\ 



Klemm. D. J. 



1972a. The leeches (Annelida: Hirudinea) of Michi- 

 gan. Mich. Acad. 4:405-444 



1972b. Freshwater leeches (Annelida: Hirudinea) of North 

 America. U.S. Environ. Prot. Agency, Biota of Freshwa- 

 ter Ecosystems, Ident. Man. 8, 53 p. 



1975. Studies on the feeding relationships of leeches (An- 

 nelida: Hirudinea) as natural associates of mollusks. 

 Sterkiana 58:1-50, 59:1-20. 



1976. Leeches (Annelida: Hirudinea) found in North 

 American mollusks. Malacol. Rev. 9:63-76. 



1977. A review of the leeches ( Annelida-Hirudinea) in the 

 Great Lakes region. Mich. Acad. 9:397-418. 



MEYER, M. C. 



1940. A revision of the leeches (Piscicolidae) living on 

 fresh-water fishes of North America. Trans. Am. Mi- 

 crosc. Soc. 59:354-376. 



1946a. A new leech, Piscicola sahnositica n. sp. (Pis- 

 cicolidae), from steelhead trout iSatnio gairdneri 

 gairdneri Richard.son, 1838). J. Parasitol. 32:467-476. 



1946b. Further notes on the leeches (Piscicolidae) living 

 on fresh-water fishes of North America. Trans. Am. Mi- 

 crosc. Soc. 65:237-249. 

 Papern.'\. l, and D. E. ZWERNER. 



1974. Massive leech infestation on a white catfish (/c- 

 talurus catus): a histopathological consideration. Proc. 

 Helminthol. Soc. Wash. 41:64-67. 



Sawyer. R. T. 



1972. North American freshwater leeches, exclusive of the 

 Piscicolidae, with a key to all species. 111. Biol. Monogr. 

 46, 154 p. 

 Sawyer. R. T., A. R. Lawi.er. a.vd R. M. Overstreet 



1975. Marine leeches of the eastern United States and the 

 Gulf of Mexico with a key to the species. J. Nat. Hist. 

 9:633-667. 



C. Dale Becker 

 Dennis D. Dauble 



Ecosystems Department 



Battelle. Pacific Northwest Laboratories 



Richland, WA 99352 



INDUCED SPAWNING AND LARVAL REARING 



OF THE YELLOWTAIL FLOUNDER, 



LIMANDA FERRUGINEA 



The yellowtail flounder, Limanda ferruginea 

 (Storer), a commercially important flatfish, occurs 

 in North American continental waters from the 

 north shore of the Gulf of St. Lawrence southward 

 to the lower part of Chesapeake Bay (Bigelow and 

 Schroeder 1953). The yellowtail flounder spawns 

 from March through August where water temper- 

 atures over its range vary from about 5° to 12°C 

 (Colton 1972). The eggs are pelagic and lack an oil 

 globule; diameter of the live eggs (range 0.79-1.01 

 mm I averages 0.88 mm (Colton and Marak 1969). 



A program to obtain viable yellowtail eggs 

 through hormone induction, to rear larvae through 

 metamorphosis, and to determine the mechanisms 

 of survival of early life stages under controlled 

 laboratory conditions was undertaken. The suc- 

 cessful induction of yellowtail flounder and sub- 

 sequent rearing of the larvae through metamor- 

 phosis marks the first time the early life history of 

 this flatfish has been completed in the laboratory. 



Materials and Methods 



Adult yellowtail flounder were captured by otter 

 trawling in Block Island Sound in the winters of 

 1974, 1975, and 1976 and transported to the Nar- 

 ragansett Laboratory in a 380-1 live car equipped 

 with an aerator. In the laboratory the fish were 

 held in a 28,000-1 aquarium. A continual supply of 

 filtered seawater was pumped to the aquarium 

 from Narragansett Bay. 



Individuals presumed to be sexually mature 

 were selected by length. Available length-weight 

 data (Lux 1969) indicated that yellowtail flounder 

 in southern New England waters mature when 

 they attain a length near 35 cm or an age of 3 yr 

 (Lux and Nichy 1969). After acclimating in the 

 laboratory, the fish were segregated by sex, mea- 

 sured and weighed, and tagged with numbered 

 plastic pennants secured through the caudal pe- 

 duncle. Yellowtail flounder were sexed by holding 

 the white underside to the light and looking 

 through the flesh. The outline of the ovary extend- 

 ing posteriorly from the mass of viscera can read- 

 ily be seen even in immature females (Royce et al. 

 1959). Yellowtail flounder are delicate and excit- 

 able. To minimize injury, the fish were anes- 

 thetized in a solution of tricane methanesulfonate 

 (MS-222') at a concentration of 1:20,000 (Leitritz 

 and Lewis 1976) during each examination. 



While the fish were held in captivity, a photo- 

 period of 1 1 h of light and 13 h of dark simulated 

 spawning light conditions. Four banks of fluores- 

 cent lights (each bank composed of 16 40-W bulbs) 

 were suspended 4 m from the ceiling and mechani- 

 cally timed. The light banks were sequentially 

 turned on and off in the morning and evening at 

 15-min intervals to simulate dawn and twilight. 

 Prior to receiving hormones the fish were fed a daily 

 diet of chopped frozen hake, whiting, or squid. Dur- 

 ing the trials the fish were not fed. 



'Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



FISHERY BULLETIN: VOL. 76. NO. 4. 1979. 



931 



