged; 46% of which were in spawning condition. The population size of yearling and older northern pike during the period March 28 through May 2, when northern pike could not be legally harvested, was 87 using the Schnabel method and 85 using the Schumacher and Eschmeyer method. Seining in Buckhorn Marsh impoundment caught 77 YOY northern pike; 72 were finclipped. The population size of YOY northern pike during September was 204 using the Schnabel method and 241 using the Schumacher and Eschmeyer method. In Burnt Ship Creek, fyke netting caught two yearling and older northern pike; both were tagged. One of those fish was in spawning condition and neither was recaptured. Seining in Burnt Ship Creek caught five YOY northern pike; all were finclipped and none were recaptured. In Buckhorn Marsh impoundment, fyke netting caught 7 yearling and older largemouth bass, all of which were tagged, and 73 YOY largemouth bass, all of which were finclipped; none of these were recaptured. In Burnt Ship Creek, fyke netting caught 6 yearling and older largemouth bass; all were tagged, and seining caught 130 YOY, 67 of which were finclipped. Only one small yellow perch was caught by fyke netting in Burnt Ship Creek.
Northern pike did not migrate out of Buckhorn Marsh impoundment and rarely migrated into it based on results from finclipping and tagging. None of the 72 YOY northern pike finclipped, and none of the 72 yearling and older northern pike tagged, inside Buckhorn Marsh impoundment were recaptured outside. Only 1 yearling and older northern pike tagged in Woods Creek and none tagged elsewhere outside Buckhorn Marsh impoundment were recaptured inside. No YOY northern pike finclipped outside Buckhorn Marsh impoundment were recaptured inside.
Largemouth bass did not migrate into or out of Buckhorn Marsh impoundment based on results from finclipping and tagging. None of the 73 YOY largemouth bass finclipped and none of the 7 yearling and older largemouth bass tagged inside Buckhorn Marsh impoundment were recaptured outside. No largemouth bass finclipped outside Buckhorn Marsh impoundment were recaptured inside.
Migration of northern pike and largemouth bass into Burnt Ship Creek from the Niagara River and out of Burnt Ship Creek to the Niagara River was limited by dense cattail stands based on visual observation of habitat and the relatively small number of yearling and older fish caught. An open channel did not exist from the mouth of Burnt Ship Creek upstream. Only two yearling and older northern pike and four yearling and older largemouth bass were caught by fyke netting and electrofishing.
Migration of northern pike and largemouth bass into Burnt Ship Creek from Buckhorn Marsh impoundment was limited based on water levels at the west weir and results from finclipping and tagging. The water elevation in Burnt Ship Creek never reached the top of the stoplogs in the west weir. The water elevation in Buckhorn Marsh impoundment rarely reached the top of the stoplogs in the west weir.
More yearling and older northern pike used Woods Creek and Gun Creek than BMRP but more yearling and older northern pike used BMRP than Spicer Creek and Big Six Mile Creek. Fyke netting and electrofishing caught 190 yearling and older northern pike in Woods Creek, 162 in Gun Creek, 26 in Spicer Creek, and 15 Big Six Mile Creek. Of those, 163 were tagged in Woods Creek, 129 in Gun Creek, 24 in Spicer Creek, and 15 Big Six Mile Creek. The peak population size of yearling and older northern pike in Woods Creek was 612 based on the Jolly-Seber 4-catch method and 528 based on the Bailey triple-catch method; in Gun Creek it was 255 based on the Jolly-Seber method and 159 based on the Bailey method. Seining caught 8 YOY northern pike in Woods Creek, 20 in Gun Creek, 17 in Big Six Mile Creek and 0 in Spicer Creek.
