Hydroacoustic survey of the jumbo squid Dosidicus gigas in the Gulf of California during March and September-October 2010

Resumo

The horizontal and vertical distribution and the dorsal mantle length (DML) of the jumbo squid (Dosidicus gigas) were investigated in the Gulf of California (26-33 °N) during March and September-October 2010 using a Simrad EY-60 echosounder (120 kHz split beam transducer) and jig sampling. During March jumbo squids were captured and echo-detected off Santa Rosalía and around and south of the Grandes Islas region, in regions where satellite sea surface temperatures ranged between 16.5 and 18 °C. Jumbo squid were also abundant south of Guaymas Basin and along the east coast with SST ranged between 17.5 and 19 °C. During September-October jumbo squids were echo detected and captured at the west coast of the gulf at regions with SST below the mean of the survey area (< 30.5 °C). Jumbo squid distribution and DML estimated using hydroacoustic methods and measured from captured squids followed the previously known seasonal migrations and temporal DML frequency distribution reported in the Gulf, in the Grandes Islas region and east coast of the Gulf during the spring and in the east coast during late summer. Hydroacoustic data showed no evident daily vertical migrations during the two sampling seasons.