2007 Volume 1 Pages 35-46
Artificial spawning nests (ASN) were experimented with and developed in order to prevent successful reproduction of largemouth bass Micropterus salmoides. A total of 128 ASN of 15 types were set on the natural spawning grounds along the south coast of Lake Izunuma (sand zone, 40-140 cm in depth). Eight ASN were set so deep, 110-140 cm, that it was impossible to observe spawning, and 14 ASN were broken mainly by bass anglers. Largemouth bass spawned in 32 ASN from early May to late June. ASN that used plastic net trays for spawning boxes showed higher spawning rates than those with plastic containers. ASN spawn boxes that were graveled with macadam showed significantly higher spawning rates. The most appropriate shielding to set up on the ASN was one that blocked three sides. Five improved ASN composed of plastic net boxes, graveled with macadam (4-5cm in diameter) inside, and plastic net screens (35cm in height) blocking up three sides were made. These were set in the natural spawning grounds and 100 percent of them were used as spawning nests by largemouth bass.
