Effect of LH‐RH Analogue Treatment on Egg Maturation (Ovulation) in Lake Trout Brood Stock

Abstract Brood-stock females of lake trout (Salvelinus namaycush) were injected with luteinizing hormone-releasing hormone analogue des-Gly10 [D-Ala6]LH-RH-ethylamide (LH-RHa) in an attempt to induce advanced final egg maturation (ovulation). Experimental fish were divided into three groups: 49 control fish received a saline injection; 45 fish received 10 μg LH-RHa/kg body weight; and 46 fish received 20 μg LH-RHa/kg body weight. Fish in all groups received a single intraperitoneal injection. Data obtained 4 d post injection were inconclusive but appeared to indicate that LH-RHa injection was exerting a positive effect on advanced final egg maturation. Data collected on day 8 postinjection confirmed this observation. By this time, only 53% of the saline-injected controls had ovulated, whereas 91 and 98% ovulation had occurred in the 10- and 20-μg LH-RHa/kg groups, respectively. Both LH-RHa treatment groups showed a significantly greater (P < 0.05) incidence of ovulation than the control group.