Migration of Pacific Sardine (Sardinops Sagax) Off the West Coast of United States in 2003–2005

Transport patterns of Pacific sardine Sardinops sagax eggs and larvae in the California Current System

“…The advection pattern of eggs and larvae to the south also results in a geographic separation from adult sardine because it is opposite of the seasonal adult migration pattern to the north during summer (Lo et al, 2011;Demer et al, 2012). If a pronounced migration of juveniles does exist, this separation may provide an opportunity to estimate year class strength by surveying a relatively small area using transects perpendicular to the coast as juveniles return northward.…”

“…Surveys were conducted using one or two vessels that continued sampling transect lines at least far enough offshore that sardine eggs were no longer being encountered in the CUFES. Thus the patterns in eggs sampled each year were believed to be reasonable approximations of the spawning area used by the stock (Lo et al, 2011).…”

“…Sardine eggs are positively buoyant and typically accumulate near the surface after spawning (Curtis et al, 2007). Their vertical distribution is affected by seawater density but generally the greatest portion of the distribution occurs in the upper 20 m. Because sardine eggs develop into larvae within a few days, the CUFES is used to survey potential sardine habitat during the spawning period to provide a synoptic estimate of the spawning habitat that has been used (Lo et al, 2011;Zwolinski et al, 2011).…”

Integrating fish and parasite data as a holistic solution for identifying the elusive stock structure of Pacific sardines (Sardinops sagax)

“…Ideally, a sampling program would encompass the known distribution of the Central California offshore stock from Vancouver, British Columbia to Ensenada, Baja California (Smith 2005. As suggested by Lo et al (2010) a coastwide survey conducted during the spring and summer of the same year would enable the spawning area in the PNW to be defined, and compared with the spawning biomass already examined during April of each year for a stock biomass estimate (e.g. Hill et al 2010).…”

“…During a coastwide survey, a coordinated sampling effort may best be achieved by dividing the known distribution of the Central California Offshore stock into six regions (Fig. 1) Lo et al (2010) sampling should be conducted at night to gain access to the Pacific sardine biomass in the upper 50 m of water column. For each survey, a minimum of 100 fish should be collected within each region with 50 fish caught in one haul at a nearshore station, and 50 fish caught in one haul at an offshore station.…”