morphological development of Hilsa (Tenualosa ilisha)
collected from Meghna Estuary, Bangladesh
G.S. Riar1, R. Ara1, S.M.N. Amin1, Mohd. S.
Kamarudin1, Md. A. Wahab2, Nur- A- Raushon3,
J. Arockiaraj4 and A. Arshad1*
Fisheries Biology and Aquatic Ecology, Department of Aquaculture, Faculty of
Agriculture, Universiti Putra Malaysia,
Serdang, Selangor, Malaysia
WorldFish, South Asia, Bangladesh, Banani, Dhaka 1213, Bangladesh
Fisheries Research Institute, Mymensingh, 2201, Bangladesh
4Faculty of Science
and Humanities, SRM University, Kattankulathur - 603 203, India
Author E-mail: email@example.com
Paper received : 10.06.2017
Revised received : 21.10.2017
Re-revised received :
Accepted : 28.12.2017
Aim: In larval fish,
food size is closely related with the length of the fish jaw, as well as
mouth gape. So far, no information is available on the larval mouth
morphology of Hilsa shad Tenualosa ilisha. Hence, observations on the
mouth morphological development during different larval stages of T.
ilisha were examined.
Methodology: Samples of T.
ilisha larvae were collected weekly from Meghna estuary, Bangladesh
between August 2016 and January 2017. The collected samples were transported
to the laboratory and the mouth morphology of larvae and early juvenile
stages were microscopically examined.
Results: The smallest
mouth size was found at 450, while was largest found was at 900.
There was no evidence of teeth, while the lower jaw was longer than the upper
jaw. The four larval stages were observed in this study; viz.
yolk-sack stage, pre-flexion stage, flexion stage, post-flexion stage. The mouth
was closed at yolk sac stage while in the pre-flexion stage, larval mouth
gape ranged between 177 and 367 μm. In the flexion stage, the range was
241 to 497 μm, in post-flexion stage it ranged between 307 and 621
μm and finally in early juvenile stage the range was 393 to 788 μm.
Interpretation: There was a
significant relationship with standard length (SL) and upper jaw length (R2
= 0.941, p < 0.05) as well as lower jaw (R2 = 0.931, p<
0.05). Significant relationship was also found with SL and mouth gap at 900
(R2 = 0.938, p < 0.05). Overall, these findings can be
considered a base data for mouth morphological development of T. ilisha.