Canadian Manuscript Report of Fisheries and Aquatic Sciences Fish Assemblage Surveys of Rondeau Bay, Ontario:

Transcription

1 Canadian Manuscript Report of Fisheries and Aquatic Sciences Fish Assemblage Surveys of Rondeau Bay, Ontario: By Amy Edwards, Jason Barnucz, and Nicholas E. Mandrak Great Lakes Laboratory for Fisheries and Aquatic Sciences Fisheries and Oceans Canada 867 Lakeshore Rd., P.O. Box 5050 Burlington ON L7R 4A6 CANADA

2 Her Majesty the Queen in Right of Canada, Cat. No. 97-4/2773E ISSN Correct citation for this publication: Edwards, A., J. Barnucz, and N.E. Mandrak Fish assemblage surveys of Rondeau Bay, Ontario: 2004 and Can. Manuscr. Rpt. Fish. Aquat. Sci. 2773: v + 43 pp. ii

3 TABLE OF CONTENTS TABLE OF CONTENTS...III ABSTRACT... V RÉSUMÉ... V 2.0 METHODS SITE SELECTION Sampling Sampling SAMPLING GEAR Boat Electrofishing Fyke Nets SAMPLING GEAR SPECIES AT RISK HABITAT DATA COLLECTION RESULTS SAMPLING Boat Electrofishing West Shore Fyke Nets West Shore Boat Electrofishing East Shore Fyke Nets East Shore SAMPLING Seine Nets Fyke Nets SPECIES AT RISK HABITAT DATA DISCUSSION Passive vs. Active Gear Types Fyke Nets vs. Boat Electrofishing Fyke nets vs. Seine Nets VARIATION BETWEEN HABITAT TYPES Fyke Net Sites Boat Electrofishing Sites SPECIES AT RISK RECOMMENDATIONS ACKNOWLEDGEMENTS LITERATURE CITED...15 iii

4 LIST OF TABLES Table 1. Summary of catch data for fyke netting and boat electrofishing, Rondeau Bay Table 2. Summary of species captured using boat electrofishing and fyke netting along the east and west shores of Rondeau Bay, Table 3. Species captured by boat electrofishing and fyke netting, Rondeau Bay, Table 4. Summary of sampling effort using fyke nets and boat electrofishing, Rondeau Bay, Table 5. Summary of catch data for fyke nets and seine nets, Rondeau Bay, Table 6. Summary of species caught with fyke nets and seine nets, Rondeau Bay, Table 7. Species captured in Rondeau Bay, Table 8. Total sampling effort for fyke net and seine net sites, Rondeau Bay, Table 9. Summary of catch data for fyke net and boat electrofishing sites, Rondeau Bay, Table 10. Summary of species captured by boat electrofishing and fyke netting, Rondeau Bay, Table 11. Total catch and total lengths (TL) (mm) for largemouth bass caught with boat electrofishing and fyke nets at 2004 Rondeau Bay sites. 22 Table 12. Total catch and species richness at 2005 Rondeau Bay sites..23 Table 13. Total numbers caught and total lengths (TL) (mm) of larger species (> 200 mm adult TL) caught using fyke nets and seine nets, Rondeau Bay, Table 14. Average species caught per site at fyke net and boat electrofishing sites, Rondeau Bay, LIST OF FIGURES Figure 1. Sites sampled in Rondeau Bay in Numbers on the map correspond to site codes in Appendix Figure 2. Sites sampled in Rondeau Bay in Numbers on the map correspond to site codes in Appendix LIST OF APPENDICES Appendix 1. Site descriptions for 2004 Rondeau Bay sampling 26 Appendix 2. Site descriptions 2005 Rondeau Bay sampling..28 Appendix 3. Common and scientific names of fishes caught in Rondeau Bay in 2004 and 2005 (according to Nelson et al. 2004)..30 Appendix 4. Species caught in Rondeau Bay, Appendix 5. Sampling effort and gear type used in Rondeau Bay, Appendix 6. Species caught in Rondeau Bay in Appendix 7. Sampling effort and gear type used in Rondeau Bay, Appendix 8. Habitat data from Rondeau Bay sites, Appendix 9. Habitat data from Rondeau Bay sites, iv

5 ABSTRACT Fisheries and Oceans Canada and the Ontario Ministry of Natural Resources conducted a survey of the fish communities in Rondeau Bay in 2004 and The objectives of the 2004 survey were: 1) to conduct a comprehensive fish community survey of Rondeau Bay utilizing a systematic approach consisting of fyke netting and boat electrofishing sampling methods; 2) to evaluate gear efficiency both within, and between, habitat types; and, 3) to evaluate the current status and distribution of fish species at risk within littoral habitats of Rondeau Bay. Sampling in 2005 was conducted to acquire current data on the fish assemblages present in the backwater channels and intermittently flooded habitats of the wetland, as these had not been sampled intensively in recent years. Special emphasis was placed on detecting species at risk. In 2004, boat electrofishing was more effective than fyke netting at detecting species and catching fishes, regardless of habitat type. Boat electrofishing and fyke net sites along the west shore of the bay detected more species compared to boat electrofishing and fyke net sites along the east shore. In 2005, sites sampled using seine nets captured more fishes and detected more species than sites sampled with fyke nets. One species at risk, spotted gar (Lepisosteus oculatus), was detected during the 2004 survey, while two were detected in 2005: spotted gar and warmouth (Lepomis gulosus). RÉSUMÉ En 2004 et en 2005, Pêches et Océans Canada et le ministère des Richesses naturelles de l Ontario ont mené une étude sur les communautés de poissons à la baie Rondeau. L étude de 2004 visait à : 1) mener une étude approfondie sur la communauté de poissons de la baie Rondeau en utilisant une approche systématique consistant en des méthodes d échantillonnage au moyen de verveux et pêche électrique en bateau; 2) évaluer l efficacité du matériel à l intérieur et entre les types d habitat; et, 3) évaluer l état actuel et la répartition des espèces de poissons en péril à l intérieur des habitats littoraux de la baie Rondeau. L échantillonnage de 2005 a été mené pour acquérir des données actuelles sur les assemblages de poissons présents dans les eaux dormantes et les habitats inondés par intermittence des terres humides, puisque ceux-ci n avaient pas été échantillonnés de manière intensive au cours des dernières années. L accent a été accordé sur le dépistage des espèces en péril. En 2004, la pêche électrique en bateau était plus efficace que les verveux pour déceler les espèces et capturer les poissons, sans égard au type d habitat. La pêche électrique en bateau et les sites de verveux le long de la rive ouest de la baie ont permis de déceler davantage d espèces comparativement à la pêche électrique en bateau le long de la rive est. En 2005, les sites d échantillonnage utilisant des sennes ont capturé davantage de poissons et ont décelé davantage d espèces que les sites d échantillonnage utilisant les verveux. Une espèce en péril, le lépisosté tacheté (Lepisosteus oculatus), a été décelée au cours de l étude de 2004, alors que deux ont été décelées en 2005 : le lépisosté tacheté et le crapet sac-à-lait (Lepomis gulosus). v

