1536 J. IISH. RES. BOARD CAN., VOL. 31(e), 1e74

Acknowledgments -I am grateful to R. L. Conleyfor aid in conducting the experiments and data analysis.Support was provided by NSF Grant GB-35988 anda NSF Centers of Excellence award to the Universityof Iowa.

G.a.rnnmrn, M, J. Jn. 1967. Size selective predationon Daphnia by rainbow trout and yellow perch.Trans. Am. Fish. Soc. 96: l-10.

Har,r, D. J., W. E. Coornn, AND E. E. WrnNtn. 1970.An experimental approach to the production dyna-mics and structure of freshwater animal communities.Limnol. Oceanogr. 15: 839-928.

HrsruNnEror, H. A. 1974. Ecological inferences frommorphological data. Annu. Rev. Ecol. Syst. 4:213-229.

Hor.r,rNc, C. S. 1966. The functional responso ofinvertebrate predators to prey density. Entomol.Soc. Can. Mem. 48: 1-86.

Krasr, A. 1970. Food specialization and bioener-getic interrelations in the fish faunas of some smallOntario waterways, p. 377-411. /n J. H. Steeleled.l Marine Food Chains, Oliver and Boyd,Edinburgh.

Ml,cAnrnun, R. H. 1972. Geographical Ecology.Harper and Row, N.Y. 269 p.

MacAnrnun, R. H., aNo E. R. PrnNr.q. 1966. Onoptimal use of a patchy environment. Am, Nat.100: 603-609.

PArnrancnr, M. H., lNo R. C. Bnr,r-. 1949. Ananalysis of the bottom fauna production in fertilizedand unfertilized ponds and its utilization by young-of-the-year fish. Mich. State Univ. Agric. Exp'Stn. Tech. Bull. 207. 35 p.

Srasunc. K. G., .qNo J. B. Movr,s. 1964. Feedinghabits, digestive rates, and growth of some Minnesotawarmwater f ishes. Trans. Am. Fish. Soc,93:269-285.

ScnonNnn, T. W. 1969. Models of optimal size forsolitary predators. Am. Nat. 1O3: 27'7-313.

1971. Theory of foeding strategies. Annu, Rev'Ecol. Syst. 2: 369-404.

Wanr, D. M. 1972, Predation by rainbow trout(Salmo gairdneri): the influence of hunger, preydensity, and prey size. J. Fish. Res. Board Can.29:1193-1201.

WEnNlx, E. E., a.No D. J. Hlrl. 19'74. Optimalforaging and the size-selection of prey by the bluegillsunfish(Lepomis macrochirus). Ecology. (Inpress)'

First Record of the American Shad (Alosa sapidissima)from Labrador Waters

G. M. H.cne1 AND H. P. Munpnv

Department of the Environment, Fisheries and Marine ServiceResource Development Branch, St. John's, Nfld.

Hrns, G. M., aNo H. P. Munpnv. 19'14. First record of the American shad (Alosasapidissima) from Labrador waters. J. Fish. Res. Board Can. 31: 1536-1537.

A single specimen of American shad (Alosa sapidissima) was captured in the SandHill River, southeastern coastal Labrador. The capture represented the first confirmedrecord of shad from Labrador and the most northerly record of this species.

Hanr, G. M., axo H. P. Mutpnv. 1974. First record of the American shad (Alosasapidissima) from Labrador waters. J. Fish. Res. Board Can. 31:1536-1537,

Les auteurs rapportent la capture d'un sp6cimen unique d'alose savoureuse (l/osasapidissima) dans la rividre Sand Hill, sur la cdte sud-est du Labrador. Il s'agit du premiersignalement authentique de l'alose savoureuse au Labrador et de la mention la plus aunord de cette espdce,

Received March 25, 7974Accepted May 28, 1974

Regu le 25 mars,7974Accept6 le 28 ma| 1974

lPresent address: Department of the Environment, Fisheries and Marine Service, Biological Station, StAndrews, N.B.

Printed in Canada (J3380) Imprim6 au Canada (J3380)

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A specimen of the American shad (Alosa sapidissima)was captured in a counting fence operated on theSand Hill River (53"35'N, 56'21'W), Labrador, onJuly 12, 1973. Water temperature was 16.1 C.The specimen was immediately frozen for examina-tion and identification.

