Download 2000-01 Amendment

F-81-R-2, Michigan
Study 484
Amended
2000-01
484. Name of Study: Population dynamics of yellow perch stocks in Michigan waters of Lake
Michigan.
A.
Problem: Since 1990, yellow perch population density in Lake Michigan has declined, and
the age structure has shifted toward older fish due to an almost complete lack of recruitment
(Great Lakes Fishery Commission 1996). These trends have been documented in southern
Lake Michigan by various agencies (Indiana Department of Natural Resources, Illinois
Natural History Survey, Illinois Department of Natural Resources, Wisconsin Department of
Natural Resources, University of Wisconsin, University of Michigan, Ball State University,
National Biological Survey) using a variety of assessment gear (graded-mesh gill nets,
seines, trawls, fyke nets, larvae nets). Other evidence for the decline has come from
monitoring sport and commercial fisheries for yellow perch. Although the trends have been
described, current data sets do not seem sufficient to identify the causes of the decline or to
suggest possible management solutions to the problem. Furthermore, it is not clear if yellow
perch density has declined in Michigan waters of Lake Michigan because the Michigan
Department of Natural Resources has not conducted assessment netting since the late 1970s.
Efforts to understand yellow perch population dynamics in Lake Michigan are made difficult
by the size and complexity of the system. In addition, exotic fauna that have invaded or been
introduced into Lake Michigan (alewife, round goby, white perch, zebra mussel, spiny water
flea) have the potential to influence yellow perch (Barnhisel 1991; Schneeberger 1991).
Yellow perch management is further complicated by the number of state, tribal, and federal
agencies that have interests in and jurisdiction over Lake Michigan waters. Sport anglers and
commercial fishers also have conflicting opinions over use and management of the yellow
perch populations.
B.
Objectives: (1) To summarize pertinent existing data from state, federal, commercial, sport,
university, and private sources; (2) to conduct assessment netting to establish baseline data
and determine whether lack of recruitment and declining yellow perch numbers are problems
in Michigan waters; (3) to determine whether factors of fish health might be affecting
abundance or recruitment of yellow perch; (4) to reestablish a program of biological data
collection for sport-caught yellow perch; (5) to investigate discreteness of yellow perch
populations in Lake Michigan; and (6) to develop information and mathematical models
from these data that will allow managers to predict, with some predetermined level of
certainty, the outcome of various yellow perch management strategies.
C.
Justification: Yellow perch are an important component of Michigan's sport fishery in Lake
Michigan. Between 1985 and 1994, an estimated 2,330,888 yellow perch have been caught
by anglers annually, more than any of the other species tabulated by the Michigan
Department of Natural Resources creel census (G. Rakoczy, MDNR, personal
communication). Although individual yellow perch are small relative to the other species,
annual harvest of yellow perch ranks third by weight behind chinook salmon and lake trout.
Yellow perch are caught from piers, small boats, and party boats, and as such are available to
nearly all segments of the angling public. Commercial fishing for yellow perch was banned
F-81-R-2, Study 484 - 2
in Michigan waters in 1970, in part because it was recognized that the value of yellow perch
is maximized when harvested by the sport fishery. Because populations inter-mix across
state boundaries in the lake, it should be the responsibility of all involved agencies to
consider each other's interests and coordinate their management strategies as much as
possible.
Apart from their value to humans, yellow perch are an important part of the Lake Michigan
biological community. Yellow perch are an indigenous species that play an important role in
energy cycling and transfer, especially in the littoral zone.
D.
Status: In southern Lake Michigan, yellow perch usually recruit to the sport fishery at age 4
for males and 3 for females when they reach a size of around 7 inches (G. Rakoczy, personal
communication). Anglers catch yellow perch throughout the open-water season and
whenever ice conditions are suitable, especially in drowned river mouths (e.g., Pentwater,
White Lake, Muskegon Lake, Lake Macatawa). Catches are greatest when fish are
concentrated prior to, during, and right after spawning. Spawning usually occurs from late
April through early June with a peak in mid-May (Auer 1982).
