|
|
Member
Posts: 174
| This is a study that Walleyes For Tomorrow provided the sonic tags.
Walleye Movement in the Winnebago System (2011-2013)
Ryan Koenigs, Winnebago Sturgeon Biologist, 16 December 2013
The Winnebago System is home to a nationally recognized walleye fishery that
receives substantial angling effort. The general angling public around the system is also
heavily engaged in the management program and collaboratively work with DNR
fisheries staff to promote, research, and effectively manage the fishery. As part of this
collaborative effort, DNR and local fishing clubs conducted a sonic telemetry study to
learn more about the movement of adult walleye within the system.
The project was designed in December of 2010
and included surgical implantation of 100 sonic tags
into adult walleye captured throughout the Winnebago
System during spring spawning assessments. These
tags have a battery life of 900 days and transmit a
unique pinging sequence 24 hours a day, 7 days a week.
When marked fish swim past one of the 35 stationary
receivers (photo insert left) spread throughout the
system, the receiver documents the date, time, and tag
number (fish number). This technology allows DNR
staff to determine the coarse movement patterns of
adult walleye in the system, while answering many of
the questions that anglers pose about how walleye
move throughout the year.
Each acoustic tag carries a cost of $320,
meaning that the total price tag of the project was
$32,000. Unfortunately our DNR fisheries budget
could not cover all of this cost, so fisheries staff
inquired to local conservation clubs about contributing
to the project. The response was overwhelming and
local conservation clubs had donated enough funds to
cover the entire cost of the project within one month.
This is just one of countless examples of when local
stakeholders have stepped up to the plate and provided
financial support to the DNR fisheries program.
Without this support our crew would not be able to
complete nearly as much work as we do.
Due to the financial support, we were able to
proceed with the project and all 100 tags were
implanted into walleye during spawning assessments
conducted in 2011. A total of 60 fish were tagged on
the Wolf River, 30 fish on the upper Fox River, and 10
fish from Lake Winnebago (tags were evenly split
between males and females at each location). Given
the duration of the tags, we were able to monitor the
movement of fish from April 2011-October 2013.
A project like this provides an exhaustive amount of information that can be
difficult to summarize due to each fish exhibiting unique movement patterns. What we
can do is summarize how the majority of the fish are moving and acknowledge that there
are always going to be outliers. One clear conclusion was that male walleye spend
considerable more time in the Wolf and upper Fox Rivers than females (Table 1, Figures
1-4). This should come as no surprise due to the spawning nature of the fish. Male
walleye typically move onto spawning marshes well before spawning activity
commences and remain there until all spawning has concluded. Females, on the other
hand, typically move onto spawning marshes just before they begin ovulating and then
leave the marsh to begin their downstream movement shortly after spawning out. Due to
this behavior, males remain in the rivers much longer than females, therefore providing
the majority of the angling action during the spring spawning runs.
It was interesting to see where the fish tagged on the upper Fox River spawned
following tagging. We intentionally allocated a higher percentage of the tags to the upper
Fox River at Eureka than any other location in hope that this tagging effort would provide
some insight into where these fish were spawning. For years now, our DNR staff have
been able to handle large numbers of fish below the Eureka Dam, but we have been
unable to capture many fish in the marshes dispersed between the Eureka and Princeton
Dams. The results in 2011 provided some insight, as 6 of the 15 females tagged at
Eureka moved upstream of the Princeton Dam and spawned in Lake Puckaway (none of
the males exhibited this movement). As Figure 3 indicates, some of these fish remained
in Lake Puckaway during the duration of the study. These results demonstrate that fish
are able to move upstream of the Princeton Dam in high water years, and that fish are
capable of readily moving between Lake Puckaway and the Winnebago System.
Days in Wolf River (Females)
Year 2011 (27) 2012 (17) 2013 (13)
Min 11 6 25
Max 62 151 167
Median 18 11 37
Mean 22.8 24.5 46.4
Days in upper Fox River (Females)
Year 2011 (12) 2012 (10) 2013 (7)
Min 4 3 27
Max 71 44 46
Median 14 24 37
Mean 24.8 22 37.5
Days in Wolf River (Males)
Year 2011 (23) 2012 (13) 2013 (8)
Min 25 26 52
Max 345 155 133
Median 36 39 78.5
Mean 49.4 49.5 86.4
Days in upper Fox River (Males)
Year 2011 (12) 2012 (7) 2013 (4)
Min 24 4 33
Max 393 65 53
Median 44.5 8 53
Mean 76.2 17.3 46.3
Table 1. Data demonstrating the number of days (minimum, maximum, median, and
mean) that tagged male and female walleye spent in the Wolf and upper Fox Rivers
(2011-2013).
The results also showed poor river fidelity across spring spawning runs for fish
tagged on the upper Fox River at Eureka. Of the fish marked on the upper Fox River,
only one spawned in the Wolf River in 2011. However, river system straying was more
prevalent in 2012 and 2013. In fact, of the 12 females initially tagged on the upper Fox
River that were still alive in 2012, 3 spawned in the Wolf River and one spawned in the
Embarrass River. Further, 2 of the 8 fish still transmitting in 2013 spawned in the Wolf
River. Only one male tagged on the upper Fox River spawned in the Wolf River during
the study, and none of the fish initially tagged on the Wolf River strayed during any of
the spawning runs. Some examples of fish straying between rivers include: fish 44190
spawned in the upper Fox River in 2011, the Embarrass River in 2012, and the Wolf
River in 2013; fish 44195 spawned in the upper Fox River in 2011 and 2013, but the
Wolf River in 2012; fish 44203 spawned in Lake Puckaway in 2011 and 2012, but
spawned in the Berlin area of the upper Fox River in 2013.
