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Surveillance for Viral Hemorrhagic Septicemia Virus in Wild Fish in Canada - Spring 2007

Summary

The Canadian Food Inspection Agency (CFIA) implemented a 2-year surveillance of wild fish in Canada for the presence of viral hemorrhagic septicaemia virus (VHS virus) in the spring of 2007. The bilateral surveillance plan was developed by the Aquatic Animal Health Division (AAHD) of CFIA, Fisheries and Oceans Canada (DFO), Animal and Plant Health Inspection Service (APHIS) of the US Department of Agriculture (USDA), U.S. Fish and Wildlife Service (USFWS), and the Great Lakes Fish Health Committee.

One thousand and fifty-five (1,055) wild fish, originating from medium to high risk watersheds for VHS virus infection, were tested for VHS virus. These fish were sampled from 3 different watersheds in Ontario (Big, French and Scugog) and 1 in Québec (St. Lawrence River - 3 freshwater sites: Lac St. Louis, Lac St. François and near Bécancour). All fish were negative for VHS virus.

The freshwater portion of the St. Lawrence River, east of Moose Saunders Dam is currently considered a high risk watershed for infection with VHS virus. Since it is connected directly to Lake Ontario, a positive watershed, it is recommended that the status of this watershed be checked annually. The risk of infection for VHS virus in the Big (high), French (high) and Scugog (medium) watersheds is unchanged as well, and it is recommended that fish in these watersheds be sampled again in 2008.

While not part of this sampling effort, DFO did confirm one (1) VHS virus-infected fish in the lower Thames River watershed resulting from the Ontario Ministry of Natural Resources (OMNR) 2007 spring survey, funded by the Canada-Ontario Agreement Respecting the Great Lakes Basin Ecosystem. It is recommended that the Lower Thames watershed be sampled in the fall of 2007.

Isolation of VHS virus was also confirmed from a fish die-off in Hamilton Harbour in May 2007. Lake Ontario is a known positive watershed for VHS virus.

Introduction

Viral hemorrhagic septicemia virus (VHS virus) is a rhabdovirus that infects a wide range of marine, brackish and freshwater fish species, including anadromous species, such as Chinook and Coho salmon, and catadromous species, such as American eels and Striped bass. To date, the virus has been found in over 65 different fish species. Four major genogroups of VHS virus have been identified (Einer-Jensen et al., 2004; Snow et al., 2004). Genogroup I consists mainly of freshwater strains of VHS virus isolated from fish in Europe. Genogroup I strains have also been isolated from marine fish around Europe and Rainbow trout raised in brackish water around Finland. Genogroups II and III are endemic in wild marine fish found around Europe. However, a genogroup III strain has also been isolated from Greenland flounder caught at the Flemish Cap, about 600 km east of Newfoundland. Genogroup IV is considered endemic in certain populations of wild marine fish along the Pacific coast of North America and in Japan (subgroup IVa). Another subgroup of genogroup IV was isolated from mummichogs, sticklebacks, Striped bass and sea-run Brown trout on the Atlantic coast of Canada (Gagné et al., 2007). The subgroup has not yet been formerly named, but is currently referred to as IVc.

Recently, in 2003, 2005, 2006 and 2007, another subgroup of genogroup IV, distinct from other sequenced North American (east and west coast) VHS virus IV isolates, has emerged in free-ranging freshwater fish species of the Great Lakes region (Elsayed et al., 2006). This subgroup has been named IVb. Multiple large die-offs in the Great Lakes region involving at least 14 different species have been attributed to VHS virus IVb since the spring of 2005. The first large die-off was recorded in the Bay of Quinte on the Canadian side of Lake Ontario in Freshwater drum. To date, subgroup IVb has not been detected in aquaculture facilities in Canada.

In response to these die-offs and in order to protect the catfish aquaculture industry, the United States Department of Agriculture issued a Federal Order on October 24, 2006 restricting movement into and throughout the U.S.A. of 37 species of live fish from Ontario, Québec and 8 States surrounding the Great Lakes. The Order has been amended twice since then; one amendment was to allow importation of live salmonids from Canada with the condition of negative test results (USFWS Blue Book protocols or equivalent; in Canada, testing is done under the Fish Health Protection Regulations), and the other amendment was to allow importation of live fish associated with fishing derby activities (http://www.aphis.usda.gov/newsroom/hot_issues/vhs/vhs.shtml; accessed August 31, 2007). Several U.S States have also imposed additional regulations regarding importation of live fish and movement of bait fish species.

