A telephone survey of eel fishermen regarding external lesions and mortalities of American eels (Anguilla rostrata) from Lake Ontario and the St. Lawrence River basin, Canada

1997 ◽  
Vol 31 (1-2) ◽  
pp. 33-49 ◽  
Author(s):  
Lucie Dutil ◽  
Denise Bélanger ◽  
Catherine M Couillard
Keyword(s):  
River Basin ◽  
Telephone Survey ◽  
Lake Ontario ◽  
Anguilla Rostrata ◽  
American Eels ◽  
St Lawrence River

Distinction between American Eels (Anguilla rostrata) of Different Geographic Origins on the Basis of Their Organochlorine Contaminant Levels

1989 ◽  
Vol 46 (5) ◽  
pp. 836-843 ◽  
Author(s):  
Martin Castonguay ◽  
Jean-Denis Dutil ◽  
Claude Desjardins
Keyword(s):  
Lake Ontario ◽  
Anguilla Rostrata ◽  
Fish Tissues ◽  
Environmental Distribution ◽  
Stock Discrimination ◽  
Geographic Origins ◽  
Organochlorine Contaminants ◽  
Organochlorine Contaminant ◽  
American Eels ◽  
St Lawrence River

This study presents evidence that organochlorine contaminant levels of fish tissues represent a valuable tool for stock discrimination. Variability of concentrations of 15 organochlorine contaminants allowed a discrimination among American eels (Anguilla rostrata) of unknown (captured during the migration down the St. Lawrence River) or known geographic origins. The study also exemplifies that information regarding environmental distribution of contaminants can be gained by comparing organic contaminant levels among groups of fish. Indeed we can infer from this study that mirex contaminated sediments have extensively (at least 400 km) drifted downstream from Lake Ontario in less than 19 yr.

Why Is Recruitment of the American Eel, Anguilla rostrata, Declining in the St. Lawrence River and Gulf?

1994 ◽  
Vol 51 (2) ◽  
pp. 479-488 ◽  
Author(s):  
M. Castonguay ◽  
P. V. Hodson ◽  
C. M. Couillard ◽  
M. J. Eckersley ◽  
J.-D. Dutil ◽  
...  
Keyword(s):  
Anguilla Rostrata ◽  
Commercial Fishing ◽  
Hydroelectric Dams ◽  
Chemical Contamination ◽  
The Past ◽  
Silver Eels ◽  
High Prevalence ◽  
American Eels ◽  
Reference Stock ◽  
St Lawrence River

We critically review four potential causes of a drastic decline in juvenile American eels, Anguilla rostrata, recruiting to Lake Ontario (81-fold decline from 1985 to 1992) and in juvenile eel densities in tributaries to the Gulf of St. Lawrence. Silver eels from the St. Lawrence River were much more contaminated and had a high prevalence of deformities and lesions than a reference stock although they were on average less contaminated in 1990 than in 1982 (1.12 versus 4.54 μgg−1 for PCB; 0.025 versus 0.07 μg∙g−1 for mirex). Lethal toxicity from chemical contamination has been known to occur in St. Lawrence River eels for the past 25–30 yr. Major habitat modifications in the St. Lawrence took place in the 1950's (St. Lawrence Seaway and hydroelectric dams), about 30 yr before recruitment started declining; this long delay argues against these perturbations being primary causes of the decline. There is little evidence that commercial fishing and oceanographic changes caused the decline. Overall, we conclude that we do not know what caused the pronounced recruitment decline. We propose research avenues and hypotheses that may advance understanding and emphasize that because of panmixia, the recruitment decline could be species wide.

Correlations between pathological changes and chemical contamination in American eels, Anguilla rostrata, from the St. Lawrence River

1997 ◽  
Vol 54 (8) ◽  
pp. 1916-1927 ◽  
Author(s):  
C M Couillard ◽  
P V Hodson ◽  
M Castonguay
Keyword(s):  
Anguilla Rostrata ◽  
Chemical Contamination ◽  
Pathological Changes ◽  
Preneoplastic Lesions ◽  
Biomarkers Of Exposure ◽  
Reproductive Impairment ◽  
Migratory Season ◽  
American Eels ◽  
The Relationship ◽  
St Lawrence River

American eel (Anguilla rostrata) from the St. Lawrence River are heavily contaminated with chemicals that may be associated with increased incidence of diseases and reproductive impairment. The relationship between tissue mirex concentration and body mass was used to separate eels into two groups: the proportion of eels migrating from contaminated areas (Lake Ontario and upper St. Lawrence River) increased as the migration season progressed. Vertebral malformations and basophilic foci in the liver (preneoplastic lesions) were more frequent at the end of the migratory season, when the eels were more heavily contaminated with organochlorine compounds. In contrast, mesenteric nematodes were more common in the first week of the season, when eels were less contaminated. Diameters and percentages of different stages of oocytes, and density and surface area of pigmented macrophage aggregates in the spleen, did not vary among weeks. While basophilic foci are specific biomarkers of exposure to environmental contaminants, vertebral malformations may be caused by a variety of other anthropogenic or natural factors.\b Further studies are needed to confirm the observed associations between chemical contamination and pathological changes.

