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COSEWIC Assessment and Update Status Report on the Lake Sturgeon in Canada

Technical Summary

Technical Summary – Western Hudson Bay (DU1)

Acipenser fulvescens

Lake sturgeon
Esturgeon jaune

Western Hudson Bay populations
SK, MB


Extent and Area Information

extent of occurrence (EO) (km2)
~300 000

specify trend (decline, stable, increasing, unknown)
Unknown

are there extreme fluctuations in EO (>1 order of magnitude)?
No

area of occupancy (AO) (km2)
<300 000

specify trend (decline, stable, increasing, unknown)
Decline

are there extreme fluctuations in AO (>1 order magnitude)?
No

number of extant locations
3?

specify trend in # locations (decline, stable, increasing, unknown)
Unknown

are there extreme fluctuations in # locations (>1 order of magnitude)?
No

habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat
Unknown


Population Information

generation time (average age of parents in the population) (indicate years, months, days, etc.)
35-54 years

number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values)
Unknown, probably low 1000s

total population trend: specify declining, stable, increasing or Unknown trend in number of mature individuals
Declining
Poorly known

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)
>98% between 1920s and 1939

are there extreme fluctuations in number of mature individuals (>1 order of magnitude)?
No

is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., ≤1 successful migrant/year)?
Probably

list each population and the number of mature individuals in each
The 1800 may be an overestimate; the lower end of the C.I. is 1304. The length weight info indicates that immature sturgeon may have been included in the estimate, and there were no sturgeon caught that were much beyond the age of sexual maturity.
Churchill Mainstem low 100s,
Little Churchill – <1800
Other tributaries – unknown








specify trend in number of populations (decline, stable, increasing, unknown)
Unknown

are there extreme fluctuations in number of populations (>1 order of magnitude)?
No


Threats

- exploitation and dams


Rescue Effect (immigration from an outside source): Unlikely

does species exist elsewhere (in Canada or outside)?
Yes

status of the outside population(s)?
DUs 2-3 – Endangered

is immigration known or possible?
Possible, but unlikely

would immigrants be adapted to survive here?
Yes

is there sufficient habitat for immigrants here?
Yes?


Quantitative Analysis

Not Applicable


Status and Reason for Designation (DU1)

Status: Endangered
Alpha-numeric code: A2ad; C1 + 2a(ii)

Reasons for Designation: A precipitous > 98% decline from 1929-1939, has been followed by a slow, steady decline in the Churchill River to the point that records of mature individuals are almost non-existent in the past five years. Historically, overexploitation probably was the primary threat; more recently dams are probably the most important threat.


Applicability of Criteria

Criterion A: (Declining Total Population): Population declined by more than 98% from 1929-1939 in the Churchill River, followed a slow, steady decline thereafter to the present. A remnant population exhibiting characteristics of stress from overfishing remains in the Little Churchill River.

Criterion B: (Small Distribution, and Decline or Fluctuation): Not Applicable – EO and AO exceed threshold limits.

Criterion C: (Small Total Population Size and Decline): Population has crashed to less than 30% of levels in the early 20th century; remnant population size although not known is likely numbered in the low 1000s or possibly 100s. (Churchill River mainstem population)

Criterion D: (Very Small Population or Restricted Distribution): Not Applicable - EO and AO exceed threshold values. Number of mature individuals is thought to be low.

Criterion E: (Quantitative Analysis): Not Applicable – no data.

 

Technical Summary – Saskatchewan River (DU2)

Acipenser fulvescens

Lake sturgeon
Esturgeon jaune

Saskatchewan River populations
AB, SK, MB


Extent and Area Information

extent of occurrence (EO) (km2)
>400 000

specify trend (decline, stable, increasing, unknown)
Unknown

are there extreme fluctuations in EO (>1 order of magnitude)?
No

area of occupancy (AO) (km2)
<400 000

specify trend (decline, stable, increasing, unknown)
Unknown

are there extreme fluctuations in AO (>1 order magnitude)?
No

number of extant locations
4

specify trend in # locations (decline, stable, increasing, unknown)
Decline

are there extreme fluctuations in # locations (>1 order of magnitude)?
No

habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat
Decline (dam construction)


Population Information

generation time (average age of parents in the population) (indicate years, months, days, etc.)
35-54 years

number of mature individuals (capable of reproduction) in the Canadian population: Assuming a 2:1 (♀♀:♂) sex ratio and 2 yr spawning cycle for ♂♂, and 4 for ♀♀then the effective population would be < 670 in AB & SK and < 450 in MB
~3300

total population trend: specify declining, stable, increasing or Unknown trend in number of mature individuals
Decline