6 1.0 INTRODUCTION Rondeau Bay is located on the north shore of Lake Erie, approximately 130 km west of Long Point and 65 km east of Point Pelee. Fisheries and Ocean Canada (DFO), and the Ontario Ministry of Natural Resources (OMNR) conducted a fish survey of the bay in The objectives of the survey were threefold: 1. to conduct a comprehensive fish community survey of Rondeau Bay utilizing a systematic approach consisting of fyke netting and boat electrofishing sampling methods; 2. to evaluate gear efficiency both within, and between, habitat types; and, 3. to evaluate the current status and distribution of fish species at risk within littoral habitats of Rondeau Bay. In 2005, DFO returned to Rondeau Bay to intensively sample the inner coastal wetland along the eastern shore of the bay within Rondeau Provincial Park, in cooperation with OMNR. The purpose of the 2005 sampling was to acquire current data on the fish assemblages present in the backwater channels and intermittently flooded habitats of the wetland, as these had not been sampled intensively in recent years. Special emphasis was placed on detecting species at risk. 2.1 SITE SELECTION 2.0 METHODS Sampling Two different ecological areas are found within Rondeau Bay. The east shore consists of wetlands created by a barrier beach system and is within the boundaries of Rondeau Provincial Park. The west shore of the bay is heavily farmed and numerous agricultural drains and creeks line the shoreline; the water is generally turbid, and there are fewer aquatic macrophytes. Original sites consisted of 16 standardized transects, approximately 300 m long, spaced equally around the perimeter of the bay. Eight sites were located on the west shore and the other eight were to be located along the east shore (Figure 1, Appendix 1). The 16 sites were to be sampled using two gear types, one passive (fyke nets) and one active (boat electrofishing); however, only seven sites were sampled along the east shore with the boat electrofishing unit due to shallow water at one site. Also, only six sites were sampled along the east shore using fyke nets. Boat electrofishing took place in June and fyke net sampling occurred in July and August. For simplicity, each site was numbered one through 15 for this report (Appendix 1). 1

7 Sampling In 2005, DFO conducted surveys in May, July and August, along the east shore of Rondeau Bay, within the wetlands created by the barrier beach system. A total of 34 sites were sampled in, and around, the wetlands of Rondeau Provincial Park (Figure 2, Appendix 2). Sixteen of these sites were sampled using both active (seine nets) and passive (fyke nets) gear types; eight sites were sampled using only fyke nets; and, 10 sites were sampled using only seine nets. Sites sampled in May were to be re-sampled in July; however, water levels in July had dropped enough that reaching the previously sampled sites was impossible. Sites 1-27 were originally to be spaced approximately 500 m apart but the complex shoreline of the inner wetlands, as well as difficulties with accessibility, made this essentially impossible. Sites ended up being selected based on accessibility and habitat features. For simplicity, each site was numbered one through 34 for this report (Appendix 2). 2.2 SAMPLING GEAR Boat Electrofishing DFO conducted the electrofishing portion of the survey using a 6 m Model SR-20 Smith-Root electrofishing boat equipped with a Model 7.5 kw Smith-Root generator, 7.5 GPP control box, three kick plates and dual foot pedals. Each transect was sampled twice; at the end of each transect the power was shut down, the boat was turned around, and sampling continued along each transect until the start was reached again. A standard power output of watts was maintained along the entire transect. Sampling data recorded at each site included capture method, sampling effort, electrofishing settings and a description of the sampling equipment. Two netters retrieved stunned fishes as they appeared, and all fishes were transferred from the river into a live-well within the boat. Species were identified, counted and released. Minimum and maximum total lengths were recorded for all species captured. Two individuals of each species were kept for lab verification Fyke Nets Fyke netting was performed by OMNR, approximately one month after boat electrofishing occurred. Two 1.2 m fyke nets, with 6.35 mm mesh, were set at each transect, one at each end of the transect. The nets were set, left overnight and fished the following day (approximately 24 h sets). Species were identified, counted and 2

