The relationship between Pacific hake (Merluccius productus) distribution and poleward subsurface flow in the California Current System

Abstract

In a search for ocean conditions potentially affecting the extent of Pacific hake (Merluccius productus) feeding migrations, we analyzed data collected in 1995 and 1998 by the National Marine Fisheries Service on abundance and distribution of hake (by echo integration), intensity and distribution of alongshore flow (from acoustic Doppler current profiler), and temperature (conductivity–temperature–depth profiles). Our results show that Pacific hake are associated with subsurface poleward flow and not a specific temperature range. Temporal and spatial patterns characterize both hake distribution and undercurrent characteristics during the two years of this study. We suggest that poleward flow in this area defines adult hake habitat, with flow properties aiding or impeding the poleward migration of the population. We conclude that although physical processes may not directly affect fish production, they may be the link between large-scale ocean–atmosphere variability and pelagic fish distribution.

Spatio-temporal comparison of Pacific white-sided dolphin echolocation click types

“…Conversely, click Type B, which occurred more frequently during the day, may be used when foraging on epipelagic fish which may be more accessible when grouped in schooling formation during the day. While diel patterns support the prey difference hypothesis for click type significance, prey type hypotheses alone do not explain the geographic differences in click type usage, as all major Pacific white-sided dolphin prey types in the SCB are generally distributed evenly throughout the region (Okutani & McGowan 1969, Mais 1974, Agostini et al 2006. Additionally, if the dolphins have the ability to modify their click structure based on prey type, it seems likely that more click types should exist given prey variability.…”

Stock delineation of migratory and resident Pacific hake in Canadian waters

“…However since the early 1990s, the northern extent of their summer feeding distribution expanded to include Queen Charlotte Sound concomitant with observed changes in the ecosystem off the west coast of Vancouver Island (McFarlane et al, 2000). Typically, in years with warmer conditions the northward distribution of Pacific hake increases, and it decreases in years with cooler conditions (Agostini et al, 2006;Ressler et al, 2007). However, from 2006 to 2008, Pacific hake were virtually absent from the west coast of Vancouver Island, and the vast majority of the migrating population was in Queen Charlotte Sound for summer feeding.…”

Building on Fisheries Acoustics for Marine Ecosystem Surveys

“…The sampling encompassed the majority of the continental shelf northward of Point Conception, California, up to and beyond Vancouver Island, Canada (Figure 2). This region included the potential sardine habitat and the historic distribution of hake (Agostini et al, 2006).…”