Iraqi Journal of Aquaculture

Zebra mussels Dreissena polymorpha are tiny bivalve
mollusca , invade water supply of cooling system unit in Al
Musayab power plant, 60 km south-west Baghdad and grow to
dense clusters. Its ability to rapidly colonize intake structures,
such as pipes and screens causing reduction in water pumping
capabilities .Some biological aspects of zebra mussel Dreissena
polymorpha have been studied and some physical & chemical
parameters were examined as alimenting factors for the species
Samples collecting was done monthly from two sites within the
water system , the first was the traveling band screen (TBS ) and
the other site was small canal collecting excess water passing
from TBS .Biological studies revealed that the samples collected
from the canal includes five size groups with average length of
5.7 ; 11.3 ; 16.7 ; 21.9 & 27.3 mm. In TBS , the individuals
found all over the year with highest number of 135 individuals
recorded in August . Individuals of a length of 11.3 & 16.7mm
were the dominant.In general, from total number of 799
individuals collected from TBS, 388 individuals were of size of
11.3mm and 239 individual were of size 16.7mm while no large
specimens of large size group of 27.3mm were recorded in
TBS.To study the settlement rate of larvae, several concreat tiles
of (25X25cm) were suspended at depths of 2,4& 6 m. in the
sedimentation pond (12m depth). The number of juveniles were
counted monthly . The result showed that there were two peaks
of settlement , one in June and the other in September and
October .Depth of 6m was the most suitable for settlement.The
average length of settled juveniles ranged between 3.5-6.1mm.
Water temperature in the site ranged between 11-32o C ,
Dissolved oxygen was 4.8-8.3ml/L . The highest value of
turbidity was 49NTU.Ca++ was 68-136mg/l and Mg++ was 34
72mg/l

Juveniles bunnyi Barbus sharpeyi were subjected to
starvation for a period of 11weeks, the proximate chemical
analysis of body composition showed that the main effect of
starvation was found on the depletion in lipid content, followed by
gradual protein decreasing, coincided with an increase in both
moisture and ash content. Muscle lipid was the more storage of
reserve than that of viscera, that’s why the lost weight from
muscles was more. This shows that energy utilized was derived
from lipid catabolism in muscle more than viscera. Both condition
factor (K) and viscera somatic index (VSI) tend to progressive
decrease as starvation period proceded, and there was an inverse
relationship between moisture and lipid content in whole
specimen.

Sixteen species belonging to 9 families of gastropods and
bivalves have been recorded from Huneish island, Yemen.
Measurments, diagnosis and coloured photos for every specimen
were provided .

Among 600 bunnei fishes transferred from Qurna marshes
to fish ponds at Basrah University/Marine Science Center, 211
fishes were infected with saprolegniasis during the period from
January to March, 2005 constituting a percentage of infection of
35.1% which was diagnosed by its clinical features and by direct
examination with 10% KOH solution and by culture. The cultutred
fungus was Saprolegnia parasitica

The stock of common carp Cyprinus carpio in
Euphrates river, near Al-Mussaib power station was studied
from September 2002 to December 2003. A total of 766
specimens were collected, their total lengths ranged from 6.2
to 55.4cm and between 9-5500g in total weight. The catch rate
was ranged between 8.4Kg/h in Summer to 30.2Kg/h in
Spring. Length-weight relationship was W= 2.7 x 10-4 L 3.04.
The lengths of fish were 23, 37, 48 and 54cm for the ages 1-4
years respectively. Growth and mortality parameters estimated
were: Ld= 65cm, K= 0.26, Z= 1.02, M= 0.60 and F= 0.42.
The exploitation rate (E) of carp was 0.41, lower than the
optimum level. The values of Lc and Lm were 18cm and
27.1cm respectively and 55.3% of population was immature. A
bimodal recruitment pattern of unequal strength was observed,
the major contribution was 71.9% of the total recruits with a
peak in May and the minor was contributed 28.1% with a peak
in October.

The present study has carried out to clarify the changes
of blood parameters of grass carp Ctenopharyngodon idella
(Valenciennes, 1844), responding to chlorofete effect under
laboratory conditions, in the presence and absence of aquatic
plant Ceratophyllum demersum (L.). Three concentrations
used during chronic exposure time extended to (15days).
Blood tests of (R. B. Cs., Hb, P.C.V.) were studied for fish
exposed to concentration investigated. The hematological
parameters decreased with the increasing of pesticide
concentrations. Moreover, values of indices (M.C.V.)
showed significant increase with the increasing of pesticide
concentration, particularly at highest concentration used
(3.8) mg/l during (5, 6 and 9) days with absence aquatic
plant. However, apparent increasing of (M.C.H.) were
observed at especially at concentration of (3.8) mg/l during
(6 and 9) days of exposure time. Significant increasing were
recoded in (M.C.V.) values for treatment aquatic plant
during (7 and 10) days at concentration (3.8) mg\l and during
(10) days for (M.C.H.). The present study showed non
significant reduction in (M.C.H.C.) values for both
treatments with and without aquatic plant..

The fisheries of the lower reaches of Tigris river, north Qurna
in Basrah Governorate have been analyzed during the period from
January to December 2005. The fishing boats used there varied in
lengths form 5 to 10m, of which 50% were motorized with 25-75 HP.
Seine and drift gill nets are the main fishing gears used, their lengths
ranged from 100 to 200m with mesh sizes of 14-100mm and 7-32mm
for seine and gill nets respectively. The number of fishermen in each
boat varied from 1 to 7. Twenty three fish species were recorded
caught in the area, of which eight were marine species, belonging to
twelve fish families, in addition to shrimps. The total catches ranged
from 629Kg in January - march to 3335Kg in July- September with
total catch of 7671Kg. Three species namely catfish Silurus
triostegus, crucian carp Carassius carassius and khishni Liza abu
comprised 86.93% of the total catches constituting 69.65%, 11.02%
and 6.26%, respectively. The average catch per unit of effort was
19.8 Kg/hr/100m for seine nets and 2.42 Kg/hr/100m for gill nets.
The diversity and evenness indices for biomass were 1.0 and 0.33,
respectively, in July-September and 1.5 and 0.52, respectively, in
October-December. The highest similarity index of species
composition was between April-June and July-September (87%), and
lowest between April-June and January-March (63%)