Distribution of early developmental stages of jack mackerel in the Southeastern Pacific ocean

Chilean jack mackerel (Trachurus murphyi) is a highly migratory pelagic species that inhabits the Southern Pacific Ocean, constituting the most important fishery for Chile. This species exhibits an onshore migration during the summer related to coastal food availability, and an offshore migration towards reproductive oceanic areas (beyond Chilean EEZ) in early spring. During the spawning peaks (November) of 1999-2007, eggs and larvae of jack mackerel were collected from systematic surveys carried out in oceanic waters (75º- 92º W) off central Chile, using 5-10 fishing vessels. The eggs abundance shows a decreasing trend for 1999- 2007 spawning period, with a strong variability of positive stations (72.7% for 1999 and 26.5% for 2007), and mean densities values ranged from 581.7 ind 10m-2 (1999) to 39.8 ind 10 m-2 (2007) constituting the lowest values of the analyzed series. For larvae, similar results were obtained, with positive stations ranged from 77.0% (2000) to 30.1% (2007), and mean densities values fluctuating between 265.9 ind 10m-2 (2000) and 65.1 ind 10m-2 (2007). Our results reveal lower abundance of eggs for 2005-2007, and more variable