Recovery strategy for the spotted gar (Lepisosteus oculatus) in Canada
- 1.1 Species assessment information from COSEWIC
- 1.2 Description
- 1.3 Populations and distribution
- 1.4 Needs of the spotted gar
- 1.5 Threats
- 1.6 Actions already completed or underway
- 1.7 Knowledge gaps
1.1 Species assessment information from COSEWIC
Common name: Spotted gar
Scientific name: Lepisosteus oculatus (Winchell, 1864)
Committee on the Status of Endangered Wildlife in Canada (COSEWIC) status: Threatened (2005)
Reason for designation: This species has a very limited range in Canada where it is known only from three coastal wetlands in Lake Erie. Although its distribution is likely limited by temperature, some of the shallow vegetated habitats that it requires for all life stages are subject to the impacts of siltation, dredging, filling, aquatic vegetation removal and harbour improvements.
Canadian occurrence: Ontario
COSEWIC status history: Designated Special Concern in April 1983. Status re-examined and confirmed in April 1994. Status re-examined and designated Threatened in November 2000, and in May 2005. Last assessment based on an update status report.
Gars are readily distinguished from other fish species by their long, narrow, armoured bodies and long snouts. The body of the spotted gar (Lepisosteus oculatus Winchell, 1864) is heavily armoured with non-overlapping, bony ganoid scales and the snout and jaws are elongated into a relatively broad beak with many sharp teeth (Figure 1). The length of the spotted gar’s snout is approximately 40-80% of the head length; the least width is approximately 10-16% of snout length (COSEWIC 2005). The total length (TL) of this species is typically 200 – 600 mm, but it can reach lengths and weights of 1120 mm TL and 2700 g, respectively (Coker et al. 2001). In Canada, the largest specimen recorded measured 767 mm TL and was caught in Rondeau Bay in 2007 (N.E. Mandrak, Fisheries and Oceans Canada [DFO], pers. comm. 2007). The spotted gar has a short, deep, caudal peduncle (i.e., point of attachment between the body and the tail). The vertebral column is curved upward in the tail, extending a short way into the upper lobe of the rounded tail. The back and upper sides are olive-green to velvety brown above the lateral line and the colouration is dull silvery below. It has a lateral band with a narrow reddish stripe. Adults have brown spots on the snout, head, body and fins. Juveniles have a fleshy extension of the spine above the upper edge of the tail and are brightly coloured with wide dark brown stripes on the back, sides and belly.
The spotted gar is distinguished from the only other native gar species found in Canada, the longnose gar (L. osseus), by its shorter, wider snout and a shorter, deeper caudal peduncle (Scott and Crossman 1998) (Figure 2). Since both species are spotted, this characteristic should not be used to distinguish between these two species. Florida gar (L. platyrhincus) have been found in the Great Lakes basin as a result of presumed aquaria releases. Florida gar are very similar to spotted gar in appearance, but lack the bony, translucent plates on the isthmus between gill openings found on the spotted gar (Figure 3) (COSEWIC 2005).
Figure 1. The spotted gar (Lepisosteus oculatus)
© Joseph R. Tomelleri
Description of Figure 1
Figure 1 is captioned “The spotted gar (Lepisosteus oculatus)”. This figure shows a coloured line drawing of a spotted gar, Latin name Lepisosteus oculatus. The drawing is copyrighted by Joseph R. Tomelleri.
Figure 2. Differences in snout length and width can be used to distinguish spotted gar (bottom) from longnose gar
Collected in Rondeau Bay, 2002 and modified from COSEWIC 2005.
Description of Figure 2
Figure 2 is captioned “Differences in snout length and width can be used to distinguish spotted gar (bottom) from longnose gar”. The figure is a photograph, taken from above, of the heads of two fishes. The topmost fish in the photograph is the longnose gar, the lower fish is the spotted gar. The length and width of the snout of each species has been highlighted by lines and arrows added to the photograph to illustrate the differences between the two species. The shorter, wider snout of the spotted gar, as compared to the longnose gar, can be seen clearly in the photograph. The fishes in the photograph were collected in Rondeau Bay, 2002. The photograph has been modified from the Committee on the Status of Endangered Wildlife in Canada 2005 report “Assessment and update status report on the spotted gar, Lepisosteus oculatus, in Canada”.
Figure 3. The spotted gar (left) can be distinguished from the Florida gar by the presence of bony plates on the isthmus
Photo by E. Holm, Royal Ontario Museum.
