Spawning activities and physical characteristics of the spawning ground of Lethenteron reissneri at the headstream of the Himekawa River, central Japan

Abstract

The spawning period of the Far Eastern brook lamprey, Lethenteron reissneri, in the headstream of the Himekawa River is estimated to be between mid-March and late May with the peak of spawning activity between early April and early May. The sex ratio (female:male) in 1999 ranged from 1 : 2.5 to 1 : 3.0 (mean 1 : 2.8) and in 2000 from 1 : 0.8 to 1 : 4.0 (mean 1 : 2.4). In Ͼ90% of the observations of spawning nests, males outnumbered females. The construction area of spawning nests tended to shift upstream during the spawning period. The nests were constructed at water depths between 5 and 70 cm, water velocity between 10 and 30 cm/s, and on substrate with pebbles of 5-20 mm in diameter. Lethenteron reissneri constructed nests on substrate similar with Petromyzon marinus, but at shallower points and in areas with a slower water velocity.have studied its physiology and embryology. The spawning season, sex ratio, and size of spawning individuals have only been reported by Yamazaki and Goto (2000b). However, there are no detailed reports of the physical characteristics of the spawning grounds.In this study, I investigated the spawning activities of L. reissneri and the physical characteristics of its spawning ground at the headstream of the Himekawa River in Nagano Prefecture, central Japan. The aim of this study is to obtain basic biological information for the habitat conservation of L. reissneri. Materials and MethodsStudy area.-The Himekawa River rises in Nagano Prefecture in Honshu Island, Japan. The study area is located at the headstream of the river, from a point where a gutter flows in just below the springhead, to a bridge 450 m downstream (36°37Ј N, 137°51Ј E) (Fig. 1). The altitude of the study area is 736-738 m, the slope of the riverbed is 1/205, the width 1-4 m, and the depth 1-100 cm. Spring water forms a swamp in the upper part of the study area. Within the 450-m reach of the study site, one tributary and three gutters of 0.3-m width join from the left bank and three gutters of 0.7-1.0 m in width from the right. The surrounding area is partly utilized as paddy fields, the surface soil of which is a lacustrine deposit 20-30 m deep consisting of argilliferous pebbles, silt, and humus. The paddy fields are located on the right bank of the Himekawa River, and a riverside forest IchthyologicalResearch

Some reproductive characteristics of endangered Caspian Lamprey (Caspiomyzon wagneri Kessler, 1870) in the Shirud River southern Caspian Sea, Iran

“…Full sexual maturity occurs at 13 to 18°C in the Kura basin (Abdurakhmanov 1962). Many lampreys are known to spawn in waters 10-12°C (e.g., Hardisty and Potter 1971;Kelly and King 2001;Takayama 2002), 10-15°C (Close et al 2002;Almeida et al 2002;Robinson and Bayer 2005), 15-24°C (Cochran and Gripentrog 1992) and rarely in waters at 22-24°C (Hardisty and Potter 1971). The water temperature during this study for Caspian Lamprey was 11-21°C.…”

Capture and collection of lampreys: the state of the science

“…Lamprey construct nests in gravel and cobble substrates similar to those of salmonids (Hardisty and Potter 1971b;Takayama 2002;Fig. 1).…”

“…1). As with salmonid redd surveys, mapping lamprey nests requires adequate water depth and clarity, as well as prior knowledge of preferred habitat types and spawning times (Takayama 2002;Jang and Lucas 2005;Stone In press). Enumeration of nests to produce estimates of adult abundance is problematic in that multiple adults may participate in nest building, or a single adult may build more than one nest (Farlinger and Beamish 1984;Jang and Lucas 2005;Mundahl and Sagan 2005).…”

“…Moreover, mixed species aggregations of spawning lamprey have also been documented (Cochran and Pettinelli 1988;Cochran and Gripentrog 1992). Nevertheless, nest surveys can be used to identify likely ammocoete rearing areas (Torgeson and Close 2004), evaluate changes in quality and quantity of spawning habitat (Cochran and Gripentrog 1992;Takayama 2002;Jang and Lucas 2005;Mundahl and Sagan 2005), and assess populations with very low abundance or recruitment (Farlinger and Beamish 1984).…”

“…Parasiticphase adults can be obtained via opportunistic capture in commercial and recreational fishing operations that target host species (Johnson and Anderson 1980;Cochran et al 2003a, b;Cochran and Lyons 2004). Finally, visual counts of lamprey nests and spawning aggregations can yield valuable data on spawning habitat, timing of spawning events, and relative abundance (Cochran and Gripentrog 1992;Takayama 2002;Jang and Lucas 2005;Stone In press).…”