Ropeless fishing gear retracting-and-releasing device

A ropeless fishing gear retracting-and-releasing device comprising:

• a casing surrounding and forming an inner space, a top opening, and at least one through hole;
• the top opening and the at least one through hole fluidly communicating with the inner space;
• the casing comprising a top cover and a bottom cover, and the top cover and the bottom cover being opposite to each other;
• the top cover mounted at and covering the top opening, and the at least one through hole formed through the bottom cover;
• a buoyancy changing device including an upper seat, a lower seat, multiple fixing rods, a driver, and at least one piston;
• the upper seat and the lower seat being opposite to each other and securely mounted in the casing;
• an end of each one of the fixing rods securely mounted on the upper seat, and another end of each one of the fixing rods securely mounted on the lower seat;
• the driver mounted in the casing;
• an end of the at least one piston connected to the driver;
• an accommodation space formed between another end of the at least one piston and the bottom cover, and the accommodation space fluidly communicating with the at least one through hole;
• a power-supplying device mounted in the casing and electrically connected to the driver;
• a controller mounted on the casing and electrically connected to the power-supplying device and the driver.