The province of Ontario has also placed some restrictions on the movement of live bait fish, and on wild egg collections and subsequent stocking. In addition, OMNR now requires an impact assessment on any new proposals to move fish (http://www.mnr.gov.on.ca/MNR/fishing/VHScontrol.html; accessed August 31, 2007).

Canada exports fish and seafood in excess of $4.3 billion CDN every year. The bulk of the exports go to the U.S.A.. Exact live fish exports (magnitude and dollar value) are unknown. In 2005, approximately 1 million dozen bait fish were exported from Ontario into the U.S.A.. That has now ceased. Other live fish exports from Canada include catfish and other species for the human food market.

Since the Great Lakes are a shared water resource, and because VHS virus is a World Organization for Animal Health (OIE)-listed disease that can impact Canada's international trade opportunities, the recent emergence of a new strain of VHS virus in freshwater fish in the Great Lakes region prompted the Canadian Food Inspection Agency (CFIA), U.S. Department of Agriculture (USDA) and U.S. Fish and Wildlife Service (USFWS) to undertake development of a bilateral VHS virus surveillance plan. The bilateral surveillance plan is consistent with OIE guidelines on surveillance for disease freedom as outlined in the OIE Manual of Diagnostic Tests for Aquatic Animals, (http://www.oie.int/eng/normes/fmanual/A_summry.htm?e1d11).

Sampling of susceptible freshwater fish species will be conducted primarily in the spring and fall when water temperatures favour the detection of VHS virus. This report outlines the implementation of surveillance for VHS virus in wild fish in the Great Lakes - St. Lawrence Basin. The effort was undertaken in Ontario and Québec fresh waters by the CFIA in partnership with provincial authorities in the spring of 2007.

This initial targeted surveillance effort will occur over a 2-year period (spring 2007 to fall 2008). Ongoing surveillance design (beginning in spring 2009, and under the auspices of the National Surveillance Program) will be based upon the evaluation of this initial surveillance period, resultant disease status of watersheds in Canada, and any planned disease control measures.

Objectives

The objectives of the bilateral surveillance effort are to:

  1. determine the current distribution of VHS virus in both cultured and wild susceptible freshwater fish populations of the United States and Canada,
  2. designate free and infected zones to facilitate disease control,
  3. implement a surveillance framework to facilitate detections of future VHS virus IV outbreaks, and
  4. validate a rapid RT-PCR screening technique.

Due to resource constraints, for the spring 2007 effort in Canada, surveillance was conducted in wild freshwater fish in medium to high risk watersheds in Ontario and Québec. Fish were also sampled in Lake Erie to serve as a validation population for a rapid screening test for VHS virus. The surveillance was based on the bilateral, CFIA and USDA document: "Surveillance Proposal for Viral Hemorrhagic Septicemia Virus In Freshwater Fish in Canada and the United States, Version 1.0" (available upon request from the Aquatic Animal Health Division, CFIA).

Materials and Methods

The spring 2007 surveillance plan consisted of 2 components:

  1. sampling of wild fish populations in medium to high risk watersheds and laboratory testing for VHS virus (test-based surveillance), and
  2. investigation of wild fish kills in Ontario and Québec (disease outbreak investigation).

CFIA-Aquatic Animal Health Division (AAHD), CFIA-Operations, DFO-NAAHLS (National Aquatic Animal Health Laboratory System), Ontario Ministry of Natural Resources (OMNR), Agriculture, Pêcheries et Alimentation Québec (MAPAQ) and the University of Guelph met on February 28 and March 1, 2007 to determine the surveillance methods for spring 2007.

Subsequent collaborative documents arising from this meeting included:

  1. Standard Operating Procedures, Field Sampling for Viral Haemorrhagic Septicaemia Virus, May 2007 (available upon request from CFIA-AAHD)
  2. List of all tertiary watersheds in Québec and Ontario that are part of the Great Lakes and St. Lawrence River Basins (Table 1)
  3. Protocol for Wild Fish Disease Investigations (available upon request from CFIA-AAHD)
  4. Laboratory Protocol for Virus Isolation and Identification by RT-PCR (under development by DFO-NAAHLS).

