Status and Conservation of the Japanese Murrelet (Synthliboramphus wumizusume) in the Izu Islands, Japan

Abstract

Harry R. Carter et al. may nest at other islands (i. e., Udonejima, Niijima, Hanshima, and Torishima) where recent estimates are not available. Conservation issues include: human settlement; past egg harvesting; recreational surf fishing at remote islands; predation by introduced predators; habitat loss due to postwar bombing of Sanbondake; habitat destruction due to human activities; habitat loss due to volcanic eruptions; relatively high levels of predation by crows, snakes, and falcons; and mortality in commercial gill nets. Additional surveys, monitoring, and assessment of conservation issues are urgently needed in Izu Islands for this rarest species of the family Alcidae which is endemic to Japan.

At-sea distribution and habitat of breeding Japanese Murrelets Synthliboramphus wumizusume: implications for conservation management

“…The 2008 Biroujima prediction is likely the most representative estimate of murrelet at-sea density near this colony given that this was the best sampled year. Furthermore, April murrelet densities predicted for Biroujima in 2008 are higher than those for the Northern Izu islands, which is consistent with colony data for Biroujima being the largest single breeding colony for the species with a population of ∼ 3,000 individuals (Iida 2008, BirdLife International Tokyo and Wild Bird Society of Japan 2017), compared to the smaller Northern Izu colonies (combined estimated population of 1,000 individuals; Carter et al 2002). Finally, 2009 was an El N iñ o year, which impacted Japanese seabirds (Mizutani et al 2013) and could explain reduced murrelet at-sea density.…”

“…The proximity of murrelet colonies to major ports and shipping lanes (e.g. Northern Izu colonies to Tokyo Bay), likely exposes breeding murrelets to the persistent threat of oiling while foraging (Carter et al 2002). A neritic distribution also exposes breeding murrelets to a higher risk of disturbance and displacement impacts from offshore wind farms (Busch et al 2013, Furness et al 2013), pertinent in Japan given their expansion is promoted in the wake of the 2011 Fukushima nuclear disaster (Busch et al 2013).…”

“…We compiled a list of all known murrelet breeding localities in Japan (Table S2) and calculated a ‘minimum distance to colony’ layer (D_COL) in order to quantify the constraints of central place foraging. Unfortunately, population estimates are unavailable for almost all colonies (but see Carter et al 2002) and thus the impact of intra-specific competition (Lewis et al 2001, Wakefield et al 2017) could not be modelled.…”

“…Indeed, the Japanese Murrelet was identified as the second most exposed seabird species to gillnet bycatch in a global assessment (Waugh et al 2011). Murrelets are taken as bycatch in driftnets and gillnets while foraging near breeding colonies (DeGange et al 1993, Carter et al 2002, Ogi 2008), and also in large-scale squid driftnet fisheries while wintering south-east of Hokkaido (Ogi et al 1993, Piatt and Gould 1994). Piatt and Gould (1994) estimated that in 1990 and 1991, 1–10% of the adult murrelet population was killed in north-west Pacific drift-net squid fisheries, highlighting the level of threat.…”

Molecular sexing in Japanese murrelet (Synthliboramphus wumizusume) and a tandem-repeat polymorphism on the W chromosome

“…Japanese murrelet (Synthliboramphus wumizusume) is a small bird that has been classified as a member of the Alcidae family. This bird inhabits and breeds on inhabited areas of islands in temperate waters around Japan [1][2][3][4] and South Korea 5 . The total population of Japanese murrelet is estimated to be approximately 4,000-10,000 individuals 1 .…”