At 6:25 a.m. on the cloudy, humid first day of summer, two teenage aquaculture students huddle at the back of their school boat as it backs away from a dock in Black Rock Harbor in western Bridgeport. Charlotte Hickey grips a heavy cylindrical metal probe that is about a foot and a half long. The students call this “the beast.” It contains electronics that precisely measure water conditions. Sienna Matregrano holds a clipboard and pen, ready to record depth, temperature, salinity, dissolved oxygen, fluorescence and turbidity. Both girls are seniors at Bridgeport Regional Vocational Aquaculture School.