Rickey. Maturity, spawning, and seasonal movement of Atheresthes stomias 



133 



can be attributed to distortion of hydrated oocytes 

 that occurs during histological processing. 



Gonosomatic indices (GSI) for immature and 

 spent/resting fish remained fairly constant across 

 seasons, whereas GSI for developing or gravid fish 

 varied considerably over time, reflecting ovarian 

 recrudescence (Table 7). Individual GSI for im- 

 mature fish ranged from 0.0017 to 0.0154 (aver- 

 age 0.0055), and individual spent/resting GSI 

 ranged from 0.0037 to 0.0259 (average 0.0135). 

 GSI for ripe/running fish (n=4; L =47.8) was not 

 calculated because loss of eggs in handling pre- 

 cluded accurate gonad weights. From histologi- 

 cal analysis, hydrated oocytes and POF were 

 found in "developing" females, indicating some 

 misclassification of spawning females. Because of 

 suspected misclassification, developing and gravid 

 GSI data were pooled by month. GSI for develop- 

 ing or gravid fish showed a rapid increase from 

 about 0.03 in August 1991 and 0.02 in July 1992 

 to 0.06 in September of both years; the highest an- 

 nual mean GSI occurred in December 1991 and No- 

 vember 1992. The highest individual GSI was 0.2201 

 in November 1992 for a 38-cm gravid female. 



1.0 

 0.8 



0) 

 TO 



E 0.6 

 o 

 "g 0.4 



Q. 

 O 



^0.2 

 0.0 



TftKP*aHBl*ffi- 



15 20 25 30 35 40 45 50 55 60 65 

 Fork Length (cm) 



-- Commercial^*- Survey 



Oregon 



Figure 4 



Maturity distributions and logistic curves for female arrowtooth 

 flounder calculated from pooled 1991-92 market and discard 

 (commercial) data, 1992 survey data, and 1973-75 data from 

 Oregon (see Footnote 3 in the text). 



Discussion 



The progression of gonad maturity stages, increase 

 in GSI, and the appearance of gravid females show 



that arrowtooth flounder spawn during fall-winter 

 off Washington. Spawning begins as early as Sep- 

 tember, extends at least through December, and is 

 completed by March. This coincides with the spawn- 

 ing season for Atheresthes evermanni in the western 