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)
>50% SK and AB,
>80% MB

are there extreme fluctuations in number of mature individuals (>1 order of magnitude)?
No

is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., ≤1 successful migrant/year)?
Yes

list each population and the number of mature individuals in each: Saskatchewan River AB – 700
North Saskatchewan River SK - ?
South Saskatchewan River SK - ?
Lower Saskatchewan River (EB Campbell Dam to Brand Rapids MB) - 1300
~ 2000 (AB+SK) + 1300 MB

specify trend in number of populations (decline, stable, increasing, unknown)
Unknown

are there extreme fluctuations in number of populations (>1 order of magnitude)?
No


Threats

Existing: overexploitation, dams, habitat degradation, and poaching


Rescue Effect (immigration from an outside source): Unlikely

does species exist elsewhere (in Canada or outside)?
Yes

status of the outside population(s)?
DU1 – Endangered
DU3 – Endangered
DU4 – virtually extirpated

is immigration known or possible?
Limited by dams, falls

would immigrants be adapted to survive here?
Yes?

is there sufficient habitat for immigrants here?
Yes?


Quantitative Analysis


Status and Reason for Designation (DU2)

Status: Endangered
Alpha-numeric code: A2b

Reasons for Designation: Seventy-six of 111 historic sites in Saskatchewan and Alberta have been lost and there has been an 80% decline reported in the Cumberland House area from 1960-2001. A 50% decdline from 1988 to 2003 has also been reported in the lower Saskatchewan River from Cumberland House to The Pas in Manitoba.


Applicability of Criteria

Criterion A: (Declining Total Population): Populations in SK and AB have demonstrated recent declines of over 50% (1998-2003) and that of SK/MB over 80% (1960-2001).

Criterion B: (Small Distribution, and Decline or Fluctuation): Not Applicable: EO and AO exceed threshold limits.

Criterion C: (Small Total Population Size and Decline): Meets the criteria for threatened (1), decline in excess of 50% over three generations and a total population of < 3300 mature individuals.

Criterion D: (Very Small Population or Restricted Distribution): Not applicable – threshold limits are exceeded.

Criterion E: (Quantitative Analysis): Not Applicable – no data.

 

Technical Summary – Nelson River (DU3)

Acipenser fulvescens

Lake sturgeon
Esturgeon jaune

Nelson River populations
MB


Extent and Area Information

extent of occurrence (EO) (km2)
~40 000

specify trend (decline, stable, increasing, unknown)
Unknown

are there extreme fluctuations in EO?
No

area of occupancy (AO) (km2)
<40 000

specify trend (decline, stable, increasing, unknown)
Unknown

are there extreme fluctuations in AO?
No

number of extant locations
<5?

specify trend in # locations
Unknown

are there extreme fluctuations in # locations?
No

habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat
Declining (dam construction)


Population Information

generation time (average age of parents in the population) (indicate years, months, days, etc.)
35-54 years

number of mature individuals (capable of reproduction) in the Canadian population: Assuming a 1:1 (♀♀:♂♂)sex ratio and 2 yr spawning cycle for ♂♂, and 4 for ♀♀then the effective population would be < 1000
<3000

total population trend
Declining

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater
89-90% in Sipiwesk Lake and Landing River

are there extreme fluctuations in number of mature individuals (>1 order of magnitude)?
No

is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., ≤1 successful migrant/year)?
Yes

list each population and the number of mature individuals in each
Effective populations – Sipiswesk lake 150, Limestone Dam 64, Others low 10s
Sipiswesk Lake ~1200
Below Limestone Dam – 500
Landing River – low 10s
Gull Lake < 500
Cross and Playgreen – extirpated
Other populations – low 100s

specify trend in number of populations
Unknown

are there extreme fluctuations in number of populations?
No


Threats

Existing: overexploitation, dams. Potential: poaching


Rescue Effect (immigration from an outside source): Unlikely

does species exist elsewhere (in Canada or outside)?
Yes

status of the outside population(s)?
DU1 Endangered
DU2 Endangered
DU4 – virtually extirpated
DU6 Special Concern

is immigration known or possible?
Possible, some fish from the Hayes River may spawn in the lower Nelson, but fate of progeny is unknown

would immigrants be adapted to survive here?
Yes

is there sufficient habitat for immigrants here?
Yes


Quantitative Analysis


Status and Reason for Designation (DU3)

Status: Endangered
Alpha-numeric code: A2b

Reasons for Designation: Portions of this designatable unit sustained large commercial fisheries from the early to mid-1900s, during which time there were dramatic declines in landings. More recently, a fishery at Sipiwesk Lake exhibited an 80-90% decline in landings from 1987-2000; and groups of 5-6 spawning fish were observed in the Landing River in 1990 compared to 100s observed several decades ago. Historically, overexploitation probably was the primary threat; more recently dams probably are the most important threat.