Description of Figure 3
Figure 3 is captioned “The spotted gar (left) can be distinguished from the Florida gar by the presence of bony plates on the isthmus”. The figure shows two photographs, side by side, of the bony plates on the isthmus of the spotted gar (photograph on the left), and the lack of the bony plates on the isthmus of the Florida gar (photograph on the right). The photographs were taken by E. Holm, Royal Ontario Museum, Toronto, Ontario.
1.3 Populations and distribution
Global range and status: The spotted gar is only found in North America where it has a wide, but disjunct distribution in the Mississippi, Great Lakes and Gulf Coast drainages of eastern North America, occurring in 18 states and Ontario (Figure 4). In the Great Lakes drainage, the spotted gar occurs in Indiana, Michigan, Ohio, Ontario and Pennsylvania (Lee et al. 1980, Page and Burr 1991). In the Mississippi drainage, it is found from Illinois in the north to Alabama and Texas in the south and from Tennessee and Florida in the east to Oklahoma in the west (Lee et al. 1980, Page and Burr 1991). The species is considered globally secure (G5) but is critically imperilled (S1) in Kansas, Ohio and Pennsylvania, and extirpated in New Mexico (NatureServe 2012) (Table 1). Less than 1% of the species’ global range is found in Canada.
Figure 4. Global distribution of the spotted gar
Modified from Page and Burr (1991).
Description of Figure 4
Figure 4 is captioned “Global distribution of the spotted gar”. The figure is a line drawing of a map of the United States and southern Canada. A scale is provided. The map shows two major areas identified with spotted gar populations. These areas are shaded. In the Great Lakes region, there is a shaded area along the southern and western shores of Lake Erie, extending to the tip of Lake Huron, including Lake St. Clair, swinging around the western end of Lake Erie, into Ontario and extending westward to the lower, eastern shores of Lake Michigan, including parts of Michigan, Ohio, and Indiana. A large shaded area encompasses parts of Texas, Oklahoma, Arkansas, Missouri, all of Louisiana and Mississippi, parts of Alabama, Florida, and Tennessee, Kentucky, lower Indiana, and Illinois. An additional small shaded area is shown in Ontario, close to the eastern end of Lake Erie. The map has been modified from A Field Guide to Freshwater Fishes of North America North of Mexico (Page and Burr 1991).
|Global (G)||G5 (09 Sept. 1996)|
|National (N)||N5||United States|
|Canada [Sub-national (S)]||S1||Ontario|
|U.S. [Sub-national (S)]||S5||Alabama, Louisiana, Mississippi, Missouri, Tennessee, Texas|
|U.S. [Sub-national (S)]||S4||Arkansas, Indiana, Kentucky, Oklahoma|
|U.S. [Sub-national (S)]||SNR||Florida|
|U.S. [Sub-national (S)]||S2S3||Georgia, Illinois, Michigan|
|U.S. [Sub-national (S)]||S1S2||Kansas|
|U.S. [Sub-national (S)]||SX||New Mexico|
|U.S. [Sub-national (S)]||S1||Ohio, Pennsylvania|
Canadian range and status: The spotted gar is considered imperilled in Canada (N1) and Ontario (S1) (NatureServe 2012), and is designated as Threatened by the Ontario Ministry of Natural Resources (OMNR 2009). The species is listed on Schedule 1 of Canada’s Species at Risk Act (SARA), and under Ontario’s Endangered Species Act, 2007.
The current range of the spotted gar in Canada includes the coastal wetlands of Lake Erie (Point Pelee National Park, Rondeau Bay, Long Point Bay [including Long Point National Wildlife Area (NWA)] and Big Creek NWA), East Lake (an embayment off Lake Ontario and south of Sandbanks Provincial Park) and Hamilton Harbour (Figure 5).
Canadian collections have been made sporadically making it difficult to assess population sizes and trends. The first confirmed captures of spotted gar were at Point Pelee National Park in 1913, at Long Point Bay in 1947 and at Rondeau Bay in 1955. Other captures recorded by commercial fishermen in 1925 and 1938 were likely also from Rondeau Bay.
Less than 15 specimens before 2000 have been recorded from these locations in Lake Erie, with one from Point Pelee National Park, one from Inner Long Point Bay, and 11 from Rondeau Bay. However, since 2000, a total of 730 spotted gar have been captured at these locations, including 546 specimens from Rondeau Bay (2007-2009), 93 specimens from Point Pelee National Park (2009), and eight specimens from Inner Long Point Bay (B. Glass, University of Windsor [UW], unpublished data).
Spotted gar have also been detected in two NWAs within the Long Point area: a single record from 1984 exists for the Long Point Unit (located at the tip of the point) of Long Point NWA (J. Robinson, Canadian Wildlife Service [CWS], pers. comm. 2009); and, in 2004, two individuals were recorded from Big Creek NWA (L. Bouvier, DFO, pers. comm. 2010).
