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Michigan Department of Natural Resources Washtenaw County (T1S, R3E, Sec. 1, 6) Surveyed May, 1991 Michael P. Herman Environment Halfmoon Lake is located within the boundaries of the Pinckney Recreation
Area and is approximately 6 miles north of the Village of Chelsea (Figure
1). The main part of this lake lies in the northwest part of Washtenaw
County and a small portion extends into southwestern Livingston County.
Halfmoon Lake is approximately 236 acres in size and part of a chain&endash;of&endash;lakes
that are included in the Middle Huron Watershed within the Huron River
Basin. There are several lakes upstream from Halfmoon Lake, including
Woodburn, Patterson, Watson, Bruin, and Blind. The only outlet of Halfmoon
Lake is approximately 20 feet wide and 2&endash;to 3&endash;feet deep;
it exits to Hi&endash;Land Lake. Water then flows in a northeasterly direction
to the Portage River, Little Portage Lake, Big Portage Lake, and finally
to the Huron River just south of the Village of Pinckney. The lake bottom consists primarily of marl in the shallow water areas
and muck and pulpy peat in deep water. There are also scattered areas
of fibrous peat, gravel, rubble, and sand which are found mainly in the
shallows. Halfmoon Lake has steep drop-offs, several submerged islands,
and water depths up to 87 feet. Approximately 75% of the lake's surface
area has water greater than 10 feet deep. Vegetation is very limited in
this lake and includes scattered areas of bulrush, white and yellow water
lily, several varieties of pondweed, and Chara or muskgrass. The latest
limnology survey was in August of 1991. Temperatures ranged from 77°F
at the surface to 54°F at the 25foot depth. Very low dissolved oxygen
levels in the thermocline were recorded, making this lake unsuitable for
the introduction of rainbow trout. The shoreline of Halfmoon Lake is moderately developed, and about 100
summer and permanent homes presently exist on this lake. The undeveloped
portions of the shoreline are a combination of mainly forested and emergent
wetlands, as well as some wooded upland. There is a state access site
and public swimming beach located on the lake's northeast shore. Bluegills, largemouth bass, yellow perch, and walleye fry were stocked
in Halfmoon Lake in the late 1930's and early 1940's. These stocking programs
were soon discontinued. Rainbow trout were stocked in Halfmoon Lake in
the early 1940's but poor survey returns led to discontinuing these plants
in 1945. Rainbow trout stocking resumed in 1955 and continued through
1969; once again, trout plants were discontinued because of poor angler
returns. An experimental plant of chinook salmon was made in 1973. A subsequent
gill net survey produced no chinooks. A private plant of approximately
12,000 walleye fingerlings was made in 1986 but none have been reported
caught. In 1987, approximately 24,000 redear sunfish fingerlings were
stocked in this lake. In the summer of 1989, a floating fishing pier was constructed by the
Fisheries Division of the DNR and placed on the northeast end of Halfmoon
Lake. The following summer, twenty fish cover structures were placed in
two groups in approximately 15 feet of water and within casting distance
of the fishing pier. The fish structure project was a cooperative effort
between the Parks and Fisheries Divisions of the DNR and the Lower Michigan
Bass Organization based in Southfield, Michigan. Each structure was built
using old Christmas trees which were anchored into a standard size cinder
block with cement. Because of heavy pleasure boat traffic and the potential
for injury that might result from the location of the fishing pier, it
was moved to Crooked Lake which is approximately 1 mile to the east. Halfmoon Lake was last surveyed in late May, 1991 with six standard 8
x 5 x 3&endash;foot trap nets (Table 1). No gill nets were used since
evaluation of the redear sunfish stocking program was the primary objective
of this survey. Species captured in descending order of abundance included
bluegills, pumpkinseeds, carp, black crappie, longnose gar, rock bass,
largemouth bass, bowfin, northern pike, yellow perch, warmouth, and white
bass. Bluegills predominated in the survey, comprising 69% by number but only
20% by weight of the total catch. The 384 bluegills in the sample averaged
7.5 inches each, which is an unusually large average size. Nearly all
of the bluegills caught in trap nets ware 6.0 inches or longer, or what
is considered to be an acceptable size to anglers (Table 1). Based on
growth analysis using fish scales, bluegills caught during the 1991 survey
exhibited growth rates that were nearly one&endash;inch above state average
growth rates (Table 2). Bluegills are targeted for sampling in inland lakes because of their
role in determining fish community structure and overall sportfishing
quality (Schneider 1981). Even though the goal of lake surveys is to sample
all fish species and all sizes present, many times only the bluegill population
is adequately sampled because bluegills are usually the most abundant
fish. Recently, a ranking system has been developed that allows fish managers
to get an idea of the relative quality of a lake's fish population (Schneider
1990). On a scale of 1 to 7, the quality of the bluegill population in
Halfmoon Lake was calculated as 6.3 or "excellent". Although black crappie are not a large component of the fishery in Halfmoon
Lake, they appeared very healthy and averaged 7.4 inches long. Based on
fish scale analysis, crappies exhibited growth that was nearly one&endash;inch
above state average rates (Table 2). Not enough northern pike and largemouth bass were captured during the
1991 survey to be statistically significant. However, growth trends indicate
that both species are growing well above state average rates (Table 2). Longnose gar and carp comprised a total of over 75% of the survey catch
by weight. Although these fish often compete for food and space with all
other fish species, growth of bluegill, crappie, bass and pike seem to
be unaffected. Pumpkinseeds comprised nearly 10% of the total catch by number. These
fish appeared very healthy and robust and over 80% were 6 inches or larger,
or what anglers consider to be "keeper" size. Survey records show that species composition has remained relatively
unchanged throughout the past 50 years with the exception of carp. Growth
trends for bluegill, crappie and largemouth bass in 1991 are comparable
to those from surveys of Halfmoon Lake in 1965, 1973, and 1983. Table 3 outlines the estimates of age frequency for bluegills and crappies
caught during the May 1991 survey of Halfmoon Lake. Bluegills up to 10
years old were found, which indicates unusually high longevity. Black
crappie, on the other hand, seem to be short&endash;lived. In general,
bluegill age groups III through VII were well represented. However, the
estimated age frequency for age V bluegills was only 16%, which suggests
that a weak year class may exist. Conversely, the estimated age frequency
for age II crappies was nearly 75%, which suggests a very strong year
class. Water temperature, spawning success, weather, food availability,
and many other variables contribute to the success or failure of a particular
year class of fish. Only one northern pike was caught in trap nets during the present survey.
