HUGHES: PACIFIC SAURY OF NORTHEASTERN PACIFIC 



Preliminary scale studies indicated that the 

 samples might be of two races of fish with 

 different growth patterns — those with a wide 

 zone of initial growth (distance between the 

 focus and first annulus) and those with a much 

 narrower zone of initial growth. Similar growth 

 patterns have been detected by Japanese sci- 

 entists on scales of fish of the western stock 

 of Pacific saury and interpreted as distinct 

 spring- and autumn-born "subpopulations" 

 (Hotta, 1960). Accordingly, fish were classified 

 as being either spring-born, autumn-born, or 

 intermediate type by examining the initial 

 growth zone of the scale. Length-weight 

 regressions and von Bertalanffy growth in 

 length parameters were determined for fish of 

 the spring- and autumn-born scale types and 

 compared statistically. In addition, electro- 

 phoretic techniques (Utter, Hodgins, and 

 Johnson, 1972) were emploj'ed to test for 

 significant inter-area heterogeneity as well as 

 heterogeneity of fish with spring- and autumn- 

 born scale features. 



STOCK COMPOSITION 



Temporal and spacial variations in length, 

 age, sex, and maturity are treated in this section. 

 In analyzing the sex ratio and age frequency 

 data, fish of the spring- and autumn-born 

 scale types were treated separately. 



Size and Age Composition 



There was a trend toward increasing length 

 and average age with increasing latitude. Mean 

 lengths in the California, Oregon, and Washing- 

 ton-Vancouver Island areas were 201 mm, 

 238 mm, and 277 mm, respectively (Figure 1). 

 Length frequency histograms (Figure 2) show 

 there was an absence of fish < 160 mm off 

 Washington-Vancouver Island which were 

 represented off Oregon and relatively abundant 

 off California. Conversely, fish > 300 mm were 

 absent off California, represented off Oregon, 

 and relatively abundant off Washington- 

 Vancouver Island. 



Samples taken off California exhibited an 

 unusual quadra-modal length -frequency distri- 

 bution believed to be a sampling artifact rather 

 than fluctuation in year-class strength. [Three 

 of six schools sampled were schooled by size 

 (Figure 1) which produced the minimum length 



mode at 165 mm and the maximum length mode 

 at 270 mm.] 



More symmetrical length distributions were 

 produced from the three schools sampled in 

 1970 and five schools sampled in 1971 off 

 Oregon. Lengths ranged from 159 mm to 293 

 mm in 1970 and 158 to 330 mm in 1971. Length 

 distributions for both years are similar, being 

 moderately skewed to the right with a mode at 

 210 mm in 1970 and 235 mm in 1971. 



The three schools sampled off Washington in 

 1970 and two schools off Washington-Vancouver 

 Island in 1971 showed more variation between 

 years than the Oregon samples. A bimodal 

 distribution was more apparent in 1971, modes 

 at 245 and 305 mm, than the moderately 

 asymmetrical distribution in 1970 with mode 

 at 260 mm. Lengths ranged from 160 to 

 334 mm in 1970, and 161 to 340 mm in 1971. The 

 upper limit of this latter range may exceed the 

 previously known maximum length of the 

 species in the eastern North Pacific Ocean. 

 Clemens and Wilby (1961) reported lengths to 

 14 inches (356 mm); however, it is unclear 

 whether this is standard or total length. The 

 two saury measuring 340 mm knob length were 

 ripe females measuring 363 and 364 mm in total 

 length and weighing 180 and 190 grams 

 respectively. 



50° 



48" 



38° 



z o 



X X 



-j 1512 



I J 



h284 

 i|9l 



_,31 



rzt 



-<5Z 



-1222 

 -1220 



100 



150 200 



KNOB LENGTH (mm) 



300 



Figure 1. — Lengths (mean, range and S.D. of mean) of 

 eastern Pacific saury plotted against latitude of capture. 

 Numbers indicate sample size per school. 



123 



