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Page 182 THE VELIGER Vol. 22; No. 2 Examination of a Reproductive Cycle of Protothaca staminea Using Histology, Wet Weight-Dry Weight Ratios, and Condition Indices BY HOWARD M. FEDER, JAMES C. HENDEE, PAT HOLMES ', GEORGE J. MUELLER and A. J. PAUL Institute of Marine Science, University of Alaska, Fairbanks, Alaska 99701 (4 Text figures) INTRODUCTION The northern limit for the littleneck clam, Protothaca staminea (Conrad, 1847), is Prince William Sound, Alaska (R. Baxter, Alaska Department of Fish and Game, personal communication). The clam is abundant in the Sound where it is preyed upon by sea stars, sea otters, and humans (Paul & Feder, 1973, 1975)-Information on growth and recruitment is available for the littleneck clam in Alaskan waters (Paul & Feder, 1973 ; Paul et al., 1976; Nickerson, 1977). In addition, the size at matu- rity and time of spawning for P. staminea has been exam- ined in British Columbia, Canada (Quayle, 1943) and south central Alaska (Nickerson, op. cit.). The major ob- jective of this investigation was to determine the reliabili- ty of using dry weight-wet weight ratios and condition in- dices to describe a reproductive cycle of P. staminea in Prince William Sound, Alaska. Histological examination of gonadal tissue was used as a basis for comparison. MATERIALS and METHODS Samples were typically obtained monthly in Simpson Bay (Figure 1) from January 1973 through January 1974. Dates of collection (January 1, February 20, March 6, April 7, May 7, June 6 and 14, July 1, August 12, Sep- tember 28, October 26, November 30, December 30, Jan- uary 20) were determined by tidal cycles and weather conditions. Current address: Alaska Department of Fish and Game, Box 686, Kodiak, Alaska 99615 Simpson Bay is located in southeastern Prince William Sound, approximately 16 km from the town of Cordova (Figure 1 ). Air temperatures ranged from -8° to -f-13 Celsius during the study period. The National Ocean Survey in 1973 recorded mean surface water tempera- tures in Cordova as a minimum of +i.2°C in January and a maximum of +i2.8°C in July. Beach surface temperatures during the study ranged from -i.2°C in January 1973 to +i2.5°C in August. During the winter, freezing of shallow tide pools and sediment surfaces was common. Histological examination was made of 264 clams. The gonadal mass of each clam was removed and preserved in Bouin's fixative. A cube of preserved gonadal tissue was removed from the mid-lateral portion of the visceral mass, dehydrated in alcohol, cleared in xylene, embedded in paraffin, sectioned at 10-20-30 jam, and stained with Ehrlich's hematoxylin (Davenport, i960). A gonadal staging method was used to describe the reproductive cycle (see Bayne, 1976; Porter, 1974; Ropes, 1968; Ropes & Stickney, 1965 for discussion of staging techniques). Six gonadal phases are described: early active, middle active, late active, ripe, spawning, and post spawning. Females Early active -Typified by the presence of follicular tissue partially or completely filling the alveoli, the proli- feration of primary ovocytes, and the elongation of these ovocytes between follicle cells. Residual ova and cellular debris often present. Middle active -A reduction in central follicular tis- sue with a subsequent increase in diameter of the central

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EXAMINATION OF A REPRODUCTIVE-CYCLE OF PROTOTHACA-STAMINEA USING HISTOLOGY, WET WEIGHT-DRY WEIGHT RATIOS, AND CONDITION INDEXES

Hm Feder, Jc Hendee, P Holmes, Gj Mueller and Aj Paul
Veliger 22: 182-187 (1979)

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