Applicability of Criteria

Criterion A: (Declining Total Population): Based on direct observation and an index of abundance, several of the populations have shown recent dramatic declines: Sipiwesk Lake - 80-90% decline in landings from 1987-2000, Landing River – groups of 5-6 spawning fishes in 2000 vs. 100s several decades ago.

Criterion B: (Small Distribution, and Decline or Fluctuation): Not Applicable – EO and AO exceed threshold limits.

Criterion C: (Small Total Population Size and Decline): Meets T C1; total number of mature individuals is probably less than 10 000, and populations have declined by more than 10% in the last three generations.

Criterion D: (Very Small Population or Restricted Distribution): Not applicable – Threshold limits exceeded.

Criterion E: (Quantitative Analysis): Not Applicable – no data.

 

Technical Summary – Red–Assiniboine Rivers – Lake Winnipeg (DU4)

Acipenser fulvescens

Lake sturgeon
Esturgeon jaune

Red-Assiniboine Rivers-Lake Winnipeg populations SK, MB, ON


Extent and Area Information

extent of occurrence (EO) (km2)
~250 000

specify trend
Decline

are there extreme fluctuations in EO?
No

area of occupancy (AO) (km2)
<250 000

specify trend
Decline

are there extreme fluctuations in AO?
No

number of extant locations
<5

specify trend in # locations
Decline

are there extreme fluctuations in # locations?
No

habitat trend:
Decline


Population Information

generation time (average age of parents in the population)
35-54 years

number of mature individuals (capable of reproduction) in the Canadian population
Very few

total population trend:
Decline

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater
Close to 100%

are there extreme fluctuations in number of mature individuals?
No

is the total population severely fragmented
Yes

list each population and the number of mature individuals in each
Lake Winnipeg – 3 in last 28 years
Assiniboine – none (excluding stocked fish)
Red River – unknown, but probably very few
Pigeon River – low 10s
East tributaries to L Winnipeg – unknown

specify trend in number of populations
Decline

are there extreme fluctuations in number of populations (>1 order of magnitude)?
No


Threats

Existing: overexploitation, dams, and habitat degradation and contamination, Potential: poaching and genetic contamination through stocking of fish from non-native populations.


Rescue Effect (immigration from an outside source): Unlikely

does species exist elsewhere (in Canada or outside)?
Yes

status of the outside population(s)?
DU2 – Endangered
DU3 – Endangered, DU5 – Endangered
North Dakota – Extirpated

is immigration known or possible?
Limited by dams

would immigrants be adapted to survive here?
Yes

is there sufficient habitat for immigrants here?
Yes?


Quantitative Analysis


Status and Reason for Designation (DU4)

Status: Endangered
Alpha-numeric code: A2bc; C2a(i)

Reasons for Designation: A very large commercial fishery existed between the late 1800s and early 1900s. Since then (i.e. in the last 3‑5 generations), the lake sturgeon has virtually disappeared from the Red-Assiniboine River and Lake Winnipeg. This was primarily the result of overfishing, although dams probably also affect remnant populations.


Applicability of Criteria

Criterion A: (Declining Total Population): Based on an index of abundance, several of the populations have shown recent dramatic declines: Lake Winnipeg – only 3 fish caught in last 28 years of index netting program. Red-Assiniboine River – no fish caught in recent standardized sampling. The loss of populations in these areas has also led to a substantial decline in the area of occupancy and extent of occurrence.

Criterion B: (Small Distribution, and Decline or Fluctuation): Not Applicable – EO and AO exceed threshold limits.

Criterion C: (Small Total Population Size and Decline): Total number of mature individuals <2500, continuing decline and no population with more than 250 mature individuals.

Criterion D: (Very Small Population or Restricted Distribution): May qualify as Threatened as the number of mature individuals is probably less than 1000.