Although population sizes are small, and the distribution is limited, the spotted gar is considered stable at Lake Erie locations based on available historical and current data (extent of occurrence and abundance data) (Essex-Erie Recovery Team [EERT] 2008).
In May 2007, a single specimen was collected by a commercial fisherman in East Lake. It is believed the same individual was caught multiple times; catches of spotted gar ceased after the specimen was provided to the OMNR (J. Bowlby, OMNR, pers. comm. 2009). Beyond these catches, no other individuals have been captured. Intensive sampling was conducted in East Lake in 2008, using gear types proven effective at detecting the species, to verify the presence of a reproducing population; however, sampling failed to detect spotted gar (B. Glass, UW, unpublished data). In addition, extensive commercial hoop netting in East Lake has not resulted in any further records of spotted gar. Therefore, the reports from a commercial fisherman, potentially of a single individual, remain the only record(s) for East Lake and it is unlikely that a reproducing population exists at this location (Bouvier and Mandrak 2010).
The first verified record of spotted gar within the Lake Ontario drainage was a single specimen caught in the Bay of Quinte (North Channel) in 1985. Despite extensive commercial fishing in the area, as well as substantial netting programs conducted by the OMNR, no additional spotted gar have been captured and it is possible that this record is the result of an introduction due to its highly disjunct nature.
Additional reports existed for spotted gar in Hamilton Harbour that had not been substantiated with voucher specimens until recently, when a single specimen was captured by the OMNR in 2010 (OMNR, unpublished data). Further sampling is required to determine whether a reproducing population exists at this location.
A single specimen was captured in 1962 in Lake St. Clair near the mouth of the Thames River but the species has not been recorded from this area since then, despite relatively extensive sampling conducted by DFO and OMNR.
There are two records of spotted gar collected in the Sydenham River from 1975; however, one was thought to be a longnose gar by a larval fish expert, and the other lacked a voucher specimen (COSEWIC 2005). Subsequent sampling in 2002 and 2003 by boat electrofishing, fyke netting and seining (N.E. Mandrak, DFO, unpublished data) in the vicinity of the original records, failed to find any spotted gar. Hence the original records have been deemed questionable.
Other specimens, reported as spotted gar in southwestern Ontario, have either been re-identified as longnose gar or voucher specimens were not retained by the collector and identification is, therefore, unconfirmed (COSEWIC 2005).
The distribution of spotted gar has always been limited in Canadian waters and, although extensive sampling has recently occurred throughout southwestern Ontario (due to a recent focus on species at risk), no other localities have been recorded for the spotted gar. For example, 20 sites at the St. Clair NWA were sampled by DFO in 2005 using fyke nets (a total of 480 hours of effort were expended) and no spotted gar were detected (Mandrak et al. 2006a). Populations within the Bay of Quinte and Lake St. Clair (if anomalous records are representative of historic populations), are presumed to be extirpated, based on recent sampling of suitable habitats at these locations (COSEWIC 2005).
Figure 5. Canadian distribution of the spotted gar
Description of Figure 5
Figure 5 is captioned “Canadian distribution of the spotted gar”. The figure is a map of southern and south central Ontario, with two insets. A legend and scale are provided. The geographical location of this map is shown on a larger scale map on an inset at the top left of the map. An inset at the top right of the map provides detail for an area of interest at the eastern end of Lake Ontario. Individual data points are identified by year of capture. The map shows that, since 2001, spotted gar has been found in areas near, or at, Point Pelee National Park, Rondeau Provincial Park, Long Point Provincial Park, an area near Hamilton, and a location near East Lake in eastern Lake Ontario. The map shows older sampling points from Point Pelee, Lake St. Clair, north shore of Lake Erie, Long Point, and the Bay of Quinte.
1.4 Needs of the spotted gar
1.4.1 Habitat and biological needs
Spawn to embryonic (yolk-sac) stage: Spawning occurs in the spring (May and June), when water temperatures reach 21°-26°C, in shallow water (less than 1 m) containing dense aquatic vegetation, such as marshes and flooded riparian areas (Goodyear et al. 1982, Scott and Crossman 1998, Snedden et al. 1999, Cudmore-Vokey and Minns 2002). In Rondeau Bay, spotted gar were observed spawning over aquatic vegetation beds that included milfoil (Myriophyllum sp.) and curly pondweed (Potamogeton crispus) (B. Glass, UW, pers. comm. 2009). The demersal and adhesive fertilized eggs attach to aquatic vegetation and debris in gelatinous masses (Coker et al. 2001, COSEWIC 2005) and hatch within one week (Cudmore-Vokey and Minns 2002). Spotted gar embryos have an adhesive organ on their snout (Simon and Wallus 1989) and, although capable of swimming, they often hang vertically from aquatic vegetation and other objects. The yolk-sac is absorbed at approximately 17 mm TL or greater – based on a growth rate of 1.3 -1.7 mm/day (Alfaro et al. 2008), and would be absorbed in approximately 10 -13 days.