Surveillance was directed towards selection of tertiary watersheds with the highest risk for VHS virus infection: watersheds that had a direct connection to known infected watersheds (Lake Ontario, Lake Erie, Lake St. Clair, and Lake Huron) and watersheds that had received large numbers of bait fish harvested from infected waters prior to regulatory restrictions. A risk of 'high' was given to tertiary watersheds that had a direct connection to positive watersheds. A risk of 'medium' indicated that the watershed had no direct connection to a positive watershed but had, in the past, received large volumes of live bait fish from positive waters. A risk of 'low' was applied to watersheds where there was no direct connection to positive waters and the watershed had not knowingly received large volumes of live bait fish. Secondary considerations for watershed selection included anticipated presence of provincial sampling crews, and distance from DFO laboratories (samples had to reach laboratories in a defined time period).

At least 170 fish (from 1 or more susceptible species) were sampled from each selected watershed. The sample size was based on detecting the virus at a prevalence of 2% within the fish population, with a test sensitivity of 85% and test specificity of 100% (viral isolation and identification by RT-PCR. Fish were collected repeatedly until the desired sample size was reached.

Sampling was conducted by OMNR or Ressources naturelles et Faune Québec (MRNFQ). In addition, the provinces of Ontario and Québec provided resources to enhance reporting and investigation of wild fish kills in their respective provinces.

Results

  1. Test-based surveillance

    An initial qualitative evaluation (positive, high, medium, or low) of the probability of VHS virus infection in each tertiary watershed of the Great Lakes-St. Lawrence Basin in Ontario and Québec is provided in Table 1. This evaluation was based on the following risk factors: direct connection to an infected watershed and history of large volumes of live bait fish introductions. A risk of 'high' denotes that the tertiary watershed has a direct connection to positive watersheds. A risk of 'medium' indicates that the watershed has no direct connection to a positive watershed but has received large volumes of live bait fish from positive waters in the past. A risk of 'low' indicates that there is no direct connection to positive waters and the watershed has not knowingly received large volumes of live bait fish.

    The initial list of 21 medium to high risk tertiary watersheds in Ontario, south of Parry Sound, and in Québec was pared down to 5 because of limitations related to availability of sampling crews and sample processing resources at DFO-NAAHLS. In addition, constraints were also imposed by rising water temperatures. Sampling began in the beginning of May and was discontinued towards the end of May due to rising water temperatures.

    All fish tested were from healthy populations. Results can be found in Table 2.

    The Ontario Ministry of Natural Resources (OMNR) received funding from the Canada-Ontario Agreement Respecting the Great Lakes Basin Ecosystem to conduct their own surveillance for VHS virus in inland waters. The OMNR-initiated surveillance was not part of the CFIA bilateral surveillance program. The DFO-VHSV National Reference Laboratory confirmed a positive result from a Largemouth bass (Micropterus salmoides) in the lower Thames River watershed. It is recommended that this watershed be sampled by CFIA in the fall of 2007.

  2. Disease outbreak investigations

    As part of the 2007 surveillance for VHS virus, the Ontario and Québec governments encouraged reporting of wild fish kills in their respective province and conducted disease investigations of fish kills. One (1) VHS virus-related Freshwater drum (Aplodinotus grunniens) die-off was reported in Ontario; the die-off occurred in Hamilton Harbour, Lake Ontario. Viral isolation and preliminary RT-PCR identification was conducted by the University of Guelph and confirmatory testing was conducted by the VHSV National Reference Laboratory at DFO-Pacific Biological Station, Nanaimo, BC. Lake Ontario is a known VHS virus-infected watershed and the isolation occurred in a previously identified susceptible species of fish.

Discussion

The following are definitions for classifying the sampled population of fish and the sampled watershed as positive for VHS virus, according to the bilateral national surveillance plan for Canada and the United States.

A. VHSV-Infected

  • Fish: A fish will be considered infected with VHS virus if a DFO laboratory, using accepted protocols, reports it positive for any strain of VHS virus by virus isolation on cell culture and subsequent confirmation by RT-PCR (reverse transcription-polymerase chain reaction). Initial positives from a new species, facility, compartment, or zone will require confirmatory identification by a Canadian Federal Reference Laboratory (DFO's Pacific Biological Station in Canada). All individual RT-PCR confirmed VHS virus isolates (or a sub-group if more than 3 positives are recovered from a single sampling event) will be identified to the genogroup and subgroup levels.
  • Watershed: A secondary or tertiary watershed will be considered infected with VHS virus if BOTH of the following conditions are met:
    1. Condition 1, laboratory evidence, is met if one (or more) fish collected from wild fish or cultured fish populations from any subunit in that watershed tests positive for VHS virus, unless the population is considered a compartment.1
    2. Condition 2, field evidence of VHS virus establishment, is met by one or more of the following:
      1. a second positive fish originates from a separate species or sampling event, OR
      2. gross pathology or histopathology is consistent with VHS disease in at least one test-positive fish (from disease outbreak investigations).

