Paralarvae and juvenile of cephalopods in the Mexican South Pacific

Abstract

Early life cephalopod stages are poorly studied and inadequately described. This study presents for the first time the composition of species, patterns of distribution, and abundance of parlarvae and juveniles of cephalopods in the Gulf of Tehuantepec, a highly productive and ecologically complex region. Paralarvae and juvenile were recovered from zooplancton samples collected with bongo tows (10-15 °N, 96-100 °O) on board of the O/V El Puma during June and September 2001. A third set of samples were obtained on board the B/P UMAR in November 2001 (14-16 °N, 93-97 °O) with a CalCOFI net. Average density of cephalopods was 16.2 organisms x 1000 m-3. Six families representing eight genera and at least 13 species were identified. The most abundant families were: Octopodidae (48.5% of specimens examined), Enoploteuthidae (15.9%), Argonautidae (13.3%), Ommastrephidae (11.5%), Onychoteuthidae (6.7%), and Cranchiidae (4.1%). The results revealed a typical tropical and oceanic cephalopod assemblage. The mantle length (ML) ranged between 0.2 and 37.8 mm; most specimens (90%) were small-sized, measuring less than 3 mm ML. The main genera and species are illustrated and their meso-scale distribution patterns are discussed. Results provide new information on the presence and relative abundance of tropical species in this region of the Eastern Pacific.