en Biology & physiology Biology & physiology 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%"><font size="3"><font face="Times New Roman"><span lang="EN-GB">The Persian sturgeon (<i>Acipenser persicus</i>)<span style="mso-spacerun: yes"> </span>is considered as an endemic sturgeon of the south part of the Caspian Sea and provides the highest Iranian caviar production. Due to overfishing, degradation of the rivers conditions of the natural reproductive habitats, the fish stocks is decreasing. The immature breeders do not response to hormonal therapy at the sturgeon hatcheries as most having PI (above 10) and large numbers of breeders caught and transported to the hatcheries were unable to reproduce. This study was attempted to find the effect of LHRHa implantation on oocytes maturation and spawning of Persian sturgeon. Broodstocks were caught from the southeast region of the Caspian Sea. The selected female broodstocks (PI>10) ranged in size from 24.0 to 37.5 kg were implanted with LHRHa cholesterol pellets at concentrations of 0 μg/kg (control), and treatments of 10, 15 <span style="mso-spacerun: yes"> </span>and 20 μg/ kg (in three replicates.</span><span lang="EN-GB" style="mso-bidi-language: FA"> </span><span lang="EN-GB">The results from this study indicated that females treated with LHRHa hormone implantation at 10, 15, 20 </span><span lang="EN-GB" style="mso-bidi-language: FA">µg per kg body weight </span><span lang="EN-GB">reached final maturation. These results were observed for all fish from treatment numbers 2 (15</span><span lang="EN-GB" style="mso-bidi-language: FA"> μg/ kg</span><span lang="EN-GB">) and 3 (20</span><span lang="EN-GB" style="mso-bidi-language: FA"> μg/kg</span><span lang="EN-GB">), however only one fish reached final maturation in treatment 1(10</span><span lang="EN-GB" style="mso-bidi-language: FA"> μg/ kg</span><span lang="EN-GB">). The current implantation of LHRHa was able to enhance breeders with PI above 10 to final maturation which under normal condition at sturgeon’s hatcheries this is not possible. The results suggested that final maturation can be achieved that lead to high fertilization (</span><span lang="EN-GB" style="mso-bidi-language: FA">78.33% ±13.87, 68.33% ±4.16 in treatment 2 and 3, respectively) </span><span lang="EN-GB">and hatching rates (</span><span lang="EN-GB" style="mso-bidi-language: FA">85.3% ±9.07, 68.33% ±7.64 in treatment 2 and 3, respectively) </span><span lang="EN-GB">and also total larvae production. Thus, the information from this study is very useful for artificial propagation of not-fully-matured females of Persian sturgeon at Sturgeon hatcheries especially in Iran. </span><b><span lang="EN-GB" style="line-height: 120% font-size: 14pt"><o:p /></span></b></font></font></p><font face="Times New Roman" size="3"> </font> Acipenser persicus, Broodstocks, LHRHa implantation, Artificial propagation, Fertilization, Hatching rates 440 459 http://jifro.ir/browse.php?a_code=A-10-1-170&slc_lang=en&sid=1 K. Amini kourosh_a_ca@yahoo.com 10031947532846004109 10031947532846004109 Yes S. S. Siraj 10031947532846004110 10031947532846004110 No B. Mojazi Amiri 10031947532846004111 10031947532846004111 No S. A. Mirhashemi Rostami 10031947532846004112 10031947532846004112 No A. Sharr 10031947532846004113 10031947532846004113 No H. Hossienzadeh 10031947532846004114 10031947532846004114 No