Ministry of
Natural Resources
Upper Great Lakes Management
Unit 1450 Seventh Avenue East Owen Sound, ON N4K 2Z1
Tel: (519) 371-5924 Fax:
(519) 371-5844
November 25, 2003
Ministere des Richesses naturelles
Unite de gestion du secteur
superieur des Grands Lac 1450, avenue Seventh Est
Owen Sound (Ontario) N4K
2Z1
Mr. Blake Smith
Grey-Bruce Conservation
Coalition 904 6th Ave. West, Owen Sound, Ont. N4K 5G4
Dear Mr. Smith
Thank you for your letter
of November 3, 2003 regarding Mr. Choronzey's October 22, 2003 article,
in the Owen Sound Sun Times. In the article Mr. Choronzey suggested that
the fin clipping of stocked chinook salmon has precipitated the collapse
of the recreational fishery on the Canadian side of Lake Huron.
As you know, the stocking
of salmon into Lake Huron commenced in the late 1960's by the State of
Michigan. It was not until the mid 1980's that Community Fisheries and
Wildlife Involvement Program (CFWIP) clubs in Ontario began stocking Ontario
waters. Since then over 90 million salmon have been stocked into Lake Huron
(see enclosed figure). It soon became apparent that these salmon adapted
readily to the conditions in Lake Huron. Fall spawning salmon were observed
in several tributaries to both the main basin and Georgian Bay before any
were stocked in Ontario waters. In 1986, naturally reproduced young of
the year were captured from 3 Georgian Bay tributaries and by 1987, 1,354
naturally reproduced juvenile chinook salmon were captured at a fish weir
on the Pottawatomi River near Owen Sound.
Given their potential for
natural reproduction and their ability to consume large numbers of forage
species, such as alewife and smelt, fisheries managers in both the United
States and Canada identified a need to improve our understanding of the
biology of salmon. The collapse of the Lake Michigan chinook salmon population
in the 1980s, as a result of over consumption of available forage, served
to highlight concerns related to stocking numbers. These concerns were
shared with Ontario angling club representatives at workshops in 1998 and
2000. As you know, there was strong support for improving our understanding
of the balance between predator stocking and forage availability and agreement
that stocking numbers should be controlled. There was also agreement that
more information on level of natural reproduction of salmon was needed
and that lake trout should also be considered with respect to the number
of predators stocked.
The Great Lakes Fishery Commission's
Lake Huron Committee discussed the matter of chinook stocking and in 1999
charged the Lake Huron Technical Committee (LHTC) to develop a study plan
to address this issue. The LHTC, which is comprised of biologists and scientists
from provincial, state, and federal departments in Michigan and Ontario,
developed a plan and the study was initiated in Ontario waters in 1999.
This study is being implemented through a partnership between the Ontario
Ministry of Natural Resources, the Michigan Department of Natural Resources,
the Chippewa Ottawa Resource Authority, and Ontario Community Fisheries
and Wildlife Involvement Program (CFWIP) clubs/hatcheries.
Prior to initiating this
study the LHTC evaluated several different options for marking salmon.
Options considered included fin clipping, Oxytetracycline (OTC) marks,
coded wire tags, and thermal marks. Since Health Canada has prohibited
the use of OTC, a common antibiotic, to mark fish until very recently this
was not an option in Ontario. Coded-wire tags (very small pieces of numbered
wire injected into the snout of young fish) are- often used to gather information
on stocked fish, however, with between 750,000 to 800,000 chinook salmon
stocked annually in Ontario and 2.5 to 3.8 million stocked by Michigan,
this method was deemed cost prohibitive. The use of thermal marks (a method
of heat stressing fish to leave identifiable marks on scales and other
bony tissues) poses a number of logistical challenges associated with adjusting
hatchery water temperatures.
Further, in order to assess
the relative merits of different marking techniques Ministry biologists
surveyed other jurisdictions across the Great Lakes. A study, very similar
to this one, where all stocked were fin clipped, was conducted on Lake
Superior in the late 1980's and early 1990's. No changes in salmon abundance
were observed and the fishery did not collapse. The states of Minnesota
(Lake Superior), Wisconsin (Lake Michigan) and New York (Lake Ontario)
are all currently using fin clipped chinook salmon to identify wild and
naturally reared fish or are experimenting with this marking technique.
The state of Wisconsin has recently advised that they are now contemplating
fin clipping all of their stocked chinook salmon, rather than continuing
to use coded wire tags.
On the U.S. side of Lake
Huron, chinook salmon were marked from 1999 to 2003 with OTC. OTC leaves
a mark in bony structures (namely vertebrae) in fish that is visible under
an ultraviolet light. This marking technique not only requires that the
salmon be killed to extract vertebrae, for examination, it also incurs
higher costs, since it necessitates a considerable amount of work to prepare
the sample and read it in the laboratory. Fin clipping was not used by
Michigan due to logistical problems associated with stocking 2.5 to 3.8
million salmon annually, and not as a result of concerns related to higher
mortalities.
