RESULTS AND DISCUSSION 
Attempts to culture and maintain a laboratory population of P. vulgaris 
have been successful thus far. Ovigerous females were obtained from adults 
hatched in the laboratory and cultured for 90 days. These egg-bearing females 
have yielded morphologically normal larvae, thereby indicating that the eggs 
resulting from lab-reared females are viable. After 16 months of culture, a total 
of 21 ovigerous females have been collected from the system. Six of these 
shrimp are females that also bore eggs in the first laboratory spawning season 
(November, 1976 to January, 1977 or 9 to 10 months ago). Problems in 
controlling photoperiod and water temperature have limited successful hatches 
to only two females. Little (4) has discussed how manipulation of these two 
environmental factors can be used to induce winter breeding in grass shrimp. 
The diet study (Table 14-1) has indicated on a gross scale that a flake food 
can be used as a diet. Ovigerous females were collected from the four £ 
flow-through systems used for both the brine shrimp and Tetra Marin diets. 
Therefore, growth, survival and reproduction are acheivable with the live and 
dried foods. 
All of the systems and techniques mentioned herein have yielded 
satisfactory results. However, some minor problems remain. One such problem 
is cannibalism, especially in the 20 and 48 £ hatching jars used as holding tanks 
for juvenile and adult grass shrimp. Obvious solutions include increasing the 
food available, either as more food per day, or as multiple daily feedings, or 
decreasing the density of shrimp. A certain degree of cannibalism is to be 
expected in mass cultures during periods of molting. 
A second problem, also in the hatching jar systems, relates to the physical 
design of the container. The concave bottom of the jar, coupled with a circular 
flow, causes a centrifuging of the shrimp into the center near the bottom. A 
flatter bottom with a larger bottom surface area to volume ratio could be a 
solution. The 40 £ kriesel systems (3) used in lobster culture efforts have the 
desired flatter bottoms, and also jetted water inflow along the sides that create 
a more uniform distribution of the shrimp. Preliminary studies studies indicate 
that the kriesel design will be very successful for juveniles and adults. 
Compared to growth in the four £ beaker systems (See Table 14-1), the kriesel 
has yielded significantly higher growth rates. Mean carapace length in the 
kriesel after nine weeks was 6.8 ± 0.69 mm (range 5.9 to 7.9 mm), a size not 
attained until an age of about 20 weeks in the beaker. 
One last problem is animals flipping out of the systems, especially the 48 £ 
jar. This appears to happen in conjunction with a molt, and the subsequent 
cannibalism pressure from other shrimp in the system. A simple solution to the 
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