LAROCHE: TROPHIC PATTERNS AMONG LARVAE OF SCULPINS (COTTIDAE) 



stages of Bala hhs, particularly stages 2-4, are 

 somewhat smaller than adult Temora and Pseu- 

 docalanus. 



Among fish larvae whose food habits have 

 been reported, cottid larvae most resemble hake 

 (genus Merluccius) in prey size at first feeding 

 and in changes of prey size with growth. The first 

 prey ingested by most marine fish larvae range 

 in width from 50 to 100 M m (Houde 1973; Hunter 

 1980). First prey of hake and cottid larvae are 

 larger: 50-400 /urn for Merluccius productus; 500 

 fxm mean prey width for M. merluccius hubbsi; 

 100-375 /urn for three species of Myoxocephalus; 

 and >800 mm for H. americanus (Sumida and 

 Moser 1980; de Ciechomski and Weiss 1974). 

 Among fish larvae that ingest 50-100 ^m wide 

 prey at first feeding, there is usually a distinct 

 and often dramatic increase in prey size with 

 development. This is seen typically as a change 

 from a diet of copepod eggs and nauplii to one of 

 advanced copepodites and adults. No dramatic 

 increase in prey size or progression in prey types 

 occurs in cottid and hake larvae. 



Hunter (1980) recently attempted to categorize 

 marine fish larvae into distinct ecological roles 

 based on those behavioral and physiological 

 traits primarily associated with feeding. Two 

 distinct groups, engrauliform and scombriform, 

 based on extensive field and laboratory observa- 

 tions of northern anchovy and Pacific mackerel 

 larvae, emerged from his analyses. Cottid larvae 

 share some scombriform traits such as relatively 

 large mouths and prey. Similarities in feeding 

 posture, maneuverability, and swimming speed 

 may be inferred because of features in body 

 shape shared by cottid and Pacific mackerel lar- 

 vae. These larvae, however, would be expected to 

 differ significantly in rates of metabolism and 

 growth because of the different environmental 

 temperature regimes they inhabit: 14°-21°C for 

 highest abundances of Pacific mackerel (Kramer 

 1960) and 0°-4°C for cottid larvae (Laroche 

 1980). In this regard, cottid larvae more closely 

 resemble hake larvae which inhabit deeper, 

 colder oceanic waters than either anchovy or 

 Pacific mackerel. Hunter (1980) suggested that 

 hake larvae may belong to a third trophic group 

 characterized by reliance on large prey, a fea- 

 ture already shown to be shared with cottid lar- 

 vae, and slow metabolism and growth. Although 

 growth rates have not been estimated for cottid 

 larvae, increases in monthly median lengths of 

 ^1 mm (Laroche 1980) and relatively stationary 

 modes in length-frequency distributions during 



winter and spring in the Damariscotta River 

 estuary (Townsend 1981) may be explained, in 

 part, by slow growth rates. 



Despite some apparent similarities, there are 

 notable differences in the early life histories of 

 hake and the five species of cottids: for example, 

 egg size, 0.98 vs. 1.5-4 mm; size at hatching, 2.4 

 vs. 5-12 mm; and stage of eye and mouth develop- 

 ment at hatching, partial vs. complete. The sig- 

 nificance of differences such as these in further 

 distinguishing ecological roles among fish larvae 

 will be better understood only after the early 

 feeding ecology of more species has been investi- 

 gated. 



ACKNOWLEDGMENTS 



The following individuals are gratefully ac- 

 knowledged for their significant contributions to 

 this study. Wayne A. Laroche and Paul C. Jensen 

 guided and assisted me in the field; John Konecki, 

 Gilbert Jaeger, Paul Montagua, and William T. 

 Peterson patiently taught me the taxonomy of in- 

 vertebrate taxa; Joseph J. Graham generously 

 supplied sampling gear and laboratory equip- 

 ment, and the numerous discussions on larval 

 fish ecology and taxonomy with him and Stanley 

 R. Chenoweth were invaluable; Hugh H. DeWitt 

 and Bernard J. McAlice provided long-term sup- 

 port and counsel; Wayne A. Laroche, Percy L. 

 Donaghay, and William T. Peterson read the 

 manuscript and suggested useful ways to im- 

 prove it. 



LITERATURE CITED 



Arthur, D. K. 



1976. Food and feeding of larvae of three fishes occurring 

 in the California Current, Sardinops sagax, Engraulis 

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 74:517-530. 

 Beyer, J. E. 



1980. Feeding success of clupeoid fish larvae and stochas- 

 tic thinking. Dana 1:65-91. 

 Blaxter, J. H. S. 



1965. The feeding of herring larvae and their ecology in 

 relation to feeding. Calif. Coop. Oceanic Fish. Invest. 

 Rep. 10:79-88. 

 Blaxter, J. H. S., and G. Hempel. 



1963. The influence of egg size on herring larvae (Clupea 

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 240. 

 Crisp, D. J. 



1962. The planktonic stages of the cirripedia Balanus 

 balanoides (L.) and Balanus balanus (L.) from north 

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 de Ciechomski, J. D., and G. Weiss. 



1974. Estudios sobre la alimentacion de larvas de la mer- 



839 



