International Journal of Marine Science, 2017, Vol.7, No.21, 200-204
200
Research Report Open Access
Otolith Mass Asymmetry in Two Parrotfish Species,
Chlorurus sordidus
(Forsskål, 1775) and
Hipposcarus harid
(Forsskål, 1775) from Hurghada, Red
Sea Coast of Egypt
Laith A. Jawad
1
, Sahar F. Mehanna
2
, Mohamed A. Abu El-Regal
3
, Yassin A. Ahmed
4
1 Flat Bush, Manukau, Auckland, New Zealand
2 Laboratory of Population Dynamics, Fisheries Division, National Institute of Oceanography and Fisheries, Suez Branch, Suez, Egypt
3 Marine Science, Department, Faculty of Science, Port Said University, Port Said, Egypt
4 Laboratory of Population Dynamics, Fisheries Division, National Institute of Oceanography and Fisheries, Red Sea Branch, Hurghada, Egypt
Corresponding email
International Journal of Marine Science, 2017, Vol.7, No. 21 doi
Received: 08 May, 2017
Accepted: 31 May, 2017
Published: 08 Jun., 2017
Copyright © 2017
Jawad et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Jawad L.A., Mehanna S.F., El-Regal M.A.A., and Ahmed Y.A., 2017, Otolith mass asymmetry in two parrotfish species,
Chlorurus sordidus
(Forsskål, 1775)
and
Hipposcarus harid
(Forsskål, 1775) from Hurghada, Red Sea coast of Egypt, International Journal of Marine Science, 7(21): 200-204 (doi:
Abstract
The asymmetry in the mass of the sagitta of the parrotfish species,
Chlorurus sordidus
and
Hipposcarus harid
collected
from Hurghada, Red Sea coast of Egypt was investigated. In the present study, the weight of the difference between the weight of the
sagitta from both the left and right sides was divided by average otolith mass. The results shown that the value of x in the two-species
studied does not related to the length of the fish, though the value of otolith weight difference has shown a trend of increase with the
fish length. The value of x was calculated to fall between -0.2 and +0.2.
Keywords
Otolith; Weight asymmetry; Parrotfish; Red Sea; Acoustic and vestibular functions
Introduction
The condition of weightlessness due to the mass asymmetry in the otolith might cause changes in the behaviour of
the fish (Egorov and Samarin, 1970; Hoffman, 1977; Von Baungarten et al., 1982; De Jong et al., 1996; Hilbig et
al., 2002; Rehman and Ankan, 2002; Takabayashi and Ohmura-Iwasaki, 2003; Lychakov and Rebane, 2004). The
inconsistency and incongruity of the otolith from both sides of the head can be due the otolith weight asymmetry
that could lead to acoustic imperfections in fishes (Lychakov and Rebane, 2005; Lychakov, 2006). Therefore, the
damage in the tasks of the vestibular and auditory sense are unavoidable, but Lychakov et al. (2006) suggested
that the certain measureable morphological and physiological outcomes of otolith asymmetry are uncertain at this
stage.
To evaluate quantitatively the physiological role of the otolith weight asymmetry, a compacted form of otolith is
considered the ultimate shape and since fish otolith has such configuration, then it is preferred for such studies
(Lychakov et al., 2006).
In fish, the otolith mass asymmetry is usually having a value of 0.2< X < +0.2 or <20% (Lychakov et al., 1988;
Lychakov, 1992; Takabayashi, 2003; Lychakov and Rebane, 2004; 2005). In addition, the previous authors reach
to a conclusion that the otolith weight asymmetry and length or weight of the fish were not related to each other
(Lychakov and Rebane, 2004; 2005). Additionally, no functional damage will be detected as the otolith mass
asymmetry drops well below the values stated above as in the symmetric fish species (Lychakov and Rebane,
2005; Lychakov et al., 2006). The mass asymmetry of otolith might affect the quality of reception as proposed by
Egorov and Samarin (1970), Lychakov (1992), Samarin (1992), Scherer (2001) and Lychakov (2002).
There are no studies on the asymmetry in weight of fishes from Egypt. Therefore, the work at hand is regarded the
pioneer work in this field and will add further information on the asymmetry in weight in fish fauna of Egypt. The
goal of this study is to calculate and to assess the inconsistency of this asymmetry of Chlorurus sordidus and
