This study evaluated the success of gravel beds to attract sunfish
for anglers.
Anglers fishing off the Eustis Lake Walk
(ELW) pier. |
The Eustis Lake Walk pier (ELW) is located on the east shore of
Lake Eustis in Eustis, Florida (Lake County). The pier is
popular with black crappie (Pomoxis nigromaculatus)
anglers during the winter but receives little angling pressure
during the late spring and summer. In an attempt to boost
angling pressure for the under-utilized sunfish (Lepomis
sp.) population, the Florida Fish and Wildlife Conservation
Commission (FWC) designed a study to evaluate the use of gravel for
attracting sunfish and improving anglers' catch and
participation.
Various concepts of using gravel for attracting sunfish were
tested for a year beginning in the spring of 2004. In November
2004, gravel was placed along the ELW pier in twenty frames. Each
frame was 3.05 x 3.65 meters and constructed of 5 x 15 centimeter
pressure treated wood. Ten frames were placed on the north
end of the ELW and the other ten were placed along the south
end. Lime rock (No. 57) and quartz river gravel (No. 7) were
each placed in ten randomly assigned frames. There were five frames
at each location, and the depth of the gravel averaged 10 cm in
each frame.
Lime rock (left) and quartz (right) used
to
construct the gravel beds in this
study.
Timed electrofishing samples were collected around the ELW during
May and June 2004, prior to the gravel installation, and
again for the same time period the following year after the
installation. Sample sites were divided into two categories:
areas designated for gravel installation which were located on
opposite ends of the pier, and control sites in areas that were to
remain natural. Each site was sampled and all sunfish were
collected, measured for total length, and released unharmed.
Electrofishing samples along the ELW indicated the gravel
attractors were effective in concentrating sport fish. Catch rates
of sunfish increased significantly from 2004 prior to the
installation of the attractors (23.9 fish an hour) to 2005
following installation (501.1 fish an hour). The catch rates
following installation were also higher than those observed in the
control sites after the attractors were installed. Bluegill
dominated the sunfish catch from the attractor sites in both years.
Remarkably, in 2005, the year following the establishment of the
gravel beds, 96 percent of the sunfish caught were bluegill.
In addition to electrofishing sampling, hook-and-line samples
and angler interview data were collected. A stratified,
roving creel, also called an angler survey, was conducted on the
ELW during the months of May and June in both 2004 and 2005 to
assess changes in angler catch. Twenty-one days each month
were randomly selected to perform total angler counts during a
randomly selected hour interval each day. Interviews were
conducted to obtain catch and effort information. These
surveys indicated that the amount of hours, or effort, anglers
fished for sunfish increased by 253 percent from 2004 to
2005. Angler catch rates for sunfish on ELW also drastically
increased from 0.54 fish an hour in 2004 to 2.56 fish an hour in
2005.
Weekly sunfish hook-and-line samples were collected by FWC staff
from April 28 to June 24, 2005, to determine if angler catch rates
differed between the two gravel types. Each angler was
assigned three randomly-selected attractor sites of each gravel
type and given 15 minutes of angling time per site. However,
statistical tests indicated that there was no significant
difference in the number of sunfish caught from the two types of
gravel.
|
FWC biologists installing a gravel bed
off the Eustis Lake Walk (ELW) pier.
|
In short, the installation of gravel beds on ELW was successful
in attracting sunfish species. Angler participation and catch
of sunfish drastically increased in gravel areas, but there was no
significant difference in the number of sunfish caught from the two
types of gravel. Therefore, the less expensive No. 57 lime
rock is recommended for use around public docks, boat ramps, and
seawalls to improve sunfish catch for anglers.
After presenting these results to a regional meeting of fishery
scientists, at least four other states are now investigating the
use of gravel for attracting sunfish.
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