Insitu's initial focus was on weather, not fisheries.
Their initial aircraft, called the AeroSonde, was based on a 100" (2.5m) spam RC thermal soarer's wing. It was designed in the early 1990s to be sold for under $10,000 and used for weather research on the grounds that, at that price, it was disposable and so could be flown into hurricanes and other extreme weather to gather meteorological data without its operators being too concerned about getting it back.
Aerosondes were launched from a modified car roofrack and operated autonomously apart from launch and landing, when initially they were hand flown. In 1998 one flew the Atlantic from Newfoundland to Benbecula in 26 hours 45 minutes.
More details and photos here: https://en.wikipedia.org/wiki/AAI_Aerosonde