Juvenile Pacific salmon (Oncorhynchus spp.), ecologically-related species, and associated biophysical data were collected along primary marine migration corridors in the northern and southern regions of southeastern Alaska in 2007. Up to 17 stations were sampled in epipelagic waters over four time periods (27 sampling days) from May to August. This survey marks 11 consecutive years of systematically monitoring how juvenile salmon interact in marine ecosystems, and was implemented to identify the relationships among biophysical parameters that influence the habitat use, marine growth, predation, stock interactions, and year-class strength of salmon. Typically, at each station, fish, zooplankton, surface water samples, and physical profile data were collected using a surface rope trawl, conical and bongo nets, water sampler, and a conductivity-temperature-depth profiler during daylight. Surface (3-m) temperatures and salinities ranged from 7.7 to 15.3 ºC and 12.3 to 30.6 PSU from May to August. A total of 48,170 fish and squid, representing 17 taxa, were captured in 97 rope trawl hauls from June to August. Juvenile salmon comprised about 7% of the total fish and squid catch. Juvenile salmon occurred frequently in the trawl hauls, with pink (O. gorbuscha), chum
(O. keta), sockeye (O. nerka), and coho salmon (O. kisutch) present in 51-92% of the trawls in the southern and northern regions, whereas juvenile Chinook salmon (O. tshawytscha) occurred in about 23% of the hauls. Of the 3,412 salmonids caught, over 97% were juveniles. Only two non-salmonid species represented catches of >30 individuals in either region: Pacific herring (Clupea pallasi) in the southern region (n = 44,637) and crested sculpin (Blepsias bilobus) in the northern region (n = 34). Catch rates of juvenile salmon in both regions were generally highest in June for all species except pink salmon. However, in the more extended, 11-yr time series in the northern region, juvenile pink salmon catches were among the lowest observed in June and July 2007, suggesting a poor adult return in the subsequent year. Mean size of juvenile salmon generally increased from June to July; however, condition residuals were lower than the longterm average for most species. Coded-wire tags were recovered from 14 juvenile coho salmon and five Chinook salmon (1 juvenile and 4 immature). All but one fish were from hatchery and wild stocks originating in southeastern Alaska. The non-Alaskan stock was a Chinook salmon that originated from the Upper Columbia River. Alaska enhanced stocks were also identified by thermal otolith marks from 67% of the chum and 4% of the sockeye salmon examined. Onboard stomach analysis of 95 potential predators, representing 8 species, did not provide evidence of predation on juvenile salmon. This research suggests that in southeastern Alaska, juvenile salmon exhibit seasonal patterns of habitat use and display species- and stock-dependent migration patterns. This third season of comparing biophysical parameters between the northern and southern regions of southeastern Alaska suggests that summer conditions differ between the regions. Long-term monitoring of key stocks of juvenile salmon, on seasonal and interannual time scales, will enable researchers to understand how growth, abundance, and ecological interactions affect year-class strength of salmon and to better understand their role in North Pacific marine ecosystems.