Increasing fish passage into Buckhorn Marsh impoundment during 2003 was not needed to promote its use by northern pike for spawning and as a nursery if the objective was to maintain a self-sustaining population in the impoundment; doing so would likely have been more detrimental than beneficial. It appears that there is a self sustaining population in Buckhorn Marsh impoundment because migration of yearling and older northern pike into Buckhorn Marsh impoundment was rare and the mean length of both YOY and yearling and older northern pike in Buckhorn Marsh impoundment was significantly smaller than that of northern pike with direct access to the Niagara River. The smaller mean length appears to reflect stunting caused by competition among northern pike, a combination of low DO levels and high temperatures in Buckhorn Marsh impoundment, or a combination of both. By the end of September, the mean length of YOY northern pike caught by seining in Buckhorn Marsh impoundment was 166 mm while that of YOY northern pike caught by seining in Woods Creek, Gun Creek, Spicer Creek, and Big Six Mile Creek combined was 229 mm. The mean length of yearling and older northern pike caught by fyke netting and electrofishing and subsequently tagged in Buckhorn Marsh impoundment was 385 mm; it was 542 mm Woods Creek, 542 mm in Gun Creek, 548 mm in Spicer Creek, and 604 mm in Big Six Mile Creek. If competition were a factor responsible for the stunting of northern pike in Buckhorn Marsh impoundment, then increasing passage of northern pike into Buckhorn Marsh impoundment would have increased competition unless fish passage out of the impoundment was also increased.
If the objective was to use Buckhorn Marsh impoundment as seasonal spawning and nursery habitat for northern pike, then increasing fish passage into and out of the impoundment was needed. However, this would likely have involved lowering the stoplog height of the east weir during the spring and summer, causing the water level of the impoundment to be lower and more susceptible to daily changes in the water level of the Niagara River. The resulting water level regime would be inconsistent with the more stable and higher water levels needed to meet the BMRP goals for wildlife species. It would also have done little to improve the relatively poor spawning and nursery habitat of the impoundment.
Increasing fish passage into Burnt Ship Creek during 2003 would likely have involved creating a more open channel, which would have promoted its use by northern pike for spawning and as a nursery because relatively few northern pike used it and access appeared to have been limited by dense stands of cattails.
Agencies
NYSDEC New York State Department of Environmental Conservation
USFWS United States Fish and Wildlife Service
Units of Measure
C Celsius, Centigrade
cm centimeter
El. elevation
m meter
m milli (prefix for one-thousandth)
μ micro (prefix for one-millionth)
μmhos/cm micromhos per centimeter
ml milliliter
mm millimeter
ppm parts per million
Environmental
DO dissolved oxygen
EAV emergent aquatic vegetation
SAV submerged aquatic vegetation
YOY young-of-the-year fish (i.e., less than one year old)
Miscellaneous
BMRP Buckhorn Marsh Restoration Project
PIT Passive
Integrated Transponder
The New York State Department of Environmental Conservation (NYSDEC), New York State Office of Parks, U.S. Army Corps of Engineers, and Town of Grand Island, New York jointly funded and implemented the Buckhorn Marsh Restoration Project (BMRP). BMRP was designed to restore and create a diversity of wetland habitat types in and near the former channel of Burnt Ship Creek. It entailed removing sediment from the former channel, creating new channels, and constructing weirs with removable stoplogs to establish more stable and higher water levels (Roblee 1998). The goals of the project were to provide nesting, brooding, escape, and resting habitat for marsh birds and to re-establish habitat that northern pike (Esox lucius) could use for spawning and as a nursery.
Buckhorn Marsh is located on the north end of Grand Island. It extends from the Chippewa Channel of the Niagara River on the west to the Tonawanda Channel of the Niagara River on the east, separating Buckhorn Island to the north from the remainder of Grand Island to the south. (Anderson 1995). The marsh includes: 1) two distinct portions of the former Burnt Ship Creek channel; from the mouth of Burnt Ship Creek to a weir (the west weir) located just east of I-190 (Burnt Ship Creek) and from the weir just east of I-190 to a weir (the east weir) located about 1,720 feet east, on the west bank of Woods Creek (Buckhorn Marsh impoundment); and 2) Woods Creek from the east weir to the mouth at the Niagara River (Figure 1.0-1).
