Complex sentence: The fishery began in the 1940s with a small number of demersal longline vessels, though the whiskery shark was not caught in substantial numbers until the 1970s, with the introduction of monofilament gillnets, hydraulic net haulers, and additional vessels.
Split into simpler sentences: The fishery began in the 1940s with a small number of demersal longline vessels. The whiskery shark was not caught in substantial numbers until the 1970s, with the introduction of monofilament gillnets, hydraulic net haulers, and additional vessels.