WILLIAMS and CLARKE: BIOLOGY OF THE GOLD SPOT HERRING 



rings became clearer with time; consequently, the 

 otoliths were stored for 2 wk, counted, and then 

 recounted 2 wk later to confirm the first counts. On 

 each occasion, counts were made along the rostral, 

 postrostral, and antirostral axes, when possible. Es- 

 pecially prominent rings were noted and were of 

 great use in tracking and comparing counts of the 

 numerous closely spaced rings of large fish. 



To determine if growth increments on the otoliths 

 were formed daily, small metamorphosing herring 

 were captured in Kaneohe Bay and held alive in 

 shaded tanks which received a continuous flow of 

 seawater from the bay at near ambient temperature. 

 A subsample of the collected herring was frozen im- 

 mediately after capture, and subsamples were 

 removed from the tanks at later dates but at the same 

 time of day (± 1 h) as the original capture. The dif- 

 ferences in numbers of rings between fish from the 

 different subsamples were compared with the num- 

 ber of days elapsed. In the first two of these ex- 

 periments, the fish were fed frozen zooplankton from 

 Kaneohe Bay 3-4 times/wk on an irregular schedule, 

 but in the last two experiments they were fed brine 

 shrimp once or twice daily, 6 d/wk. The fish also prob- 

 ably ate some plankton from the seawater supply to 

 the tanks. 



RESULTS 

 Appearance and General Biology 



Catches of the purse seine sets indicated that the 

 gold spot herring first appeared in Kaneohe Bay in 

 mid- 197 5, but did not begin spawning in the area un- 

 til 1976. No herring were taken in a total of 25 sets 

 with the small purse seine on 12 dates between Sep- 

 tember 1974 and July 1975. The first catch was an 

 adult taken on 23 July 1975, and 11 others (66-117 

 mm SL) plus a 28 mm juvenile were taken in 27 sets 

 on 11 dates between July and December 1975. In the 

 first six months of 1976, 28 sets on 12 dates yielded 

 65 fully transformed herring 45-120 mm SL — most 

 of them adults. Two of these sets (in March and April) 

 also collected a total of 14 herring just beginning 

 transformation from the larval stage. Catches in- 

 creased markedly in the second half of the year. A 

 single set taken in late June 1976 took 131 transform- 

 ing or small juveniles (19-37 mm SL), and almost all 

 subsequent sets with the small purse seine took 

 herring of a wide size range. Two experimental sets 

 with the large seine in May 1975 caught no herring. 

 Adults (up to 120 per set) were taken in subse- 

 quent sets in April, May, and October 1976 and 

 June 1977. 



There was general agreement between collections 

 made by others in the bay and our visual observations 

 that gold spot herring were not present in the bay 

 prior to mid- 1975 and that recruitment of juveniles 

 was not substantial until 1976. Adult or near-adult 

 herring first appeared over reef flats during the day 

 shortly after the first purse seine catches. Although 

 our records do not unequivocally indicate whether or 

 not juveniles were present in 1975, large schools 

 (thousands of individuals) of transforming herring 

 were definitely not observed until 1976. Subsequent 

 to 1976, transforming or small juvenile herring were 

 observed or caught in all months of the year, but were 

 more abundant from June to November or Decem- 

 ber. In 1976-79, adults were present in catches or ob- 

 servations from March to December, and except for 

 1979 were present in abundance primarily from May 

 to October. Their presence was, however, sporadic 

 even during the latter months, and in 1979 few were 

 seen or caught at any time. 



Our observations in Kaneohe Bay appear to be rep- 

 resentative of inshore areas all around the island of 

 Oahu. Casual reports by other scientific personnel as 

 well as by commercial and recreational fishermen in- 

 dicated that "sardines" appeared and subsequently 

 increased markedly in abundance elsewhere on Oahu 

 at about the same times as in Kaneohe Bay and that 

 subsequently they were most abundant from spring 

 to fall. Unfortunately, we did not obtain any 

 specimens of "sardines" from other areas of Oahu 

 until late 1976, but it is extremely unlikely that the 

 casual observations refer to the Marquesan sardine, 

 the only species with which the gold spot herring 

 might be confused. We have examined specimens 

 taken in 1976-82 from a wide variety of locations on 

 Oahu (from day collections in the surf zone to 

 specimens taken under night lights several km 

 offshore) and found all to beH. quadrimaculatus. We 

 find no evidence that, prior to 1975, "sardines" of any 

 sort were ever sufficiently abundant to attract atten- 

 tion, and the most recent specimens of S. marquesen- 

 sis from Oahu were taken in 1968. 



During the day, the gold spot herring of all sizes in 

 Kaneohe Bay were mostly found over sand-rubble 

 reef flats 1-2 m deep in fairly clear water or in some- 

 what deeper water around piers, floating docks, etc. 

 They were absent from these areas at night. Although 

 our nighttime purse seine sampling was inadequate 

 to properly consider dispersion, the catches in- 

 dicated that juveniles moved into deeper water at 

 night, but tended to remain within a few hundred 

 meters of the reef or shore. Adults were taken 

 routinely up to 1 km away from the nearest shallow 

 water. We have also examined adults taken under 



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