8 released. Minimum and maximum total lengths were recorded for each species. Two individuals of each species were kept for lab verification. 2.3 SAMPLING GEAR Sixteen sites (1-4, 6-9, and 24-27) located within the wetlands of Rondeau Provincial Park, were sampled using two gear types: a 9 m bag seine with 6.35 mm mesh, and a 1.2 m fyke net with 6.35 mm mesh. Seining was carried out before fyke nets were set. Three seine hauls were performed at each site except sites 12 and 24-27, which were seined twice each. Fyke nets were set, left overnight, and fished the following day (approximately 24 h sets). Sites 5, 10 and 11 were sampled with the 9 m bag seine with 6.35 mm mesh. Each site was seined three times. Sites were sampled with a 1.2 m fyke net with 6.35 mm mesh. Fyke nets were left to soak for approximately 24 h. Sites located just outside the wetlands, on sandy flats, were sampled with a 15 m boat seine. Each site was seined once. 2.4 SPECIES AT RISK Discrete individual total length measurements and digital photos were taken of all species at risk caught during both 2004 and 2005 sampling. Any Ictiobus sp. or spotted gar (Lepisosteus oculatus) (common and scientific names according to Nelson et al. 2004, listed in Appendix 3) specimens collected during 2004 sampling were also fin clipped. The fin clip, taken from the caudal fin, was placed in ethanol or dried in a scale envelope. 2.5 HABITAT DATA COLLECTION Habitat data at each of the 2004 and 2005 sites were described by recording air and water temperature, conductivity, maximum water depth, distance from shore, maximum sampling depth, substrate type, aquatic vegetation and Secchi depth. Habitat data were recorded upon completion of sampling. All habitat data for 2004 sampling used in this report were obtained during the boat electrofishing portion of the project as habitat data collected during the fyke net portion were incomplete. 3

9 3.0 RESULTS SAMPLING Boat Electrofishing West Shore Eight sites were sampled along the west shore with the boat electrofishing unit. The total catch for all sites was 614 fishes and the species richness was 28 (Tables 1, 2 and 3). Yellow perch (Perca flavescens), pumpkinseed (Lepomis gibbosus), emerald shiner (Notropis atherinoides) and bluegill (Lepomis macrochirus) accounted for approximately 65% of the total catch (Appendix 4). Site 4 had the lowest total catch (29) and Site 5 had the highest (206) (Appendix 4). The average CPUE was fish/h; the average effort per site was h; and, the total overall effort was 1.98 h (Table 4). Complete details of 2004 boat electrofishing sampling effort are in Appendix Fyke Nets West Shore A total of 329 fishes representing 23 species were caught at eight sites along the west shore of Rondeau Bay using fyke nets (Tables 1, 2 and 3). The majority of the catch was comprised of bluegill (124) and pumpkinseed (69) (Appendix 4). Site 3 had the lowest catch (19) and Site 7 had the highest (74) (Appendix 4). The average CPUE was fish/h; the average effort per site was h; and, the total effort expended over the eight sites was h (Table 4). Complete details of 2004 fyke net sampling effort are in Appendix Boat Electrofishing East Shore Seven sites were sampled along the east shore of the bay; the eighth site was not sampled as the water was too shallow. The total catch of all sites combined was 1011 (Table 1). Five species made up approximately 74% of the catch: pumpkinseed, spottail shiner (Notropis hudsonius), bluegill, yellow perch and emerald shiner (Appendix 4). The total number of species captured was 25 (Tables 2 and 3). Sites 10 and 13 had the lowest (44) and highest (268) individual catches, respectively (Appendix 4). The average CPUE was fish/h; the average effort per site was h; and, the total effort expended over the seven sites was 1.74 h (Table 4) Fyke Nets East Shore Six sites were sampled with fyke nets along the east shore producing a total catch of 279 fishes. Bluegill (137) and pumpkinseed (54) made up approximately 68% of the total catch (Table 1, Appendix 4). Species richness was 13 (Tables 2 and 3). 4

10 Sites 13 and 9 had the lowest (6) and highest (117) catch, respectively (Appendix 4). The average CPUE was 1.01 fish/h; the average effort per site was 46 h; and, the total sampling effort was 276 h (Table 4) SAMPLING Seine Nets A total of 2130 fishes, representing 24 species, were collected from 26 seine net sites in Rondeau Bay during 2005 sampling (Table 5, 6 and 7). Pumpkinseed, blackchin shiner (Notropis heterodon) and banded killifish (Fundulus diaphanus) comprised almost half the total catch (46%) (Appendix 6). Site 6 had the lowest total catch (2) and Site 5 had the highest (323). The average CPUE was fish/haul; the average effort was 2.27 hauls; and, the total effort was 59 hauls (Table 8). Complete details of 2005 seine net sampling effort are in Appendix Fyke Nets Fyke nets set at 24 sites along the coastal wetlands of Rondeau Bay yielded a total catch of 259 fishes representing 18 species (Tables 5, 6 and 7). Species composition was dominated by pumpkinseed which comprised 40% of the catch, while spotted gar (13%), bluegill (11%) and largemouth bass (Micropterus salmoides) (11%) were the next most abundant species (Appendix 6). The average CPUE was fish/h; the average effort was h; and, the total sampling effort was 500 h (Table 8). Complete details of fyke net sampling effort are in Appendix SPECIES AT RISK 2004 Sampling Two species at risk were detected in Rondeau Bay during 2004 sampling, all of them along the west shore. Six specimens from the Ictiobus genus were caught at four boat electrofishing sites (Appendix 4). One spotted gar was collected at a fyke net site (Site 2), and four more were collected by boat electrofishing (Appendix 4) Sampling DFO sampling in 2005 yielded two species at risk from Rondeau Bay: spotted gar and warmouth (Lepomis gulosus). Thirty-four spotted gar were detected at seven sites (4, 6, 7, 8, 9, 12 and 13), and two warmouth were collected from Site 27 (Appendix 6). Both species were only collected with fyke nets. 5

