OBSERVATIONS ON THE SPAWNING DISTRIBUTION AND BIOLOGY OF OFFSHORE PACIFIC HAKE (MERLUCCIUS-PRODUCTUS)

Two cruises were conducted in February 1990 and 1991 to examine the di stribution and biology of spawning offshore Pacific hake. The fish spa wned during winter, in the southern portion of their range, i.e., sout h of Cape Mendocino, and offshore of the shelf break over bottom depth s exceeding 1,000 m. In 1990, the schools were 110-167 km (60-90 nmi) offshore in midwater depths ranging from 140 to 240 m, over bottom dep ths of 3,600 and 4,200 m. In 1991 there were six schools containing sp awning hake from 35 degrees to 40.5 degrees N, spanning 720 km (390 nm i). There were more males than females in the spawning schools. In 199 1 some schools of predominantly post-spawners were encountered; they t ended to be inshore of the spawners and were mainly female. The most s urprising of the results was the presence of a north-south dine in bio logical parameters during spawning similar to the one occurring in sum mer. We discuss the implications of our results for the present migrat ion hypothesis.