During the relicensing process for the Niagara Power Project, NYSDEC and the U.S. Fish and Wildlife Service (USFWS) expressed an interest in enhancing northern pike reproduction in BMRP. However, there were no systematically collected data available to assess the use of BMRP for reproduction by northern pike. As part of the alternative licensing process, the New York Power Authority (NYPA) agreed to conduct a study and collect data that could be used to inform settlement discussions. NYPA agreed to fund such a study in 2003. The initial objectives of the study were:
· determine whether northern pike used BMRP for spawning and as a nursery, and if so,
· estimate how many northern pike used it,
· establish whether northern pike traversed the west weir or the east weir, and
evaluate the need to increase fish passage into or out of BMRP as an approach for promoting its use by northern pike for spawning and as a nursery while maintaining BMRP goals for wildlife species.
NYSDEC and USFWS subsequently requested that the study be expanded. The objectives of the expanded study were to:
· determine whether largemouth bass (Micropterus salmoides) and yellow perch (Perca flavescens) used BMRP for spawning and as a nursery, and if so,
· estimate how many used it and whether they traversed the west weir or the east weir,
· determine the relative abundance and composition of all fish species in BMRP and Woods Creek,
· compare the use of BMRP by northern pike for spawning and as a nursery with that of Woods Creek, Big Six Mile Creek, Gun Creek, and Spicer Creek
Buckhorn Marsh Impoundment, Burnt Ship Creek and Woods Creek
The Investigation Area for the study was BMRP, Woods Creek, Big Six Mile Creek, Gun Creek, and Spicer Creek (Figure 2.0-1).
The methods for conducting field sampling were detailed in a set of Standard Operating Procedures (Appendix A). They were developed jointly by the New York Power Authority, Gomez and Sullivan, and Stantec Consulting Services, Inc., which conducted field sampling.
Sampling for spawning northern pike, largemouth bass, and yellow perch was scheduled to occur in BMRP and Woods Creek weekly from the first week in February - or as soon after the first week in February that ice did not prevent sampling, through July 3. This period includes the reported spawning season for northern pike in the Niagara River – late-February to April (Harrison and Hadley 1983), yellow perch – mid-April to early-May, and largemouth bass – late-spring to early-summer (Scott and Crossman 1973). Sampling for spawning northern pike was scheduled to occur in Gun Creek, Spicer Creek, and Big Six Mile Creek from the first week in February - or as soon after the first week in February that ice did not prevent sampling, through May. Due to an unusually cold winter, fyke nets could not be set safely until ice melted during the last week in March and sampling for northern pike in Gun Creek, Spicer Creek, and Big Six Mile Creek was extended through the second week in June.
Fyke nets were selected as the primary collection gear for spawning fish and were scheduled to be set for 72 consecutive hours per week. Fyke nets collect northern pike, largemouth bass and yellow perch effectively when these fish are active during the spring; cause relatively little capture stress; can be fished 24 hours a day; could be deployed in all of the areas of interest in this study; and were used to collect fish during 2001 in Woods Creek, Gun Creek, Spicer Creek, and Big Six Mile Creek (Environnement Illimité 2002). Because fyke nets could not be set safely until the last week in March and the spawning season for northern pike is reported to be early March through early April (Harrison and Hadley 1983), it was possible that the spawning season for northern pike would be very short in 2003. Therefore, sampling was occasionally conducted seven days per week during late-March and April.
Electrofishing was selected to supplement collections of northern pike, largemouth bass, and yellow perch made using fyke nets with the intent of sampling in areas between and around fyke nets and was scheduled to be done one day per week. Limited electrofishing began in late-February.
A fyke net measuring 4 feet in diameter at the mouth, with a 9-inch diameter fyke opening, a 50-foot long by 4 feet high lead, and 20-foot long by 4 feet high wings was used where water depth was 4 feet or greater. A fyke net measuring 2.5 feet in diameter, with a 9-inch diameter fyke opening, a 50-foot long by 2.5 feet high lead, and 20-foot long by 2.5 feet high wings was used where water depth was less than 4 feet. Netting material was 1-inch bar mesh nylon with a dark coating to reduce net visibility and to keep algal growth to a minimum.