Criterion E: (Quantitative Analysis): Not Applicable – no data.

 

Technical Summary – Winnipeg River – English River (DU5)

Acipenser fulvescens

Lake sturgeon
Esturgeon jaune

Winnipeg River-English River populations
MB, ON


Extent and Area Information

extent of occurrence (EO) (km2)
~15 000

specify trend
Unknown

are there extreme fluctuations in EO?
No

area of occupancy (AO) (km2)
<1 000

specify trend
Unknown

are there extreme fluctuations in AO?
No

number of extant locations
8?

specify trend in # locations
Decline

are there extreme fluctuations in # locations?
No

habitat trend:
Declining


Population Information

generation time (average age of parents in the population)
35-54 years

number of mature individuals (capable of reproduction) in the Canadian population
Unknown

total population trend:
Unknown

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater
54.9

are there extreme fluctuations in number of mature individuals?
No

is the total population severely fragmented?
Yes

list each population and the number of mature individuals in each
Below Seven Sisters Dam – <10, probably extirpated
Seven Sisters Dam to Slave Falls – unknown
Slave Falls to Scott Rapids – <650
Scott Rapids to Eaglenest – <10, probably extirpated
English, Wabigoon, Black Sturgeon rivers – Unknown, but probably <500 mature individuals

specify trend in number of populations
Decline

are there extreme fluctuations in number of populations?
No


Threats

Existing: overexploitation, dams. Potential: poaching, genetic contamination if stocked with non-native population, or accidental release at Rainy River hatchery.


Rescue Effect (immigration from an outside source): Unlikely

does species exist elsewhere (in Canada or outside)?
Yes

status of the outside population(s)?
DU4 – Endangered
DU6 – Special Concern
DU7 – Special Concern
DU8 – Threatened
North Dakota – Extirpated
Minnesota – Vulnerable

is immigration known or possible?
Upstream movement not possible due to falls and dams

would immigrants be adapted to survive here?
Yes

is there sufficient habitat for immigrants here?
Yes?


Quantitative Analysis


Status and Reason for Designation (DU5)

Status: Endangered
Alpha-numeric code: A2bcd

Reasons for Designation: Historically, the lake sturgeon populations in this designatable unit supported a large commercial fishery. However, there are limited historical and recent data. The limited recent data available show that populations are declining in the Winnipeg River above Seven Sisters Dam, and essentially have disappeared below the dam. Historically, overexploitation probably was the primary threat; now dams and poaching probably are the most important threats.


Applicability of Criteria

Criterion A: (Declining Total Population): EN A2bcd. The loss of two populations in the area has also led to a substantial decline in the area of occupancy and extent of occurrence. The overall population is declining and has demonstrated a decline of over 50% in the last three generations.

Criterion B: (Small Distribution, and Decline or Fluctuation): TH 2ab(i, ii, iii, iv, v). The species occurs at 8 locations with an area of occupancy of < 2000 km2.

Criterion C: (Small Total Population Size and Decline): TH 2a(i). The overall population has declined by 55% in the last two generations, and this decline appears to be continuing. The remaining populations are fragmented by natural barriers and dams: two populations of 8 have probably been lost, and no population contains more than 1000 mature individuals.

Criterion D: (Very Small Population or Restricted Distribution): Population and distribution data exceed threshold limits.

Criterion E: (Quantitative Analysis): Not Applicable – no data.

 

Technical Summary – Lake of the Woods – Rainy River (DU6)

Acipenser fulvescens

Lake sturgeon
Esturgeon jaune

Lake of the Woods-Rainy River populations
ON


Extent and Area Information

extent of occurrence (EO) (km2)
~100 000

specify trend
Unknown

are there extreme fluctuations in EO?
No

area of occupancy (AO) (km2)
<100 000

specify trend
Unknown

are there extreme fluctuations in AO?
No

number of extant locations
2+

specify trend in # locations
Stable

are there extreme fluctuations in # locations?
No

habitat trend:
Increasing, following a decline


Population Information

generation time (average age of parents in the population) (indicate years, months, days, etc.)
35-54 years

number of mature individuals (capable of reproduction) in the Canadian population
50 000 fish >1m (adults and sub-adults) in Lake of the Woods/Rainy River – increasing. Unknown, for other populations

total population trend:
Increase

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater
Unknown

are there extreme fluctuations in number of mature individuals?
No

is the total population severely fragmented?
No

list each population and the number of mature individuals in each
Lake of the Woods/Rainy River 50 000 fish >1m (adults and sub-adults)
Rainy Lake, Seine River, Namakan Reservoir, Little Turtle Lake, Sturgeon Lake, Russell Lake, Tanner Lake, Maligne River – unknown, but depressed and in low abundance

specify trend in number of populations
Stable

are there extreme fluctuations in number of populations?
No


Threats

Existing: overexploitation, dams. Potential: poaching, genetic contamination if stocked with non-native population, or accidental release at Rainy River hatchery, and further impoundments.


