They travel upriver to spawn, and make audible grunting noises that have been described as resembling the sound of a motorbike.
ðeɪ tɹˈævəl ˌʌpɹˈɪvɚ tə spˈɔːn, ænd mˌeɪk ˈɔːdᵻbəl ɡɹˈʌntɪŋ nˈɔɪzᵻz ðæt hɐvbɪn dᵻskɹˈaɪbd æz ɹᵻzˈɛmblɪŋ ðə sˈaʊnd əvə mˈoʊɾɚbˌaɪk.