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Recovery Strategy for the Lake Chubsucker

 

1.1 Species Assessment Information from COSEWIC

Common Name: Lake Chubsucker
Scientific Name: Erimyzon sucetta
Status: Threatened
Last Examination and Change: 2001, THR (status update report in prep.)
Canadian Occurrence: Ontario
Reason for designation: Within Canada, this species occurs only in southwestern Ontario where it has been found at seven locations and has not been found at three of these since 1983. Never abundant, the species is in decline throughout its range as a result of siltation and drainage of wetlands.
Status History: Designated Special Concern in April 1994. Status re-examined and uplisted to Threatened in November 2001. Last assessment based on an existing status report with an addendum.

1.2 Description

The lake chubsucker is a robust, slightly compressed, deep-bodied member of the sucker family, Catostomidae (Figure 1).  It has a wide head, blunt snout, a small protruding downward directed mouth and a moderately deep-arched back. The fish’s dorsal surface is deep olive to greenish-bronze.  The underside is green-yellow to yellow-white.  Scales on the back and upper sides are dark-edged, creating a crosshatched pattern.  The lateral stripe, if present, is either continuous (and often striking in juveniles) or broken into lateral blotches or bands.  A lateral line is lacking. The dorsal fin has a short base without a rounded or pointed anterior lobe and has fewer than 20 rays, distinguishing this genus from Carpiodes, Cycleptus and Ictiobus.  In Canada, it is typically less than 254 mm in total length, but has been reported to reach lengths and weights up to 292 mm and 397 g, respectively (Coker et al. 2001). Individuals tend to be smaller in Canada than in their southern range.

Lake Chubsucker

Figure 1.  The lake chubsucker (Erimyzon sucetta).  © Joseph R. Tomelleri.

1.3 Populations and Distribution

Global Range: The lake chubsucker has a fragmented, disjunct distribution from the lower coastal plain extending from Texas to Virginia, to a northern element in the southern Great Lakes drainages (Figure 2).  It occurs in 1 province and 22 states (introduced to Nebraska). The species is considered globally secure but is imperiled in Ontario (S2) and considered extirpated in Iowa and Pennsylvania, and possibly New York (Table 1).  Less than 5% of the species’ global range currently occurs in Canada.

Lake Chubsucker Distribution

Figure 2. Global distribution of the lake chubsucker. Modified from Page and Burr (1991). (Source: Mandrak et al. submitted).

 

Table 1.  Global, national, and sub-national ranks for the lake chubsucker.

RankJurisdiction Rank
Global (G)G5 (Aug. 17, 2001)

National (N)CANADA

US

 N2

N5

Sub-National (S)CANADA

US

Ontario (S2)

Alabama (S5), Arkansas (S2?), Florida (SNR), Georgia (S5), Illinois (S2S3), Indiana (S3), Iowa (SX), Kentucky (S2), Louisiana (S5), Michigan (S4), Mississippi (S5), Missouri (S2), Nebraska (SNA), New York (SH), North Carolina (S4), North Dakota (SNR), Ohio (S2), Oklahoma (S3), Pennsylvania (SX), South Carolina (SNR), Tennessee (S3S4), Texas (S3), Virginia (S2), Wisconsin (S3)

Source: NatureServe. 2005. (Accessed Jan. 30, 2006).  Refer to Appendix 1 for definition of status rankings.

Canadian Range: In Canada, the lake chubsucker is only known to occur in southwestern Ontario (Figure 3). It has been found in the Ausable River (tributary of Lake Huron), Lake St. Clair (Mitchell’s Bay, St. Clair National Wildlife Area and Walpole Island), Thames River (Jeanette’s Creek), Lake Erie (Point Pelee, Rondeau Bay, and Long Point Bay), several tributaries of Big Creek and Niagara rivers (Tee Creek and Lyons Creek).  Since Tee Creek is a tributary of Lyons Creek, these occurrences may have been part of the same population.  All populations should be considered nationally significant due to the species’ restriction to southwestern Ontario.