Rescue Effect (immigration from an outside source): Unlikely

does species exist elsewhere (in Canada or outside)?
Yes

status of the outside population(s)?
DU5 – Endangered
DU7 – Special Concern
DU8 – Threatened
Minnesota – Extirpated

is immigration known or possible?
Unlikely due to natural barriers and dams

would immigrants be adapted to survive here?
Yes

is there sufficient habitat for immigrants here?
Yes?


Quantitative Analysis


Status and Reason for Designation (DU6)

Status: Special Concern
Alpha-numeric code: Not Applicable

Reasons for Designation: Historically, populations in this designatable unit supported a substantial commercial fishery. Although this led to a severe decline, recovery has been sustained since 1970. Dams have not impeded access to important stretches of suitable habitat, but do restrict immigration from the adjacent Winnipeg River.


Applicability of Criteria

Criterion A: (Declining Total Population): Not Applicable – populations have declined in the past, but have shown recovery since the 1970s.

Criterion B: (Small Distribution, and Decline or Fluctuation): Not Applicable – EO and AO exceed threshold limits.

Criterion C: (Small Total Population Size and Decline): Not Applicable – population and decline information unknown.

Criterion D: (Very Small Population or Restricted Distribution): Population and distribution data exceed threshold limits.

Criterion E: (Quantitative Analysis): Not Applicable – no data.

 

Technical Summary – Southern Hudson Bay – James Bay (DU7)

Acipenser fulvescens

Lake sturgeon
Esturgeon jaune

Southern Hudson Bay-James Bay populations
MB, ON, QC


Extent and Area Information

extent of occurrence (EO) (km2)
~1 000 000

specify trend
Stable

are there extreme fluctuations in EO?
No

area of occupancy (AO) (km2)
<1 000 000

specify trend
Stable?

are there extreme fluctuations in AO?
No

number of extant locations
>10

specify trend in # locations
Stable?

are there extreme fluctuations in # locations?
No

habitat trend:
Decline?


Population Information

generation time (average age of parents in the population
35-54 years

number of mature individuals (capable of reproduction) in the Canadian population
Unknown

total population trend:
Unknown

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater

are there extreme fluctuations in number of mature individuals?
No

is the total population severely fragmented?
Yes

list each population and the number of mature individuals in each
Unknown

specify trend in number of populations
Unknown

are there extreme fluctuations in number of populations?
No


Threats

Existing: dams, poaching Potential: overexploitation via new commercial harvest and increasing road access.


Rescue Effect (immigration from an outside source): Unlikely

does species exist elsewhere (in Canada or outside)?
Yes

status of the outside population(s)?
DUs 1-5 – Endangered
DU6 – Special Concern
DU8 – Threatened

is immigration known or possible?
Possible, but unlikely

would immigrants be adapted to survive here?
Yes

is there sufficient habitat for immigrants here?
Unknown


Quantitative Analysis


Status and Reason for Designation (DU7)

Status: Special Concern
Alpha-numeric code: Not applicable

Reasons for Designation: There are limited population data available for populations in this designatable unit and there have been declines in habitat and possibly abundance for some population components related to exploitation and the multitude of dams. The increased access to relatively unimpacted populations and the likelihood of increased hydroelectric development in some areas are causes for concern for this designatable unit.


Applicability of Criteria

Criterion A: (Declining Total Population): Not Applicable – there have been declines in habitat, and possibly populations, but no trend data is available.

Criterion B: (Small Distribution, and Decline or Fluctuation): Not Applicable – EO and AO exceed threshold limits.

Criterion C: (Small Total Population Size and Decline): Not applicable – No information available on population sizes and decline.

Criterion D: (Very Small Population or Restricted Distribution): EO, AO and population size exceed threshold limits.

Criterion E: (Quantitative Analysis): Not Applicable – no data.