11 3.4 HABITAT DATA 2004 Every site, except for one (Site 9), had aquatic macrophytes present over at least 50% of the site (Appendix 8). The west shore sites had mostly submergent vegetation, while the east shore sites had an even mixture of both submergent and emergent vegetation (Appendix 8). Substrates were predominantly silt, sand and some detritus. Secchi depths, on average, at the west shore sites were less than those of the east shore sites (Appendix 8); however, this difference was not significant (t= , df=12, p>0.05) The vast majority of sites had emergent and/or submergent vegetation present over at least 50% of the site (Appendix 9). Secchi depths ranged from approximately 0.5 m to > 1 m (Appendix 9). Silt and/or detritus were the dominant substrate types at most sites, except for seven sites sampled with the 15 m boat seine where the substrate at the majority of these sites was predominantly sand (Appendix 9). 4.1 Passive vs. Active Gear Types 4.0 DISCUSSION Fyke Nets vs. Boat Electrofishing 2004 During the 2004 Rondeau Bay sampling period, boat electrofishing had a higher overall success rate, with respect to number of species and total number of fishes caught, compared to fyke netting, regardless of habitat type. More than twice as many fishes were caught using boat electrofishing (1625) than fyke netting (608) (Table 9). Two species (smallmouth bass (Micropterus dolomieu) and white crappie (Pomoxis annularis)) were collected only with fyke nets; whereas, eight species were collected only with the electrofishing unit (Tables 3 and 10). Boat electrofishing yielded a total species richness of 29, while fyke netting yielded 23 species (Table 10). The fyke nets were not as effective as the boat electrofishing unit at catching smaller species such as emerald shiner, spottail shiner, mimic shiner (Notropis volucellus), blackchin shiner and bluntnose minnow (Pimephales notatus) (Appendix 4). These fishes were likely small enough to swim out of the nets. Holland and Peters (1992) observed smaller fishes (< 150 mm) falling through the mesh of the nets as they were lifted out of the water. Although they used nets with larger mesh sizes (25, 32 and 38 mm) compared to the nets used by DFO and MNR, it would be reasonable to expect that smaller fishes 6

12 relative to the mesh size, would be able to escape the nets. Holland and Peters (1992) also discovered a pattern of decreasing CPUE with increasing mesh size within four different habitats; and, in a study comparing hoop nets with six different mesh sizes Hesse et al. (1982; cited in Holland and Peter 1992) determined that CPUE was greatest for the smaller mesh nets (6 and 25 mm, compared to 38, 50, 63 and 76 mm). This pattern is likely because nets with smaller mesh sizes are able to catch and retain smaller fishes and more of these fishes can be contained within a hoop net compared to larger fishes. Further explanations for the relative lack of smaller fishes caught using the fyke nets could include: large fishes move farther than small fish in a given period of time and are more likely to encounter the net (Portt et al. 2006); the greater catchability of large fishes using fyke nets might be due to their tendency to seek cover, which could be provided by the net (Ricker 1975; cited in Portt et al. 2006); and, predation on small fishes by larger fishes can occur within fyke nets, effectively biasing the sample (Portt et al. 2006). Boat electrofishing was more effective at catching yellow perch and pumpkinseed (Appendix 4) while fyke netting appeared to be more effective at catching smaller largemouth bass. Of the 12 largemouth bass caught using fyke nets, only one had a total length (TL) over 100 mm. Conversely, boat electrofishing seemed to be better at catching larger individuals of largemouth bass (Table 11). Chow-Fraser et al. (2005) reported similar results with fyke nets and boat electrofishing: fyke nets obtained greater catches of juvenile largemouth bass while boat electrofishing was more effective at catching adult largemouths. Black crappie (Pomoxis nigromaculatus), white crappie and juvenile smallmouth bass were the only species for which fyke net catch rates surpassed electrofishing catch rates (Appendix 4). Previous studies have shown that both hoop nets and trap nets were selective for both crappie species (Pugh and Schramm 1998, McInerny and Cross 2004). It has been suggested the species selectivity of these types of nets is related to their ability to provide cover for cover-oriented species (Hubert and Schmitt 1982; cited in Krueger et al. 1998). White crappie is a cover-oriented species (Markham et al. 1991), as is black crappie (Keast 1968), which could be one explanation for the higher numbers of crappie caught with fyke nets compared to electrofishing. It should be noted that four out of five white crappie voucher specimens kept for laboratory identification were later re-identified as black crappie. This should be taken into consideration when examining crappie abundance. 7

13 To make a valid comparison of effort between the two gear types, it is necessary to compare the amount of time taken to obtain a sample using fyke nets (i.e. setting and fishing the nets (excluding soak time)), to electrofishing. Therefore, catch per unit effort should be measured as fish/person-hour as discussed by Pugh and Schramm (1998). However, in this case, the time it took to set and fish the fyke nets was not recorded and it is not possible to make a direct comparison to boat electrofishing. Pugh and Schramm (1998) compared electrofishing and hoop netting in the lower Mississippi River, measuring CPUE as fish/person-hour, and they found the CPUE for boat electrofishing was 5-8 times greater than hoop netting Fyke nets vs. Seine Nets In 2005, 16 sites were sampled using both fyke nets and bag seines. Approximately four times as many fishes were captured using the seine nets (782) compared to fyke nets (196) (Table 12). Seine nets also yielded a higher species richness (22) than fyke nets (17) (Table 12). Three sites sampled using a 9 m bag seine had almost eight times as many fishes as eight sites sampled with fyke nets (Table 12). Seven sites sampled using only a 15 m boat seine net had the highest total catch (848) compared to any of the other sites sampled using 9 m bag seines or fyke nets (Table 12). This could be a result either of the larger size of the net and its ability to cover a larger area, or the difference in habitat characteristics at these seven sites compared to the other sites. The majority of the boat seine sites had predominantly sand substrates, while the remaining 27 sites had substrates consisting mainly of silt, some sand and detritus (Appendix 9). Overall, seine nets detected seven more species than fyke nets (Table 6). The majority of these were smaller species such as the brook silverside (Labidesthes sicculus), blackchin shiner, spottail shiner and mimic shiner (Appendix 6). Although some smaller fishes, such as juvenile northern pike (Esox lucius) and largemouth bass, were captured using the fyke nets, seine nets overall were more efficient at catching larger numbers and more species of smaller fishes (Appendix 6). Both seine nets and fyke nets were successful at detecting larger individuals of species such as brown bullhead (Ameiurus nebulosus) and bowfin (Amia calva); however, more large fishes were caught with fyke nets, including common carp (Cyprinus carpio), longnose gar (Lepisosteus osseus) and spotted gar, none of which were detected using seine nets (Table 13, Appendix 6). This is probably due to the ability of larger fishes to avoid the seine net. The catchability of a given species using seine nets decreases as swimming speed increases (Bayley and 8