B. VHSV-Free

  • Watershed: Wild fish populations in a secondary or tertiary watershed will be classified VHS virus-free if surveillance is negative for VHS virus, and if biosecurity and ongoing surveillance are addressed. Conditions 1, 2 and 3 below must all be met.
    1. Condition 1, negative wild fish surveillance, is met if one or more of the following statements is true:
      1. Susceptible species are absent and there is no history of VHS virus occurrence.
      2. VHS virus risk, per expert-derived evaluation of contextual factors, is considered negligible.
      3. Two years of once a year (spring or fall) testing of fish populations from selected watershed subunits is negative for VHS virus.
      4. A Bayesian model combining field surveillance and risk factor evidence streams calculates the watershed probability of VHS virus infection 0.10.
    2. Condition 2, adequate biosecurity, is met if biosecurity conditions and disease reporting protocols to protect the watershed from new VHS virus introductions are documented, accepted by the Competent Authorities, and maintained.
    3. Condition 3, ongoing surveillance, is met if either of the following is true:
      1. Secondary watersheds comprising, crossing or abutting any defined geopolitical zone maintain a low-risk status.
      2. Wild fish surveillance (either test-based or validated Active Observational2 surveillance) is ongoing if the watershed is considered high-risk.

According to these definitions, VHS virus-positive tertiary watersheds in Canada include Lake Huron, St. Clair River, Lake St. Clair, Detroit River, Lake Erie, Niagara River, Lake Ontario and the St. Lawrence River west of the Moose Saunders Dam at Cornwall, ON. Fish were not sampled in these areas, except one population of White bass (Morone chrysops) in Lake Erie used to validate a rapid RT-PCR method for detection of VHS virus in future surveillance efforts. Results from these fish are not included in this surveillance report as the validation is on-going.

Negative test results indicate that we are 95% certain that less than 2% of the sampled populations of wild fish in this study would be infected with VHS virus if the virus was present. This finding indicates that we are reasonably certain that the sampled populations of fish were free of VHS virus. However, these findings cannot be used to make claims of freedom at the tertiary watershed level; the sampled watersheds cannot be said to be free of VHS virus.

For the next sampling period more information will be collected on important risk factors for VHS virus infection of a watershed to help with interpretation of the test-based surveillance results. CFIA and USDA are currently conducting an expert-derived evaluation of risk factors for VHS virus infection at the watershed level; the results of the evaluation along with surveillance results in each watershed will be used to calculate an estimate of the probability of infection. Thereafter, results from each surveillance period will be used to update the probability of infection for each tertiary watershed. These probabilities will be reported in future reports. For example, it is expected that the probability of VHS virus infection for the St. Lawrence River east of the Moose Saunders Dam or east of the Beauharnois Dam will decrease because these dams serve as barriers to fish movement.

The probability of VHS virus infection for a watershed will determine the amount of sampling that will be required in the future in order to declare a watershed free of the virus. Consultation between AAHD-CFIA and watershed stakeholders will determine if this objective will meet the needs of fish disease control and fish trade requirements.

References

Einer-Jensen K, Ahrens P, Forsberg R, Lorenzen N. 2004. Evolution of the fish rhabdovirus viral haemorrhagic septicaemia virus. Journal of General Virology 85: 1167-1179.

Elsayed E, Faisal M, Thomas M, Whelan G, Batts W, Winton J (2006) Isolation of viral haemorrhagic septicaemia virus from muskellunge, Esox masquinongy (Mitchill), in Lake St Clair, Michigan, USA reveals a new sublineage of the North American genotype. Journal of Fish Diseases 29:611-619.

Gagné N, MacKinnon A-M, Boston L, Souter B, Cook-Versloot M, Griffiths S, Olivier G. 2007. Isolation of viral hemorrhagic septicemia virus from mummichog, stickleback, striped bass and brown trout in eastern Canada. Journal of Fish Diseases 30: 213-223.

