International Journal of Marine Science 2016, Vol.6, No.42, 1-8
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female has shown to have positive allometry (b<1). No negative allometry growth was observed in the
morphometric characters of both male and female of
S. dumerili.
The growth pattern of certain morphometric characters was shown to be species-specific patterns such as the body
depth allometry in
S. dumerili
, which possesses a deeper body. The profiles of the middle part of the body were
always found to deepen, something that is necessary for maneuvering (quick starts and rapid turns) (Webb, 1984).
Such results were obtained for several species of the family Sparidae by Niklioudakis et al. (2014). The noticeable
growth in the abdominal region suggests greater development of the intestine (Elbal et al., 2004), a finding similar
to other studies that have shown that the middle part of the body increases later throughout ontogeny (after head
and tail) in bilateral species (Osse et al., 1997; Van Snik et al., 1997; Gozlan et al., 1999), as opposed to
asymmetrical species (
Paralichthys californicus
, Gisbert et al., 2002). The other positive and negative allometric
patterns of different morphometric characters obtained in this study are associated with changes in body form
related to requirements of the carangiform swimming pattern that this species is used.
In the present results and in the case of male and female specimens, all morphometric indices shown high correlation
value (above 0.9), while in the case of undifferentiated sexes, moderate correlation value was shown (0.7 to 0.95).
When all specimens (male, female and undifferentiated) combined the correlation was high (>0.9).This indicates
that the growth of
S. dumerili
in one area of the body do not grow as the same growth rate of the total length of the
fish probably because when juvenile specimens were included in the account. Similar results were obtained by
Oniye et al. (2006) and Safi et al. (2014) on
Protopterus annectens
and
Pomadasys stridens
respectively.
Niklioudakis et al. (2014)
suggested that individual morphological characters was generally independent of
species, but on the temperature of the environment the fish that developing in. Accordingly, the strength of the
relationship (r
2
in Table 1) for the eight morphometric characters were higher for male and female specimens than
those specimens contained undifferentiated sexes, implying that decreasing temperature induces increasing
variability in morphological change, i.e. the change is less synchronized between characters. Since this group of
specimens contains specimens of different ages and juvenile, therefore the strength of the relationship of the
morphometric characters was less and it may possible that the morphometric characters is more synchronized with
water temperature rather than with other morphometric characters (
Niklioudakis et al., 2014).
The range of the total length given for
Seriola dumerili
at maturity is 800 to 1270 mm and the maximum and the
common total length recorded are 1900and 1000 mm respectively (Froese and Pauly, 2016). The range of the
specimens studied in this work is less than the range given for this species and the largest specimen (1660 mm TL)
falls near the upper limit of the range given for this species in the literature.
Several specimens of
Seriola dumerili
were collected from different parts of the world having total length falls
within the range of the total length of the specimens obtained in the present study from the Tunisian waters (Lin and
Shao, 1999, 299 mm, Taiwan; Mazzola et al., 2000, 404 mm, Gulf of Castellammare, North West Sicily; Monteroa
et al., 2004, 310-420 mm, Puertode Mazarrón, Spain).
Meristic characters of
Seriola dumerili
are in agreement with specimens of this species collected from other parts
the Mediterranean Sea and the Black Sea by Fischer et al (1987) except for the upper range of the anal fin ray was
lower (21 rays) by one ray than that reported by Fischer et al (1987).This difference in the upper range of anal fin
rays indicates that different locations and environment have considerable impact on meristic characters where
interaction between genetics and environment occurred(Marr, 1957; Swain and Foote,1999).
The LLRs values of male, female, combined sexes and undifferentiated sexes were highly significant (P< 0.001)
(Tables 2) and they were compared with those available by Froese and Pauly (2016).The value of the coefficient
“b” for the FL-SL obtained in the present study is higher than that given by Froese and Pauly, (2016) for combined
sexes, but for TL-FL, the “b” value was slightly lower than that given by Froese and Pauly (2016). For such variations,
the ecological conditions of the habits or variation in the physiology of animals, or both, are responsible (Le Cren, 1951).