Canadian collections have not been made in a standardized manner, nor have there been specific studies on population size, making it difficult to assess population sizes and trends.  The paucity of records, however, suggests low abundance.  The population in the Old Ausable Channel (OAC) of the Ausable River is thought to have remained in stable condition since its discovery in 1982 (ARRT 2005).  Populations in Point Pelee National Park and Long Point Bay are also thought to be stable (EERT 2007).  Extensive sampling of over 300 sites at Point Pelee in 2002-03 using a variety of methods produced 25 individuals at 22 sites (Mandrak et al. submitted).  The species had not been recorded at Rondeau Bay since 1963, until 2005, when a single individual was found despite considerable search effort in 2004 and 2005 (Tom Macdougall, OMNR pers comm. Feb. 16, 2006).  It has not been collected from Jeanette’s Creek or Tee Creek since 1970, or from Big Creek tributaries and Mitchell’s Bay since 1989 (Mandrak et. al. submitted).  Recent surveys in areas of historic occurrence in the upper Big Creek watershed have not taken place and many nearshore areas with suitable habitat in Long Point Bay have not yet been sampled.  Recent detailed fish biomass surveys which were undertaken in Tee Creek from 2003 to 2005 yielded no catches of this species (A. Yagi, OMNR, pers. comm.), however, the species persists along a 1.8 km stretch of Lyons Creek where clear water is maintained by overflow of the Welland Canal (Mandrak et al. submitted).  Further surveys are required to verify the status of populations from Jeanette’s Creek, Tee Creek, Big Creek tributaries and Mitchell’s Bay.

Canadian distribution

Figure 3. Canadian distribution of the lake chubsucker.

1.4 Needs of the LakeChubsucker

1.4.1 Habitat and biological needs

The lake chubsucker is a warm water species, with a preferred temperature range of 28 - 34 oC (Coker et al. 2001).  It is an omnivorous bottom feeder, feeding primarily on plankton, small crustaceans, mussels, aquatic insects, filamentous algae and other plant material.  Suitable habitat includes clear, well-vegetated, slow-moving or still waters with substrates of gravel, sand and silt mixed with organic debris: such as those provided by backwaters, bayous, drainage ditches, floodplain lakes, marshes, oxbows, sloughs and wetlands (see Mandrak et al. submitted).  In Ontario, the species has typically been captured in heavily vegetated, stagnant bays, channels, ponds and swamps with low turbidity and clay, silt, sand and organic debris substrates (Mandrak et al. submitted).  Within Lake St. Clair and Lake Erie, coastal wetlands are particularly significant for this species (EERT 2007).  Barriers between coastal wetlands, adjacent Lake Erie, appear to maintain the species’ preferred clear, well-vegetated habitat in the coastal wetlands.

Lake chubsuckers move into marshes to spawn, although they are thought to have limited dispersal ability.  Therefore, suitable spawning sites must be in close proximity to available habitat. In the Great Lakes area, spawning sites may include shallow waters of bays, lower reaches of tributaries, ponds and marshes where eggs are scattered over beds of aquatic vegetation, dead grass or filamentous algae (Goodyear et al. 1982).  In Ontario, spawning likely occurs between April and June.  Mature adult females (age 3 yr +) lay from 3,000 to 20,000 eggs (Becker 1983) on aquatic vegetation.  Eggs hatch in water temperatures of 22-29 oC.

Nursery habitat for this species occurs over silt, sand or clay within the first two meters of vegetated water (Lane et al. 1996 in Mandrak et al. submitted).  Mandrak et al. (submitted) provide habitat descriptions from Leslie and Timmins’ (1997) study of this species’ early life history based on collections from Long Point’s Inner Bay, Lake Erie.  Age 0+ specimens were found inhabiting a vegetated drainage ditch with water temperatures of 24-28oC; specimens on Walpole Island, Lake St. Clair were found in approximately 10cm of water under a layer of leaves in a roadside ditch intermittently connected to the St. Clair River in early January; and age 1+ specimens on Long Point were found in marshes associated with Eleocharis, Carex and Typha.  