Assessment netting in Indiana, Illinois, and Wisconsin waters has indicated that the last
strong year class of yellow perch occurred in 1988 in southern Lake Michigan. Plankton-net
tows have shown that relatively stable densities of larval yellow perch were produced from
1988 through 1993, but fell to virtually zero in 1994 for unknown reasons. Catches of
young-of-the-year (YOY) yellow perch have declined in both trawling and seining gear at
least since 1990. Lack of recruitment is believed to be responsible for declining catch trends
in assessment gill nets and trawls, and for a shift toward increasingly larger and older-aged
perch in assessment, commercial, and sport catches during the 1990’s (Great Lakes Fishery
Commission 1996). It is not known if yellow perch are exhibiting similar trends in Michigan
waters.
Various historical data for yellow perch in Michigan waters of Lake Michigan are available,
but since 1985, Michigan DNR yellow perch data consist only of estimates of catch, effort
and limited biological data from the creel census. Length measurements and scale samples
were taken as part of the creel census from 1985 through 1992. These data have not been
rigorously examined. No biological data are available for yellow perch in Michigan waters
after the 1992 creel census. Between 1985 and 1995, sport catches of yellow perch did not
decrease in Michigan waters, but fluctuated between 1.6 and 3.2 million fish per year.
However, recreational catch in Michigan waters in 1996 (approximately 800,000 fish) was
the lowest yet recorded. Given this sharp decline in catch, it is even more critical that we
continue to monitor the yellow perch population in Lake Michigan through the statewide
creel survey.
Based on the current status of yellow perch populations, state agencies have banded together
to impose coordinated regulations. Beginning in 1995, daily sport bag limits for yellow
perch were reduced from no limit to 25 fish in Indiana and Illinois, from 50 to 25 fish in
Wisconsin, and from 100 to 50 fish in Michigan. The higher daily bag limit in Michigan was
agreed to because Michigan banned commercial fisheries for yellow perch in 1970. A 65%
reduction from 1994 catches of yellow perch was imposed on commercial fisheries operating
in Indiana, Illinois, and Wisconsin. In addition, a general closure of the yellow perch fishery
was put into effect during the entire month of June in all Lake Michigan waters south of the
45th parallel. In 1997, recreational yellow perch limits will be five fish in Wisconsin waters
F-81-R-2, Study 484 - 3
of Lake Michigan (excluding Green Bay), 15 fish in Illinois and Indiana waters, and 35 fish
in Michigan waters south of the 45th parallel. The June closure will remain in effect in
Wisconsin and Illinois, and commercial yellow perch fishing will no longer be permitted
outside of Green Bay.
In addition to coordination of regulations, interagency cooperation also resulted in the
formation of a task group to address current yellow perch problems. Michigan DNR
representatives are and will continue to be active members of this task group.
This study is being amended in 2000-01 to more accurately reflect the distribution of effort
during the final years of the study. Work will shift from field collections to laboratory sample
processing, data analysis, and report writing. The study will also be extended one year to
accommodate editing and finishing of the final report by Research Administration in 2002-03.
Literature Cited:
Auer, N. A. 1982. Family Percidae, perches. Pages 581-648 in N. A. Auer, editor.
Identification of larval fishes of the Great Lakes basin with emphasis on the Lake
Michigan drainage. Great Lakes Fishery Commission, Special Publication 82-3, Ann
Arbor, Michigan.
Barnhisel, D. R. 1991. Zooplankton spine induces aversion in small fish predators.
Oecologia 88:444-450.
Great Lakes Fishery Commission. 1996. Multi-agency yellow perch research initiative.
Yellow Perch Task Group, Lake Michigan Technical Committee.
Schneeberger, P. J. 1991. Seasonal incidence of Bythotrephes cederstroemi in the diet of
yellow perch (ages 0-4) in Little Bay de Noc, Lake Michigan, 1988.
E.
Procedure:
Job 1. Review literature and summarize existing data.
In an effort to establish historical trends and identify potential factors affecting
yellow perch population fluctuations and recruitment, data will be sought from a
variety of sources including; a) commercial - catch records will be summarized from
as far back as possible to obtain perspective on historical population fluctuations; b)
universities - contacts will be established with universities other than those
participating in the task group. For example, Michigan State University has a longrunning yellow perch data set associated with their studies at the Ludington Pump
Storage facility; c) private - Consumers Power Co. has ongoing studies at various
power plant locations (including Ludington, Port Sheldon); and d) sport - angler
clubs and charter associations. Of interest from all these sources is anything relating
to yellow perch catch, effort, mortality, population fluctuations, discreteness,
spawning areas, growth, health, parasites, movement, economics, recruitment, size,
age, or diet.
