Operational Plan for the Restoration of Diadromous Fishes to the ...

Pattern of Introduction and Dispersal in Lakes
The pattern of introduction and dispersal in lakes from the discovery record in Table
6 is graphically illustrated in a map time series in Appendix C. The following results
were obtained from examining Table 7 and the discovery time series:
a. The first known occurrence in Maine was documented in North Pond in
1969 20 . Little North Pond and North Pond are connected and managed as
the same water.
b. Forty-one lakes have a medium or high reliability of pike presence. Pike were
likely introduced in 23 lakes (56%) through human-caused introduction and
18 lakes (44%) by dispersing from an established source population.
c. The current pike distribution in Maine has resulted from 23 separate
unauthorized introductions.
d. In 10 of the 16 introduced watersheds, pike have not been found to have left
their original waters or expand their distribution. In four cases, pike moved
into adjacent waters. In only two watersheds (Cobbosseecontee and
Messalonskee Stream watersheds) did pike move to any great extent.
However, both of those watersheds are substantially made up of lakes and
ponds, and in at least one of these instances, the pike moved downstream
after being introduced.
e. The pattern of introductions appears to occur in clusters where several illegal
introductions will occur in adjacent watersheds within the same time period.
f. In 15 of 23 introductions, the introductions were the first recorded occurrence
of pike in the watershed.
g. There are seven cases where the potential source is identified for which pike
may have dispersed to another lake. The dispersal period ranged from 1 to
22 years. The average and medium dispersal period was 7 and 3 years,
respectively (Table 8).
Table 8 Northern pike dispersal in Maine lakes
From Lake Year Discovered To Lake Year Discovered
Little North Pond 1
1969 North Pond 1991
Little Bear and Bear Ponds 1999 Crystal Pond 2000
Sabattus Pond 1994 Little Sabattus Pond 2000
Little Bear, Bear and Crystal Ponds 1999/2000 Long Pond 2002
Cobbosseecontee Lake 1996 Little Cobbosseecontee Lake 2004
Long Pond 2002 Round Pond 2005
Pushaw Lake 2003 Mud Pond 2006
20 Based on a back calculation of when pike were most likely introduced (Little North Pond and North
Pond are connected and managed as the same water).
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