Hello Virginia, I am looking over old queries and sad to say yours is a trifle difficult, Irish records in the 1700s are not great for individuals and in the main we rely on church records where they exist, hence religion can be important so we know where to look etc
I looked in a few places to no avail, including a volunteer project on land registry from about 1700, in McLysaghts surnames of Ireland it is not listed, Sharkey; Sharkett and Shinnick in Cork sometimes translated as Shirkwin but no more information, there is site on surnames you can search for origins but to get detail you pay. https://www.oxfordreference.com/display/10.1093/acref/9780199677764.001… See only Shirkey and Shirkie.
I had a final thought and searched the available online church records for Dublin; Kerry and Cork only and got two Shirk people born in Dublin and two sponsors in Cork, I knew a Stark family in Cork also, only one is in the 1700s, Dennis in 1781, all appear to be Catholic, you can see the records for your self here for free, sign in but free, https://www.irishgenealogy.ie/en/ Click on Church Records and enter Shirk and between years, I got the3 others in the early 1800s, both Cork and Dublin are or where major ports, still are.
Good Luck
Pat