meaningful ecological, physiological and behavioral research developed once 

 larvae could be routinely cultured. A myriad of foods has been used to rear 

 marine fish larvae (64), but five foods have been more successful in recent 

 years for meeting larval nutritional requirements. These are the rotifer 

 Brachionus plicatilis, the nauplius of brine shrimp Artemia salina, copepods 

 from wild plankton collections, the harpacticoid copepods Tisbe and Tigriopus 

 spp., and the naked dinoflagellate Gymnodinhim splendens. 



Prey Concentrations 



Marine fish larvae are visual feeders, with Umited ability to search a volume 

 of water for suitable food items during a unit of time. Suitable items usually 

 are living organisms of a size that can be ingested, are nutritionally adequate, 

 and are present at concentrations which allow a larva to encounter enough 

 items during a day to meet its metabolic demands and to provide some excess 

 for growth. Typical marine fish larvae are 2-3.5 mm long when they begin to 

 search actively for food. Acceptable prey usually are 20-150 jum in breadth (7, 

 31, 56, 92). Some large and rather atypical larvae, like Atlantic herring, Clupea 

 harengus, or plaice Pleuronectes platessa, can begin feeding on items in excess 

 of 300 jum in breadth (10, 80, 82). Perhaps not surprisingly, required 

 concentrations of prey for newly-feeding larvae have been shown to vary 

 greatly in laboratory studies, the variation in large part reflecting size 

 differences in the prey that has been offered. 



Prey concentrations that have been used successfully to rear larvae have 

 ranged from 1 x 10 to 2 x 10 per liter, although required concentrations for 

 significant survival probably lie in the range 10 to 10" per Hter. The higliest 

 reported concentrations (1-2 x 10 per Uter) were of the large dinoflagellate 

 Gymnodinium splendens, which can be used to culture northern anchovy 

 larvae during the first week of Ufe (47, 57, 95). Lowest concentrations (442 

 per Uter) were of brine shrimp Artemia salina naupUi used to culture Atlantic 

 herring larvae (82, 83). Neither G. splendens nox A. salina is usually available to 

 marine fish larvae in nature, although Kiefer and Lasker (53) recently have 

 shown that G. splendens may be present at \A x 10 per liter in the 

 chlorophyll maximum layer of the Southern CaUfornia Bight. Northern 

 anchovy larvae can concentrate in the chlorophyll maximum layer and can feed 

 on G. splendens when its concentration exceeds 2x10 per hter (56). The 

 most common prey reported from stomach analyses of marine fish larvae in 

 nature are nauplii and other stages of copepods. Using cope pod nauplii as food 

 Houde (45) reported 10 percent survival at metamorphosis when per liter 

 nauplii concentrations were 34 for sea bream Archosargus rhomboidalis, 107 

 for bay anchovy Anchoa mitchilli, and 130 for lined sole, Achinis lineatus. 

 Other studies with wild plankton (predominantly copepod nauphi) as prey 

 have reported higher concentrations required for significant survival than those 



178 