14 Herendeen 2000) (i.e. catchability decreases with increasing fish size (Portt et al. 2006)). Seine nets were more effective at detecting smaller benthic species such as darters. Two darter species (Iowa darter (Etheostoma exile) and johnny darter (Etheostoma nigrum)) were caught with seine nets; no darter species were detected using fyke nets (Appendix 6). This could be a result of the seine net covering a large area of bottom substrate during sampling, increasing the chances of encountering benthic fishes such as darters; whereas, fyke nets are set higher in the water column and are less likely to be encountered by these fishes. The limited mobility of darter species compared to larger more pelagic species likely also reduces the probability that darter species would encounter the fyke net (Portt et al. 2006). As mentioned previously, to make a valid comparison of effort expended between two gear types, effort should be recorded as fish/person hour (i.e. for fyke nets the time it takes to set and fish the nets, excluding soak time). However, the time it took to set the fyke nets during the 2005 sampling was only recorded for half of the fyke net sites, and the time it took to fish the nets was not recorded for any of them. Similarly, the time it took to seine the sites and process the fish was recorded for only 12 of the 26 seine net sites. Therefore, a true comparison of effort between the two gear types cannot be done. 4.2 VARIATION BETWEEN HABITAT TYPES Fyke Net Sites Eight sites were sampled along the west shore using fyke nets, and six sites were sampled along the east shore. The west shore of Rondeau Bay is more degraded, with fewer aquatic macrophytes and higher turbidity levels (not significantly higher) due to agricultural drains and runoff. The total sampling effort was greater along the west shore as it had two more sites than the east shore. Both the average CPUE and average effort/site were slightly higher for the east shore sites when compared to the west shore sites (Table 4). Sampling along the west shore sites detected 10 more species (23) compared to the east shore sites (13). The west shore sites detected an average of 8.25 species per site while the east shore detected an average of 6.83 (Tables 2, 3 and 14); although, this difference was not significant (t = , df = 12, p > 0.05). This variation could simply be due to the extra sites sampled along the west shore; however, it does not seem enough to explain the difference in species richness between the two shores. The more turbid water at the west shore sites may have played 9

15 a part in the higher total catch and higher species richness for those sites by making the nets less visible to fishes; for example, Barko et al. (2004) found that species richness, especially of adult fishes, decreased as Secchi depth increased Boat Electrofishing Sites Total sampling effort and average effort per site were comparable between the two ecological areas (Table 4). However, the total catch and average CPUE from the east shore sites almost doubled that of the west shore sites (Tables 1 and 4). This could be a result of the higher level of aquatic macrophytes along the east shore, providing more habitat for more fishes. Water quality may have been better along the east shore as the shoreline is not developed. It is also possible that the turbid water along the west shore contributed to the lower total catch as the netters may not have been able to see stunned fish. In very turbid environments, it can be impossible to see stunned fish below the water surface making directed netting impossible; netters are reduced to sweeping or positioning the net behind the anode (Reynolds 1983, Port et al. 2006). Although the east shore sites had a higher total catch and average CPUE, the west shore yielded a higher species richness as well as a higher average species per site value (Tables 2, 3 and 14). Despite the presence of suitable habitat, goldfish (Carassius auratus), longnose gar, northern pike and spotted gar were not detected along the east shore. It is possible that the clear waters along the east shore allowed these fishes to see and avoid the electrofishing boat. McInerny and Cross (1996) observed largemouth bass actively avoiding the electrofishing boat in Minnesota lakes with clear water. Another reason for lower detection along the east shore could have been the difficulty in sampling some of the marsh cells that are found along that shore. Some of these cells were not sampled as the boat was too large to access them and the sampling efficiency in other marsh cells may not have been maximized because of the difficulty in manoeuvring the boat. 4.3 SPECIES AT RISK 2004 One of the objectives of the 2004 survey was to examine the status and distribution of fish species at risk within the littoral habitats of Rondeau Bay. Historical records exist for four fish species at risk within the bay. They are (their status as designated by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in parentheses): lake chubsucker (Erimyzon sucetta) (Threatened); 10

16 pugnose shiner (Notropis anogenus) (Endangered); spotted gar (Threatened); and, warmouth (Special Concern). Of these four species, only spotted gar were detected during the 2004 sampling period. The bigmouth buffalo (Ictiobus cyprinellus) (Special Concern) was only recently detected in Rondeau Bay (2002) during a DFO survey monitoring the status of spotted gar (N.E. Mandrak, DFO, unpubl. data). Specimens from the Ictiobus genus were detected again during the 2004 sampling. These individuals had a subterminal mouth and, thus, were not bigmouth buffalo (Mandrak and Cudmore 2006). Tissue samples were taken for DNA analyses to determine whether the Ictiobus specimens were black buffalo (Ictiobus niger) (Special Concern) or smallmouth buffalo (Ictiobus bubalus), as distinguishing between these two species using physical characteristics alone is very difficult (H. Bart, Tulane University, pers.comm.). The first record of spotted gar in Rondeau Bay was collected in 1955 and, prior to 2004, less than 50 spotted gar specimens had been collected in Canada, 19 of which were caught in Rondeau Bay (Mandrak and Cudmore-Vokey 2004a). Both the spotted gar and Ictiobus specimens were only detected along the west shore of the bay during the 2004 sampling period. All six Ictiobus specimens, and four of five spotted gar specimens, were collected using the boat electrofishing unit (Appendix 4). It is not known why spotted gar or Ictiobus sp. were not detected along the east shore during 2004 sampling. The habitat along that shore appeared suitable for both species, which both prefer slow, shallow, vegetated, clear water; although, Ictiobus sp. can tolerate high turbidity and low dissolved oxygen levels (Mandrak and Cudmore- Vokey 2004a). No lake chubsucker or pugnose shiner were detected during the 2004 sampling period, which could be a result of the gear type used. Some species are caught more readily using specific gear types; a combination of boat electrofishing and boat seining is very effective at detecting pugnose shiner and lake chubsucker (N.E. Mandrak, DFO, unpubl. data). However, despite sampling in the 1980s and 1990s, the pugnose shiner has not been recorded in Rondeau Bay since 1963, and it is probable that a population no longer exists in the bay (Holm and Mandrak 2002). The lake chubsucker has not been collected from Rondeau Bay since 1983; however, it is believed that they may still be present and may be detected with more intensive sampling (Mandrak and Crossman 1994). Although the 2004 sampling was intensive, it did not include the use of seine 11

