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Paulino, C., Aroni, E., Xu, H., Alburqueque, E., & Demarcq, H. (2017). Use of nighttime visible images in the study of the spatial and temporal variability of fishing areas of jumbo flying squid ( Dosidicus gigas ) outside Peruvian EEZ 2004-2015. Fisheries Research, 191, 144–153.
Abstract: We analyzed the temporal variability of the fishing fleet of Dosidicus gigas, located outside the exclusive economic zone of Peru (EEZ), with a spatial luminosity index. The nighttime satellite images were provided by the Operational Linescan System (DMSP-OLS) from 2004 to 2015. 2995 images were processed, selecting pixels in the range of 30â63 Digital Number (DN), to identify the presence of vessels in the image.
The time series showed an extensive latitudinal distribution of the fishing fleet from 6Â°S to 32Â°S, with years of low (2005â2009) and high (2004, 2010â2015) presence, describing a recurrent seasonal pattern of latitudinal displacement measured from its center of gravity (CG). The CG reaches its southernmost position between February to April and its northernmost position between August to October. Some vessels were also detected within the Peruvian EEZ.
The latitudinal inertia presented values of 0.3â1 indicating high fleet concentration between 12Â°S to 17Â°S and the longitudinal inertia presented values >2, showing the wide distribution of the resource. Luminous pixels showed high fishing occurrence (>18 times) on a single pixel, in front of Chimbote around 9Â°51′Sâ82Â°31′W from 2004 to 2011. From 2012 to 2015 areas of high fishing occurrence increased in front of Huarmey (10Â°36′S/82Â°41′W) and San Juan de Marcona (15Â°53′S/80Â°6′W).
For both periods, high intensity pixels (DN >60) show extensive areas of fishing operation between 9Â°S to 20Â°S along 200 nautical miles from the coast, while values between 30 and 45 DN could be mostly associated with the search for fishing zones. Since 2012, pixels with DN >58 have increased, indicating a greater fishing activity likely related to a higher availability of the resource or a better knowledge of the fishing zones, associated with an increase of the fishing effort and a possible higher pressure on the resource.
Yamashita, Y., Matsushita, Y., & Azuno, T. (2012). Catch performance of coastal squid jigging boats using LED panels in combination with metal halide lamps. Fisheries Research, 113(1), 182–189.
Abstract: Squid attracting light systems consisting of low power light emitting diode panels (LEDs) and conventional metal halide lamps (MHs) were tested to describe the influence of combinations of LEDs and MHs on squid catch. Fishing trials using LEDs (9 kW) and different numbers of MHs were carried out in August and September 2009 targeting two squid species: (1) Japanese common squid Todarodes pacificus in northern waters of the Sea of Japan (off Hokkaido) by 4 coastal squid jigging boats (19 gross tonnage) and (2) swordtip squid Photololigo edulis in western waters (off Iki) by 5 boats of the same class. Catches of both species tended to increase with the number of MHs. Generalized Linear Model analysis revealed that in addition to the number of MHs, the catch amount was influenced by fishing power (ability) of boat and by the monthly variation of squid abundance (only for P. edulis off Iki). The expected catch (number of boxes) was not proportional to the number of MHs. The largest catch was expected for P. edulis off Iki by using LEDs with 24 MHs. The optimal combination of LEDs and MHs for T. pacificus off Hokkaido was less clear because the combination with 36 MHs had the largest positive effect on the catch; this was the maximum number MHs used.