NOTES 



OFFSHORE WINTER MIGRATION OF 



THE ATLANTIC SILVERSIDE, 



MENIDIA MENIDIA ' 



The Atlantic silverside, Menidia menidia, is an 

 abundant fish in coastal waters of the western 

 Atlantic ranging from Florida to Nova Scotia. 

 During spring, summer, and fall, the habitat of 

 M. menidia includes intertidal creeks, marshes, 

 and the shore zone of estuaries and embayments 

 (Hildebrand and Schroeder 1928; Bigelow and 

 Schroeder 1953). In such areas, ichthyofaunal 

 surveys often cite M. menidia as the most numer- 

 ous species encountered (Mulkana 1966; Rich- 

 ards and Castagna 1970; Chestmore et al. 1973; 

 Briggs 1975; Anderson etal. 1977; Hillmanetal. 

 1977). The entire life cycle of M. menidia is com- 

 pleted in 1 yr. Reproduction occurs in the spring, 

 juveniles grow rapidly during the summer and 

 reach full adult size by late fall. However, con- 

 siderable uncertainty exists concerning winter 

 ecology and habitat. In populations from Chesa- 

 peake Bay northward, Atlantic silversides are 

 rare or absent from the shallow waters of the 

 shore zone in midwinter ( Warfel and Merriman 

 1944; Bayliff 1950; Hoff and Ibara 1977; Conover 

 and Ross in press). Hildebrand and Schroeder 

 (1928) and Richards and Castagna (1970) re- 

 ported that M. menidia were captured in mid- 

 winter with bottom trawls in deepwater areas of 

 Chesapeake Bay and deep estuarine channels in 

 eastern Virginia. Catches of M. menidia have 

 also been occasionally reported up to 15 km off- 

 shore (Clark et al. 1969; Fahay 1975). However, 

 Needier (1940) noted that Atlantic silversides 

 could be taken through the ice in Malpeque Bay, 

 P.E.I, (although he presented no data concerning 

 relative seasonal abundance), and investigations 

 in South Carolina found an abundance of M. 

 menidia in intertidal marsh creeks during win- 

 ter (Cain and Dean 1976; Shenker and Dean 

 1979). 



Because the Atlantic silverside is an important 

 forage fish (Merriman 1941; Bayliff 1950; Bige- 

 low and Schroeder 1953) and reaches a high level 

 of biomass in the shore zone of marshes and estu- 

 aries (7.8 g/m 2 wet weight) (Conover and Ross in 



'Contribution No. 73 of the Massachusetts Cooperative Fish- 

 ery Research Unit. 



press), the winter movement patterns of this an- 

 nual species could represent a significant path- 

 way of energy flow from and/or within estuarine 

 systems. This paper demonstrates that Atlantic 

 silversides migrate offshore in winter, and we 

 discuss aspects of their winter ecology and distri- 

 bution by examining catch records of the bottom 

 trawl survey program of the Northeast Fisheries 

 Center (NEFC) of the National Marine Fisheries 

 Service (NMFS). 



Methods 



A modern series of standardized bottom trawl 

 surveys was begun in 1963 by the Bureau of Com- 

 mercial Fisheries (BCF) Woods Hole Laboratory 

 (Grosslein 1969). Initially, fall surveys encom- 

 passed the general range of offshore groundfish 

 stocks of primary interest (i.e., gadoids) and thus 

 was confined to the area between Hudson Can- 

 yon and Nova Scotia and depths from 27 to 366 

 m. Later, as the goals and emphasis of the survey 

 program expanded to include a wider variety of 

 species, both fall and spring surveys were con- 

 ducted and the sampling area was extended 

 southward to Cape Hatteras (1967). The offshore 

 survey region was stratified into geographic 

 zones based on depth contours and area (Gross- 

 lein 1969). A stratified random sampling design 

 was employed to locate trawl stations within 

 depth strata and the number of stations was allo- 

 cated in proportion to stratum area. A standard 

 No. 36 Yankee bottom trawl with a 1.25 cm 

 stretched mesh cod end liner was towed at each 

 station for 30 min at an average of 3.5 kn; how- 

 ever, spring offshore surveys since 1973 have 

 used the larger No. 41 Yankee trawl. Stations 

 were sampled continuously 24 h/d during 

 cruises. 



Synoptic bottom trawl surveys in the near- 

 shore environment were begun in 1972 by the 

 NMFS Sandy Hook Laboratory. Early surveys 

 in the inshore region (defined as depth strata of 

 5-27 m) assessed the technical and geographic 

 feasibility of using offshore sampling gear in 

 waters as shallow as 5 m. Since autumn 1972, 

 inshore surveys have been conducted each fall 

 and spring with summer cruises added in 1977 

 and a winter cruise in 1978. Of 18 inshore cruises 

 through 1978, most (17) included the region from 



FISHERY BULLETIN: VOL. 80. NO. 1. 1982 



145 



