ovulated spontaneously. These eggs did not develop 

 and disappeared from the brood pouches after a few 

 days. Thus, there appears to be no sperm storage 

 in /. baltica, and females must be accompanied by 

 a male at the time of their molts to ensure the 

 development of their broods. 



One interesting observation was that males en- 

 gage in amplexus significantly more often after than 

 before their molts. This may be explained by the 

 observation that neurons become detached from the 

 exoskeleton a few days before the molt (Guse 1983). 

 Thus, if contact and/or water-borne pheromones are 

 secreted by receptive female /. baltica as they are 

 in some other peracarid females (Borowsky 1984, 

 1985, 1986), it is possible that the males cannot sense 

 the stimuli produced by females shortly before their 

 own molts, and therefore are less likely to engage 

 in amplexus at that time. 



Conclusion 



The results of the present study show that /. 

 baltica adults can be maintained in the laboratory, 

 and will reproduce freely with minimal effort and 

 at minimal cost. Females fed exclusively on Ulva lac- 

 tuca produced many broods in succession in non- 

 aerated, uncycled water. While further study is 

 necessary to determine whether juveniles will 

 develop under these conditions, and, if so, what the 

 yield will be, the observations reported here suggest 

 the feasibility of culturing this species for fish 

 mariculture systems. 



Literature Cited 



Borowsky, B. 



1984. The effects of receptive females' secretions on some 

 reproductive behaviors in the amphipod crustacean Micro- 

 deuto-pus gryllotalpa (Costa). Mar. Biol. 84:183-187. 



1985. The responses of the amphipod crustacean Gammarus 

 palustris to conspecifics' and congenerics' secretions. J. 

 Chem. Ecol. 11:1545-1552. 



1986. Laboratory observations of the pattern of reproduction 

 oi Elasmopus Levis (Crustacea: Amphipoda). Mar. Behav. 

 Physiol. 12:245-256. 



GusE, G. W. 



1983. Ultrastructure development and molting of the aesthe- 

 tascs oi Neomysis integer and Idotea baltica (Crustea: Mala- 

 costraca). Zoomorphology 103:121-133. 



Healy, B., and M. O'Neill. 



1984. The life cycle and population dynamics of Idotea 

 pelagica and Idotea. granuloma (Isopoda: Valvifera) in south- 

 east Ireland. J. Mar. Biol. Assoc. U.K. 64:21-33. 



Marcus, N. H. 



1986. Introduction to the symposium: photoperiodism in the 

 marine environment. Am. Zool. 26:387-388. 

 MoBius, K. 



1873. Die wirbellosen tiere der ostsee. Jahresber. Comm. 



Wiss. Unters. Dtsch. Meere 2 Kiel. 

 Salemaa, H. 



1979. Ecology of Idotea-spp- isopoda in the northern 

 Baltic. Ophelia 18:133-150. 

 Steele, V. J., and D. H. Steele. 



1986. The influence of photoperiod on the timing of reproduc- 

 tive cycles in Gamrnarus species (Crustacea, Amphipoda). 

 Am. Zool. 26:459-467. 

 Strong, K. W. 



1978. Breeding and bionomics of Idotea baltica (Pallas) 

 (Crustacea: Isopoda). Proc. N.S. Inst. Sci. 28:217-230. 



Strong, K. W., and G. R. Daborn. 



1979. Growth and energy utilization of the intertidal isopod 

 Idotea baltica (Crustacea: Isopoda). J. Exp. Mar. Biol. Ecol. 

 41:101-124. 



Sywula, T. 



1964. A study on the taxonomy, ecology and geographical 

 distribution of species of the genus Idotea fabricius (Isopoda, 

 Crustacea) in the Polish Baltic. 1. Taxonomical part. 2. Eco- 

 logical and zoogeographical part. Bull. Soc. Amis Sci. Lett. 

 Poznan ser D 4:141-200. 



Tinturier-Hamelin, E. 



1963. Polychromatisme et determination genetique du sexe 

 chez I'espece polytypique Idotea baltica (Pallas) (Isopode 

 Valvifere). Cah. Biol. Mar. 4:473-591. 



Betty Borowsky 



Osbom Laboratories of Marine Sciences 

 New York Aquarium 

 Boardwalk at West 8th Street 

 Brooklyn, NY 11224 



OCCURRENCE OF THE FIRST FRESHWATER 



MIGRATION OF THE GIZZARD SHAD, 



DOROSOMA CEPEDIANUM, IN 



THE CONNECTICUT RIVER, MASSACHUSETTS' 



Occurrence of a freshwater migration of the gizzard 

 shad, Dorosoma cepedianum (Lesuer) (Clupeidae), 

 is documented for the first time in a New England 

 river system. Adult gizzard shad were observed and 

 collected at the Connecticut River fishlift facility in 

 Holyoke and upstream in Massachusetts during 

 1985 and 1986. It is believed that the Connecticut 

 River migrants are derived from a population re- 

 cently observed in Long Island Sound and already 

 occurring in the Hudson and Connecticut River 

 estuaries and Nan tic Bay. 



The gizzard shad is a widely distributed species 

 occurring in marine and tidal freshwaters along the 



'Contribution No. 104 of the Massachusetts Cooperative Fishery 

 Research Unit, which is supported by the U.S. Fish and Wildlife 

 Service, Massachusetts Division of Fisheries and Wildlife, Massa- 

 chusetts Division of Marine Fisheries, and the University of 

 Massachusetts. 



380 



FISHERY BULLETIN: VOL. 85, NO. 2, 1987. 