Spatial and Temporal Variations in Chemical Contamination of American Eels, Anguilla rostrata, Captured in the Estuary of the St, Lawrence River

1994 ◽  
Vol 51 (2) ◽  
pp. 464-478 ◽  
Author(s):  
P. V. Hodson ◽  
M. Castonguay ◽  
C. M. Couillard ◽  
C. Desjardins ◽  
E. Pelletier ◽  
...  
Keyword(s):  
Temporal Variations ◽  
Polynuclear Aromatic Hydrocarbons ◽  
Delphinapterus Leucas ◽  
Anguilla Rostrata ◽  
Chemical Contamination ◽  
Reference Sites ◽  
Beluga Whales ◽  
Pcb Congeners ◽  
American Eels ◽  
St Lawrence River

Levels of polychlorinated biphenyls (PCBs), mirex, and pesticides were 10–100 times higher in migratory adult American eels, Anguilla rostrata, sampled at Kamouraska, Quebec, in 1990 than in eels from an uncontaminated reference tributary; concentrations in eels within the estuary varied little among sites. In contrast, mercury levels were the same at estuarine and reference sites, suggesting natural sources or atmospheric deposition of mercury. Dioxins, furans, and polynuclear aromatic hydrocarbons were virtually absent at all sites. During the 7 wk of migration, levels of PCBs, mirex, and pesticides in eels increased, while mercury did not. Since 1982, levels of PCBs and mirex have declined by 68 and 56%, respectively, and the percentage of eels exceeding human health guidelines for PCBs and mirex was about twofold lower in 1990 than in 1982. Levels of other pesticides have also declined, except that dieldrin is unchanged since 1982. While chemical concentrations are declining, levels of specific, highly toxic PCB congeners are sufficiently high that eel consumption by beluga whales (Delphinapterus leucas) is still likely to be hazardous. The hazard to the eels themselves is unknown due to a scarcity of toxicity data, but the highest concentrations of chemicals were observed in gonads.

The migration of stocked, trapped and transported, and wild female American silver eels through the Gulf of St. Lawrence

2018 ◽  
Vol 75 (11) ◽  
pp. 2024-2037 ◽  
Author(s):  
Mélanie Béguer-Pon ◽  
Guy Verreault ◽  
David Stanley ◽  
Martin Castonguay ◽  
Julian J. Dodson
Keyword(s):  
Detection Efficiency ◽  
Anguilla Rostrata ◽  
Migration Speed ◽  
Hydroelectric Dams ◽  
Wild Female ◽  
Swimming Depth ◽  
Silver Eels ◽  
Diel Vertical Migrations ◽  
American Eels ◽  
St Lawrence River

The stocking of juvenile eels and trap and transport programs of large yellow (American) eels (Anguilla rostrata) were initiated in Ontario to mitigate mortalities observed at hydroelectric dams and to increase escapement from the upper St. Lawrence River and Lake Ontario (Canada). A total of 380 migrating female silver eels (stocked, trapped and transported, and wild) were tagged with acoustic transmitters between 2011 and 2014. Their migration and escapement at the exit of the Gulf of St. Lawrence, the Cabot Strait, were recorded using acoustic receivers. Escapement rates varied between 8.9% and 20.0% annually (mean = 11.4%). A high proportion of stocked eels were detected (N = 27 of 43 detected at Cabot Strait), demonstrating their ability to escape the Gulf. No differences in migration speed or crossing locations at Cabot Strait were found among the three categories. Eels crossing Cabot Strait did not display diel and tidal patterns, but their estimated swimming depth indicated diel vertical migrations. The low escapement rates observed may be related to predation events and (or) the low and variable detection efficiency of the acoustic receivers’ line.

Eels at the Edge: Science, Status, and Conservation Concerns

2009 ◽  
Keyword(s):  
Aquatic Ecosystem ◽  
Sustainable Management ◽  
Management Practices ◽  
Lake Ontario ◽  
Abundant Species ◽  
Fishing Effort ◽  
Anguilla Rostrata ◽  
American Eel ◽  
Commercial Species ◽  
St Lawrence River

<em>Abstract.</em>—The American eel <em>Anguilla rostrata </em>is an important component of the aquatic ecosystem of Lake Ontario and the upper St. Lawrence River and historically has been one of the most valuable commercial species in Ontario waters of this system. Between 1984 and 1993, reported annual harvest ranged from 104 to 124 metric tons. Since 1993, eel harvests have declined precipitously in all areas above the Moses-Saunders Power Dam in spite of an increase in price per kg. During 2002, fishers held 85 eel licenses and harvested 12 metric tons (mt) of maturing yellow eel, mostly with hoop nets and trap nets. The numbers of eels migrating into this system in recent years suggests that if fishing effort remains constant, commercial harvests in areas above the dam will be under 3 mt per year between now and 2010. Provincial management programs have imposed license and season restrictions, reduced quotas, and more detailed catch reporting. Sustainable management practices throughout the range of this panmictic species will be required to restore the eel as an abundant species in Lake Ontario and the upper St. Lawrence River.

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