I've always put commas before and after "respectively", but am looking at the sentence below and feel like they're not necessary.
The Italian and French surveys were carried out respectively in 2008 and 2009.
Any informed opinions on this?
"Respectively" is being used as an adverbial phrase—or word—in this sentence, and the applicable rule in the Chicago Manual of Style would be § 6.31.
"Shorter adverbial phrases are less likely to merit a comma than longer ones." Furthermore, if an adverbial phrase does not add anything essential to the sentence [à la being used in a nonrestrictive way], it should be offset by commas. However, it appears here that "respectively" does add essential meaning to the sentence similar to "Jackson made history with three consecutive swings." compared with "Henrietta turned fifty a decade later, in 1931."
Without "respectively," the additional dates would lose significant character [without it, the Italians and French were both carried out during both 2008 and 2009], and thus, "respectively" is essential to the meaning, and therefore, does not warrant a comma.
The example sentences for 'respectively' provided by Oxford Dictionaries Online and Merriam-Webster would appear to confirm that it is not always necessary to use a comma or commas with the term.
There is no need to use commas in the case of "The Italian and French surveys were carried out respectively in 2008 and 2009"but you would need to use commas if the sentence were to read "The Italian and French surveys were carried out in 2008 and 2009, respectively."
In American English, you would write:
"The Italian and French surveys were carried out in 2008 and 2009, respectively.",
but
"The Italian and French surveys were carried out respectively in 2008 and 2009."
In British English, you do not need commas in either case.
See the examples in https://dictionary.cambridge.org/dictionary/english/respectively, where the British English examples come first, and the American ones come after the title "AMERICAN DICTIONARY".