Larvae (Young of the Year [YOY]): Young-of-the-year remain at the spawning site until their yolk-sacs are absorbed at which point they disperse and begin feeding (Simon and Wallus 1989), remaining in shallow (less than 1 m) littoral zones containing vegetation and substrates of mud, silt and sand (Goodyear et al. 1982).
Juvenile (age 1 until sexual maturity [2-3 yrs males; 3-4 yrs females]): There is no published information on the habitat requirements for juvenile spotted gar; however, they are likely to be similar to those of YOY and adults.
Adult: In Canada, adult spotted gar are found in the shallow (0-5 m), warm waters of coastal wetlands with abundant vegetation in Lake Erie (Lane et al. 1996); habitat data for the East Lake capture site are not available. In general, the species prefers quiet pools, backwaters and bays with an abundance of aquatic vegetation (Parker and McKee 1984, Page and Burr 1991) or submerged branches (Snedden et al. 1999). Dense vegetation provides necessary camouflage and reduces visibility to potential prey (Coen et al. 1981); as the spotted gar is an ambush predator, dense vegetation is critical for its foraging behaviour. Collection sites in Lake Erie had dense vegetation and included water lily (Nuphar sp.), cattails (Typha sp.), Canada waterweed (Elodea canadensis), pondweed (Potamogeton sp.), stonewort (Chara sp.), milfoil, water celery (Vallisneria sp.) and hornwort (Ceratophyllum sp.) (Parker and McKee 1984, B. Glass, UW, pers. comm. 2009). In Oklahoma, spotted gar are primarily associated with smartweed (Polygonum sp.), pondweed, milfoil and water-willow (Justicia sp.) (Tyler and Granger 1984). Preferred substrates include silt, clay and sand (Lane et al. 1996). Canadian spotted gar capture sites had Secchi depths of 0.3 - >3 m, dissolved oxygen levels of 9-11 mg/L and water temperatures of 15-17°C (in September) (Parker and McKee 1984).
Diel and seasonal movements of the spotted gar have been studied in Louisiana by Snedden et al. (1999). Greatest movement occurred as water temperatures and levels rose during the spring. Large home ranges were established in the spring, typically in inundated floodplains, which provided suitable spawning and nursery habitat. Small home ranges were usually established during summer, fall and winter (median 6.6 hectares) (Snedden et al. 1999). However, approximately one third of spotted gar tracked, established significantly larger home ranges (median 265 ha) that were usually considerable distances from initial capture sites (Snedden et al. 1999). These new home ranges consisted of seasonally inundated floodplain habitats and heavily vegetated marshes with little or no flow. Except in spring, spotted gar is more active at night, which is thought to coincide with their feeding period.
1.4.2 Ecological role
Spotted gar is one of the most abundant predators in structurally complex shallow water habitats in the southern United States (COSEWIC 2005) and is considered to be a key element of the food web (Snedden et al. 1999); in areas where they are locally abundant (e.g., Rondeau Bay) they may also have a key ecological role. The spotted gar is primarily a piscivorous ambush predator that also consumes crayfishes and aquatic insects (COSEWIC 2005). In Ontario, Scott (1967) listed Yellow Perch (Perca flavescens) and minnows (Cyprinidae) as forming a large part of the diet. Since spotted gar tends to remain close to the surface, prey species that occupy these areas are more susceptible to predation (Ostrand et al. 2004). Also, as the spotted gar is able to inhabit waters with low oxygen levels, it is able to forage in areas where other predators cannot (Burleson et al. 1998, Snedden et al. 1999). Spotted gar co-occurs with longnose gar in Long Point Bay, Point Pelee National Park and Rondeau Bay, but are absent from many suitable habitats in southwestern Ontario where longnose gar is abundant (N.E. Mandrak, DFO, unpublished data); further investigation is required to determine the interspecific interactions between these species.
The spotted gar is a known host for a freshwater mussel, the Round Pearlshell (Glebula rotundata; a freshwater mussel with a life-cycle that includes an obligate parasite larval stage, usually on a fish host), in the United States (Parker et al. 1984) and, therefore, has the potential to be a freshwater mussel host in Canadian waters. In addition, other species of gar are known hosts for some species of freshwater mussels found in Canada. For example, the longnose gar is one host for the Giant Floater (Pyganodon grandis) (D. Woolnough, Trent University, pers. comm. 2007).