Electrofishing was done using a backpack electrofishing unit (Smith-Root model 15A) by wading in Spicer Creek and Gun Creek where the substrate was firm and from a 7-foot inflatable raft in Burnt Ship Creek where the substrate was extremely soft. Electrofishing was done using a boat-mounted unit (either a Honda or Smith-Root generator, and an electrofisher Type VI or 2.5 GPP control box) in Woods Creek, Big Six Mile Creek, and Buckhorn Marsh impoundment. The boat used for boat electrofishing was either 15 feet long or 18 feet long.
Six 4-foot fyke nets were set in Buckhorn Marsh impoundment (Figure 2.1-1). On the east end, one net was set in a channel with its mouth facing the weir and wings extending to shore so that it could intercept fish if they migrated into the marsh from Woods Creek and another net was set just west of the net facing the weir, with its mouth facing away from the weir and wings extending to shore so that it could intercept fish migrating from the marsh to Woods Creek. Two nets were set on the west end with their respective leads extending to shore, one net was set in the north channel facing east, and one was set in the south channel facing east to provide sampling throughout the marsh between the weirs.
Three 4-foot fyke nets were set in Woods Creek (Figure 2.1-1). Between the east weir and the Niagara River, one net was set facing downstream to intercept fish entering the creek and one was set facing upstream to intercept fish leaving the creek. Upstream of the east weir, one net was set facing downstream to intercept fish swimming past the weir. On the first occasion that ice conditions permitted the setting of fyke nets (March 24, 2003), one of the three nets was set approximately 50 feet upstream of River Road, instead of immediately upstream of the east weir, for one twenty-four hour period. No nets were set at this location afterwards.
One 4-foot fyke net and one 2.5-foot fyke net were set in Burnt Ship Creek with their leads extending to shore in a direction intended to intercept fish entering the creek (Figure 2.1-1).
Two 2.5-foot fyke nets were set in both Gun (Figure 2.1-2) and Spicer Creeks (Figure 2.1-3), and two 4-foot fyke nets were set in Big Six Mile Creek (Figure 2.1-4).
All yearling and older northern pike, yellow perch, largemouth bass and muskellunge (Esox masquinongy) were scanned for a PIT tag and a coded wire tag. Although it was not an objective of this study to determine the use of BMRP and the Grand Island tributaries by muskellunge, the species supports an important recreational fishery in the upper Niagara River and is known to be found in BMRP and the Grand Island tributaries. Therefore, muskellunge were measured and tagged opportunistically. If a tag was not detected and the fish was not healthy, it was measured and returned to the water without being tagged. If a PIT tag was detected, its number was recorded; if a coded wire tag was detected, its presence was recorded. PIT tag numbers were unique and were the principal source of information on when and where a fish was caught and tagged. Coded wire tags were used to help assess tag retention of PIT tags, along with visual observation of a scar at the insertion site for PIT tags.
In Buckhorn Marsh impoundment, Burnt Ship Creek, and Woods Creek, if no tag was detected in a northern pike, largemouth bass, yellow perch, or muskellunge and the fish was healthy and equal to or greater than a minimum size (which ranged from 150 mm to 200 mm depending on the species and when during the sampling program that the fish was caught), the fish was measured and implanted with a PIT tag and a coded wire tag, unless the coded wire tag injector malfunctioned. If the coded wire tag injector malfunctioned, a finclip was used. In Gun Creek, Spicer Creek, and Big Six Mile Creek only northern pike were measured and tagged.
A PIT tag was inserted into the isthmus using a 24-gage needle (Figure 2.1.1.2-1). Before implanting a PIT tag the tag number was recorded. A coded wire tag was inserted into either the left or right cheek. After tagging, the presence of the PIT tag and coded wire tag was verified using a PIT tag detector and a coded wire tag detector. If either tag could not be detected in the fish, a second tag was inserted into the fish. The fish were then returned to the water.