However, pike are better sampled with gill nets, which were not used in
1991. Past surveys of this lake with gill nets have resulted in the capture
of relatively good numbers of northern pike. Northern pike caught in 1983
and in 1991 exhibited growth trends that were well above the state average
rate. Very few carp have been captured in past surveys of Halfmoon Lake. The
1991 survey resulted in the capture of 47 carp, averaging over 27 inches
and over 9 pounds each. Carp dominated the survey by weight, comprising
nearly 70% of the entire catch. Although the apparent large population
of carp have not yet had a measurable negative impact on the other fish
populations sampled, it is possible that changes in the general fish population
of Halfmoon Lake may occur in the future if carp numbers continue to increase. No ciscoes were taken in the 1991 survey and they may have become extinct.
They were reported in surveys dating back to 1942. Several reports of
mid&endash;summer ciscoe mortalities have been received by the Jackson
District Fisheries office throughout the years. Surveys subsequent to
1942 resulted in the capture of fewer and fewer ciscoes. Reasons for the
decline of ciscoes in Halfmoon Lake may include, but are not limited to,
increased predation by northern pike and deteriorating water quality.
In general, there is a movement in spring and early summer from shallow
to deeper water, when ciscoes move into the colder layers. This seasonal
migration may lead to mass mortalities if the layer of water below the
thermocline (hypolimnion) becomes depleted of oxygen (McCrimmon 1952).
An August, 1991 limnology survey of Halfmoon Lake showed that very little
oxygen existed in or below the thermocline. Halfmoon Lake is used mainly by pleasure craft other than fishing boats
throughout much of the summer, and there is seasonally intense competition
for use of the lake. Even though some anglers report good bluegill and
bass fishing success in recent years, the steep drop-offs and the general
lack of fish concentrating cover in this lake may make it difficult for
anglers to locate fish. As a result, bluegills and other gamefish are
probably underutilized. Because pumpkinseeds and redear sunfish have similar food and habitat
requirements, redears were expected to flourish in Halfmoon Lake. In addition,
the lake has a marl bottom and similar features to other area lakes where
redears have done well. It was hoped that the introduction of redear sunfish
would give anglers an opportunity to catch a trophy panfish. Based on
the growth of redears in other area lakes, redear sunfish stocked in Halfmoon
Lake in 1987 should have been at least 8 to 9 inches long in 1991; however,
none were caught in the trap nets. The presence of large numbers of carp
in this lake may have had a negative effect on redear growth and survival,
since redears feed mainly on the bottom and could be in competition with
carp for food. No redear sunfish were caught during the present survey. It should be
noted that the redears stocked into Halfmoon Lake were some of the last
fingerlings harvested from the rearing pond in 1987. In general, the last
fish harvested from a pond experience increased stress because of reduced
water volumes which causes crowding, lowered oxygen levels, turbidity,
and increased water temperatures. Additionally, the fingerlings stocked
in 1987 were only 1&endash;inch long. The average size of redear fingerlings
stocked in other District 13 lakes has been approximately 2 inches. The
quality of redear fingerlings stocked into this lake remains suspect.
When available, Halfmoon Lake should be stocked with redear sunfish fingerlings
for 3 years in succession and the fishery evaluated 3 years later. Halfmoon Lake has a reputation among anglers for catches of large bluegill,
as well as crappie and largemouth bass of acceptable size. In general,
anglers are satisfied with the existing fishery. Report completed: March 5,1992. McCrimmon, H. R. 1952. Mortality of coregonid fish in Lake Simcoe during
spring temperature warm&endash;up. Canadian Field&endash;Naturalist 66(4):
112. Schneider, J. C. 1981. Fish communities in warmwater lakes. Michigan
Department of Natural Resources. fisheries Research Report 1890, Ann Arbor. Schneider, J. C. 1990. Classifying bluegill populations from lake survey
data. Michigan Department of Natural Resources, fisheries Technical Report
90010, Ann Arbor. Table 1.-Number, weight and length indices of fish collected from
Halfmoon Lake with trap nets, May 29, 1991.
Table 2.-Average total length (inches) at age, and growth relative
to the state average, for two species of fish sampled from Halfmoon Lake
with trap nets, May 29, 1991. Number of fish aged is given in parenthesis.
Table 3.-Estimated age frequency (percent) of two species of fish
caught from Halfmoon Lake with trap nets, May 29, 1991.
Last Update: 08/06/02
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