Although the eggs of the spotted gar were previously thought to be toxic to some species (Scott and Crossman 1998), recent studies have shown that the ichthyotoxin of gar eggs may not act as a protective mechanism from fish predators (Ostrand et al. 1996).
1.4.3 Limiting factors
There are several limiting factors that may influence the recovery potential of the spotted gar. Water temperature likely limits the distribution of the species in southwestern Ontario; however, expansion of its range northward may occur under climate warming scenarios (Mandrak 1989). The availability of quiet, backwater areas with dense aquatic vegetation is limited in the waters of southwestern Ontario. Remaining populations are also widely separated and may be isolated. Some of the currently occupied habitats only intermittently provide access to Lake Erie, thus limiting migration and dispersal opportunities. Such isolation could lead to low genetic diversity, low reproductive fitness and inbreeding depression, but this has not been studied.
The recovery potential of spotted gar populations may be influenced by factors impacting specific life-stages. Ferrara (2001) studied the life-stages of the spotted gar to determine which had the greatest influence on population growth rates. Results suggested that the survival of juvenile spotted gar had the highest influence on population growth rate. Therefore, in theory, management actions that enhance the survival of juveniles should result in the largest population growth rate as compared to actions targeting other life-stages.
1.5.1 Threat classification
All known and suspected threats affecting the spotted gar in Canada are listed in order of concern in Table 2. Seven potential threats were ranked based on their expected relative impacts. Where possible, the spatial extent, frequency, causal certainty, and expected severity of the threat has been identified. Overall level of concern is also given for each threat. The threat classification parameters are defined as follows:
- Overall level of concern – composite level of concern regarding the threat to the species, taking into account the four parameters listed below (H/M/L)
- Extent – spatial extent of the threat in the waterbody (widespread/localized);
- Frequency – frequency with which the threat occurs in the waterbody (seasonal/continuous);
- Causal certainty – level of certainty that it is a threat to the species (High – H, Medium – M, Low - L); and,
- Severity – severity of the threat in the waterbody (H/M/L).
|Specific threat||Overall level of concern|
(high, medium, low)
(high, medium, low)
(high, medium, low)
|Aquatic vegetation removal||M||W||S||M||Unknown|
|Barriers to movement||L||L||C||M||Unknown|
1.5.2 Description of threats
Habitat modifications: Quiet, vegetated, shallow habitats, vital to all stages of the spotted gar life-history, are rapidly disappearing, or are being degraded as a result of siltation, dredging, filling and harbour improvements (COSEWIC 2005). Habitat loss can result from shoreline hardening and the construction of in-water and shoreline structures (e.g., piers, groynes, docks) within spotted gar habitat. Within Rondeau Harbour, historic losses and degradation of nearshore habitat has occurred where shoreline development resulted in shoreline hardening.
Aquatic vegetation removal: The removal or control of aquatic vegetation is a type of habitat modification that merits special attention due to the importance of aquatic vegetation to spotted gar. The physical act of removing aquatic vegetation can be harmful to the species; the mechanical removal of vegetation disturbs sediments and creates turbid conditions; and, vegetation removal using herbicides introduces potentially harmful chemicals into the water. Though large scale aquatic vegetation removal is believed to be a serious threat to the spotted gar, the amount of vegetation being removed and the degree to which this may impact the species is unknown.
Historic large-scale, and recent small-scale, vegetation removals conducted in Rondeau Harbour removed spotted gar habitat. However, with recent overgrowths of aquatic vegetation in Rondeau Bay (Gilbert et al. 2007), it is possible that limited vegetation removal could benefit the species in such conditions; additional research is required to determine this.
Aquatic vegetation removal is also occurring in the Inner Bay at Long Point, especially within the cottage community channels, where aquatic vegetation is becoming more of a management issue (due to overgrowth). Additionally, the draw seine fishery within Long Point Bay removes aquatic vegetation in the spring to facilitate fishing (J. Robinson,Â CWS, pers. comm. 2009).
In the Point Pelee area, close to 60% of the historic marshes that once hydrologically connected the existing park with present day Hillman Marsh were drained between the 1890s and 1950s for agricultural use. This likely led to a considerable reduction in the amount of habitat available for the spotted gar population within the Point Pelee area (V. McKay, Parks Canada Agency [PCA], pers. comm. 2008).