1.4.2 Ecological role

The significance of this species’ role in the ecosystem is not known due to its rarity; however, because of its specific habitat requirements (clear, slow-moving, heavily-vegetated waters), declining populations are indicative of deteriorating ecosystem conditions.  In Ontario, the species is often found with blackchin shiner (Notropis heterodon), blacknose shiner (N. heterolepis) and pugnose shiner (N. anogenus) – species which prefer similar habitats (Mandrak et al. submitted).  In Niagara area wetland streams, the species most commonly associated with such habitats include grass pickerel (Esox americanus vermiculatus), golden shiner (Notemigonus crysoleucas), brown bullhead (Ameriurus nebulosus) and central mudminnow (Umbra limi) (A. Yagi, OMNR, pers. comm.).  The lake chubsucker has been identified as an ideal forage fish for bass (Carlander 1969in Mandrak et al. submitted), but it is unlikely to be prominent in bass’ diet due to its general rarity.

1.4.3 Limiting factors

The lake chubsucker is at its northern range limit in Canada. This species has very specific habitat requirements and is intolerant of turbidity and highly silted waters (Mandrak et al. submitted).  The lake chubsucker appears to have limited dispersal ability (Leslie and Timmins 1997) which may prevent the re-establishment of extirpated populations.

1.5 Threats

1.5.1 Threat classification

Threats thought to be affecting the lake chubsucker are listed in Table 2.  Nine unique threats were ranked based on their relative impact, spatial extent and expected severity.

Table 2. Threat classification table for the lake chubsucker.

ThreatRelative ImpactSpatial ExtentEvaluation of Threat
AWetland Habitat LossPredominantWidespreadProbable
BSediment Loading & TurbidityPredominantWidespreadProbable
CChannelization/ Altered Water FlowContributingLocalSpeculative
DExotic SpeciesContributingWidespreadSpeculative
EVegetation Removal/ ControlContributingLocalSpeculative
FBarriers to MovementContributingLocalSpeculative
GClimate ChangeContributingWidespreadSpeculative
HIncidental Harvest (Commercial and Bait Fisheries)ContributingLocalSpeculative
IChanges to Trophic DynamicsContributingLocalSpeculative

1.5.2 Description of threats

The lake chubsucker is subject to a broad array of threats across its range. Threats to this species include siltation; increased turbidity and loss of its preferred wetland habitat (clear, still, well vegetated waters) through habitat alteration, channelization, wetland drainage, vegetation removal/ control, pollution, changes to rates of flow, and possibly exotic species and climate change.  In southwestern Ontario, the leading causes of habitat loss for this species appear to be the draining of wetlands and siltation due to agricultural practices.  Unless further drainage and siltation of habitat is prevented, population declines will continue to occur (Mandrak et al. submitted).  Remaining populations of the lake chubsucker are found predominantly in coastal wetlands where barriers between wetlands and the adjacent lake waters appear to maintain suitable habitat (but also prevent movement).  Exotic species such as common carp (Cyprinus carpio) and common reed grass (Phragmites australis) may pose a threat to some populations through alteration of wetland habitats.  However, the establishment of the exotic zebra mussel (Dreissena polymorpha) may have improved habitat conditions in some areas through increased water clarity.  Incidental harvest in commercial and bait fisheries may represent an additional threat but requires further investigation.

Climate change is expected to have significant effects on aquatic communities of the Great Lakes basin in the coming decades.  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 species at risk fishes as most vulnerable; their results showed that lake chubsucker ranked 4th highest in final vulnerability scores of 99 fish species that use lacustrine habitats.  In this study, 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.

The following summarizes information on threats to extant and extirpated populations.  An overview is provided in table 3.

