290
A. Simms
in the data. Fig. 9 (B) indicates that, in some areas, there is a need to cull the mature
clam population, especially at Indian Hole.
According to Newell and Hidu (1994) the expected spatial distribution of
clams in an area ranges from highly dispersed in the juvenile size class to a highly
aggregated pattern in the recruit and brooding classes. Mapping the size class densities
as continuous surfaces indicates that a similar pattern occurs in Big Barasway (Fig. 10)
and to a lesser degree in Indian Hole and Little Barasway. Fig. 11 confirms the
increasing spatial aggregation from juvenile to brooding stock classes whereby an
inverse relationship exists between the larger clam size classes and percent area
occupied. For example, in Big Barasway juvenile clams (LT 35 mm) are found in 95
percent of the surveyed area while brooding stock clams (GE 63.5 m) are found in only
17 per cent of the area.
Fig. 11 also presents information on the clam population characteristics. In Big
Barasway there is a large decrease in clam density from the juvenile to pre-recruit class
(Fig. 11 (B)). The average density drops from a high of 124/m sq. for the juvenile class
to 30/m sq. for the pre-recruit class. There is also a dramatic change in densities at
Indian Hole where the average density drops from 125/m sq. for the pre-recruit class to
53/m sq. for the recruit class. Little Barasway shows a more gradual change where the
average densities are 57, 55, 43/m sq. for the juvenile, pre-recruit and recruit classes
respectively. Indian Hole has the highest densities in all classes while Big Barasway has
the second highest juvenile density but the lowest densities in all other classes. The
frequency size class information presented in Fig. 11 (C) indicates that 80 percent of the
sampled clam population in Big Barasway is juvenile and the recruit population
accounts for only 10 percent of the sampled data. The trends at Indian Hole and Little
Barasway are similar. The juvenile classes at these locations account for 47 and 42
percent of the clams sampled, however, Little Barasway has a higher percentage of
recruits (23 percent) than Indian Hole with 14 percent. Although Indian Hole has a
higher density of clams/m sq. Little Barasway has the highest percentage of recruit
clams suggesting a possible higher survival rate for clams at this location. The low
percentages associated with the larger clams at Big Barasway needs further study in
order to understand the dramatic changes in the observed densities. Although the area
appears to be experiencing high predation, an analysis of the data did not reveal any
correlation between the presence or absence of predators and the size class distribution.
Aquaculture Management and GIS
GIS can be used to manage and organize operations at an aquaculture site. The harvest
plan presented in this chapter is an example that demonstrates how a GIS can be used to
help aquaculture operators map and evaluate their proposed activities. Through GIS the
operator
A. Simms
in the data. Fig. 9 (B) indicates that, in some areas, there is a need to cull the mature
clam population, especially at Indian Hole.
According to Newell and Hidu (1994) the expected spatial distribution of
clams in an area ranges from highly dispersed in the juvenile size class to a highly
aggregated pattern in the recruit and brooding classes. Mapping the size class densities
as continuous surfaces indicates that a similar pattern occurs in Big Barasway (Fig. 10)
and to a lesser degree in Indian Hole and Little Barasway. Fig. 11 confirms the
increasing spatial aggregation from juvenile to brooding stock classes whereby an
inverse relationship exists between the larger clam size classes and percent area
occupied. For example, in Big Barasway juvenile clams (LT 35 mm) are found in 95
percent of the surveyed area while brooding stock clams (GE 63.5 m) are found in only
17 per cent of the area.
Fig. 11 also presents information on the clam population characteristics. In Big
Barasway there is a large decrease in clam density from the juvenile to pre-recruit class
(Fig. 11 (B)). The average density drops from a high of 124/m sq. for the juvenile class
to 30/m sq. for the pre-recruit class. There is also a dramatic change in densities at
Indian Hole where the average density drops from 125/m sq. for the pre-recruit class to
53/m sq. for the recruit class. Little Barasway shows a more gradual change where the
average densities are 57, 55, 43/m sq. for the juvenile, pre-recruit and recruit classes
respectively. Indian Hole has the highest densities in all classes while Big Barasway has
the second highest juvenile density but the lowest densities in all other classes. The
frequency size class information presented in Fig. 11 (C) indicates that 80 percent of the
sampled clam population in Big Barasway is juvenile and the recruit population
accounts for only 10 percent of the sampled data. The trends at Indian Hole and Little
Barasway are similar. The juvenile classes at these locations account for 47 and 42
percent of the clams sampled, however, Little Barasway has a higher percentage of
recruits (23 percent) than Indian Hole with 14 percent. Although Indian Hole has a
higher density of clams/m sq. Little Barasway has the highest percentage of recruit
clams suggesting a possible higher survival rate for clams at this location. The low
percentages associated with the larger clams at Big Barasway needs further study in
order to understand the dramatic changes in the observed densities. Although the area
appears to be experiencing high predation, an analysis of the data did not reveal any
correlation between the presence or absence of predators and the size class distribution.
Aquaculture Management and GIS
GIS can be used to manage and organize operations at an aquaculture site. The harvest
plan presented in this chapter is an example that demonstrates how a GIS can be used to
help aquaculture operators map and evaluate their proposed activities. Through GIS the
operator