Another trend was that a percentage of the fish marked on the Wolf River never
moved downstream further than the Upriver Lakes. Females demonstrated this
movement more than the males, but fish from both sexes never moved downstream to
Lake Winnebago. Fish marked on the upper Fox River were also less likely to remain in
the Upriver Lakes than fish marked on the Wolf River.
Overall, females remained in the Upriver Lakes longer than males (Table 2).
Two factors contrubute to this trend; 1) females reach the Upriver Lakes earlier because
they spend less time in the rivers, and 2) a higher percentage of females remain in the
Upriver Lakes throughout the summer. Fish tagged on the upper Fox River also spent
less time in the Upriver Lakes than fish marked on the Wolf River, likely due to
geographical distribution of the Winnebago System. The Wolf River drains into Lake
Poygan and thus fish have to move through all three Upriver Lakes before entering Lake
Winnebago. Whereas, the upper Fox River drains to Lake Butte des Morts, meaning that
fish only have to move through one Upriver Lake before entering Lake Winnebago.
Although some fish did remained in the Upriver Lakes throughout the summer,
the majority still moved downstream into Lake Winnebago. Most of the walleye that
spawned in the Wolf River entered Lake Winnebago during early to mid-May, while the
majority of fish that spawned in the Fox River entered Lake Winnebago in mid to late
April. Again, this disparity is likely due to where the rivers drain to and that fish from
the Wolf River need to move through all three Upriver Lakes to reach Lake Winnebago.
Regardless of when fish reach Lake Winnebago, the telemetry results clearly
demonstrate a large upstream movement of adult fish in late-fall. More specifically, fish
are moving from Lake Winnebago into the Upriver Lakes to overwinter. This movement,
occurring mostly between mid-October and December, was observed in both fall 2011
and 2012 (Figures 1-4). Fish from both the upper Fox and Wolf River exhibited this
movement, but there were a number of females from the upper Fox River that remained
in Lake Winnebago through the winter months. So in essence, most of the fish enter
Lake Winnebago sometime in May and remain there until October-December (Table 3).
These results address a lot of questions about the ice fishing on Lake Winnebago.
Walleye, especially larger walleye, do not show up in the harvest of most ice fishermen.
Experienced ice anglers can typically catch numbers of late-ice walleye around the mouth
of the Fox River in Oshkosh, but walleye can be tough to locate throughout most of the
ice fishing season. As the telemetry data indicate, this a product of there not being large
numbers of adult walleye remaining in Lake Winnebago during that time. The late ice
fishing can be good though because the fish that do remain in the lake through the winter
congregate in front of Oshkosh as they begin their upstream spawning migration.
All of the results and trends discussed thus far have described movement of fish
marked on the upper Fox and Wolf Rivers. As described earlier, we also implanted tags
into 10 fish captured in Lake Winnebago, mostly from west shore reefs just south of the
mouth of the Fox River in Oshkosh. The results from these fish were not very clear, thus
why they weren’t included in most of the analyses. Four of the 10 fish were not
contacted at any of our receivers, meaning that they never left Lake Winnebago during
the study period, they were harvested or they died of natural causes. Of the remaining six
fish, two moved upstream into the Upriver Lakes shortly after tagging and then moved
back downstream into Lake Winnebago. Both of these fish were never contacted after
May 14, 2011. So that leaves just four fish that provided quality data during the study
period. Three of the four fish spawned in Lake Winnebago in 2012, while the fourth
spawned in the Wolf River between Weyauwega and New London. 2013 was a different
scenario, where two of the fish spawned in the upper Fox River and the remaining two
spawned in the Wolf River.
Unfortunately quite a few of the tagged fish succumbed to mortality during the
course of the study, as observed in Figures 1-4. Both natural causes and harvest by
anglers were sources of this mortality, but there were a few instances where DNR staff
were able to re-implant tags from harvested fish into other living fish. Our age and
growth data indicate that 30-35% of the adult population succumbs to mortality in an
average year, so we were anticipating a high percentage of the tagged fish would no
longer be living by the end of the study. That’s just part of the game when dealing with a
heavily exploited fishery, mortality is going to be a factor.
Even with the mortalities, this was a very beneficial study to both our DNR staff
and to the general angling public. Anglers are very interested in how fish move
throughout the system and will look to apply these data to their fishing practices in the
years ahead. We have already been receiving inquiries about whether we would be
looking to raise additional funds to tag more fish. At this time, it doesn’t look like
something we will be pursuing. The results from the first 100 fish showed some
definitive trends, as described in this summary, and we are confident that another 100 fish
would yield similar results. There is also a tremendous amount of work that goes into
compiling the data into a usable format and then summarizing it. We would consider
tagging more fish in the future if a need presented itself.
I hope you enjoyed the summary and find the results as interesting as I did. Once
again, this project could not have been completed without the support of local
conservation clubs.
Days in Winnebago (Females - Wolf)
Year 2011 (8) 2012 (8)
Min 58 135
Max 284 225
Median 181 202
Mean 179.6 192
Days in Winnebago (Females - upper Fox)
Year 2011 (10) 2012 (7)
Min 175 215
Max 334 356
Median 217.5 273
Mean 245.5 278.9
Days in Winnebago (Males - Wolf)
Year 2011 (12) 2012 (6)
Min 93 141
Max 268 187
Median 157 155.5
Mean 166.8 161.8
Days in Winnebago (Males - upper Fox)
Year 2011 (10) 2012 (3)
Min 12 176
Max 267 206
Median 157 202
Mean 162.6 194.7
Edited by RSR 2/5/2017 1:25 PM
| |
| |
|
Walleye Movement in the Winnebago System