enough and active enough to live independently of 

 the currents (Graham 1956). This change in life 

 style usually occurs during their first year of life 

 and is reflected in their diet because they change 

 from feeding mainly on plankton to benthic organ- 

 isms (Nikolsky 1963). This paper identifies the 

 types of food eaten by several species of juvenile 

 groundfish, and further examines their change in 

 diet with fish length. 



Methods 



Stomachs were collected from juvenile fish 

 caught during annual spring and fall groundfish 

 surveys conducted by the National Marine Fish- 

 eries Service (NMFS). A scheme of stratified 

 random sampling was conducted within the five 

 geographic areas of the northwest Atlantic (Fig- 

 ure 1). All bottom trawl tows were 30 min in 

 duration and fishing continued over 24 h/d. (Fur- 

 ther details of the bottom trawl survey techniques 

 may be obtained from the Resource Surveys Inves- 

 tigation, Northeast Fisheries Center Woods Hole 

 Laboratory, NMFS, NOAA, Woods Hole, MA 

 02543.) The feeding data for all species except 

 haddock are based on collections made from 1969 

 through 1972; juvenile haddock were collected 

 from 1953 to 1976, inclusive. The species collected 

 were: Atlantic cod, Gadus morhua; haddock, Mel- 

 anogrammus aeglefinus; silver hake, Merluccius 

 bilinearis; pollock, Pollachius uirens; red hake, 

 Urophycis chuss; white hake, U. tenuis; spotted 

 hake, U. regius; fourbeard rockling, Enchelyopus 

 cimbrius; American plaice, Hippoglossoides pla- 

 tessoides; and yellowtail flounder, Limanda fer- 

 ruginea. All of these species reach maturity when 

 2 or 3 yr old. This paper deals only with fish 

 approximately 1 yr old or younger. The length, 

 fork length (FL) when applicable, otherwise total 

 length (TL), attained by each species when ap- 

 proximately 1 yr old is given at the bottom of Table 

 1 as the maximum length in each length range. 

 Fish were either saved whole or their stomachs 

 were excised aboard ship, labeled, and indi- 

 vidually wrapped in gauze. All samples were pre- 

 served in 3.7% formaldehyde. The stomach con- 

 tents of 3,065 fish, from 10 species, were analyzed. 

 In the laboratory the individual stomachs were 

 opened and their contents emptied onto a screen 

 sieve with mesh openings of 0.18 mm. The con- 

 tents were washed and then transferred into a 

 dish from which the various prey items were 

 manually sorted and counted. Prey were identi- 





Figure l. — Geographic areas of the northwest Atlantic, where 

 the feeding habits of juvenile fish were studied. Fish were caught 

 during bottom trawl surveys conducted from 1953 through 1976. 



fied to the lowest taxonomic grouping possible, 

 damp dried on absorbent paper, and immediately 

 weighed to the nearest 0.001 g. Well-digested prey 

 which were only identified within major prey 

 categories (i.e., Crustacea and Pisces) or species 

 within a major prey category which amounted to 

 <0.1% of the diet of all predators are listed as 

 "Other" in Table 1. Organisms of little apparent 

 dietary significance and not belonging to any of 

 the major prey categories listed make up the 

 values calculated for the "Miscellaneous" 

 category. 



201 



