Automatic Bluefin Tuna (Thunnus thynnus) biomass estimation during transfers using acoustic and computer vision techniques

[EN] In this work, acoustic and computer vision techniques are combined to develop an automatic procedure for biomass estimation of tuna during transfers. A side scan sonar working at 200¿kHz and a stereo camera, positioned facing towards the surface to record the ventral aspect of fish, are set as acquisition equipment. Moreover, a floating structure has been devised to place the sensors between cages in transfers, creating a transfer canal that allows data acquisition while fish swim from donor to receiving cage. Biomass assessment is computed by counting transferred tuna and sizing a representative sample of the stock. The number of transferred tuna is automatically deduced from acoustic echograms by means of image processing techniques, whereas tuna size is computed from the stereo videos using our automatic computer vision procedure based on a deformable model of the fish ventral silhouette. The results show that the system achieves automatic tuna counting with error below 10%, achieving around 1% error in the best configuration, and automatic tuna sizing of more than 20% of the stock, with highly accurate Snout Fork Length estimation when compared to true data from harvests. These results fulfil the requirements imposed by International Commission for the Conservation of Atlantic Tunas for compliant transfer operations.
This work was supported by funding from the BIACOP project, ES13/41, from the EU Fisheries Control Programme through the Secretaría General de Pesca, Ministerio de Agricultura, Alimentación y Medio Ambiente (MAGRAMA), and by ACUSTUNA project ref. CTM2015-70446-R (MINECO/ERDF, EU). The BIACOP project has been possible thanks to the collaboration of the Spanish company Grup Balfegó S.L. that also supplied boats and divers to acquire underwater video in the Mediterranean Sea. Special personal acknowledgements to Manuel Guijarro and Antonio López, and to David Baizán from IMA – Acuicultura Integrada Multitrófica S.L.U., for their assistance with the design and construction of the floating structures.