FISHERY BULLETIN: VOL. 79, NO. 3 



down by scallop age, over a 2-yr period, in addition 

 to a histological description of the gametogenic 

 cycle. Seasonal changes in total fat, sterol, and 

 unsaponifiable fat within the adductor muscle 

 have been described by Idler et al. (1964), and six 

 major phospholipids identified from whole-body 

 extracts by Shieh (1968). 



The present study was undertaken to identify 

 and localize the major energy reserves of P. 

 magellanicus , to follow the levels of these reserves 

 within each identified storage tissue over a 1-yr 

 period, and to monitor the gametogenic cycle 

 histologically. 



MATERIALS AND METHODS 



Deep-sea scallops were collected by divers at 

 approximately 6-8 wk intervals from natural beds 

 at the mouth of the Damariscotta River, off 

 Farnham Pt., Linekin Neck, Boothbay, Maine, in 

 10-30 m of water. Deep-sea scallops ranged from 

 79.8 to 163.0 mm shell height (X = 119.0, SD = 17.5 

 mm, A'^ = 165), although individual size varied 

 considerably within each sample. Animals were 

 transported to the laboratory in chilled seawater 

 and maintained overnight in a running seawater 

 system. Twenty deep-sea scallops (10 of each sex 

 whenever possible) were chosen for subsequent 

 analyses. Shell height was measured for each 

 deep-sea scallop prior to dissection. Wet weights 

 were recorded for total body (exclusive of mantle 

 cavity water), shell, both catch and quick compo- 

 nents of the adductor muscle, digestive gland, and 

 "gonadal mass" (defined as all gonadal tissue, 

 overlying epidermis, inclusive connective tissue, 

 and intestinal loop). The contents of the intestinal 

 loop were gently squeezed out prior to weighing. 

 Similarly, the stomach and surrounding digestive 

 gland were split open, and all food material 

 flushed out with seawater. Gastric shield and 

 crystalline style were excluded from digestive 

 gland and gonadal mass wet weights. Tissues 

 were individually frozen and stored at -20° C 

 for subsequent biochemical analyses. 



Body Component Indices 



Individual soft-body component indices were 

 calculated for catch adductor (CAI), quick ad- 

 ductor (QAI), digestive gland (DGI), and gonadal 

 mass (GMI) according to Giese et al. (1967): body 

 component index = wet weight of body component 

 -i- total wet body weight. Total wet body weight 



450 



was determined by subtracting wet shell weight 

 from total wet weight, and therefore includes the 

 weight of extrapallial fluid which would have 

 been lost if body weights were determined follow- 

 ing separation of the animal from its valves. 

 Linear regression analysis of body component 

 index values (GMI, DGI, QAI, and CAI) on shell 

 height revealed that all indices were independent 

 of body size within the sampled range. The use of 

 index values for comparisons between samples 

 containing different size distributions of deep-sea 

 scallops was therefore justified. 



Histological and Histochemical Monitoring 



Following wet weight determinations, a small 

 piece of GMI tissue was fixed in Bouin's fluid for 

 histological examination of gametogenesis. Tis- 

 sues were later dehydrated, embedded in poly- 

 ester wax (Steedman 1960), sectioned at 7 ^m, and 

 stained in 2% aqueous celestin blue. Gametogenic 

 state was characterized as either early, mid, or 

 late developing, ripe, partially spawned, or spent, 

 based on a shortened version of the nine stages 

 described by Naidu (1970). During early develop- 

 ment, gonadal follicles are predominantly empty 

 except for a few layers of spermatocytes or a 

 single layer of oocytes closely oppressed to the 

 follicular wall. In middeveloping follicles, the 

 lumen is more restricted. Oocytes are enlarged in 

 females, whereas in males, spermatids and sper- 

 matozoa become increasingly common although 

 spermatocytes are still predominant. The folli- 

 cular lumen is occluded by mature or maturing 

 spermatozoa and oocytes in late-developing go- 

 nads, although immature stages are common 

 toward the periphery of the follicles. In ripe 

 gonads, follicles are tightly packed with mature 

 gametes. Follicles show a progressive loss of 

 ripe gametes as spawning proceeds, ultimately 

 becoming empty when deep-sea scallops are com- 

 pletely spent. 



Gametogenic values were assigned to each stage 

 (early developing = 1, middeveloping = 2, late 

 developing = 3, ripe = 4, partially spawned = 2, 

 spent = 0). The mode, median, and range of 

 gametogenic values were used for comparisons 

 between sample dates. 



To insure that tissues examined biochemically 

 were sites of major energy reserves, a variety of 

 tissues were fixed and histochemically examined 

 from one or two animals of each sex during each 

 sample period. In addition to the catch and quick 