Job 2. Conduct standardized assessment sampling.
F-81-R-2, Study 484 - 4
Different types of fishing gear will be used in an effort to collect the various life
stages of yellow perch. The S/V Steelhead will deploy overnight gillnet (1 to 3.5inch stretch mesh nylon) sets to collect yearling and older yellow perch at four
southern Lake Michigan ports (Grand Haven, Saugatuck, South Haven, St. Joseph)
in April. Nets will be set perpendicular to the 10 and 20 m depth contours. The
presence of competitors and predators will be evaluated as factors with potential for
influencing yellow perch recruitment. Similar data will also be collected in
conjunction with studies at the Ludington Pump Storage facility.
Trawling for YOY yellow perch will be conducted by District 9 and 12 personnel in
July and August using a semi-balloon nylon otter trawl having a 16-ft headrope and a
21-ft footrope. The body and codend of the net will be composed of 0.75-inch and
0.62-inch bar mesh, respectively, while the codend inner liner will be constructed of
0.25-inch stretch mesh. Ten-minute hauls will be made at depths from 1 to 5 meters
at each of the ports sampled in spring assessment netting. Catch-per-unit-of-effort
will be reported for all species collected. Beach seining will be conducted at
intervals to calibrate trawling with other state agency sampling procedures. Seine
hauls will be 200-ft long parallel to the shoreline using a 50-ft long by 6-ft high
nylon beach seine with 0.25-inch mesh.
All yellow perch collected (all methods) will be counted, weighed, and measured. A
representative number of scales will be collected in 10 mm intervals to confirm ages.
Fish species that are considered potential competitors with or predators on yellow
perch will also be collected as they may provide important clues relating to
recruitment of yellow perch. Stomach samples of yellow perch and competitor /
predator species will be collected for diet analysis. Addition of species other than
yellow perch will provide an index of inshore fish populations not currently sampled
by other MDNR programs.
Other sampling (zooplankton collection, larval fish netting) will be conducted by
MDNR personnel as deemed necessary and where time permits. Some additional
sampling of yellow perch early life history stages and lower trophic levels
(phytoplankton, zooplankton, benthos) may also be conducted by graduate students
or on a contract basis as funding permits.
Job 3. Investigate the potential impacts of disease on yellow perch populations.
Early Mortality Syndrome (EMS) has been found to be very detrimental to fry
survival of coho salmon, rainbow trout, and other species. Survival has increased
dramatically when these fry were treated with thiamine. EMS or other facets of fish
health may be influencing recruitment of yellow perch as well. To investigate these
possibilities, Fish Quality Laboratory personnel will collect mature male and female
yellow perch from Lake Michigan. Investigations will include thiamine treatments,
tissue analyses, blood sample work-up, and examination of yellow perch for internal
parasites.
Wisconsin DNR is also investigating the possibility that EMS affects yellow perch
recruitment, both in Lake Michigan and in an inland lake that will serve as a
reference for Lake Michigan findings. Our analyses will be coordinated with State
of Wisconsin personnel for continuity of procedure.
F-81-R-2, Study 484 - 5
Job 4. Collect and analyze biological data from sport-caught yellow perch.
Data from the recreational creel will be collected at the five sites for which fisheriesindependent assessment data is available. At any given site, data will be collected
from up to 400 angler-caught yellow perch per month. For each fish, length will be
measured to the nearest millimeter. Scale samples will be taken from below the
lateral line under the distal end of the pectoral fin. Permission from anglers will
need to be obtained to make a small ventral cut allowing examination of the fish's
gonads to determine sex and level of maturity. Maturity will be subjectively
categorized on a scale of 0 to 6 where 0 = unknown - gonads undeveloped to the
degree that sex cannot be distinguished, or gonads not examined; 1 = immature - sex
can be distinguished but gonads undeveloped; 2 = mature - gonads partly developed;
3 = mature - gonads well developed; 4 = ripe/running - fish in spawning condition; 5
= spent - ovaries or testes empty; and 6 = reabsorbing - fish that retain sex products
past spawning season.