Seining was the primary method used for collecting young-of-the-year (YOY) fish. Electrofishing was selected to supplement collections of northern pike, largemouth bass, and yellow perch made by seineing. Seining was done from the first week of June through the last week of September one day per week in Buckhorn Marsh impoundment, Burnt Ship Creek, and Woods Creek collectively and one day per week in Spicer Creek, Gun Creek, and Big Six Mile Creek collectively. Electrofishing was also done from the first week of June through the last week of September one day per week in Buckhorn Marsh impoundment, Burnt Ship Creek, and Woods Creek collectively and one day per week in Spicer Creek, Gun Creek, and Big Six Mile Creek collectively. Seines were made of ¼ inch mesh, were 6 feet deep, and were either 20 feet or 50 feet long. The 20-foot seine was used primarily in Gun Creek and Spicer Creek downstream of East River Road because the creeks are relatively narrow. The 50-foot seine was used in all other areas.
Those northern pike, largemouth bass, yellow perch and muskellunge caught with seines were immediately placed into 5 gallon plastic buckets. Young-of-the-year fish were marked according to Tables 2 and 3 in the Standard Operating Procedures in Appendix A. Marks (fin clips) were applied to the fish using sharp, blunt-ended scissors. Fish were not anesthetized.
In Buckhorn Marsh impoundment, Burnt Ship Creek, and Woods Creek all fish caught by fyke netting and seining were identified to species in the field where practicable and counted. In Gun Creek, Spicer Creek, and Big Six Mile Creek, only northern pike, largemouth bass, yellow perch, and muskellunge were routinely counted; the presence of other species was noted. Because electrofishing was used specifically to supplement the catch of northern pike, largemouth bass, and yellow perch, other species caught by electrofishing were not consistently enumerated (see Standard Operating Procedures in Appendix A).
Water
quality measurements were taken at the surface immediately prior to seining,
electrofishing, and tending fyke nets.
Dissolved oxygen and temperature were measured using a YSI Oxymeter;
conductivity was measured using an Oakton EC Tester, and pH was measured using
a Oakton pH Tester2. All water quality
equipment was calibrated according to the manufacturer’s specifications at the
beginning and end of each day.
Specifications of the water quality meters are in Appendix
A.
As
part of another study, water surface elevations were collected on a 15-minute
time step at 24 temporary locations during 2003 using In-Situ miniTROLL,
Professional Model (30 psi) gauges. Data
in the present report are for four locations: BSC-03 (in Burnt Ship Creek
approximately 150 feet west of the west weir), BHM-01 (in Buckhorn Marsh
impoundment approximately 100 feet east of the west weir), BHM-02 (in Buckhorn
Marsh impoundment approximately 150 feet west of the east weir), and WC-01 (in
Woods Creek approximately 250 feet east of the east weir, Figure
2.1.4-1)
To assess the fish spawning and nursery habitat in BMRP, data were collected along cross-sectional and longitudinal transects in Buckhorn Marsh impoundment and Burnt Ship Creek during late April 2003, before extensive growth of submerged aquatic vegetation (SAV) and emergent aquatic vegetation (EAV) was expected, and during August 2003, when SAV and EAV were expected to be at their peak.
In Buckhorn Marsh impoundment, sixteen cross-sectional transects were established (Figure 2.1.5-1). The cross-sectional transects were perpendicular to the centerline of the channel. Each cross-sectional transect traversed the bankfull width of the channel or up to a point where fish passage would be precluded. At approximately every 10 feet along each cross-sectional transect, water depth, substrate type, percent cover of each species of SAV and EAV (in 10% increments), approximate % decomposing vegetation (e.g., decomposing SAV, EAV or deciduous leaves) and instream and riparian cover were measured and recorded. The percent cover of SAV is presented as “sparse” (10, 20%), “moderately dense” (30, 40, 50%), “dense” (60, 70%) and “very dense” (80, 90, 100%).
In Burnt Ship Creek, a longitudinal transect was established along the channel centerline from the mouth at the Niagara River upstream to a foot path east of Route 190 (Figure 2.1.5-1). The start and end of open water areas, EAV, SAV, or other unique habitats along the channel’s centerline were delineated. Water depths and substrates were recorded every 100 feet, and at least one measurement in each emergent vegetation stand if the stand was less than 100 feet long, in all habitat types in an effort to determine pathways for fish passage. Two cross-sectional transects were established in the open water channel of Burnt Ship Creek. These transects were located near fyke net sites. Data were collected as described for Buckhorn Marsh impoundment.
