It must have been earlier than 1968.
The 2nd Willem Barendsz was build in 1955 by Wilton-Fijenoord Schiedam for Ned. Mij. voor de Walvisvaart, Amsterdam. Her subsequent story goes like that:
10/65: Sold to South Africa and converted into a fish-factory.
1973: Sold to for Won Yang Fisheries Co., South Korea, renamed Yu Sin.
1978: Renamed Gae Cheog No 1.
1981: Renamed Gae Cheog.
1988: To Alaska as Ocean Pioneer.
No further information available to me.
As for the first ship - built in 1931 as oil tanker Pan Gothia - she has been renamed Bloemendael in 1955 and sold in 1960 to Japan and renamed Nitti Maru. She was scrapped in 1966.