Sediment loading: Sediment loading affects inland watercourses, coastal wetlands and nearshore habitats by decreasing water clarity, increasing siltation of substrates, and may have a role in the selective transport of pollutants including phosphorus. Sediment loading is often caused by a variety of sources, including poor agricultural and land management practices, improper drain maintenance practices, dredging activities and the removal of riparian vegetation. Increased turbidity as a result of sediment loading, as documented at Point Pelee National Park (H. Surette, University of Guelph, pers. comm. 2007), can limit the ability of the spotted gar to feed. Turbidity and siltation can negatively impact species by causing reductions in respiration, vision, prey abundance, as well as smothering their eggs. Siltation from tile drainage has been evidenced in Rondeau Bay, particularly during storm events (Gilbert et al. 2007). Water entering Rondeau Bay from tributaries on the north and west shores is high in nutrients and suspended solid concentrations (including sediment) and has resulted in considerable long-term impacts on the bay, nearshore areas, and riparian wetland habitat (Gilbert et al. 2007).
Nutrient loading: Nutrient loading, which is often associated with sediment loading, has been identified as a primary threat to the three coastal wetlands currently occupied by the spotted gar (Essex-Erie Recovery Team [EERT] 2008). Nutrient (nitrates and phosphorus) enrichment of waterways can negatively influence aquatic health through algal blooms and associated reduced dissolved oxygen concentrations. Elevated nutrient (nitrogen and phosphorus) concentrations can impact spotted gar populations directly (e.g., altering habitat) or indirectly (e.g., reducing prey abundance). This is particularly evident in Rondeau Bay where nutrient loading from adjacent agriculture and residential areas is negatively impacting wetland habitats (Gilbert et al. 2007). Where nutrient inputs are elevated, vegetation diversity has declined and native species of emergent and submergent wetland vegetation, preferred by spotted gar, are outcompeted by cattail and common reed grass (Phragmites australis). Although wetlands are highly valued for their water filtering capacity, these systems are negatively impacted when nutrient (and chemical) concentrations exceed background levels (Gilbert et al. 2007).
Exotic species: Exotic species may affect the spotted gar in several different ways including competition for space, habitat, and food, and restructuring of aquatic food webs. There are now at least 182 exotic species known from the Great Lakes (Ricciardi 2006) and some of these species are likely to impact the spotted gar or its habitat. The Common Carp (Cyprinus carpio), Round Goby (Neogobius melanostomus), and Zebra and Quagga mussels (Dreissena spp.), are exotic species that have had a dramatic effect on the aquatic community of Lake Erie and will continue to alter/transform ecosystems and ecosystem processes. It should be noted that the establishment of the Zebra Mussel may have improved habitat conditions by improving water clarity which promotes aquatic plant establishment at some locations (Ontario Federation of Anglers and Hunters, 2011). The Round Goby has spread throughout Lake Erie. Beach seining surveys on Pelee Island and along the north shore of Lake Erie in 2005-06 found the Round Goby present at all 34 sites surveyed (Reid and Mandrak 2008). Since spotted gar typically feed on fishes near the surface, the shift to a fish community increasingly dominated by Round Goby (a bottom-dwelling species) may negatively impact this species. It is also possible that Round Goby may eat spotted gar eggs; the Round Goby is known to eat the eggs of native darter and sculpin species (Fuller et al. 2009). Exotic species such as Common Carp, common reed grass and possibly hybrid cattails are a concern for existing populations of spotted gar since these species can cause significant alterations of native wetland habitats.
The exotic Florida gar has been collected in the Great Lakes basin (likely the result of aquaria releases). This related species could represent an additional threat to the spotted gar, either through hybridization or competition, if the species becomes established. There are reports of hybridization where these species overlap in Florida (Lee et al. 1980) and Florida gar are sometimes available in local aquarium stores.
Climate change: Climate change is expected to have significant effects on aquatic communities of the Great Lakes basin through several mechanisms, including increases in water and air temperatures; changes in water levels (i.e., lowering); shortening of the duration of ice cover; increases in the frequency of extreme weather events; emergence of diseases; and, shifts in predator-prey dynamics (Lemmen and Warren 2004). It is anticipated that the effects of climate change will be widespread and should be considered a contributing impact to species at risk and all habitats. Not all of the effects of climate change will negatively affect species at risk – those species that are limited in their range by cool water temperature, such as the spotted gar, may expand their distribution provided that dispersal corridors of suitable habitat are available. However, a suite of reactions related to changes in evaporation patterns, vegetation communities, lower lake levels, increased intensity and frequency of storms, and decreases in summer stream water levels may offset the direct benefits of increased temperatures.
