Use of VIIRS DNB satellite images to detect jigger ships involved in the Illex argentinus fishery

- Use of VIIRS DNB (Nighttime lights) images to identify the jigger ships.
- Validation was carried out using GPS positioning of the Argentine jigger fleet.
- The algorithms developed to identify the ships showed excellent results.

The distribution of Illex argentinus squid extends from 23°S to 54°S. The largest catches of the species, which represents one of the most important fisheries in Argentina, take place between 35°S and 52°S. Argentina's fisheries administration keeps close records of the Argentine fleet position and the Cephalopod laboratory at the Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP) monitors and suggests actions for the management of the resource. The catches are carried out both within national and adjacent international waters. Fleets from different countries participate in the fisheries operating jigger vessels during the night with strong lights to attract the squid. One of the greatest difficulties in the evaluation of the status of this resource is to know the number of foreign vessels fishing outside the Argentine Exclusive Economic Zone (EEZ). The Visible Infrared Imaging Radiometer (VIIRS) day/night band (DNB) satellite images are a useful tool to monitor and quantify these fleets, building on the capacity of the sensors to detect the light emitted by the lamps placed on the ship decks. In this work, we report the development of a specific new method (set of algorithms) to process the images and identify automatically the jigger ships that compose the overseas fleet. Results were validated using the positioning data of the Argentine jigger fleet and comparing light emissions of these vessels against those identified by the new method. The process of identifying ships has proved to be robust considering the statistical results obtained: mean relative error (MRE) of 0.03% and a root-mean-square error (RMSE) of 1.62 ships.