*U.S. Dept. of Commerce / NOAA / OAR / PMEL / Publications*

Copyright ©1996 by Blackwell Science Ltd. Further electronic distribution is not allowed.

**Figure 1.** The study area in the western Gulf of Alaska with a
schematic of pollock location as a function of life history stage. The sea valley extends
southwestward from the northern end of Kodiak Island to the vicinity of Sutwik Island
where it turns south toward the continental slope. The insert shows the location of the
Alaska Coastal Current and the Alaskan Stream.

**Figure 2.** Estimates of Lloyd's index of patchiness for eggs
(solid box) and larvae (open circle). Results from a given survey, regardless
of egg or larval size (age), are shown as a function of the mean survey date.
The error bars show the standard error of the index estimates. The heavy line
shows the mean index for larvae from model results (Hermann
*et al.*, 1996a).

**Figure 3.** Lloyd's index of patchiness as a function of egg
stages and larval length (age). Age was estimated using results from Bailey
*et al.* (1996). Larvae were grouped by 2-mm bins for lengths <17 mm
and by 8-mm bins for larger animals. Data sets that consisted of >90% zeros
were not used. A line connects the mean values of **P** for each
stage (eggs) and for each length bin (larvae).

**Figure 4.** Contours of pollock larvae in Shelikof Strait. The three
types of distributions are shown in panels: (a) transient event [1MF88], (b) and (c)
Sutwik Island [4MF88A and 4MF89], and (d) eddy, 2MF90 (dotted line shows the 2,250
larvae/10 m^{2} contour). Panel (e) shows contours from the survey with the
greatest abundance [2SH81] and an example of a high Lloyd's Index [**P** = 16.1].
Panel (f) shows a distribution with a low patchiness [**P** = 5.2;
3MF91]. Contour intervals are 10, 50, 100, 500, 1000, 5000, 10,000 and 50,000
larvae/10 m^{2}.

**Figure 5.** Concentration of newly hatched larvae as a function of
distance downstream from midpoint of the hatching distribution from the advective model.

**Figure 6.** The relationship between larval swimming speed and the
radius of a patch they are capable of maintaining in the presence of horizontal diffusion.
See text for details of the model. Dashed line represents the approximate radius of eddies
in Shelikof Strait and the resulting minimum radial swimming speed to maintain the larval
patch against diffusion.

**Table 1.** Observations and statistics of pollock eggs sampled for each
cruise (the last two digits are year). The area of the grid, the number of tows, the mean
number of eggs caught and the standard deviation are given. Lloyd's index was calculated
following eqns (1-3).

**Table 2.** Observations and statistics of pollock larvae sampled for
each cruise (the last two digits are year). A 60-cm bongo net was used unless otherwise
indicated, by † for Methot net and * for Tucker trawl. The "% in patch"
column is the percentage of the total number of larvae that were caught at stations where
the "no./Tow" > mean + 1 SD for the survey. In the Sutwik Island
column "yes" indicates a patch existed near or northeast of Sutwik Island, and *
indicates that the survey did not include the Sutwik Island region.

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