الفهرس 
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Abstract
The present study provides an update of the basic biological and
fisheries information of the Brushtooth lizardfish Saurida undosquamis
(Richardson, 1848) in two sites (the northern Red Sea (represented by the
northern Gulf of Suez at Suez) and the Mediterranean Sea (represented by the
southeastern coast of the Mediterranean Sea at Port Said). It also evaluates the
species’ status to implement the best planning target to conserve its stock in
the Egyptian waters.
Morphometric Measurements and Population Structure:
A total of 1110 specimens were randomly collected monthly for a
duration of 13 months (from March 2018 to March 2019) from the
Mediterranean Sea, whereas the period of collection was for 8 months (from
September 2018 to April 2019) from the Gulf of Suez (during the opened
fishing season). Samples were collected from the ports of Suez and Port Said
by fishermen using trawl nets. All length characters (TL, StL, HL, SnL OL,
and IOW) were measured using a ruler to the nearest 0.01mm, while a balance
to the nearest 0.01gm measured the weights (Twt and Gwt). The meristic
characters were counted as dorsal fin rays, anal rays, pectoral, and caudal-fin
rays.
The 493 specimens (250 males and 101 females) collected from the
Gulf of Suez had the total length varying between 9.9 cm and 32 cm with an
average of 18.20 cm, while the total weight varied between 5.87 gm and
207.91gm, with an average of 44.88 gm. Males length varied between 12.8
and 30.5 cm while their weight ranged from 10.64 gm to 196.48 gm. For
females, size varied between 12.1 cm and 32 cm. Their weight ranged from
10.05 gm to 207.91 gm.
For the Mediterranean Sea population, the total length of 617
specimens (316 males and 171 females) ranged between 8.5 and 32 cm with
an average of 17.73 cm, while the total weight varied between 2.77 gm and
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227.1 gm with an average of 42.26 gm. Males length varied between 8.5 cm
and 28.8 cm while their weight ranged from 3.77 gm to 148.6 gm. For females,
size varied between 9.4 cm and 32 cm. Their weight ranged from 4.59 gm to
227.1 gm.
The regressions of the relationships in the two study sites illustrated
that body weight was a positive allometric function of total length. The lengthweight
relationships were as follows:
Twt = 0.0044 TL3.108 R2 = 0.980 (Gulf of Suez population)
Twt = 0.0032 TL3.2367 R2 = 0.976 (Mediterranean Sea population)
Twt = 0.005 TL3.0625 R2 = 0.964 (Males-Gulf of Suez)
Twt = 0.0038 TL3.1611 R2 = 0.986 (Females-Gulf of Suez)
Twt = 0.0045 TL3.1146 R2 = 0.967 (Males- Mediterranean Sea)
Twt = 0.0028 TL3.2915 R2 = 0.979 (Females- Mediterranean Sea)
The highest values of Kf were observed in length groups 20-22 cm
(0.679) and 22-24 cm (0.696) from the Gulf of Suez population and the
Mediterranean one, respectively. Kc values were highest for individuals
falling within the length group 22-24 cm (0.627) and 20-22 cm (0.606) for the
Gulf of Suez population and the Mediterranean one, respectively. For the Gulf
of Suez population, the highest values of Kf were recorded in April 2019,
while the highest Kc was in November 2018. For the Mediterranean Sea
population, August 2018 had the highest values of Kf, while in March 2018,
the highest Kc values were recorded.
The Gulf of Suez population had six distinct age groups with the
highest mean length 30.49±1.140 of age group VI. The length composition of
the Mediterranean Sea population was separated into five age groups with the
maximum mean length 30.75±1.840 of age group V.
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The Von Bertalanffy equations for theoretical growth in both length
and weight were as follows:
Lt = 45.494 [1-exp {-0.1489 (t+1.095)}] (Gulf of Suez population)
Lt = 42.881 [1-exp{-0.1358 (t+1.846)}] (Mediterranean Sea population)
Wt = 625.711 [1-exp {-0.1489 (t+1.095)}]3.108 (Gulf of Suez population)
Wt = 614.188 [1-exp {-0.1358 (t+1.846)}]3.2367 (Mediterranean Sea population)
The overall growth performance was computed for both populations
and the calculated growth performance indices were:
Φ = 2.488 (Gulf of Suez population)
Φ = 2.397 (Mediterranean Sea population)
The age composition of both populations showed that age groups I and
II represented over 60.5% and 69.6% of the populations from the Gulf of Suez
and the Mediterranean Sea, respectively.
The estimations of mortalities and the exploitation rates of both
populations were as follows:
Total mortality coefficient (Z)
Z = 1.19Y-1 (Gulf of Suez population)
Z = 1.03Y-1 (Mediterranean Sea population)
Natural mortality coefficient (M)
M = 0.42 (Gulf of Suez population)
M = 0.39 (Mediterranean Sea population)
Fishing mortality coefficient (F)
F = 0.77 (Gulf of Suez population)
F = 0.64 (Mediterranean Sea population)
Exploitation rate (E)
E = 0.65 (Gulf of Suez population)
E = 0.62 (Mediterranean Sea population)
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Reproductive Biology:
The estimated sex ratio showed that for the Gulf of Suez population,
males exhibited a higher number than females all of the year except in March
2019, where females were dominant (52.4%). Males recorded the highest
percentage in September 2018, by 85.1%. Overall sex ratio was 1:0.40. For
the Mediterranean Sea population, males also dominated almost all the year
except in July and August 2018, where females recorded the higher values
(51.7% and 53.1%, respectively). Males recorded the highest percentage in
January 2019 by 87%. Overall sex ratio was 1:0.54.
On the other hand, the fish length corresponding to 50% (L50) was 17.3
cm for males and 18.2 cm for females. The corresponding was equal to 2.17
and 2.34 for males and females, respectively, for the Gulf of Suez population.
For the Mediterranean one, the fish length corresponding to 50% (L50) was
16.9 cm for males and 17.8 cm for females. The age (tm) was equal to 1.9 and
2.10 for males and females, respectively.
Regarding the maturity stages, the highest percentage of the running
stage (V) was found during April 2019 with (42%) and (65%) for males and
females, respectively, from the Gulf of Suez. For the Mediterranean Sea
population, the highest percentage of the running stage (V) was found during
February (47.37%) and (60%) for males and females, respectively.
For the Gulf of Suez population, females acquired higher average
values of GSI than males, and a peak was reached in April 2019 for both males
(4.95 ± 3.75) and females (5.51 ± 3.54). For the Mediterranean Sea population,
the maximum average values of GSI for both sexes were recorded in August
2018 (5.30 ± 3.581) for males and (5.39 ± 3.708) for females. Females
obtained higher average values (in nine months out of thirteen) than males