istration system. The drop in the number of legal
size sturgeon in this section and the high exploita-
tion rate are cause for concern, especially in a stock
that has so few spawning size fish. Additional har-
vest restrictions are needed.
Lower sectionThe Lower section of the river currently supports
the highest standing stock of lake sturgeon of any
section of the Menominee River. This stock ex-
panded as water quality improved over the last two
decades. Sturgeon move freely between the river
and the waters of Green Bay. The population esti-
mate in 1990 was made during July, and it is not
known how the standing stock changes seasonally.
The number of sturgeon found in this section may
be quite different during the fall fishing season. The
exploitation rate for this section was 18.7%. 'This is
higher than on either of the other sections of river.
The size structure of the stock in July showed a lack
offish over 152 cm in length. The harvest continued
to increase. There is no statistical difference (p <
0.05) in the mean length of sturgeon harvested
when comparing the first six years of registration
data (1983-1988) with the last five years (1989-
1993).
Further investigations are needed to determine
the standing stock of sturgeon in this section of riv-
er. However the apparent high exploitation rate
and the lack of any fish > 152 cm TL is a cause for
concern. Current regulations should be modified to
further restrict the harvest.Table 6. Portion of the season in which harvest of lake sturgeon
has taken place on the Menominee River 1983-1993.
Period of season Percentage of the harvest1 - 14 September 43
15 - 30 September 29
1 - 14 October 14
15 October-1 November 14Management recommendationsLake sturgeon stocks of the Menominee River, with
the exception of those fish in the Lower section.
spend their entire life in riverine habitat (Priegel^2 ,
Thuemler 1988). In many parts of their range lake
sturgeon spawn in river systems but spend most of
their life in lacustrine habitat (Lyons & Kempin-
ger^6 , Baker^7 , Houston 1987). Lake sturgeon are cur-
rently round and were historically abundant only in
lakes or in large rivers with extensive shallow water
areas (Harkness & Dymond 1961, Priegel & Wirth
1977). In the Menominee Rivere lake sturgeon
could historically move freely into and out of the
waters of Green Bay. With the construction of dams
on the river in the 1800s this population was frag-
mented into separate stocks. The long term goal of
the Wisconsin and Michigan Departments of Nat-
ural Resources is to have free passage of lake stur-
geon throughout their former range in the Menomi-
nee River (Thuemler & Schnicke^8 ). This goal will
take many years to achieve and interim measures
are needed to protect the current sturgeon stocks in
the river.
Two alternatives could be used to decrease ex-
ploitation. especially in the lower two sections of
river. Imposition of a higher size limit is not being
considered because it would tend to further bias the
harvest towards larger female fish. Shortening the
current two month fishing season would be possi-
ble, however the season would have to be shortened
to about two weeks to effect a 50% reduction in ex-
ploitation (Table 6). The second alternative would
be complete closure of the season every other year.
This should halve the exploitation rates and yet still
allow some harvest, and might be acceptable if a
catch and release only season operated in the year
when harvest was prohibited. This would permit an-(^6) Lyons, & J.J. Kempinger. 1992. Movements of adult lake stur-
geon in the Lake Winnebago system. Wisc. Dept. Nat. Res., Res.
Report 156. Madison.
(^7) Baker, J.P. 1980. The distribution, ecology, and management of
the lake sturgeon (Acipenser fulvescens Rafinesque) in Michi-
gan. Mich. Dep. Nat. Res., Fish. Res. Report No. 1883. Ann Ar-
bor. 95 pp. 8
Thuemler, T.E. & G. Schnicke. 1993. Menominee River fisheries
plan. File Report. Wisc. Dept. Nat. Res., Madison. 51 pp.