Every year, volunteers around the watershed hang small wire cages (10"x 10"
x 6") from their docks. One cage is filled with oyster shells while the
other cage is filled with crushed concrete. The cages remain hanging from the
docks for about 6 months from June through January. Volunteers pull their cages
out of the water every month or so, give them a few shakes to keep them from
becoming too muddy, and then put them back in the water to continue growing.
From about mid-June through October or
November, oysters reproduce in the river and spat (larvae) floating
through the water during this time discover the cages and settle on this
substrate.
In January, once oysters stop actively
growing for the winter, volunteers pull their cages out of the water and
bring them to us. We then sift through lots of marsh critters and mud to count
the number of spat from each cage. The point of counting the spat is to help us
better understand the distribution of spat throughout the river, based on the
location of each volunteer's cage.
"Marsh critters"
Using the data collected we have found an
increase in the amount of oyster spat in the river. In 2013, the total number
of spat collected by all 25 volunteers was 1,319, including 520 from the Elizabeth River. These numbers give us a good indication
that spat settlement in the Lynnhaven River during the summer of 2014 was
better than during the summer of the previous year, which is great news! This also means that our 2014 oyster restoration projects probably fared well with natural
spat settlement!
This data also helped confirm
that crushed concrete can perform very well as a substitute for shell in future
oyster reef restoration projects. Crushed concrete is a great alternative to limited and expensive oyster shell.
Number of Spat Collected in 2013 & 2014:
2013
|
2014
|
|
# Spat Shell Cage
|
499
|
951
|
# Spat Concrete
Cage
|
820
|
925
|
Total # Spat
|
1,319
(520 from Elizabeth River)
|
1,876
|
You can read more about the spat catcher
program in the Virginian Pilot Beacon article written by Mary Reid Barrow here.
Written by: Emily Bodsford
Edited by: Meredith Malone and Trista Imrich
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