17 nets, which have been shown to be very effective at detecting lake chubsucker (N.E. Mandrak, DFO, unpubl. data). Warmouth was first reported in Canada at Rondeau Bay in 1966 and has since been detected in the bay in 1967, 1968 and 1999 (Mandrak and Cudmore-Vokey 2004b). As only a few specimens were collected each time, it is not clear if there is an established population in the bay, or if these fish were strays from Point Pelee (Mandrak and Cudmore-Vokey 2004b). No warmouth were detected during the 2004 sampling, although suitable habitat was sampled Two species at risk were detected during the 2005 survey along the inner coastal wetlands of the east shore of Rondeau Bay. Thirty-four spotted gar were captured from seven fyke net sites and two warmouth were collected from one fyke net site (Appendix 6). Spotted gar was caught exclusively with fyke nets in sites located in the southeast corner of the bay. These sites were sampled in May when water levels were high in the back waters and side channels of the wetland. Due to lower water levels in July and August, which made navigating these inner coastal wetlands impossible, the sites were not re-sampled. Spotted gar was not detected during either of the sampling events in July or August. Aquatic macrophytes were present at spotted gar capture sites and the same bottom substrate (silt) was present at each site. As with spotted gar, warmouth was also only detected with the fyke nets. Although suitable habitat was present at most of the 34 sites sampled in 2005, warmouth was only detected at one site (27). As mentioned previously, the low numbers of warmouth collected in Rondeau Bay make it difficult to determine whether there is an established population present, and it is possible that the specimens collected are strays. Site 27, where two warmouth were captured, is located at the northeast corner of the bay (Figure 2, Appendix 6). This site had a predominantly sand bottom with some silt present, and submergent vegetation was present over approximately 60% of the site (Appendix 9). Pugnose shiner and lake chubsucker were not found in Rondeau Bay during 2005 sampling despite intensive sampling of suitable habitats and the use of seine nets, which have proven effective at detecting both species (see above). 12

18 5.0 RECOMMENDATIONS When using multiple gear types to survey sites in a standardized manner, it is important that sites are sampled at the same time or within days with each gear type. This reduces the influence of confounding factors on the comparison (e.g. seasonal variation in fish assemblages and seasonal variation in fish and physical habitat). In studies comparing boat electrofishing to fyke nets and hoop nets, sampling using the various gear types was done within days of each other (Pugh and Schramm 1998, Chow-Fraser et al. 2005). Completed field sheets are very important when it comes to looking for trends in catch data (i.e. numbers caught, species caught); if data are not recorded completely, it is difficult to draw conclusions. Field sheets should be familiar to all involved in data collection and the importance of having them filled out completely and properly should be emphasized. Future sampling of Rondeau Bay should incorporate fyke nets of different mesh sizes as different mesh sizes have been shown to be size and species selective (Holland and Peters 1992). Having different mesh sizes may increase the likelihood of obtaining a more representative sample of the fish assemblage. Night sampling using active gear types, such as electrofishing and seine nets, should also be considered for future sampling in the bay as various studies have demonstrated that higher CPUE and species richness values are obtained when sampling at night compared to day sampling (e.g. Paragamian 1989, Dumont and Dennis 1993, McInerny and Cross 2000, 2004, Pierce et al. 2001). The use of short gill net sets should be considered as gill nets have been shown to be effective at detecting buffalo species (Jester 1977, N.E. Mandrak, DFO, unpubl. data). Further sampling should also be conducted in the back channels and intermittently flooded areas of the bay during the spring months (or whenever water levels permit access) using a boat electrofishing unit and a boat seine. A combination of these gear types has been shown to be effective at detecting lake chubsucker and pugnose shiner (N.E. Mandrak, DFO, unpubl. data). 13

19 6.0 ACKNOWLEDGEMENTS Wheatley OMNR carried out the fyke netting portion of the survey. Funding was provided by the OMNR through the Canada-Ontario Agreement (COA), and the DFO SARCEP program. Andrew Doolittle (DFO, Great Lakes Laboratory for Fisheries and Aquatic Sciences) provided the site maps. Special thanks to Jason Barnucz and all the DFO summer students involved in the sampling. 14