In a recent assessment of the projected impacts of climate change on coastal wetland fish communities in the lower Great Lakes, Doka et al. (2006) predicted several fishes at risk as most vulnerable. Their results showed that the spotted gar ranked 5th highest in vulnerability scores of 99 fish species that use lacustrine (lake) habitats. Vulnerabilities were based on an assessment of climate change risk associated with coastal wetland and thermal preferences for different life-stages as well as species’ distributions.
Barriers to movement: Natural or man-made barriers may afford protection for some species from competitors, exotic species and predators. Therefore, any breaches in the barrier could have negative impacts on local fish communities. For example, another fish species at risk, the Lake Chubsucker (Erimyzon sucetta) is found in two diked wetlands where water level management is ongoing (Big Creek NWA and St. Clair NWA); in this instance, it appears as though the dikes are maintaining Lake Chubsucker habitat (Staton et al. 2010). Natural barriers at Point Pelee National Park are breached naturally on occasion; however, breaches may be occurring more frequently as a result of human alterations to the shoreline coastal processes that have increased the rates of coastal erosion (V. McKay, PCA, pers. comm. 2007). Conversely, barriers may prevent access to suitable habitat, lead to fragmentation of populations and limit any rescue effect. In some instances, culverts present a physical or velocity barrier (e.g., perched above the streambed or sized improperly) to fish passage between wetland areas and upstream habitat.
Wetlands with natural or artificially maintained barriers include Point Pelee National Park and Big Creek NWA (Long Point region). Spotted gar have not been recorded from waterbodies where water level management occurs.
Fishing pressure: Although it is not legal to fish for the spotted gar (either commercially or recreationally), the species may still be captured incidentally. The extent to which the spotted gar may be affected by such incidental harvest is unknown, but is believed to be low. The potential for incidental harvest as a result of baitfishing, coarse fish spearing, sport fishing and commercial fishing (e.g., trap-netting and draw seining at Long Point) requires further investigation.
1.6 Actions already completed or underway
Essex-Erie Recovery Strategy: The Essex-Erie Recovery Team is co-chaired by DFO and the Essex Region Conservation Authority, and receives support from ,many agencies and individuals. The Essex-Erie Recovery Strategy (EERS) is a multi-species recovery strategy that covers 14 fishes at risk, including the spotted gar throughout its historic range. The long-term goal of this strategy is “to maintain and restore ecosystem quality and function in the Essex-Erie region to support viable populations of fish species at risk, across their current and former range” (EERT 2008). This recovery program will play a central role in recovering spotted gar populations. The EERT has identified the three coastal wetlands in Lake Erie with extant populations as core areas for directing recovery efforts to benefit the spotted gar and other high priority fishes. Implementation of this strategy (including stewardship actions to reduce identified threats) is proceeding through the efforts of the recovery team and associated Recovery Implementation Groups (RIGs). In addition, some parks and protected areas have ongoing stewardship and awareness initiatives. At Point Pelee National Park, seasonal programs provide increased awareness of species at risk issues such as habitat loss, contaminants, exotic species and water quality concerns within the park. Similar programs occur at Rondeau Provincial Park. For further details on specific actions currently underway, refer to the approaches identified in Table 6. Funding for many of these actions is supported by the Government of Canada’s Habitat Stewardship Program (HSP) for Species at Risk.
Rondeau Bay aquatic vegetation issues working group: This multi-agency working group was initially formed to provide a forum for the discussion of issues related to aquatic vegetation in Rondeau Bay. There has been growing concern over the past few decades by government agencies and the public over the dramatic fluctuations in the aquatic vegetation community in Rondeau Bay. In recent years, the overgrowth of aquatic vegetation has resulted in increased pressure on regulatory agencies to approve aquatic vegetation removal projects to allow for boat access and recreational uses in the bay. Specifically, the working group will work to ensure that aquatic vegetation removal projects do not negatively impact the spotted gar and other species at risk. More broadly, the group will seek to facilitate solutions to balance competing human interests with efforts to protect and improve habitat conditions for fish and wildlife in the bay, with a focus on fishes at risk. The objectives of the group include the promotion and protection of species at risk as well as to provide guidance and support to stewardship initiatives within the Rondeau Bay watershed. Several stewardship groups aimed at improving land use practices and aquatic habitat are currently active within the basin.
Spotted gar research: A graduate student from the University of Windsor, in cooperation with DFO, has completed a study on age and growth of spotted gar (Glass et al. 2011), and is conducting studies (initiated in 2007) on the genetic variation of spotted gar and the movements of spotted gar within Rondeau Bay (via radio tracking) to determine home range and habitat utilization (N. Mandrak, DFO, pers. comm. 2011).
