La biologie du suceur cuivré (Moxostoma hubbsi) comparée à celle de quatre autres espèces de Moxostoma (M. anisurum, M. carinatum, M. macrolepidotum et M. valenciennesi)

Abstract

The copper redhorse, Moxostoma hubbsi (Legendre), which was discovered in 1942, is a threatened and endemic fish species of the lowlands around Montréal (Quebec). A survey of historical data, an investigation of the preserved specimens, and a comparison of selected biological characteristics of the five Quebec Moxostoma species living in sympatry in the Richelieu River show that this redhorse has a unique combination of life history characteristics. Compared with the other redhorses, it is among the most long-lived (more than 20 years), has the highest growth rate and fecundity, and is the latest spawner, its reproduction probably taking place at the end of June or at the beginning of July. The copper redhorse shows a high degree of specialization in the use of alimentary resources and feeds almost exclusively upon molluscs. The comparison of the stomach contents of the different species living in sympatry shows little diet overlap. This may be due to the specialization of their pharyngeal apparatus and to a certain degree of spatial segregation. Similar to its congeners, the copper redhorse shows a predilection for lowland rivers of medium size characterized by abrupt banks and uniformly deep channels (4–7 m) flowing over a solid clay, sand, or gravel bottom. The most populated sections of river have rather slow currents; they are interspersed by sections of rapids suitable for spawning. In the St. Lawrence system, the range of the copper redhorse is much more restricted than that of other redhorses, and this species appears much more vulnerable to habitat degradation.

Parasites of Illegally Introduced Tench (Tinca tinca) in the Richelieu River, Quebec, Canada

“…comm.). The species was subsequently found in abundance in the 1960s in the Yamaska (upstream of the Saint-Hyacinthe dam) and Noire rivers (Mongeau et al 1986(Mongeau et al , 1992. At that time, these rivers ranked, respectively, second and third in terms of the number of specimens collected (Mongeau et al 1986).…”

“…Although the current is slow, usually less than 0.3 m/s, certain segments have short stretches of fast-flowing water where the species finds conditions favourable to reproduction. Adults are absent from shallow sections with dense vegetation as well as from locations where the water is heavily polluted and turbid (Mongeau et al 1986(Mongeau et al , 1988(Mongeau et al , 1992). …”

“…The size (total length) of spawners is generally greater than 500 mm (Mongeau et al 1986(Mongeau et al , 1992, although according to Jenkins (1970), males can reproduce once they reach 475 mm. Both sexes reach sexual maturity at the beginning of the 10th year; hence, the reproductive lifespan appears to be at least 20 years.…”

“…In 12 females captured in 1984 in the Chambly Basin that varied from 547 to 690 mm in total length, fecundity ranged from 34,900 to 111,860 eggs. The fecundity of a 2 kg female is approximately 32,750 eggs (Mongeau et al 1986(Mongeau et al , 1992. The weight of female spawners correlates positively with the number of eggs produced and with the diameter of the eggs released (Branchaud and Gendron 1993, Branchaud et al 1995, Mongeau et al 1986, 1992.…”

“…The females are generally more corpulent than the males. On the basis of the results obtained by back calculation, a copper redhorse measures on average 370, 550 and 670 mm respectively at 5, 10 and 20 years (Mongeau et al 1986(Mongeau et al , 1992. To date, the largest specimen captured measured 780 mm (Vachon and Chagnon 2004).…”