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It is known that several copepods are part of the diet of paralarvae and juveniles of cephalopods, but during the short time that recently hatched paralarvae overlap spatiotemporally with adult stages of the nominal preys, these roles can reverse. Paralarvae (size range 0.5 to 3.5 mm of mantle length) of Dosidicus gigas and Sthenoteuthis oualaniensis were the most abundant in the cephalopod community along the west coast of the Baja California peninsula and the Gulf of California where zooplankton collections have been done from 1997 to 2006. Evidence of copepod predation on these paralarvae was registered only in the oceanographic cruises made in November 2004 and 2006 in the mouth of the Gulf of California. Zooplankton samples were collected with a CalCOFI net towed obliquely (200 m depth) and with a Neuston net (1 m wide x 0.5 m height, 335 µm). Attacks of zooplanktonic predators upon ommastrephid paralarvae have not been previously reported in this area. Paralarvae collected along the west coast of Baja California had no evidence of such attacks. The warm-water cosmopolitan copepod Oncaea mediterranea was the only predator observed attacking paralarvae. In 2004, predation activity was detected in two oceanic stations, representing only 10% of the total sampling stations, and in 2006, copepod predation was observed at 46% of the stations. In this last year, predation was observed in the same region as during 2004 but also near Bahía de La Paz, where the frequency of predation was higher. Most attacks were associated with a high abundance of paralarvae collected near the surface, and occurred in organisms averaging 1.2 mm mantle

Palabras clave: Oncaea mediterranea; Omastrephid paralarvae; Predation.

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