Threats to Extant Populations:

AusableRiver:Within the Ausable River watershed, the OAC population is believed to be stable and is protected from influxes of suspended solids in the river by a dam; therefore, siltation is not currently a serious threat to this population.  Although much of the OAC habitat receives protection due to its presence in a Provincial Park, the ecosystem is vulnerable to non-indigenous, introduced species.  The potential use of live baitfish in this habitat may present a real risk of introducing non-indigenous species to the otherwise essentially closed system.  Common carp presently occur at low densities here, but represent a potential threat to the lake chubsucker if their numbers increase (ARRT 2005).  The destructive feeding behavior of common carp, involving the uprooting of aquatic vegetation and associated elevation of turbidity levels can cause deterioration of wetland habitat. Development activities occurring outside the Pinery Provincial Park in close proximity to the OAC may be exerting negative pressures on the system (ARRT 2005).  Changes to trophic dynamics may also be a concern for this population.  Recent shifts in the aquatic community have resulted in an increased prevalence of larger predatory centrarchids and the appearance of northern pike (Esox lucius) in the OAC (ARRT 2005).

Lake St. Clair: Development along the shorelines of Lake St. Clair is a potential threat to the population occupying the east shore of Lake St. Clair.

Lake Erie (Rondeau Bay, Long Point Bay, Point Pelee): The main threats to the lake chubsucker in the Lake Erie coastal wetlands are thought to be siltation, turbidity and wetland loss.  Additional and related threats include sediment and nutrient loadings, alterations to shoreline processes (EERT 2007).  

Niagara River, Lyons Creek: The lake chubsucker presently occurs along a 1.8 km stretch of clear water maintained by the clean overflow water of the Welland Canal (Mandrak et al. submitted). The remainder of the Creek is now highly degraded and siltation may remain an immediate threat to this population.  In addition, PCB contamination within Lyons Creek has been an ongoing concern with site remediation plans in the early stages (I. Barret, NPCA, pers. comm.).

Threats to Historically OccupiedHabitats:

ThamesRiverpopulation, Jeanette’s Creek: The main threats thought to be associated with this population’s possible extirpation are increased siltation and turbidity from agriculture, industry and urbanization (TRRT 2005).

Upper tributaries of Big Creek (Long Point Region):Conditions/ threats within these tributaries are unknown at this time.

Niagara River, Tee Creek:  This population/ subpopulation is now likely extirpated as a result of habitat degradation, primarily resulting from agriculture-induced siltation and turbidity (Mandrak et al. submitted). The historically occupied reaches of Tee Creek are now separated from extant populations in Lyons Creek by large distances of very poor habitat.  Tee Creek now has a fairly entrenched channel and is classified as a municipal drain (I. Barret, NPCA, pers. comm.).

Table 3: Predominant threats to populations of the lake chubsucker in Ontario.

SystemDistributionPopulation StatusPredominant Threats
Ausable RiverOld Ausable ChannelStableChanges in trophic dynamics, exotic species, nutrients?
Thames RiverJeanette’s CreekExtirpatedHabitat loss, sediment loading and turbidity, channelization/ altered water flow.
Lake St. ClairWalpole IslandExtantUnknown
Mitchell’s BayExtirpated?Shoreline development
St. Clair WMAExtantUnknown
Lake ErieLong Point BayDeclining?Habitat loss and siltation
Point PeleeStableHabitat loss and siltation
Rondeau BayDeclining?Nutrient loading, vegetation removal/ control
Big Creek tributaries (Long Point region)Extirpated?Unknown
Niagara RiverTee CreekExtirpatedHabitat loss, sediment loading and turbidity
Lyons CreekDecliningHabitat loss, sediment loading and turbidity

1.6 Actions Already Completed or Underway

Ecosystem Recovery Strategies:  The following aquatic ecosystem-based recovery strategies address several lake chubsucker populations and are currently being implemented by their respective recovery teams.  Recovery activities implemented by these teams include active stewardship and outreach/awareness programs to reduce identified threats. 

