1:00 - 2:30 p.m. Tuesday, November 9, 2004
1. Sturgeon Health and
2. Utilization of GIS Technology for
3. Habitat Suitability / Classification
4. Sturgeon Passage/Hydropower
5. Issues and Problems as
Sturgeon Populations Rebuild
6. Habitat Restoration and Enhancement
Oriented Session: Sturgeon Health and Contaminants
The session began with a round of self-introductions
and identification of topics for discussion.
- Contaminant exposure, loadings and effects on fish
- Human consumption concerns due to contaminants
- Viral and bacterial disease and parasites.
Doug Aloisi, Doug Carlson, Rob Elliott (facilitator),
Alexandre Litvinov, Perry McLeod-Shalougesic, Rob Mellow
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.
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
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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