Iranian Journal of Fisheries Sciences
مجله علوم شیلاتی ایران
IJFS
Agriculture
http://jifro.ir
1
admin
1562-2916
10.18869/acadpub.ijfs
en
jalali
1391
4
1
gregorian
2012
7
1
11
3
online
1
fulltext
en
Significant changes in pelagic fish stocks of Clupeonella spp. in the south Caspian Sea
Genetics
Genetics
پژوهشي
Orginal research papers
<font face="Times New Roman" size="3"> </font><p class="MsoNormal" style="margin: 0cm 0cm 0pt text-align: justify line-height: 120% vertical-align: top"><font face="Times New Roman"><font size="3"><span style="mso-bidi-language: FA">The present study was carried out
during 2006-2007 along the southern Caspian Sea.</span><span class="hps"><span style="color: black mso-ansi-language: EN"> </span></span><span style="mso-bidi-language: FA">The</span><span class="hps"><span style="color: black mso-ansi-language: EN"> </span></span><span style="mso-bidi-language: FA">species composition showed that the common kilka, </span><i><span lang="UZ" style="mso-bidi-language: FA mso-ansi-language: UZ">Clupeonella </span></i><i><span style="mso-bidi-language: FA">c</span></i><i><span lang="UZ" style="mso-bidi-language: FA mso-ansi-language: UZ">ultriventris</span></i><i><span lang="UZ" style="mso-bidi-language: FA"> </span></i><i><span lang="UZ" style="mso-bidi-language: FA mso-ansi-language: UZ">caspia</span></i><span style="mso-bidi-language: FA">, is
dominant species with 89% and then anchovy, </span><i><span lang="UZ" style="mso-bidi-language: FA mso-ansi-language: UZ">C. engrauliformis</span></i><span style="mso-bidi-language: FA">, has shown only 8.7%</span><span lang="EN-AU" style="mso-bidi-language: FA mso-ansi-language: EN-AU"> while it was already dominant
species in the past decades.</span></font><em><span lang="EN-AU" style="color: rgb(51, 51, 51) line-height: 120% font-size: 11pt mso-ansi-language: EN"> </span></em><em><span lang="EN" style="color: rgb(51, 51, 51) line-height: 120% font-size: 11pt font-style: normal mso-ansi-language: EN">The overall results indicated that common kilka was
replaced with anchovy kilka as previous dominant kilka species due to invasion
of </span></em><font size="3"><i><span lang="EN-AU" style="mso-bidi-language: FA mso-ansi-language: EN-AU">Mnemiopsis</span></i><span lang="EN-AU" style="mso-bidi-language: FA mso-ansi-language: EN-AU"> <i>leidyi</i> to the southern Caspian Sea.</span><span style="mso-bidi-language: FA"> Anchovy suffered greatly from <i>M. leidyi</i> so
that the total catch dropped from 95000 mt in 1999 to less than 20000</span></font><span style="line-height: 120% font-size: 10pt mso-bidi-language: FA"> </span><font size="3"><span style="mso-bidi-language: FA">mt in 2007. </span><span lang="EN-AU" style="mso-bidi-language: FA mso-ansi-language: EN-AU">In our survey, 1415 fish
specimens were collected randomly, including 221 anchovy, 281 bigeye and 913
common kilka. The mean length of anchovy was 117.8 ± 0.27 mm, while it was
about 93.0 mm during 1995 to 1998 before the invasion of <i>M. leidyi</i>. Analysis
of age classes indicated the mean age of 4.5 ± 0.04 years for anchovy, 3.6 ±
0.03 for common kilka and 4.6 ± 0.08 for big eye <i>C. grimmi</i>.</span><span lang="EN-AU"> </span><span lang="EN-AU" style="mso-bidi-language: FA mso-ansi-language: EN-AU">According to the age and the length structure of the specimens in this
study, it could be concluded that in recent years, young fish population of
anchovy has been decreased in comparison with the last decade. The results
showed that some biological characteristics of kilka population were affected
by </span><i><span style="mso-bidi-language: FA">M. leidyi</span></i><span lang="EN-AU" style="mso-bidi-language: FA mso-ansi-language: EN-AU">. Recently
fishing activities take place in shallow waters where schools of kilka are in
suitable density for fishing.</span><span lang="EN-AU"> </span><span lang="EN-AU" style="mso-bidi-language: FA mso-ansi-language: EN-AU">According to our results,
ctenophore occupied the anchovy habitat where it was mainly more than 50 m
depth.</span><span lang="EN-AU"> </span><span lang="EN-AU" style="mso-bidi-language: FA mso-ansi-language: EN-AU">The fishing has moved to areas with depths less
than 50 meters where it was the main reason to change in species composition.</span><span class="hps"><span lang="EN" style="color: black mso-ansi-language: EN"><o:p /></span></span></font></font></p><font face="Times New Roman" size="3"> </font>
Age structure, Caspian Sea, Clupeonella, Species composition, Mnemiopsis leidyi
559
569
http://jifro.ir/browse.php?a_code=A-10-1-179&slc_lang=en&sid=1
F.
Parafkandeh Haghighi
Parafkandeh@hotmail.com
10031947532846003995
10031947532846003995
Yes
F.
Kaymaram
10031947532846003996
10031947532846003996
No