20 7.0 LITERATURE CITED Barko, V.A., D.P. Herzog, R.A. Hrabik and J.S. Scheibe Relationship among fish assemblages and main-channel border physical habitats in the unimpounded upper Mississippi River. Transactions of the North American Fisheries Society 133: Bayley, P.B. and R.A. Herndeen The efficiency of a seine net. Transactions of the American Fisheries Society 129: Chow-Fraser, P., K. Kostuk, T. Seilheimer, M. Weimer, T. MacDougall, and T. Theÿsmeÿer Effect of wetland quality on sampling bias associated with two fish survey methods for coastal wetlands of the lower Great Lakes. To be published in Simon, T.P. and P.M. Stewart (Eds). Coastal wetlands of the Laurentian Great Lakes: health, habitat and indicators. CRC Press. (in press) Dumont, S.C. and J.A. Dennis Comparison of day and night electrofishing in Texas reservoirs. North American Journal of Fisheries Management 17: Goodchild, C.D Status report on the bigmouth buffalo, Ictiobus cyprinellus, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 49 pp. Holland, R.S. and E.J. Peters Differential catch by hoop nets of three mesh sizes in the lower Platte River. North American Journal of Fisheries Management 12: Holm, E. and N.E. Mandrak Update COSEWIC status report on the pugnose shiner, Notropis anogenus, in Canada, in COSEWIC assessment and update status report on the pugnose shiner, Notropis anogenus, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, ON. 15 pp. Jester, D.B. Effects of color, mesh size, fishing in seasonal concentrations, and baiting on catch rates of fishes in gill nets. Transactions of the American Fisheries Society 106(1): Keast, A Feeding biology of the black crappie, Pomoxis nigromaculatus. Journal of the Fisheries Research Board of Canada 25: Krueger, K.L., W.A. Hubert, and R.M Price Tandem-set fyke nets for sampling benthic fishes in lakes. North American Journal of Fisheries Management 18: Mandrak, N.E. and E.J. Crossman Status report on the lake chubsucker, Erimyzon sucetta, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, ON. 15 pp. 15

21 Mandrak, N. E. and B. Cudmore-Vokey. 2004a. Update COSEWIC status report on the spotted gar, Lepisosteus oculatus, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, ON. 17 pp. Mandrak, N.E., and B. Cudmore-Vokey. 2004b. Update COSEWIC status report on the warmouth, Lepomis gulosus (Cuvier), in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, ON. 19 pp. Markham, J.L., D.L. Johnson, and R.W. Petering White crappie summer movements and habitat use in Delaware Reservoir, Ohio. North American Journal of Fisheries Management 11: McInerny, M.C. and T.K. Cross Seasonal and diel variation in electrofishing size-selectivity and catch-per-hour of largemouth bass in Minnesota lakes. Minnesota Department of Natural Resources, St. Paul, MN. Investigational Report pp. McInerny, M.C. and T.K. Cross Effects of sampling time, intraspecific density, and environmental variables on electrofishing catch per effort of largemouth bass in Minnesota lakes. North American Journal of Fisheries Management 20: McInerny, M.C. and T.K. Cross Comparison of day electrofishing, night electrofishing and trap netting for sampling inshore fish in Minnesota lakes. Minnesota Department of Natural Resources. Special Publication 161, MN. Nelson, J.S., E.J. Crossman, H.Espinosa-Perez, L.T. Findley, C.R. Gilbert, R.N. Lea, and J.D. Williams Common and scientific names of fishes from the United States, Canada, and Mexico. American Fisheries Society. Special Publication 29, Bethesda, MD. 386 pp. Paragamian, V.L A comparison of day and night electrofishing: size structure and catch per unit effort for smallmouth bass. North American Journal of Fisheries Management 9: Pierce, C.L., A.M. Corcoran, A.N. Gronbach, S. Hsia, B.J. Mullarkey, and A.J. Schwartzhoff Influence of diel period on electrofishing and beach seining assessments of littoral fish assemblages. North American Journal of Fisheries Management 21: Portt, C.B., G.A. Coker, D.L. Ming, and R.G. Randall. A review of fish sampling methods commonly used in Canadian freshwater habitats. Canadian Technical Report of Fisheries and Aquatic Sciences v + 51 pp. Pugh, L.L. and H.L. Schramm Comparison of electrofishing and hoop netting in lotic habitats of the lower Mississippi River. North American Journal of Fisheries Management 18: Reynolds, J.B Electrofishing. Pages in L.A. Nielson and D.L. Johnson, editors. Fisheries Techniques. American Fisheries Society, Bethesda, MD. 16

22 Table 1. Summary of catch data for fyke netting and boat electrofishing, Rondeau Bay Gear Type Boat Electrofishing Fyke Netting Catch Data East Shore West Shore East Shore West Shore Total Fishes Caught Average Fishes Caught/Site Minimum Fishes Caught/Site Maximum Fishes Caught/Site Table 2. Summary of species captured using boat electrofishing and fyke netting along the east and west shores of Rondeau Bay, Gear Type Boat Electrofishing Fyke Netting East Shore West Shore East Shore West Shore Species Richness Unique Species Common Species Total Species Richness

23 Table 3. Species captured by boat electrofishing and fyke netting, Rondeau Bay Boat Electrofishing Gear Type Fyke Netting Species East Shore West Shore East Shore West Shore banded killifish black bullhead black crappie blackchin shiner bluegill bluntnose minnow bowfin brook silverside brown bullhead common carp emerald shiner freshwater drum gizzard shad golden shiner goldfish Ictiobus sp. largemouth bass longnose gar mimic shiner northern pike pumpkinseed rock bass round goby smallmouth bass spotfin shiner spottail shiner spotted gar white crappie white perch yellow bullhead yellow perch Total Species Richness Legend Present Absent 18

24 Table 4. Summary of sampling effort using fyke nets and boat electrofishing, Rondeau Bay Gear Type Boat Electrofishing Fyke Netting Sampling Effort East Shore West Shore East Shore West Shore Average CPUE (fish/h) Average Effort/Site (h) Total Sampling Effort (h) Table 5. Summary of catch data for fyke nets and seine nets, Rondeau Bay Gear Type Fyke Netting Seine Netting Catch Data Total Fishes Caught Average Fishes Caught/Site Minimum Fishes Caught/Site 1 2 Maximum Fishes Caught/Site Table 6. Summary of species caught with fyke nets and seine nets, Rondeau Bay Gear Type Fyke Net Seine Net Species Richness Unique Species 4 11 Common Species 14 Total Species Richness 28 19

