Complex sentence: The jobs in tourism were not as deaf-friendly as fishing and farming had been, and as intermarriage and further migration further joined the people of Martha's Vineyard to the mainland, the island community came more and more to resemble the wider community there.
Split into simpler sentences: The jobs in tourism were not as deaf-friendly as fishing and farming had been. Further, as intermarriage and further migration further joined the people of Martha's Vineyard to the mainland, the island community more and more resembled the wider community there.