Snow M, Bain N, Black J, Taupin V, Cunningham CO, King JA, Skall HF, Raynard RS. 2004. Genetic population structure of marine viral haemorrhagic septicaemia virus (VHSV). Diseases of Aquatic Organisms 61: 11-21.


1 One or more fish culture facilities under a common biosecurity management system containing an aquatic animal population with a distinct health status with respect to a specific disease or diseases for which required surveillance and control measures are applied and basic biosecurity conditions are met for the purpose of international trade. Such compartments must be clearly documented by the Competent Authority. In Canada, the OIE-recognized Competent Authority is the CFIA.

For the purposes of this surveillance plan, a compartment is a fish culture facility with the following characteristics:

  1. Biosecurity (i.e., separation from the environment)
  2. Protected water source (ground or treated surface water if in a positive zone)
  3. Equipment, personnel and vessel cleaning/disinfection practices
  4. Movement controls (continued in the footnotes on page 7)
  5. A documented health program
  6. Management practices with documented standard operating procedures, and
  7. Association with a licensed veterinarian or experienced (> 1 year) fish health practitioner

2 Active observational surveillance is the process of actively and systematically looking for diseased animals by a knowledgeable individual, on a frequent, pre-planned, and ongoing basis, where a predefined plan of action is implemented when affected animals are discovered. For more details, see "Surveillance Proposal for Viral Hemorrhagic Septicemia Virus In Freshwater Fish in Canada and the United States, Version 1.0" (available upon request from the Aquatic Animal Health Division, CFIA).


Table 1: Qualitative evaluation for risk of VHS virus infection of tertiary watersheds in the Great Lakes Basin, including the St. Lawrence River (up to its tidal limit). These watersheds are located in Ontario and Québec. A risk of 'high' denotes that the tertiary watershed has a direct connection to positive watersheds. A risk of 'medium' indicates that the watershed has no direct connection to a positive watershed but has received large volumes of live bait fish from positive waters in the past. A risk of 'low' indicates that there is no direct connection to positive waters and the watershed has not knowingly received large volumes of live bait fish. Watershed codes and names were derived from the National Scale Frameworks Hydrology - Drainage Areas, Canada database [http://geogratis.cgdi.gc.ca/geogratis/en/option/select.do?id=27730].

Province of Québec
Secondary Watershed Code Number Tertiary Watershed Code Number Name Risk of VHSV Infection
154 821 Lower St. Lawrence - du Loup Low
154 911 Etchemin Low
154 944 Chaudière Low
154 967 Bécancour Low
154 946 Lower St. Lawrence - du Chêne Low
154 900 Batiscan Low
154 912 Sainte-Anne Low
154 888 Jacques-Cartier Low
154 891 Montmorency Low
154 859 Lower St. Lawrence - Gouffre Low
154 807 Malbaie Low
156 839 Headwaters Saint-Maurice Low
156 833 Upper Saint-Maurice Low
156 907 Manouane Low
156 955 Matawin Low
156 918 Vermillon Low
156 854 Central Saint-Maurice Low
156 934 Lower Saint-Maurice Low
170 977 Nicolet Low
170 984 Lower Saint-François Low
170 974 Upper Saint-François Low
170 988 Yamaska Low
170 1003 Lake Champlain Low
170 989 Richelieu Low
170 1002 St-Lawrence - île de Montréal Low
170 968 St-Lawrence - du Loup - Lac Saint-Pierre Low
170 980 L'Assomption Low
165 932 Upper Ottawa-Kinojévis Low
165 929 Upper Ottawa - Headwaters Low
163 913 Upper Gatineau Low
163 936 Upper Lièvre Low
163 966 Rouge and Nord Low
163 991 Petite Nation Low
163 995 Lower Lièvre Low
163 987 Lower Gatineau Low
167 981 Dumoine Low
167 979 Coulonge Low
167 990 Noire Low
167   St. Lawrence River east of Moose Saunders Dam High

 

