This paper presents data on guano production on the Namibian islands from 1843 to 1895, reconstructed from the nineteenth century customs records of the Cape Colony and United Kingdom. As the latter was the primary market for Namibian guano during this period, the data series can be considered to encompass the global production on the islands. Interpretation of the records as a proxy index for fish stock abundance is complicated by the interplay of cultural and environmental factors in influencing annual production. When compared with rainfall records from the Royal Observatory in Cape Town (1846- 1895), the guano data are suggestive of a relationship between guano production and environment, but firm conclusions must await better proxy records, perhaps based on fish scales in seafloor sediments off the Namibian coast.