Awareness – incidental harvest: Although not legal, some incidental harvest of spotted gar by commercial fishers is possible at Long Point Bay. An information package has been developed and distributed to commercial fishers that may harvest in occupied wetlands. The information package includes a description and illustration of the species, a map of known areas of occupation and a description of preferred habitats. Fishermen were asked to avoid areas of known occurrence and to report areas of incidental captures. In Point Pelee National Park, fish species at risk information packages were distributed in 2008 and 2009 to all day use and seasonal sport fishers, including an explanatory letter, a DFO fact sheet for the spotted gar and other fish species at risk in the marsh and a species report form. Sport fishers were asked not to target these fishes at risk, to release them as quickly as possible if they were caught accidentally and to report their capture to park staff using the form provided (V. McKay, PCA, pers. comm. 2009). Incidental harvest by recreational anglers is also a possibility at Long Point Bay and Rondeau Bay; although, further investigation is required to determine if this is actually occurring and to what degree it is a threat.
Recent surveys: The following table summarizes recent fish surveys conducted by various groups/agencies within areas of known occurrence of the spotted gar.
|Waterbody/ general area||Survey description (years of survey effort)||Gear type|
|Lake St. Clair||Essex-Erie targeted sampling for fishes at risk, DFO (2007)||seine, additional gear (trap nets and Windermere traps)|
|Lake St. Clair||Nearshore fish community survey, OMNR (2005, 2007)||seine|
|Lake St. Clair||Fish community survey, Michigan Department of Natural Resources (1996-2001)||trawl|
|Lake St. Clair||YOY index seine survey, OMNR (annual)||seine|
|Lake St. Clair||Fall trap-net survey, OMNR (1974-2007, annually)||additional gear (trap nets and Windermere traps)|
|St. Clair NWA||DFO fish assemblage survey (2005)||fyke nets|
|Lake Erie||Coastal wetlands sampling along Lake Erie, OMNR (2004-2005)||backpack electrofishing unit|
|Lake Erie||Nearshore beach seining surveys, OMNR and DFO (2005-2006) (Reid and Mandrak 2008)||seine|
|Lake Erie||Nearshore seine survey, west and west-central basins, OMNR (2007-2008)||seine|
|Point Pelee National Park||Fish species composition study (Surette 2006), University of Guelph, DFO and Point Pelee National Park (2002-2003)||seine, trawl, boat electrofishing unit, fyke nets, additional gear (trap nets and Windermere traps)|
|Point Pelee National Park||Spotted gar research, UW and DFO (2009)||fyke nets|
|Rondeau Bay||Targeted sampling, DFO (2002)||boat electrofishing unit|
|Rondeau Bay||Fish community surveys, OMNR and DFO (2004-2005)||seine, boat electrofishing unit, fyke nets|
|Rondeau Bay||Spotted gar research, UW, DFO (2007-2009)||boat electrofishing unit, fyke nets|
|Long Point Bay||Index surveys of Long Point Bay, OMNR (annually)||trawl|
|Long Point Bay||Targeted sampling, DFO (2004, 2005)||seine, boat electrofishing unit, fyke nets, additional gear (trap nets and Windermere traps)|
|Long Point Bay||Essex-Erie targeted sampling for species at risk (Turkey Point), DFO (2007)||seine, boat electrofishing unit, additional gear (trap nets and Windermere traps)|
|Long Point Bay||Fish community sampling, OMNR (2008)|
|Long Point NWA||DFO fish assemblage survey (2002, 2004-2005)||boat electrofishing unit, fyke nets|
|Big Creek and Big Creek NWA||DFO fish assemblage survey (2002, 2005)||seine, boat electrofishing unit, fyke nets|
|Big Creek and Big Creek NWA||Targeted sampling, OMNR (2004)||seine|
1.7 Knowledge gaps
There are numerous aspects regarding the biology, ecology, distribution and abundance of the spotted gar that remain unknown. This information is required to refine recovery approaches and to aid in refining critical habitat identification. Information is lacking regarding home range size, habitat use, seasonal movements and connectivity of populations at Point Pelee National Park, Rondeau Bay, Big Creek NWA and Long Point Bay. Primary threats that may be impacting populations have not been fully assessed (e.g., source of threat, extent). Competition with the more abundant longnose gar may pose a threat to the spotted gar. The association of these two closely related species, as well as the likelihood of Florida gar becoming established in Canada, need to be further investigated.
Aboriginal traditional knowledge will be sought through consultation and engagement processes to fill knowledge gaps and aid in the conservation of spotted gar.
- Date Modified: