Photo-coupled data acquisition system and method

A method of obtaining a value of a variable of interest concerning a sample of organisms received on a surface, the method comprising:

• emitting an initial intensity of diffused light onto the sample,
• the surface receiving the diffused light and reflecting the diffused light through the sample, the sample thereby attenuating the initial intensity;
• measuring a reflected intensity of the diffused light;
• and
• correlating the measured reflected intensity to the variable of interest.

A method of determining when to stop providing feed to a sample of fish swimming in sea water and contained in an open sea cage, the method comprising:

• transmitting a diffused light having an initial intensity across the sample, the sample thereby attenuating the light;
• measuring plurality of attenuated intensity values of the transmitted light, the attenuated intensity values being obtained at a regular rate over a given period of time;
• identifying a first frequency of variation of the plurality of attenuated intensity values over the period of time corresponding to the movement of the fish;
• identifying a second frequency of variation of the plurality of attenuated intensity values over the period of time corresponding to the movement of feed;
• and
• determining when to stop providing feed based on a variation of the attenuated intensity values corresponding to the second frequency.