Analytical methods were developed by Dennis Dunning (Ph.D.) and John Magee (CFP), who also conducted the analyses and interpreted the results.
For Buckhorn Marsh impoundment, two multiple-census methods for closed populations were used for estimating the abundance of yearling and older northern pike: the Schumacher and Eschmeyer and the modified Schnabel (Ricker 1975). They will produce unbiased estimates if the following conditions are met: 1) marked fish suffer the same natural mortality as the unmarked fish, 2) marked fish are as vulnerable to capture as the unmarked ones, 3) marked fish do not lose their mark, 4) marked fish become randomly mixed with unmarked fish or the distribution of fishing effort in subsequent sampling is proportional to the number of fish present in different parts of the body of water, 5) all marks are recognized and reported on recovery, and 6) there is only a negligible amount of recruitment to the catchable population during the time the recaptures were being made, i.e., the population is closed. Additionally, to reduce the potential effects of angling, the population estimates covered the period from March 24, the first date that northern pike were tagged in Buckhorn Marsh impoundment through May 2, the day before the season for legally harvesting northern pike opened.
The best estimate of abundance N using the Schumacher and Eschmeyer method (equation 3.12 in Ricker 1975) is the reciprocal of:
where
N is the estimate of
abundance,
Mt is the total marked fish at large at the start of the tth day , i.e., the number previously marked less any accidentally killed at previous recaptures,
M is the sum of Mt
, the total number marked,
Ct is the
total number caught on day t,
Rt is the
number of recaptures in the sample Ct,, and
R is the sum of Rt
, the total recaptures during the period of the estimate.
The variance (equation 3.13 in Ricker 1975) is:
where m is the number of catches examined. Instead of computing confidence limits directly for N, it is better to compute them for the more symmetrically distributed 1/N (Ricker 1975). The variance of 1/N (equation 3.14 in Ricker 1975) is:
For computing confidence limits for 1/N, t-values
were used corresponding to m-1 degrees of freedom. Confidence limits for N were found by
inverting those obtained for 1/N.
The best estimate of abundance N using the adjusted Schnabel method (equation 3.17 in Ricker 1975) is:
where approximate 95% confidence limits were calculated by considering R as a Poisson variable (from Appendix II in Ricker 1975):
For Woods Creek and Gun Creek, two multiple-census methods for open populations were used: Bailey’s triple catch method for small samples and the modified Jolly-Seber 4-catch method (Ricker 1975). They will produce unbiased estimates if the first five conditions listed for the closed population methods are met. The open population methods, unlike those for closed populations, allow the number of northern pike to change due to migration, mortality, recruitment or some combination of those. Northern pike typically migrate into and out of spawning areas during the spring.
Bailey’s triple catch method uses fish caught during three time periods. During the first period (Time 1), fish are tagged. During Time 2, recaptures are noted, fish not previously tagged are tagged, and all fish are returned to the water. During Time 3, recaptures from fish tagged during Time 1 and Time 2 are noted. The best estimate of abundance N2 using Bailey’s triple catch method for small samples (equation 5.11 in Ricker 1975) is:
where
N2 is the
abundance of fish during time 2,
M2 is the number
of fish tagged during time 2,
C2 is the number
of fish caught and examined for tags during time 2,
R12 is the
number of fish recaptured during time 2 that were tagged during time 1,
R13 is the
number of fish recaptured during time 3 that were tagged during time 1,
R13 is the
number of fish recaptured during time 3 that were tagged during time 1,
R23 is the
number of fish recaptured during time 3 that were tagged during time 2.
The variance of N2 (equation 5.14 in Ricker 1975) is:
The modified Jolly-Seber 4-catch method uses fish caught during four time periods. During the first period (Time 1), fish are tagged. During Time 2, the total catch and the recaptured fish are enumerated, fish not previously tagged are tagged, and all fish are returned to the water. During Time 3, recaptures from fish tagged during Time 1 and Time 2 are enumerated, fish not previously tagged are tagged, and all fish are returned to the water. During Time 4, recaptures from fish tagged during Time 1, Time 2, and Time 3 are enumerated. The best estimate of N