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Farm and Home Biosecurity
Consumer/General Public and Livestock/Row Crop Producer
SVCV and Arkansas Fish Production
The Politics and History of SVCV
The Spring Viremia of Carp (SVC) virus (SVCV) has never been found in
Arkansas, however, the recent discovery of SVCV on a fish farm in North Carolina
and in the wild fish of Wisconsin may complicate selling and moving cyprinid
fish within the US. There are two reasons that SVCV will have such a great
impact. First, it is one of the top 5 most heavily regulated fish viruses in the
world. When SVCV is reported in a new country or region, it activates disease
control and eradication bureaucracy both in the US and internationally.
Secondly, the reason that SVCV ended up on the top 5 fish viruses list is
because it is a nasty virus with the potential to inflict high mortality on
infected fish populations. In order to minimize the impact of SVCV on Arkansas
fish producers, it may be critical for farmers to take proactive steps to
convince regulatory agencies and customers that Arkansas fish are completely
safe and superior to wild fish in environmental impact and safety.
In order to explain why SVCV is so important, we need to look at
international laws, state laws, and the biology of SVCV. The SVC virus has been
a significant problem in Europe for centuries. Its primary impact has been on
cultured common carp. In Europe, SVCV has not been implicated in deaths of wild
fish. The virus is known to kill a variety of cultured fish including cyprinids
like common carp, koi, grass carp, and goldfish. It has also been reported to
kill the European Wels catfish (the "sheatfish") and, in a Hawaiian outbreak,
marine shrimp. Additionally there are other reports involving experimental
infections of a diverse group of fish species. There has been very little work
done on the sensitivity of North American fishes to SVCV, however, the European
experience would indicate that the virus is probably capable of infecting many
cyprinid fish.
In North America, SVCV was first discovered in the spring of 2002. The
University of Arkansas at Pine Bluff Fish Disease Diagnostic Laboratory was
called in to investigate the cause of koi carp losses on a North Carolina farm.
Several lots of those fish were positive for SVCV. Since then, it has been
discovered in fish from a major carp kill in Cedar Lake Wisconsin. Additional
surveys completed since that time have implicated SVCV in fish kills in other WI
waters. The WI outbreaks have no association with aquaculture and, since they
happened in wild fish, represent a departure from the behavior of the disease in
Europe.
Because the SVCV in North America and Wisconsin represented the first
isolations of this exotic virus on our continent, its discovery triggered a lot
of national and international activity. The isolation had to be reported to the
USDA-APHIS and that agency had to report to the OIE. APHIS is responsible for
controlling the movement of animal and plant diseases within the US and across
our international borders. The OIE is an international organization that
publishes guidelines for dealing with international movements of animal
diseases. That organization does not make laws or regulations, but agreements to
follow OIE guidelines are critical parts of international agreements on trade.
In the case of SVCV, the OIE designates an international reference lab,
describes appropriate diagnostic procedures, issues guidelines for defining what
an SVCV-free some might be, and keeps track of where SVCV is present. The US was
an SVCV-free zone. Therefore, APHIS was required to report that we now have SVCV.
Our trading partners will decide how to react to that news. APHIS is responsible
for deciding how to handle the outbreak on the fish farm (ignore, quarantine, or
eradicate) and to work with USFWS and state authorities on a plan to deal with
SVCV in the wild.
If APHIS decides to eradicate SVCV from commercial aquaculture, a part of
that eradication plan may include disease inspection requirements governing the
movement of fish within the US and across international borders. This may mean
additional hassle for farmers moving fish and will provide some impetus for
individual states to revise their import requirements.
SVC; the Disease
SVC multiplies in fish during the winter, and then kills fish in the spring
as the water warms. It is possible for outbreaks to occur in the fall if
temperature patterns are right. The most likely temperature range for SVC fish
kills is 15-20 C (60-70 F). Fill kills occurring at temperatures greater than 70
F are not likely to be SVC. Fish infected with SVCV look a lot like fish with
other bacterial or parasitic diseases and do not serve as useful indications
that the disease is present. Typical signs are swollen abdomen, red patches on
the skin, and red spots on the swim bladder. When temperatures are right,
mortality may be very high.
Preventing SVC Problems
The only way to prevent SVCV problems is to avoid introducing the virus. A
previous article in Arkansas Aquafarming (also published on the web at http://www.aragriculture.org/biosecurity/producer/fish_farms.htm)
detailed "biosecurity" measures that will prevent the introduction of SVCV. It
is clear that any new fish, especially carp or koi, are potential source of the
virus. Equally important, the recent outbreaks in Wisconsin have made it even
more clear that surface water supplies are risky and that well water and water
recycled within a farm are far safer. The best news for Arkansas is that the
consensus of European SVCV experts is that the virus is unlikely to survive for
long periods in the southern US where summer water temperatures are high. If
that is correct, then virus introduced in the fall might propagate through the
winter and kill fish in the spring, but it is unlikely to survive through the
summer. The problems with SVCV in Wisconsin may be related to the cooler
climate. Lower temperatures may also have played a role in the North Carolina
outbreak as much of the water used by the farm was drawn from coolwater streams.
This is very encouraging for the Arkansas industry that is well isolated from
cool water but should in no way be regarded as a guarantee that we won’t have to
face SVCV problems. Remember, SVCV has already behaved differently in Wisconsin
than in Europe.
Dealing With SVCV-Related Regulation Of Fish Movements.
It is likely that many states will require some sort of SVCV certification of
fish to be imported. A lot by lot inspection is possible, but given that SVCV
virus cannot be found in the summer when it is hot and that lot inspections are
cumbersome and less reliable, it makes sense to use farm certifications instead.
The UAPB Fish Disease Diagnostic Program has been approved by APHIS to inspect
farms for SVCV since 1996. Under this program, an APHIS-approved veterinarian
visits the farm twice a year and supervises the collection of a sample of 150
fish. This sample is sent to UAPB where we inspect it for fish viruses (due to
the expense of this procedure, we do charge for this service). If the results
are negative, we report that to the farm, the veterinarian, and APHIS. For the
next 6 months, the farmer can obtain official USDA paperwork saying that their
farm has been found to be free of SVCV and other viruses. The main goal of this
program is international export; however, many farms have found that the
certification is an advantage for interstate shipping too. One Arkansas farm has
been inspected twice a year since 1996 and was in an excellent marketing
position following the report of SVCV in North Carolina. At least 7 additional
farms have joined the program this fall. In the event that a farm is confirmed
to be positive for SVCV, we would notify APHIS and decisions regarding future
fish movements would be up to them.
It is not yet clear that the APHIS inspection program will meet all of the
requirements of future state regulations, however, a history of farm inspections
is a powerful tool for negotiations with customers and regulators. It may also
play a valuable role in a more comprehensive bait certification program that
might include viruses, exotic fish species, zebra mussels, and invasive aquatic
plants. There is no doubt that farm-raised fish are superior to wild-caught even
if the only consideration is the impact of removing large numbers of the fish
from the wild. Perhaps the time has come to document and market the important
health and exotic species advantages of the farm raised product.
Farmers that are interested in beginning farm inspections for SVCV should
contact Andy Goodwin at the UAPB Disease Laboratory (1-870-543-8137,
agoodwin@uaex.edu). Those concerned about
future interstate regulations or interested in talking about a baitfish
certification program should contact Eric Park, President of the Arkansas Bait
and Ornamental Fish Growers Association (1-501-231-8607).
Dr. Andy Goodwin
University of Arkansas at Pine Bluff
Fish Disease Diagnostic Laboratories
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