25 Table 7. Species captured in Rondeau Bay, Gear Type Species Fyke Net Seine Net Ameiurus sp. banded killifish black crappie blackchin shiner bluegill bluntnose minnow bowfin brook silverside brown bullhead central mudminnow common carp fathead minnow golden shiner Iowa darter johnny darter largemouth bass longnose gar mimic shiner northern pike pumpkinseed rock bass round goby smallmouth bass spottail shiner spotted gar tadpole madtom warmouth yellow perch Total Species Richness Legend Present Absent Table 8. Total sampling effort for fyke net and seine net sites, Rondeau Bay Gear Type Fyke Net Seine Net Sampling Effort Average CPUE fish/h fish/haul Average Effort/Site hours 2.27 hauls Total Sampling Effort 500 hours 59 hauls 20

26 Table 9. Summary of catch data for fyke net and boat electrofishing sites, Rondeau Bay Gear Type Catch Data Fyke Netting Boat Electrofishing Total Fishes Caught Average Fish Caught/Site Minimum Fish Caught/Site 6 29 Maximum Fish Caught/Site Table 10. Summary of species captured by boat electrofishing and fyke netting, Rondeau Bay Gear Type Fyke Netting Boat Electrofishing Species Richness Unique Species 2 8 Common Species 21 Total Species Richness (Boat Electrofishing + Fyke net) 31 21

27 Table 11. Total catch and total lengths (TL) (mm) for largemouth bass caught with boat electrofishing and fyke nets at 2004 Rondeau Bay sites. Site Gear Type Minimum (mm) Maximum (mm) Number Captured 1 Boat Electrofishing Boat Electrofishing Boat Electrofishing Boat Electrofishing Boat Electrofishing Boat Electrofishing Boat Electrofishing Boat Electrofishing Boat Electrofishing Boat Electrofishing Boat Electrofishing Boat Electrofishing Average Length (mm) - electrofishing Total 50 2 Fyke Netting Fyke Netting Fyke Netting Fyke Netting Fyke Netting Fyke Netting Fyke Netting Average Length (mm) fyke netting Total 12 22

28 Table 12. Total catch and species richness at 2005 Rondeau Bay sites. Fyke Net (Sites 1-4, 6-9, 12-15, 24-27) 9 m Bag Seine (Sites 1-4, 6-9, 12-15, 24-27) Fyke Net (Sites 16-23) 9 m Bag Seine (Sites 5, 10, 11) 15 m Boat Seine (Sites 28-34) Total Catch Species Richness Table 13. Total numbers caught and total lengths (TL) of larger species (> 200 mm adult TL) caught using fyke nets and seine nets, Rondeau Bay, Gear Type Fyke Net Seine Net Species # caught Min/Max TL (mm) # caught Min/Max TL (mm) bowfin brown bullhead common carp largemouth bass longnose gar northern pike smallmouth bass spotted gar Table 14. Average number of species caught per site at fyke net and boat electrofishing sites, Rondeau Bay Species Numbers Per Site Site Boat Electrofishing East Shore Boat Electrofishing West Shore Fyke Nets East Shore Fyke Nets West Shore Average Species/Site

29 Figure 1. Sites sampled in Rondeau Bay in Numbers on the map correspond to site codes in Appendix 1. 24

30 Figure 2. Sites sampled in Rondeau Bay in Numbers on the map correspond to site codes in Appendix 2. 25

31 Appendix 1. Site descriptions for 2004 Rondeau Bay sampling. Site Field Number Date Narrative Locality Description Start Latitude Start Longitude 1 RONCOA04BE /06/2004 NE corner of bay; NW shore, NE of Rondeau Bay Estates RONCOA04BE /06/2004 NE corner of bay; NW shore, SW of Rondeau Bay Estates RONCOA04BE /06/2004 NW shore; mouth of Indian Creek; East of Shrewsbury RONCOA04BE /06/2004 NW shore; mouth of Flat Creek RONCOA04BE /06/2004 NW shore; NE of Shrewsbury Dock RONCOA04BE /06/2004 NW shore; SW of Shrewsbury Dock RONCOA04BE /06/2004 NW shore; off of point SW of Georgie Creek RONCOA04BE /06/2004 NW shore; N of Erieau, SW corner of Rondeau Bay RONCOA04BE /06/2004 NE corner of bay; SE shore, adjacent to Rondeau Park marina RONCOA04BE /06/2004 NE corner of bay; SE shore, SW of Yacht Club RONCOA04BE /06/2004 SE shore; Rondeau Provincial Park, directly opposite mouth of Indian Creek RONCOA04BE /06/2004 SE shore; S of Rondeau Marsh lookout RONCOA04BE /06/2004 SE shore; N of duck blind RONCOA04BE /06/2004 SE shore; opposite Shrewsbury docks RONCOA04BE /06/2004 SE shore; opposite Georgie Creek RONCOA04HN A 26/07/2004 NE corner of bay; NW shore, NE of Rondeau Bay Estates RONCOA04HN B 26/07/2004 NE corner of bay; NW shore, NE of Rondeau Bay Estates RONCOA04HN A 26/07/2004 NE corner of bay; NW shore, SW of Rondeau Bay Estates RONCOA04HN B 26/07/2004 NE corner of bay; NW shore, SW of Rondeau Bay Estates RONCOA04HN A 27/07/2004 NW shore; mouth of Indian Creek; East of Shrewsbury RONCOA04HN B 27/07/2004 NW shore; mouth of Indian Creek; East of Shrewsbury RONCOA04HN A 27/07/2004 NW shore; mouth of Flat Creek RONCOA04HN B 27/07/2004 NW shore; mouth of Flat Creek RONCOA04HN A 28/07/2004 NW shore; NE of Shrewsbury Dock RONCOA04HN B 28/07/2004 NW shore; NE of Shrewsbury Dock RONCOA04HN A 28/07/2004 NW shore; SW of Shrewsbury Dock RONCOA04HN B 28/07/2004 NW shore; SW of Shrewsbury Dock