Similar data will be solicited from party-boat (charter) captains and from anglers
through something like the angler diary program. Twice each month, the charter
captains will be asked to record the lengths of every yellow perch caught during the
entire day. Alternatively, District 9 and 12 personnel will ride these boats at the
same intervals and record the desired data.
Yellow perch length and age data collected between 1985 and 1992 from Michigan's
creel census will be analyzed and compared to similar data from other agencies.
Job 5. Investigate discreteness of yellow perch populations in Lake Michigan.
Discreteness of yellow perch populations will be determined through tagging, as well
as through comparison of growth rates, condition, and other physiological variables
among populations.
To be effective, tagging must be coordinated lake-wide and all state agencies must
participate. Tagging will be conducted during spring (when maximum stock
separation likely occurs), in conjunction with other agencies through the Lake
Michigan Committee Yellow Perch Task Group study. Yellow perch will be tagged
in Lake Michigan as well as connected drowned river mouths, to determine how fish
in these areas relate to populations in the main basin. Besides providing much
needed information on fish movements, growth, exploitation rates, and mixing of
stocks, this coordinated effort should serve as a model for future cooperative studies
on the Great Lakes.
Job 6. Develop information and mathematical models related to yellow perch management
strategies.
Successful modeling of Lake Michigan yellow perch populations will require
collection of an expanded biological data set. Minimally, information on length,
weight, age, sex, maturity, egg production, diet, movement, harvest rates, and
predation is needed. This data will be collected in Jobs 1-5 (see above). Modeling
efforts will be aimed at investigating energetic tradeoffs for inshore fish populations,
F-81-R-2, Study 484 - 6
predictability of yellow perch population fluctuations, and the influence of
commercial and recreational harvest on yellow perch populations.
Job 7. Evaluate results, write reports, and develop future study plans for Michigan waters
of Lake Michigan south of the 45th parallel.
Results of research will be presented in summaries to various MDNR and external
committees, annual progress reports, and peer-reviewed journals. Study plans will
be revised as necessary.
Job 8. Publish report through the Fisheries Division’s editing and finishing process for
Research and Technical reports.
F.
Schedule:
Year
Work planned
1997-98
Job 1.
Job 2.
Job 3.
Job 4.
Job 5.
Job 6.
Job 7.
Review literature.
Conduct assessment sampling.
Investigate potential impacts of disease.
Collect and analyze creel data.
Investigate discreteness of perch populations.
Develop models.
Evaluate results, write reports.
1998-99
Job 1.
Job 2.
Job 3.
Job 4.
Job 5.
Job 6.
Job 7.
Review literature.
Conduct assessment sampling.
Investigate potential impacts of disease.
Collect and analyze creel data.
Investigate discreteness of perch populations.
Develop models.
Evaluate results, write reports.
1999-00
Job 1.
Job 2.
Job 3.
Job 4.
Job 5.
Job 6.
Job 7.
Review literature.
Conduct assessment sampling.
Investigate potential impacts of disease.
Collect and analyze creel data.
Investigate discreteness of perch populations.
Develop models.
Evaluate results, write reports.
2000-01
Job 1.
Job 2.
Job 4.
Job 5.
Job 6.
Job 7.
Job 1.
Job 6.
Review literature.
Conduct assessment sampling.
Collect and analyze creel data.
Investigate discreteness of perch populations.
Develop models.
Evaluate results, write reports.
Review literature.
Develop models.
2001-02
F-81-R-2, Study 484 - 7
Year
2002-03
Work planned
Job 7.
Evaluate results, write reports.
Job 8.
Publish report.
G.
Geographical Location: Charlevoix Great Lakes Fishery Station, Charlevoix, Michigan;
District Offices; Fish Health Lab (Wolf Lake Hatchery); Ludington Pump Storage Facility;
field sampling locations.
H.
Personnel: David F. Clapp, Fishery Research Biologist; crew of the S/V Steelhead; Fisheries
Division personnel at District offices and the Fish Health Lab; Research Administrative
personnel, and contract editor.