Msgr. Rouchouze was appointed Vicar Apostolic of Eastern Oceania and Titular Bishop of Nilopolis on 14 June 1833 with ordinary jurisdiction over the Hawai‘i prefecture apostolic. He was subsequently consecrated to the episcopate in Rome, on 22 December 1833 by the Prefect of the Propaganda Fide, Cardinal Carlo Maria Pedicini.[5] On 29 June 1834, in Golden Square in London, Msgr. Rouchouze served as principal co-consecrator in the episcopal ordination of Msgr. John Bede Polding, O.S.B., Titular Bishop of Hierocaesarea and Vicar Apostolic elect of New Holland.
Rouchouze left Le Havre on 29 October 1834 and arrived in Valparaíso, Chile on 19 February 1835. After staying a few months, he went on to Mangareva in the Gambier Islands on 9 May 1835. He baptized the island's king Maputeoa and his family on 25 August 1836.[6] On 4 April 1839, Msgr. Rouchouze returned to blessed the first stone for the St. Michael's Cathedral, Rikitea in Mangareva.[7] He said the first pontifical Mass in the Marquesas at Tahuata on 6 February 1839. He arrived in Honolulu on 14 May 1840.[8]
On 8 December 1842 the ship Marie-Joseph was blessed in Saint Malo in Brittany. Shortly thereafter, Msgr. Rouchouze, accompanied by six priests, one sub-deacon, seven lays brothers and ten sisters, left Saint Malo for Oceania on the Marie-Joseph. Sister Caliste Le Gris died at sea. Unwilling to bury her at sea, they put into Island of Saint Catherine near Florianópolis in Brazil and buried her there. On 19 February 1843[9] Rouchouze and his remaining missionaries left the island. Evaristo, a Mangarevan youth, fell ill and also died while they were in Brazil. The ship was last sited off the Falkland Islands on 13 March 1843. Rouchouze and his companions were never seen again and were presumed to have perished at sea.[10][11]
^Lettres des missionnaires maristes en Océanie (1836–1854) – Page 721 2008 "Mgr ROUCHOUZE Étienne : 1798 à Chazeau, Loire – 1842 en mer Père picpucien, Vicaire apostolique de l'Océanie orientale il s'installe d'abord à Mangareva aux Gambier, puis, à Tahiti, comme évêque de 1833 à 1836. Il disparaît en mer ..."
^Yannick Essertel L'aventure missionnaire lyonnaise: 1815–1962 2001 Page 215 "Mgr Rouchouze, vicaire apostolique de l'Océanie orientale. A la demande du Père Coudrin, Rome confie au Père Étienne Rouchouze1 l'évangélisation de l'Océanie orientale le 20 mai 1833. Le vicariat est formé des îles Gambier, de Tahiti, ..."
^Pierre-Yves Toullelan Missionnaires au quotidien à Tahiti: les Picpuciens en Polynésie Page 136 – 1995 "À Mgr Rouchouze (vicaire apostolique de 1836 à 1840) succèdent Mgr Baudichon (1844–1848) et Mgr Jaussen (1848–1884). L'abandon de Mgr Baudichon entraîne la nomination pour les Marquises de Mgr Dordillon (1855–1888).
^Pires, Mary Dolorine. "Disparition du Marie-Joseph". Paroisse de la Cathédrale de Papeete. Archived from the original on 4 March 2016. Retrieved 27 July 2015.