Province of Ontario
Secondary Watershed Code Number Tertiary Watershed Code Number Name Risk of VHSV Infection
157 994 Pigeon Low
157 964 Dog Low
157 952 Black Sturgeon Low
157 860 Nipigon Low
157 954 Jackpine Low
164 939 Little Pic Low
164 921 Pic Low
164 951 White Low
164 970 Michipicoten-Magpie Low
164 996 Agawa Low
164 1006 Goulais Low
176 1026 Garden High
176 999 Upper Mississagi Low
176 1013 Lower Mississagi High
176 1017 Serpent High
176 998 Spanish High
176 1001 Vermillion Low
176 1027 Killarney High
177 1037 Manitoulin Island High
177 1035 Magnetewan High
177 1022 Muskoka High
177 1033 Severn-Lake Simcoe High
177 1042 Nottawasaga High
168 997 Upper Wanapitei Low
168 992 Sturgeon Low
168 1012 Lower Wanapitei High
168 1008 French High
165 972 Montreal Low
165 960 Blanche Low
165 983 Upper Ottawa-Kipawa Low
167 1004 Central Ottawa-Dumoine Low
167 1014 Petawawa Low
167 1010 Central Ottawa-Bonnechere Low
167 1020 Upper Madawaska Low
167 1019 Lower Madawaska Low
163 1016 Central Ottawa-Mississippi Low
163 1007 Lower Ottawa-South Nation Low
163 1015 Rideau Medium*
172 1029 Cataraqui High
181 1028 Gull Low
181 1036 Kawartha Lakes Medium
181 1046 Scugog Medium
181 1041 Otonabee Medium
181 1047 Ganaraska High
181 1030 Trent High
181 1031 Moira High
181 1032 Napanee High
181 1044 Picton High
181 1049 Humber-Don High
181 1052 Credit-16 Mile High
181 1056 Niagara High
180 1045 Southwest Georgian Bay High
180 1040 Bruce Peninsula High
180 1048 Saugeen High
180 1051 Penetangore High
180 1053 Maitland High
180 1058 Ausable High
182 1068 Cedar High
182 1063 Lower Thames High**
182 1064 Sydenham High
182 1066 Rondeau High
182 1054 Upper Thames Low
182 1062 Big High
182 1057 Lower Grand High
182 1050 Upper Grand Low
182 973 Lake Superior High
182 1023 Connection between Lakes Superior and Huron High
182 1021 Lake Huron Positive
182 1065 St. Clair River Positive
182 1067 Lake St. Clair Positive
182 1069 Detroit River Positive
182 1060 Lake Erie Positive
182 1061 Upper Niagara River Positive
182 1055 Lower Niagara River Positive
182 1043 Lake Ontario Positive
182 St. Lawrence River west of Moose Saunders Dam Positive

* There is a direct connection with Lake Ontario through a lock system with high boat traffic (Rideau Canal Waterway).

** One positive fish was identified in the Lower Thames watershed through a sampling scheme conducted by the Ontario Ministry of Natural Resources and confirmed by the DFO-VHSV National Reference Laboratory.


Table 2: List of watersheds and fish species tested in Ontario and Québec in the spring of 2007.

Province of Québec
Sampling Site - Watershed Fish species (number tested) Date Sampled Fish Collection Method
Lac St. François - St. Lawrence River Yellow perch (173)
Perca flavescens
May 7/07 Seine
Lac St. Louis - St. Lawrence River Yellow perch (170)
Perca flavescens
May 14/07 Seine
Gentilly (Bécancour) - St. Lawrence River Yellow perch (190)
Perca flavescens
May 14/07 Seine

 

Province of Ontario
Sampling Site - Watershed Fish species (number tested) Date Sampled Fish Collection Method
Lake Scugog - Scugog Yellow perch (85)
Perca flavescens
Spottail shiner (85)
Notropis hudsonius
May 6/07 Minnow traps
Lake Simcoe - Severn- LakeSimcoe Emerald shiner
Notropis atherinoides
Yellow perch
Perca flavescens
May 6/07
Not tested*
NA**
Lake Nipissing - French Brown bullhead (147)
Ictalurus nebulosus
Northern pike (2)
Esox lucius
Largemouth bass (10)
Micropterus salmoides
Pumpkinseed (12)
Lepomis gibbosus (3)
Rock bass (4)
Ambloplites rupestris
May 14 and 15/07 Trap nets
Big Creek - Big Emerald shiners (140)
Notropis atherinoides
Yellow perch (14)
Perca flavescens
Northern pike (12)
Esox lucius
Freshwater drum (2)
Aplodinotus grunniens
Rock bass (4)
Ambloplites rupestris
Bluegill (6)
Lepomis macrochirus
May 28/07 Electrofishing

 


* Fish from Lake Simcoe were not tested because shipping problems delayed the arrival of the fish to DFO laboratories. Laboratory personnel determined the fish were in an advanced state of deterioration and were not suitable for testing.

** Fishing method is not available.