Initial Inventory

Pond A1

On 6 April 2004, the pond was seined twice with a fingerling seine. Fish were weighed back to the pond with a hydraulic boom. A total of 2,697 lb were caught in the first haul and 5,290 lb were caught in the second haul. A larger biomass was captured in the second seine haul because a more efficient seining technique was used (no sock was attached to the seine as it was pulled across the pond). The sum of all fish captured was 7,987 lb. However, it is unlikely that all the fish in the pond were caught with only two seine hauls. Unpublished results from a study conducted in commercial pond (Appendix 1) suggested that an average of 88 ± 9 % (mean in percent ± standard deviation) of the biomass of a pond is caught after two seine hauls. Assuming a harvest efficiency of 88%, the initial inventory of the pond on April 6^th was estimated to be 9,076 lb (1,008 lb/acre).

The average weight (± SD) of the fish caught in the first haul (0.6 ± 0.5 lb) was significantly different than the average weight of the fish caught in the second haul (1.0 ± 0.9 lb). The size distribution of the fish caught in the first haul was also slightly different from the size distribution of the fish caught in the second haul (Figure 1). The differences observed between the two seine hauls may be explained by the fact that a different seining technique was used in the second seine haul (no sock was attached to the seine as it was pulled across the pond).

The size distribution of the overall pond inventory (Table 1, Table 3, and Figure 1) was estimated by combining the data from the two seine hauls. A total of 9,076 lb and 10,880 heads at an average weight of 0.8 lb was estimated to be the inventory in pond A1 on April 6^th, 2004.

Pond A2

On 7 April 2004, the pond was seined twice with a fingerling seine. Fish were weighed back to the pond with a hydraulic boom. A total of 9,631 lb were caught in the first haul and 1,197 lb were caught in the second haul. The sum of all fish captured was 10,828 lb. However, it is unlikely that all the fish in the pond were caught with only two seine hauls. Unpublished results from a study conducted in commercial pond (Appendix 1) suggested that an average of 88 ± 9 % (mean in percent ± standard deviation) of the biomass of a pond is caught after two seine hauls. Assuming a harvest efficiency of 88%, the initial inventory of the pond on April 7^th was estimated to be 12,305 lb (1,367 lb/acre).

The average weight (± SD) of the fish caught in the first haul (0.7 ± 0.6 lb) was significantly different than the average weight of the fish caught in the second haul (0.4 ± 0.4 lb). The size distribution of the fish caught in the first haul was also slightly different from the size distribution of the fish caught in the second haul (Figure 2) even though the pond was seined the same way for both times.

The size distribution of the overall pond inventory (Table 1, Table 3 and Figure 2) was estimated by combining the data from the two seine hauls. A total of 12,305 lb and 19,261 heads at an average weight of 0.6 lb was estimated to be the inventory in pond A2 on April 7^th, 2003.

Pond B1

On 13 April 2004, the pond was seined twice with a fingerling seine. Fish were weighed back to the pond with a hydraulic boom. A total of 14,806 lb were caught in the first haul and 4,946 lb were caught in the second haul. The sum of all fish captured was 19,752 lb. However, it is unlikely that all the fish in the pond were caught with only two seine hauls. Unpublished results from a study conducted in commercial pond (Appendix 1) suggested that an average of 88 ± 9 % (mean in percent ± standard deviation) of the biomass of a pond is caught after two seine hauls. Assuming a harvest efficiency of 88%, the initial inventory of the pond on April 13^th was estimated to be 22,445 lb (2,040 lb/acre).

The average weight (± SD) of the fish caught in the first haul (0.6 ± 0.3 lb) was equal to the average weight of the fish caught in the second haul (0.6 ± 0.3 lb). However, the size distribution of the fish caught in the first haul was slightly different from the size distribution of the fish caught in the second haul (Figure 3). 

The size distribution of the overall pond inventory (Table 1 and Figure 3) was estimated by combining the data from the two seine hauls. A total of 22,445 lb and 37,974 heads at an average weight of 0.6 lb was estimated to be the inventory in pond B1 on April 13^th, 2003.

Pond C1

On 22 April 2004, the pond was seined twice with a fingerling seine. Fish from both seine hauls were pooled in a single live-car. Captured fish were graded with the UAPB in-pond floating bar grader to separate food-size fish from sub-marketable fish. The graded market-size fish were weighed and loaded onto a hauling truck with a hydraulic boom and sold to a processing plant. The small fish that swam through the bars were captured in a separate live-car and were weighed back to the pond with a hydraulic boom. A total of 24,201 lb of market-size fish were loaded onto the truck to be sold to the processing plant and 22,636 lb of small fish were released back to the pond. However, it is likely that some fish were not caught with two seine hauls. Unpublished results from a study conducted in commercial pond (Appendix 1) suggested that an average of 88 ± 9 % (mean in percent ± standard deviation) of the biomass of a pond is caught after two seine hauls. Assuming a harvest efficiency of 88%, the initial inventory of the pond on April 22^th was estimated to be 29,023 lb (2,902 lb/acre).

Random fish samples were collected from the live-car before grading and from the live-car that captured the small graded fish that were later released back to the pond. The average weight (± SD) of the fish before grading was 0.8 ± 0.6 lb. The average weight of the small graded fish was 0.6 ± 0.2 lb. The size distribution of the fish before grading and of the small graded fish are presented in Figure 4.

The size distribution of the overall pond inventory (Table 1 and Figure 4) was estimated by combining the data from the pre-grade and post-grade samples. A total of 29,023 lb and 46,796 heads at an average weight of 0.6 lb was estimated to be the inventory in pond C1 on April 22^nd, 2003.

Pond C2

On 16 April 2004, the pond was seined twice with a fingerling seine. Fish were kept in live-cars and weighed back to the pond with a hydraulic boom. A total of 34,862 lb were caught in the first haul and 3,722 lb were caught in the second haul. The sum of all fish captured was 38,584 lb. However, it is unlikely that all the fish in the pond were caught with only two seine hauls. Unpublished results from a study conducted in commercial pond (Appendix 1) suggested that an average of 88 ± 9 % (mean in percent ± standard deviation) of the biomass of a pond is caught after two seine hauls. Assuming a harvest efficiency of 88%, the amount of fish that was not captured by the seine was estimated to be 5,261 lb.

The average weight (± SD) of the fish captured in the first seine haul was 0.9 ± 0.6 lb and the size distribution is presented in Figure 5. The average weight (± SD) of the fish captured in the second seine haul was similar (0.9 ± 0.7 lb) and the size distribution is presented in Figure 5. However, the farm manager decided to harvest the large biomass of market-size fish captured in the first haul. Therefore, all fish from the first haul were transferred to a sock with a mesh-size of 2 inches and allowed to grade for about one hour. The smaller fish swam back to the pond and the larger ones retained by the sock were weighed and harvested out of the pond with a hydraulic boom. A total of 20,985 lb of fish averaging 1.7 lb was harvested from the sock. The size distribution of harvested fish is presented in figure 5.

After that harvest, the size distribution of the remaining overall fish inventory (Table 1 and Figure 5) on April 16^th was estimated to be 22,860 lb (2,286 lb/acre) and 38,452 heads, and to average 0.6 lb per fish.