472 



Fishery Bulletin 105(4) 



monthly recoveries vs. annual recoveries compared to 

 annual recoveries). The method and notation above is 

 therefore extended to estimate a separate overdisper- 

 sion parameter (k) for each type of data aggregation 

 included in the analysis. The likelihood equation (Eq. 3) 

 becomes 



l{Rc4.i\K<i.I'K) = 



K+«c, 



 d I \^c.d.l 



-1! 



YiK-i)\ 



1 + - 



K 



-'^c.dj 



R. 



MJ 



+ 1 



(4) 



where the likelihood component notation remains the 

 same, but the subscripts are revised to include the 

 following: data aggregation type (c), data set (d), and 

 time-space combination (/, identical within each c; e.g., 

 month-area or year-area depending on the level of data 

 aggregation). 



Data sources 



English sole (Parophrys vetulus) was selected for analy- 

 sis because of the large amount of tagging data avail- 

 able and the commercial importance of the species. 

 English sole are widely distributed from southern 

 California to Alaska (Hart, 1973) and are frequently 

 captured by the bottom-trawl fisheries of both the 

 United States and Canada. Many English sole tagging 

 programs have been conducted by both U.S. and Cana- 

 dian scientists since the 1930s. These have included 



55°N 



50°N 



45°N 



40°N - 



35°N - 



> ^i>B 



600 

 500 

 400 

 300 km 

 200 

  100 



L 



Canada 



Pacific 

 Ocean 



1B north 



Unite(d 

 States 



18 mid 



IB south 



1A north 



lA south "*"^ 



-140°W 



-135°W 



-1 30°W 



-125°W 



-120°W 



Figure 1 



Map of areas based on historical Pacific Marine Fisheries Com- 

 mission (PFMC) boundaries used in this analysis. The largest 

 PMFC areas, lA and 2B, were subdivided to make the latitudinal 

 ranges more consistent across all areas. 



releases off the coast of British Columbia (Ketchen, 

 1956; Forrester, 1969), Washington (Pattie, 1969), 

 Oregon (Harry, 1956), and California (Jow, 1969). Addi- 

 tional tagging within Puget Sound (Menasveta, 1958; 

 Day, 1976) and the Strait of Georgia have focused spe- 

 cifically on population dynamics within these waters. 

 Most tagging data reported between 1946 and 1979 

 were available only through unpublished reports from 

 the Research Board of Canada, Oregon Department of 

 Fish and Wildlife, and the Washington Department 

 of Fisheries. In total, 44 tagging events (defined as 

 tags released in one area during a one-month period) 

 resulted in the release of 57,839 tags of which 9988 

 (17.3 % ) were recovered. The primary objective of most 

 of these studies was to determine the amount of migra- 

 tion (as a percentage of the total population) that 

 occurred among areas with the highest abundance of 

 English sole (e.g., Harry, 1956). 



Tag recoveries have been most frequently reported 

 for the historical Pacific Marine Fisheries Commission 

 (PMFC) areas; these areas were therefore the logi- 

 cal (and only) spatial context in which to analyze the 

 results. To reduce the latitudinal range of the largest 

 PMFC areas, PMFC area lA was divided into two sub- 

 areas (north and south of Point Conception) and PMFC 

 area IB was divided into three subareas (north of Point 

 Arena, between Point Arena and Pigeon Point, and 

 south of Pigeon Point). This division of areas resulted 

 in 17 PMFC-like areas (area 5E is shown for reference 

 only; for simplicity, all data from 5E were treated as if 

 they were collected from 5C or 5D (i.e., 5E data 

 were integrated into similar 5C and 5D ar- 

 eas to make the areas linear) with an average 

 latitudinal span of 138 km (range = 83-204 km. 

 Fig. 1). Reporting of tag releases and recoveries 

 was sufficiently detailed to allow an analysis 

 that included these additional boundaries and 

 that did not exclude any studies. 



Only studies reporting the area, month, and 

 year for each tagging event were included in 

 this analysis. Additionally, tag recoveries must 

 have been reported at one of four levels of reso- 

 lution: type-1 resolution, where data were avail- 

 able for year, month, and area for each individ- 

 ual tag recovery; type-2 resolution, where data 

 were available for month and area only; type-3 

 resolution, where data were available for area 

 only; and type-4 resolution, where data were 

 only available to indicate recovery inside or 

 outside the area of tagging. After this screen- 

 ing (removing 16,375 releases), there were 25 

 English sole tagging events from the open coast 

 remaining in the analysis, including 17,056 

 releases and 3464 recoveries; these projects, 

 summarized in Jow (1969), Forrester (1969), 

 and Pattie (1969) ranged from southern Cali- 

 fornia to northern British Columbia and from 

 1936 to 1965 (Table 1). 



There were many differences among indi- 

 vidual studies that had to be reconciled or ac- 



