Subject Oriented Sessions

1:00 - 2:30 p.m. Tuesday, November 9, 2004

1. Sturgeon Health and Contaminants
2. Utilization of GIS Technology for Sturgeon Rehabilitation
3. Habitat Suitability / Classification
4. Sturgeon Passage/Hydropower Operation
5. Issues and Problems as Sturgeon Populations Rebuild
6. Habitat Restoration and Enhancement

Subject Oriented Session: Sturgeon Health and Contaminants

Introductions:
The session began with a round of self-introductions and identification of topics for discussion.

Topics covered:
- Botulism
- Contaminant exposure, loadings and effects on fish
- Human consumption concerns due to contaminants
- Viral and bacterial disease and parasites.

Participant List:
Doug Aloisi, Doug Carlson, Rob Elliott (facilitator), Alexandre Litvinov, Perry McLeod-Shalougesic, Rob Mellow

Discussion Summary:
Botulism

The group discussed the recent reports and observations of botulism related mortalities of lake sturgeon around the Great Lakes. Doug Carlson gave a Powerpoint presentation on the botulism related sturgeon mortalities observed in Lakes Ontario and Erie. Elevated incidence of sturgeon mortalities were observed in Lake Erie beginning in 1999 when Type E botulism was implicated in the die-off of numerous water birds, including loons, as well as several species of fish, including lake sturgeon. In New York waters of Lake Erie, reported lake sturgeon mortalities rose from 2 in 1999 to 8 in 2000, and 27 in 2001, and then declined to 3 in 2002 and then 1in 2003. In Lake Ontario, a similar trend was observed from 2002-2004 when 6, 27 and 6 dead sturgeon reported. The timing of an apparent increase in mortalities was similar in Green Bay were 6, 23, and 8 dead sturgeon were reported in 2002, 2003 and 2004.

Botulism is presumed to be the cause of most of these mortalities though it has only been confirmed in a few specimens. The advanced stage of decomposition of most recovered fish precludes verification that botulism was the cause of death. Type E botulism is caused by exposure to the bacterium Clostridium botulinum which grows in oxygen-deficient nutrient rich environments. Increased growth of the filamentous alga Cladophora glomerata, colonization by zebra and quagga mussels, and invasion of round goby, and the combined effect on water quality and contribution to the food chain are all thought to be involved in this recently observed increase in botulism outbreaks. The reason for the declines observed are unclear but may be related to decreased abundance of various species vectors but could possibly be related to environmental conditions.

Contaminants

Data describing contamination of lake sturgeon is limited but enough data exist to indicate that body burden levels vary greatly across the basin. Consumption advisories also vary significantly across the basin. In some waters such as Green Bay, observed contaminant levels can be extremely high and fish are under a “do not eat” advisory. Contaminant levels in other areas such as Lake St. Clair appear to be fairly low and advisories do not call for restricted consumption. However, due to the observed highly migratory behavior of these fish, the limited human consumption of lake sturgeon that does exist in various areas throughout the basin may result in very unsafe exposures due to the unknown contamination of any one fish.

Information on the effects on lake sturgeon due to contaminant exposure and/or uptake also is limited. It was suggested during our discussion that the Russian literature may have more information than is available in North America and a comprehensive literature review may be beneficial. Doyon et al. (Can. J. Fish. Aquat. Sci. 56:1428-1436, 1999) reports increased fin and craniofacial malformations consistent with possible chemical contaminant effects. Metal uptake due to exposure from mining operations is another concern and is the focus of some research and monitoring being conducted on the Groundhog River, near Timmins, Ontario. The question of contaminants being involved in observed variable hatching success often experienced when collecting gametes from the wild was also raised. However, definitive data is lacking and numerous other factors could also be involved. The need to conduct contaminant effect studies was identified. The question of how important contaminant transport up into tributaries by species like Pacific salmon was raised.

Viral and Bacterial Diseases and Parasites

Iridovirus was apparently a hot topic a few years ago but current status is unknown. There is a need to find out more about how the virus manifests itself in lake sturgeon. Sampling is being done and requires only the collection of small fin tissue samples. Screening for this and other viral and bacterial diseases (furunculosis, enteric redmouth, IPN, IHN, etc.) are conducted on cultured sturgeon following standard protocols at federal hatcheries. The La Crosse and Bozeman USFWS fish health labs are capable of conducting the necessary tissue histology. The question was raised as to the prevalence of parasites such as Arqulus (fish lice) in sturgeon. Little was known by the group but it was thought this was probably more common in other fish species.


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