 

Technical Summary – Great Lakes – Upper St. Lawrence (DU8)

Acipenser fulvescens

Lake sturgeon
Esturgeon jaune

Great Lakes-Upper St. Lawrence populations
ON, QC


Extent and Area Information

extent of occurrence (EO) (km2)
~600 000

specify trend (decline, stable, increasing, unknown)
Decline

are there extreme fluctuations in EO?
No

area of occupancy (AO) (km2)
<600 000

specify trend
Decline

are there extreme fluctuations in AO?
No

number of extant locations
<70

specify trend in # locations
Decline

are there extreme fluctuations in # locations?
No

habitat trend:
Decline


Population Information

generation time (average age of parents in the population)
35-54 years

number of mature individuals (capable of reproduction) in the Canadian population
Unknown

total population trend:
Dramatic deline 2-3 generations in the past, in last generation some populations in decline, some stable and some increasing

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater
99% in the Great Lakes

are there extreme fluctuations in number of mature individuals?
Unknown

is the total population severely fragmented?
Yes

list each population and the number of mature individuals in each

(N.B. Population data are combined by major drainage basin, there are 63 known extant populations in this DU)
For basin and tributaries:
Lake Superior – 6 populations remain of 14, <1000 in each
Lake Huron – 8 remain of 21, <1000 in each;
Lake Nipissing – unknown; Lake Simcoe – 0;
Lake St. Clair – 5000 (not aged), may include migrants from Detroit and St. Clair rivers as well as lakes Huron and Erie; Lake Erie – 3 populations remain of 4, <1000 in each Lake Ontario – 3, populations remain of 5, spawning in 2, <1000 in each
Ottawa River – tributaries extirpated, mainstem very few Lake Timiskaming – likely 1 population, severely depleted, low 100s
Upper St. Lawrence River – 14 of 14 populations remaining, previous decline due to contaminants and exploitation, populations had recovered, but are now showing signs of overexploitaion; only 3 populations may be >1000 mature individuals

specify trend in number of populations
For basin and tributaries
Lake Superior – decline
Lake Huron – unknown
Lake Nipissing – unknown
Lake Simcoe – decline
Lake St. Clair – increase
Lake Erie – slight increase
Lake Ontario – slight increase
Lake Temiskaming – decline
Upper St. Lawrence – decline, showing signs of overexploitation
Ottawa River – decline

are there extreme fluctuations in number of populations?
No


Threats

Existing: overexploitation, dams, poaching, habitat degradation and contamination


Rescue Effect (immigration from an outside source): Unlikely

does species exist elsewhere (in Canada or outside)?
Yes

status of the outside population(s)?
DU6 – Special Concern
DU7 – Special Concern
Minnesota and Wisconsin – Vulnerable
Michigan and Illinois – Imperiled
Indiana, Pennsylvaia, New York, Vermont – Critically Imperiled

is immigration known or possible?
Possible, but unlikely

would immigrants be adapted to survive here?
Yes

is there sufficient habitat for immigrants here?
Yes?


Quantitative Analysis


Status and Reason for Designation (DU8)

Status: Threatened
Alpha-numeric code: Meets criteria for Endangered A2abcd, but designated Threatened A2abcd because although a quarter of the populations have been lost, more than half of the remaining populations are either stable or recovering.

Reasons for Designation: A very large commercial fishery existed in the Great Lakes between the mid-1800s and early 1900s (i.e. 2-3 generations ago) during which time populations of this species were reduced to a small fraction of their original size, and appear to be still at very low levels. Populations appear to be declining in parts of the Ottawa River, and disappearing from many of its tributaries due to dams. There has been a recent decline in the population in the St. Lawrence River probably due to overexploitation despite recovery efforts. The direct and indirect effects of dams, chemical control of sea lamprey, contaminants and invasive species currently threaten populations.


Applicability of Criteria

Criterion A: (Declining Total Population): Meets A2abcd – The majority of populations (all in the Great Lakes portion) in this Designatable Unit exhibited close to a 100% decline in population size between the mid-1800s to early 1900s. Since that time, most lake Sturgeon populations have failed to increase in size, and 21 of the 63 known Canadian populations in this Designatable Unit now are considered extirpated.

Criterion B: (Small Distribution, and Decline or Fluctuation): Not applicable – Wide distribution.

Criterion C: (Small Total Population Size and Decline): Not Applicable – Population sizes exceed thresholds.

Criterion D: (Very Small Population or Restricted Distribution): Not Applicable – Wide distribution.

Criterion E: (Quantitative Analysis): Not Applicable – no data.