39 



Abstract.— The fourbeard rockling, 

 Enchelyopus cimbnus, is a small gadid 

 fish found primarily over mud bottoms 

 along the continental margins of the 

 North Atlantic. This study defines the 

 age classes of the fourbeard rockling 

 from the Gulf of Maine, analyzes stom- 

 ach contents, and characterizes the 

 fish's metazoan parasite fauna. Age was 

 determined from sectioned sagittal 

 otoliths. Nine age classes were identi- 

 fied and compared with the Fraser-Lee 

 back-calculation method. The rate of 

 linear growth was constant throughout 

 age classes. The diet of fourbeard rock- 

 ling consisted primarily of bivalves, 

 copepods, and decapods, in both num- 

 ber and frequency of occurrence indi- 

 ces. Prey composition in the diet 

 changed with age. One-year-old fish 

 preyed primarily upon copepods; bivalves 

 were second in importance. The reverse 

 was seen in 2-7 year old fish. Data on 

 food habits suggest that the fourbeard 

 rockling is a "grazer" Parasites of this 

 species were one larval nematode, from 

 the family Raphidascaridinae, one lar- 

 val cestode, Grillotia erinaceus, and the 

 two species of adult digenetic trema- 

 todes, Genolinea laticauda and Gono- 

 cerca phycidis. Prevalence and abun- 

 dance data indicate that the parasitic 

 fauna was dominated by Raphidascar- 

 idinae sp. and G. erinaceus. 



Age and growth, dietary habits, 



and parasitism of the fourbeard rockling, 



Enchelyopus cimbnus, from the Gulf of Maine 



Heather L. Deree 



226 Belleville Rd. 



New Bedford, Massachusetts 02745 



E-mail address MROUSS(g'concentric.net 



Manuscript accepted 17 April 1998. 

 Fish. Bull. 97:39-52 (1999). 



The fourbeard rockling, Enchely- 

 opus cimbrius L., is a small gadid 

 fish found primarily over soft mud 

 or sand bottoms along the continen- 

 tal margins of the North Atlantic 

 Ocean (Bigelow and Schroeder, 

 1953). This fish lives in burrows 

 during daylight hours and forage at 

 night (Keats and Steele, 1990). Al- 

 though larval stages o{E. cimbrius 

 are well documented throughout its 

 range (Battle, 1929; Demir et al., 

 1985), limited information exists 

 about the age and growth of this spe- 

 cies. This study estimates growth 

 rates ofE. cimbrius fi-om the Gulf of 

 Maine, analyses stomach contents, 

 and characterizes the metazoan 

 parasitic fauna. 



Dietary studies for this species 

 have been made at various locali- 

 ties in the eastern North Atlantic 

 (Nagabhushanam, 1965; Wheeler, 

 1969; Mattson, 1981; Moller-Buchner 

 et al.. 1984; Tully and O Ceidigh, 

 1989), but little is known of the food 

 habits for the western Atlantic, and 

 there have been no dietary reports 

 for E. cimbrius from the Gulf of 

 Maine. Diets of E. cimbrius vary 

 with location but have been found 

 to consist primarily of polychaetes 

 or crustaceans (Tyler, 1972; Lang- 

 ton and Bowman, 1980; Keats and 

 Steele, 1990). 



Records of parasitism of E. cim- 

 brius are all apparently coincidental 

 with parasite surveys. Reported 

 parasites include a protozoan (Lom 

 and Laird, 1969), a coccidian (Odense 

 and Logan, 1976), an acanthoceph- 



alan (Linton, 1899), digenetic 

 trematodes (Linton, 1899; Gibson 

 and Bray 1984; Brinkmann, 1988), 

 and a nematode (Nagabhushanam, 

 1965). No survey of parasites to date 

 has been specifically devoted to this 

 host species. 



Materials and methods 



A collection of 727 fourbeard rock- 

 lings was obtained during the Gulf 

 of Maine Northern Shrimp Survey 

 GM 93-20, 2-13 August 1993. Col- 

 lections were made during daylight 

 hours at 41 randomly generated sta- 

 tions at depths ranging from 79 to 

 254 m aboard the NOAA RV Gloria 

 Michelle equipped with a 4-seam 

 modified commercial shrimp trawl 

 with a 35-mm stretched mesh. In 

 case of large hauls, a 1-kg random 

 subsample was taken. An additional 

 36 fish, for stomach analyses, were 

 collected from 6 stations at depths 

 of 170-227 m during the GM 94-12 

 survey between 2 August and 3 Au- 

 gust 1994 by using identical gear 

 and methods. 



Specimens collected during the 

 GM 93-20 survey were frozen im- 

 mediately at sea. To assess the ef- 

 fects of freezing on shrinkage, 218 

 fresh specimens were individually 

 tagged, measured to the nearest 

 mm for total length (TL), frozen, 

 then remeasured after being thawed 

 for 24 h. Fish were then weighed to 

 the nearest g on a top loading bal- 

 ance and sexed. In addition, both 



