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Recruitment Processes Program

Age-0 Walleye Pollock EcoFOCI Late-Summer Survey, Gulf of Alaska

figure 11, see caption
Figure 11.  Standardized, power-transformed abundance (top) and mean standard length (bottom) of age-0 walleye pollock in the western Gulf of Alaska during late summer 2009.

Scientists from the Recruitment Processes Program studied age-0 walleye pollock in the Gulf of Alaska during late summer 2009 aboard the NOAA ship Miller Freeman. Predetermined midwater collection sites formed grids over the continental shelf near Kodiak Island and between Shelikof Strait and the Shumagin Islands; additional prospective sampling occurred at seven sites near Unimak Island (Fig. 11).

The cruise objective was to obtain a third year (2005, 2007, 2009) of data for comparing the food availability and food quality for age-0 walleye pollock in the Kodiak and Shelikof-Shumagin regions. A secondary objective was to extend a time series of age-0 walleye pollock abundance at index sites within the Shelikof-Shumagin area.

A total of 7,807 age-0 walleye pollock were collected at 48 of the 79 sites (61% frequency of occurrence, FO). The standard length of all measured individuals (30 113 mm) averaged 68 mm. Highest abundances occurred at northeastern and near-shore sites within the Shelikof-Shumagin area (89% FO) (Fig. 11, top).

Preliminary mean abundance at index sites was higher in 2009 than in 2001 and 2003, but lower than in 2000, 2005, and 2007. Within the Kodiak Island nursery (39% FO), most fish were collected near shore. Few fish were collected near Unimak Island (29% FO).

On average, the largest age-0 walleye pollock were collected near Kodiak Island in the upper reaches of Chiniak and Barnabus sea valleys; from there, mean length decreased offshore and southwestward (Fig. 11, bottom). Fish stomach contents are currently being examined and will be compared to the density and taxonomic composition in zooplankton samples.

By Matt Wilson
 

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