They are also very tough to monitor, so population estimates are wobbly.

由于这种鱼很难监测到，所以对它们数量的估计也不稳定。

youdao

Volunteers listen for frogs, identify the species, and give population estimates.

那里的统计员通过听青蛙的叫声来辨别青蛙的种类，然后给出数量的估计。

youdao

Early 21st-century population estimates indicated some 4, 500 Wampanoag descendants.

21世纪初的人口估计显示大概有4500名万帕诺亚格人。

youdao

Population estimates from two thousand seven show more than five hundred eighty-eight thousand people living within D.C.borders.

VOA: special.2009.03.20

But counting the world's third largest population -- about three hundred nine million by current estimates -- is no easy job.

VOA: special.2010.03.20

The United Nations estimates that females age ten to twenty-four are one-eighth of the world's population.

VOA: special.2010.06.24

The 2001 Census disclosed previous population estimates had exaggerated the population of Scotland by some 50, 000.

BBC: Scotland's population rose slightly in 2003

Labour says its calculations, based on pupil population estimates, show around 14, 545 teachers are needed.

BBC: Schools face teacher shortage crisis, claims Labour

Population estimates are especially problematic in Pakistan's large cities, such as Karachi and Lahore.

ECONOMIST: Pakistan��s sensitive census