The morphometric and meristic data for thespecimen were: number of gill rakers on lower partof anterior arch, 65; greatest total lengtlt,535 mm;fork length, 472 mm; greatest girth, 315 mm; headlength, 105 mm; depth of head,37 mm; length ofmandible, 48 mm; orbital diameter, 16 mm; snoutto anterior orbit of eye. 22mm; dorsal fln rays, 16;anal fin rays, 19; pelvic fin rays, 9; pectoral fin rays,15; number of vertebrae, 57 (excluding the hypuraland basioccipital). These morphometric and meristicdata are within the range reported by Leim (1924)and Leim and Scott (1966) for this species. Thespecimen was a mature female, 1580 g in wholeweight. The stomach was empty of food.

Received November 16, 19'73Accepted May 27, 1974

Printed in Canada (J3226)Imprim6 au Canada (J3226)

The specimen represented the first documentedrecord of the shad in Labrador and a significant

extension of its northerly range of distribution.

Hodder (1966) discussed the distribution of shad

in Ner.vfoundland and Labrador waters, and re-ported two specimens from the southeast coast of

Newfoundland. One of these, from St. Phillips(47'36'N, 52"52'W\, Conception Bay, was theprevious most northerly record of the species.

Hooprn. V. M. 1966. Two further records of theAmerican shad in Newfoundland waters. Trans.Am. Fish. Soc. 95: 228-229.

Lrru, A. H. 1924. The life history of the shadAlosa sapidissina (Wilson) with special reference tothe factors limiting its abundance. Contrib. Can'Biol. N.S. 2: 161-284.

Lnrrra, A. H., ,r,No W. B. Scorr' 1966. Fishes of theAtlantic Coast of Canada. Bull. Fish' Res. BoardCan. 155: 485 P.

Bilateral Hyperplasia of the Thymus in a Rainbow Trout(Salmo gairdneri)

I. F. McAnoLE AND R. J. Ronnnts

Unit of Aquatic PathoblologYUniversity of Stirling, Stirling, Scotland

McAnnr,r, J. F., aNo R. J. Rosnnts. 1974. Bilateral hyperplasia of the thymus in arainbow trottt (Salmo gairdneri). J. Fish. Res. Board Can. 37: 1537-1539,

Bilateral hyperplasia of the thymus is described in a 3-year-old male rainbow trout(Salmo gairdneri). Two large well-circumscribed lesions were noted in the dorsal gill chamberwhich consisted of lymphoid and epithelial elements. Structures resembling Hassal'scorpuscles were also seen.

McAnorn, J. F., aNo R. J. Rossnrs, 1974. Bilateral hyperplasia of the thymus in arainbow trout (Salmo gairdneri). J. Fish. Res. Board Can. 31: 1537-1539.

Nous d6crivons une hyperplasie bilat6rale du thymus chez une truite arc-en-ciel m1leAg6e de 3 ans. Nous avons not6 deux grandes l6sions bien limitdes dans la partie dorsale dela chambre branchiale, consistant en 6l6ments lymphoides et 6pith6liaux. Nous avons 6ga1e-ment vu des structures ressemblant d des corpuscules d'Hassal.

Regu le 16 novembre, 1973Accept6 le 27 ma|, 1974

IN animals diseases of the thymus gland, other insufficiency and in cases of testicular or ovarlanthan neoplasia, are rare (Jubb and Kennedy 1970). hypoplasia (Wright and Symmers 1966). ThisIn man hyperplasia of the thymus occurs in cases report describes a case of bilateral thymic hyper-of primary thyrotoxicosis and occasionally acro- plasia in a 3-year-old rainbow trout (Salmo gaird-megaly. It also occurs in cases of adrenal cortical neri).

During routine examination of a male rainbowtrout from an ornamental pond, two large (1 x 5cm) hard, well-circumscribed growths were observed

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This article has been cited by:

1. Daniel J. Hasselman, Richard A. Hinrichsen, Barbara A. Shields, Curtis C. Ebbesmeyer. 2012.American Shad of the Pacific Coast: A Harmful Invasive Species or Benign Introduction?. Fisheries37:3, 115-122. [CrossRef]

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