Evaluación acústica de recursos pelágicos en las Islas Galápagos (diciembre de 1994) | Evaluation of acoustic pelagic resources in the Galapagos Islands (December 1994)
1995
Vicuña, H. | Chalén, X. | Mendieta, E. | Aguilar, F.
A research survey was carried out in the southeast of the San Cristóbal island of the Galápagos Province (Galápagos Islands, Ecuador), between the 6th and 23th of december 1994; a 9 637 km2 was covered, from ca., 100 m depth waters. The Simrad EK-500 (38 kHz) acoustic equipment was used on board the I/V Tohallí of the National Fisheries Institute. The catch was compounded of 98% of makarell (Scomber japonicus) and 2% of south sardine (Sadinops sagax). The estimated results for biological and acoustic parameters for S. sagax were: sex ratio (male and female): 36% y 64%; furcal length range: 21-32 cm; mean legth: 26,6 cm; mean weith: 0,254 kg; theoreticals target strength and weight target strength (TS, TSkg): -38,9 dB and -33,0 dB. Mictofid catches were not obtained even though their ecotraces appeared in the echograms. The estimated small pelagic fish density (mainly compounded by makarell) was ca., 2,2 t km-2, the mackarell school fish´s biomass was estimated in previous years (1988, 1991); unfavorably enviroment conditions might have affected the distribution of resources (there exists superficial termic anomalies up to 3~'C: even though there might exist seasonal variations in the resources abundance.
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