INDUCED SPAWNING OF THE NORTHERN ANCHOVY, 



Engraulh mordax GIRARD 



Roderick Leong^ 



ABSTRACT 



Anchovies were induced to mature their gonads by an artificial photoperiod of 4 hr light and 20 hr dark- 

 ness at 15° C. Single injections of suspensions of salmon pituitary, carp pituitary, or a solution of human 

 chorionic gonadotropin (HCG) promoted increase in egg diameters but did not induce spawning. Two in- 

 jections, a first of HCG and the second 2 days later of either salmon pituitary or carp pituitary, in- 

 duced spawning. At each spawning 6,000 to 16,000 eggs were collected, and 257c to 80% of the eggs 

 hatched. Larvae grown from these eggs were morijhologically similar to those caught in the sea. 



An investigation was started at the National 

 Marine Fisheries Service Fisher.v-Oceanography 

 Center, La Jolla, Cahf., in 1969, to examine 

 methods for spawning the northern anchovy, 

 Eng vaults mordax Girard, under controlled lab- 

 oratory conditions in order to supply eggs and 

 larvae for experimental studies. The strategy- 

 for spawning anchovies in captivity was to pro- 

 vide an environment in which the fish would 

 mature their gonads and subsequently to induce 

 spawning through hormone treatment. The role 

 of the environment and the use of hormone in- 

 jections for inducing spawning in other sijecies 

 of fish has been well documented by Pickford 

 and Atz (1957). This report describes a meth- 

 od for bringing the anchovy to ripeness and 

 the effectiveness of various hormone treatments 

 in inducing spawning. As far as is known this 

 was the first successful attempt to artificially 

 mature and spawn this pelagic fish in the lab- 

 oratory. 



MATERIALS AND METHODS 



Anchovies, averaging 90 mm in length, were 

 purchased from a San Diego bait dealer in 

 March of 1969, transported to the laboratory, 

 and held in circular plastic lined wading pools 

 4.6 m in diameter with 0.9 m of water. By 

 the beginning of the injection trials in August 

 of 1970, the fish had grown to an average length 

 of 125 mm, at which length half of the fish should 



have been mature (Clark and Phillips, 1952). 

 The fish were subjected to a photoperiod of 4 hr 

 light (32 ft-c at the brightest spot on the surface 

 of the water) and 20 hr dark (1 ft-c) for 3 

 months prior to the trials. Observations in 

 the preceding year revealed that anchovies tend 

 to mature more readily under relatively pro- 

 longed dark conditions. The tanks were con- 

 stantly supplied with fresh seawater and the 

 temperature was maintained at 15° C (Lasker 

 and Vlymen, 1969). Much of the spawning of 

 anchovies in nature occurs at or near this tem- 

 perature (Ahlstrom, 1956). The fish were fed 

 twice a day. In the first feeding, given at the 

 beginning of the 4-hr light period, the fish were 

 fed 6% of their live body weight in rotating 

 daily rations of ground squid, ground anchovies, 

 and brine shrimp. In the second feeding, given 

 near the end of the light period, the fish were 

 fed l''r of their body weight in trout chow." 

 Under this light, temperature, and food regimen 

 approximately one-fourth of the fish developed 

 gonads which weighed more than 6Sf of their 

 body weight. 



Three series of injection trials were conduct- 

 ed. In the first series the following dosages 

 and types of injections were tested: 2.5, 5.0, and 

 pituitary" pi'epared essentially by the method of 

 10.0 mg of salmon (Oncorhynchus tshaivyfscha) 



' National Marine Fisheries Service Fishery-Ocean- 

 ography Center, La Jolla, Calif. 92037. 



Manuscript received January 1971. 



FISHERY BULLETIN: VOL. 69, NO. 2, 1971, 



" Ralston Purina trout chow, size 2. Reference to 

 commercial products does not imply endorsement. 



" Obtained through the courtesy of Dr. Irwin Haydock 

 and the California Department of Fish and Game, Nim- 

 bus Fish Hatchery, Rancho Cordova, Calif. 



357 



