GIS and Aquaculture: Soft-Shell Clam Site Assessment
293
This expression will produce a map with four values. The no harvest, harvest only, cull
only and the combined cull and harvest areas will be coded 0,1,2,3 respectively. The
harvest plan map produce by this analysis is presented in Fig. 12 and the harvest only or
cull and harvest areas are easily identified. A profile analysis was performed at Indian
Hole on the estimated metric ton/hectare map. A proposed harvest track was digitized
on the Harvest Map and a profile was generated (Fig. 12). The profile result indicates a
low expected yield of about 1 metric ton/hectare at the start and a high of 26
tons/hectare is available at about 300 m from the start. However, at about 1 kilometre
from the start the expected yield drops to 0 tons/hectare. The area where the expected
yield drops to zero is at the beginning of a no harvesting zone. These areas may consist
of either juvenile or pre-recruit clam beds that should not be disturbed. Thus the harvest
plan map could be improved by adding other layers such as maps that identify areas that
maybe important for juvenile or pre-recruit clams. The profile analysis can also be used
to evaluate proposed harvesting tracks and select only those tracks that offer the highest
yield/hectare.
The calculation of harvesting area and the expected yield/hectare provides an
estimate of the total market biomass for all three areas. Big Barasway has the highest
market biomass at 236 metric tons followed Indian Hole and Little Barasway with 223
and 216 metric tons respectively (Fig. 12). An examination of the average yields/hectare
indicates that Indian Hole is the most productive at 13.94 metric tons/hectare followed
closely by Little Barasway at 11.37 tons/hectare. Finally, Big Barasway is the least
productive area at 7.37 tons/hectare.
Conclusion
The information presented in this study indicates that GIS is an important tool for the
aquaculture industry. These systems can be used to monitor, quantify and evaluate the
soft-shell beds near Burgeo. Management issues such as water quality, resource
sustainability as well as the economic viability of the clam resource can be assessed
within a GIS environment. The results of the analysis in this study suggest potential
problems with faecal coliform contamination from local cottages. Furthermore, at Big
Barasway the relatively low counts and densities at the recruit and brooding size classes
raise questions about clam mortality. This trend is also supported by the fact that the
Big Barasway average yield/hectare is approximately half of the average yield
calculated for Indian Hole although the area is twice as large (Fig. 12).
Finally, data collection for aquaculture site assessment is required if a resource
is to be managed effectively. GIS applications provide insights into the quality of the
physical environment as well as the sustainability of a resource. However, it is the
aquaculture operators who ultimately make the final decisions.
293
This expression will produce a map with four values. The no harvest, harvest only, cull
only and the combined cull and harvest areas will be coded 0,1,2,3 respectively. The
harvest plan map produce by this analysis is presented in Fig. 12 and the harvest only or
cull and harvest areas are easily identified. A profile analysis was performed at Indian
Hole on the estimated metric ton/hectare map. A proposed harvest track was digitized
on the Harvest Map and a profile was generated (Fig. 12). The profile result indicates a
low expected yield of about 1 metric ton/hectare at the start and a high of 26
tons/hectare is available at about 300 m from the start. However, at about 1 kilometre
from the start the expected yield drops to 0 tons/hectare. The area where the expected
yield drops to zero is at the beginning of a no harvesting zone. These areas may consist
of either juvenile or pre-recruit clam beds that should not be disturbed. Thus the harvest
plan map could be improved by adding other layers such as maps that identify areas that
maybe important for juvenile or pre-recruit clams. The profile analysis can also be used
to evaluate proposed harvesting tracks and select only those tracks that offer the highest
yield/hectare.
The calculation of harvesting area and the expected yield/hectare provides an
estimate of the total market biomass for all three areas. Big Barasway has the highest
market biomass at 236 metric tons followed Indian Hole and Little Barasway with 223
and 216 metric tons respectively (Fig. 12). An examination of the average yields/hectare
indicates that Indian Hole is the most productive at 13.94 metric tons/hectare followed
closely by Little Barasway at 11.37 tons/hectare. Finally, Big Barasway is the least
productive area at 7.37 tons/hectare.
Conclusion
The information presented in this study indicates that GIS is an important tool for the
aquaculture industry. These systems can be used to monitor, quantify and evaluate the
soft-shell beds near Burgeo. Management issues such as water quality, resource
sustainability as well as the economic viability of the clam resource can be assessed
within a GIS environment. The results of the analysis in this study suggest potential
problems with faecal coliform contamination from local cottages. Furthermore, at Big
Barasway the relatively low counts and densities at the recruit and brooding size classes
raise questions about clam mortality. This trend is also supported by the fact that the
Big Barasway average yield/hectare is approximately half of the average yield
calculated for Indian Hole although the area is twice as large (Fig. 12).
Finally, data collection for aquaculture site assessment is required if a resource
is to be managed effectively. GIS applications provide insights into the quality of the
physical environment as well as the sustainability of a resource. However, it is the
aquaculture operators who ultimately make the final decisions.