Fin clipping has been used
by resource managers to gather information on stocked fish for decades.
The removal of a fin can provide scientists with valuable information on
movement, survival, and growth of stocked fish. For example, all lake trout
stocked into Lake Huron by the U.S. and Ontario are fin clipped. The information
from these clips has been used to track stocked fish, assess survival to
attacks by sea lamprey, and evaluate progress towards rehabilitation objectives.
A number of benefits associated with the use of fin clipping as a marking
method have been identified. These include the fact that fish do not need
to be killed to determine their origin and assessment is very rapid (i.e.
no laboratory analysis is required compared to coded wire tags, OTC, and
thermal marks). In the case of this study, fish were monitored for several
weeks after fin clipping and no unusual mortalities were observed prior
to stocking.
There are risks associated
with many aspects of fisheries management. It is generally accepted that
there is greater risk with increased uncertainty. In this case, the uncertainty
associated with natural recruitment was considered significant and therefore
so was the risk. Stress can be imposed on a fish community through factors
such as harvesting, habitat loss, invasion by exotic species, pollution,
and climate change. Resource managers are challenged to address these and
other potential stresses with a tool kit that includes the regulation of
harvest and gear type, habitat rehabilitation, species recovery plans,
the imposition of seasons, and fish stocking. In order to use these tools
effectively, information is required to minimize risk and ensure the sustainability
of fish populations and the fisheries that are dependant upon them. In
this case, there is a risk that levels of natural reproduction by salmon
are sufficiently high that stocking could result in a situation where an
over abundance of predators could collapse the forage base and therefore
the entire salmon fishery. The consequences of such a collapse would have
implications not only for the recreational fishery and its associated economic
benefits but also for the fish community in general. Is the risk of marking
fish for a few years greater or less than the potential that the fishery
might collapse? In the case of Lake Michigan, the fishery has never completely
recovered. Would species such as alewife disappear or be greatly reduced
in abundance? Would this allow native species such as lake herring to rebound?
Would a new exotic invader utilize the niche vacated by alewife and smelt?
These are all very challenging questions and unfortunately, ones that do
not have easy answers.
Mr. Choronzey provides information
that suggests that a decline in the number of chinook salmon is occurring
and he suggests that this is a result of the fin clipping component of
the natural reproduction study. Creel/angler surveys indicate that numbers
of chinook salmon caught in the recreational fishery, on both the U.S.
and
Canadian side of Lake Huron, were generally stable up to 2002. These surveys
also suggest that catch success rates for chinook salmon were increasing
in most waters up to 2002. They did decline in 2003, but still remained
higher than in all years previous to 2002. This suggests that there were
no negative consequences as a result of clipping study up to 2002. In 2003,
there are reports that the spring fishery was excellent though catches
in the Owen Sound Salmon Spectacular and the Chantry Chinook Classic did
decline. This decline could be attributed to a number of possible factors,
including higher than usual spring harvests, stocking rates, fin clipping,
or insufficient forage. The OMNR has also considered these factors. In
2000, the lowest numbers of chinook salmon were stocked by CFWIP clubs
on the Canadian side of Lake Huron as a result of a disease outbreak shortly
after egg collections. This age class of fish (three years of age) would
have contributed significantly to derby catches in 2003 suggesting that
the reduced harvests may reflect the lower stocking levels in 2000. Also,
based on anecdotal reports, returns of spawning chinook salmon to tributaries
of Lake Huron were average this fall. To complicate matters further, preliminary
results from the natural reproduction study suggest that the majority of
chinook salmon in Lake Huron were naturally produced. As a result of these
conflicting sources of information, uncertainty exists regarding the total
abundance of chinook salmon in Lake Huron.
In contrast to the uncertainty
regarding overall abundance, it is clear that growth rates of chinook salmon
have been in decline for several years (see enclosed figure). Forage fish
assessment information indicates that smelt and alewife numbers have also
declined for several years (see enclosed figure). Although this data is
not yet included on the figure this decline was precipitous from 2002 to
2003. There is little doubt, in our minds, that the decline in the availability
of forage fish has lead to a decline in chinook salmon size over time as
chinook salmon show a clear affinity for alewife as their preferred forage.
This reduction in growth may also have influenced the survival of salmon
in Lake Huron and hence their abundance.
In summary, the fishery collapse
on Lake Michigan coupled with the uncertainty around levels of natural
reproduction by chinook salmon in Lake Huron indicated that it was imperative
that resource managers improve their understanding of this species. There
is currently little evidence that fin clipping has caused a collapse of
salmon stocks anywhere in the Great Lakes. The valuable information gained
from this study regarding chinook salmon in Lake Huron will undoubtedly
enable fishery managers and stakeholders to make more informed and effective
decisions regarding the management of the predator/prey balance in Lake
Huron.
If you have any other questions
or concerns regarding this matter please feel free to contact my office
at 371- 0420.
David A. Mcleish lake Manaqer
See
charts related to this letter here.
