Abstract:
Macrobrachium rosenbergii, generally known as giant freshwater prawn (GFP), is a key
crustacean species broadly cultured in the world due to its rapid growth rate, ability to grow
in a wide range of salinity levels, high consumer preference and market price. Although GFP
culture is at a preliminary stage of development in inland aquaculture of Sri Lanka, their post
larvae are regularly stocked in irrigation reservoirs to develop a culture-based fishery. Due to
high market value of GFP, it plays an important role in the local economy. Assessing the
relationships of flesh and shell yield with morphometric characters of GFP help support
stakeholders at the value chain when marketing the product. Therefore, present study was
aimed at evaluating the flesh and shell yield of GFP, in relation to their body weight and
carapace length, which are the morphometric parameters that can be easily obtained in the
field. Variations due to sex, and the size of the inhabitant reservoirs were considered. Three
hundred GFP specimens (150 blue claw males and 150 females) were collected from the
culture-based fishery harvest at major (>800ha), medium (200-800ha) and minor (<200ha)
perennial reservoirs in northcentral and southern provinces. After taking morphometric
parameters, specimens were dissected, degutted and flesh and shell parts were weighed
separately. Significant correlations between flesh yield (%) and body weight was found in
both male (r=-0.3920, p value<0.0001) and female GFP (r=-0.2170, p value=0.0076), but not
between the shell yield and body weight. Correlations between flesh yield (%) and carapace
length was also ascertained in both male (r=-0.2930, p value=0.0002) and female GFP (r=-
0.1590, p value=0.0051). Of the size categories of GFP caught from reservoirs, strongest
relationships were ascertained for both sexes from major perennial reservoirs. Albeit, there
was no significant difference (ANOVA: p>0.05) in flesh and shell yield amongst the three
reservoir categories. Thus, study concluded that the flesh yield of male and female GFP can
be predicted using either body weight or carapace length, which might be useful in processing
industry.