Friedlander and Ziemann; Impact of hatchery releases on recruitment of Polydactylus sexfilis 



35 



Table 2 



Results of catch and effort from recreational creel surveys for Pacific threadfin conducted along the windward coast of Oahu 

 between 1994 and 1998. 



Gear type 



Angling 

 Gillnet 

 Throw net 

 Spear 

 Total 



Number of 

 interviews 



464 

 22 

 42 

 23 



551 



Total effort 

 (h) 



3647 



327 



93 



81 



4148 



Number of 

 threadfin 



CPUE 

 (number/h) 



Number of 



hatchery-reared 



threadfin 



123 



35 



3 







161 



0.03 

 0.11 

 0.03 

 0.00 

 0.04 



40 

 1 

 

 



41 



Proportion 

 hatchery-reared 



0.33 

 0.03 

 0.00 

 0.00 

 0.25 



Table 3 



Summary of wild and tagged Pacific threadfin obtained from the recreational fishery from March 1998 to May 1999. 



1998 



Region 



Proportion 

 Hatchery- hatchery- 



reared Wild Total reared 



Ewa 

 Kahana 

 Kailua 

 Kaneohe 

 Laie 

 Mokapu 

 Mokuleia 

 North Shore 

 Sandy Beach 

 Waianae 

 Waimanalo 

 Total 





 2 



35 

 5 



11 

 

 

 3 

 1 

 

 9 



66 



18 

 15 

 14 

 85 



237 



13 



8 



121 

 32 

 18 

 16 



577 



18 

 17 

 49 

 90 



248 



13 



8 



124 

 33 

 18 

 25 



643 



0.00 

 0.12 

 0.71 

 0.06 

 0.04 

 0.00 

 0.00 

 0.02 

 0.03 

 0.00 

 0.36 

 0.10 



1999 



Total 



Hatchery- 

 reared 



Wild 



Proportion 

 hatchery- 

 Total reared 



Proportion 

 Hatchery- hatchery- 



reared Wild Total reared 







6 



4 



28 



17 



34 



















8 



97 







129 



6 



221 



373 



317 







3 



9 







84 



1142 







135 



10 



249 



390 



351 







3 



9 







92 



1239 



0.00 

 0.04 

 0.40 

 0.11 

 0.04 

 0.10 

 0.00 

 0.00 

 0.00 

 0.00 

 0.09 

 0.08 



Condition factors between sites and among release size 

 classes were compared by using a two-way ANOVA (F); a = 

 0.05. A Mann-Whitney rank sum test (T) was used to com- 

 pare the gonadosomatic index (GSI=ovary weight/body 

 weightxlOO) between hatchery-reared and wild Pacific 

 threadfin recovered in the 1999 reward progi-am. 



Results 



CPUE for Pacific threadfin from 551 creel survey inter- 

 views of recreational fishermen from 1994 to 1998 was 

 very low (0.04 fish/h for all gear types combined) (Table 2): 

 1 per 33 hours by angling or 1 per 9 hours by gillnet. 

 These values are probably low estimates because the creel 

 survey was not directed at fishermen who targeted Pacific 

 threadfin. Even though we saw a very small number of 

 Pacific threadfin in the creel surveys, hatchery-reared fish 



made up 33% (40 of 123) of the angling catch and 25% (41 

 of 161) of the overall catch. 



The voluntary reward program between March 1998 

 and May 1999 yielded 1882 Pacific threadfin (Table 3), of 

 which 163 were hatchery-reared Pacific threadfin (8.7'^(). 

 The period March-May 1998 provided 643 Pacific thread- 

 fin, compared to 1239 for the period September 1998-May 

 1999. Tag information was readable for 63 of 66 fish recov- 

 ered in 1998 (3 damaged tags) and all 97 tags recovered 

 in 1999. Of the total readable tags, fish released in 1997 

 made up 93. 77^ (n=59) of the 1998 reward fish and 95.9% 

 («=93) of the 1999 reward fish. Four fish from 1996 re- 

 leases were recovered in each year. Although most fish re- 

 covered in the reward program were from the windward or 

 eastern side of Oahu, 168 fish (26.1% ), including 4 hatch- 

 ery fish from the North Shore area, did come from other 

 areas around the island in 1998 (Fig. 2). Three reward fish 

 were returned from the North Shore in 1999. No hatchery- 



