Almaco jack (Seriola rivoliana), in the pen at a fish farm off The Big Island, Hawaii, United States of America, Pacific, North America

Almaco jack (Seriola rivoliana), in the pen at a fish farm off The Big Island, Hawaii, United States of America, Pacific, North America

Pen containing almaco jacks (Seriola rivoliana), off the Big Island of Hawaii, United States of America, Pacific, North America

A young girl gathering catfish from the family fishing pen on Rio El Dorado, Amazon Basin, Loreto, Peru, South America

Young girls gathering catfish from the family fishing pen on Rio El Dorado, Amazon Basin, Loreto, Peru, South America

Australia, South Australia, Port Lincoln, Southern bluefin tuna (Thunnus maccoyii) circle in a holding pen.

Australia, South Australia, Port Lincoln, A dead Southern bluefin tuna (Thunnus maccoyii) caught in a tuna pen.