AusableRiver Ecosystem (OAC population):  The long-term goal of this strategy is “to sustain a healthy native aquatic community in the Ausable River through an ecosystem approach that focuses on the recovery of species at risk” (ARRT 2005).  The Ausable River Recovery Team has facilitated the development of a management plan for the OAC and is working towards the identification of critical habitat for the lake chubsucker within the OAC.

Essex-Erie Region Fishes (Point Pelee, Rondeau Bay, Long Point Bay and Big Creek populations):  The long-term goal of this strategy is “to maintain and restore ecosystem quality and function in the Essex-Erie region in order to support viable populations of fish species at risk, across their current and former range.” (EERT 2007).  The Essex-Erie region is located on the north shore of Lake Erie and bordered to the east by the Grand River watershed, to the west by the Detroit River and to the north by Lake St. Clair and Thames River watershed.

ThamesRiver Ecosystem (Jeanette’s Creek historical population):The long-term goal of this strategy is “to use an ecosystem approach to stabilize and improve species at risk populations within the Thames River ecosystem and to reduce or eliminate threats to these species and their associated habitats, so that their long-term viability in the watershed is ensured.” (TRRT 2005).

Awareness – Incidental Harvest:  A color brochure of fish species at risk (including lake chubsucker) was distributed to bait fish harvesters in 2006 to raise general awareness and help prevent incidental harvest through this means.

Recent Surveys:  The following table summarizes recent fish surveys conducted by various agencies within areas of known occurrence of the lake chubsucker.

Table 4: Summary of recent fish surveys in areas of lakechubsuckeroccurrence (adapted from EERT 2007; Mandrak et al. submitted).

Waterbody/ General AreaSurvey Description (years of survey effort)
Ausable  (OAC)
  • DFO targeted sampling 2002, 2004a,c,d,e
  • Complimentary habitat surveys also conducted by DFO
Essex region
  • ERCA sampling of inland watercourses (2000-2001)c, targeted sampling (2004)c, surveys of drains and inland watercourses (2004)c
Lake Erie
  • OMNR coastal wetlands along Lake Erie (2004-2005)c
Point Pelee
  • DFO and Point Pelee National Park (2002-2003)a,b,d,e
Rondeau Bay
  • DFO targeted sampling in 2002d
  • OMNR and DFO (2004-2005)a,e
Lake St. Clair (St. Clair NWA)
  • DFO sampling (2003, 2004)d?
Lake St. Clair (Walpole Island)
  • Royal Ontario Museum (2001-02)
Lake St. Clair (Mitchell’s Bay)
  • DFO/ University of Guelph sampling (2003, 2004)d,e
Long Point Bay
  • OMNR Index Surveys of Long Point Bay (annually)b
  • DFO targeted sampling in 2004, 2005 (including dyked marshes)a,d,e
Lyons Creek
  • DFO targeted sampling 2004 along the entire creek.

Gear type: a-seine, b-trawl, c-backpack electrofishing unit, d-boat electrofishing unit, e-additional gear (trap nets, hoop nets, Windermere traps).

1.7 Knowledge Gaps

Very little is known about the life history or biology of this species.  There is a specific need to examine any physiological or environmental tolerances that the lake chubsucker may have.  Threat clarification is required, as well as determination of significant contributors to extirpation where populations have been lost (Jeanette’s Creek and Tee Creek).  Additional sampling is required to determine the full extent of the lake chubsucker’s distribution across all Ontario populations, except in the OAC where the extent of distribution is relatively well known.  Sampling efforts are sometimes hampered by the lack of adequate methods for small, highly vegetated pond areas with soft organic substrates and water depths greater than 1m (Mandrak et al. submitted).  The impacts of introduced fishes (i.e. common carp, northern pike, centrarchids) and other exotic species on the lake chubsucker and its habitat require further investigation.