MACY: CLASSIFYING LONG-FINNED SQUID INTO SEXUAL MATURITY STAGES 



uals of both sexes were correctly grouped, and 

 the new discriminant functions did not differ 

 appreciably from the original ones. Thus the 

 method was shown to be internally consistent 

 (precise). Accordingly, during 1977 and 1978 

 only the four or five measurements necessary for 

 classification purposes were routinely taken. 



The Four Maturity Stages 



A description of the general characteristics of 

 each of the four maturity stages of L. pealei fol- 

 lows. Figures 3a and b illustrate the important 

 morphometric changes indicated by the discrim- 

 inant analysis results. 



Stage 0: These juvenile squid lack visible go- 

 nads (Fig. 3a) and are very broad for their 

 length. 



Stage 1: In females (Fig. 3a) the nidamental 

 glands appear as thin white streaks, averaging 

 8% of DML (Table 3). In males the testis appears 

 as a pale oval body, about 11% of DML, and is 

 frequently obscured by the stomach and cae- 

 cum. 



Stage 2: Both the nidamental glands and tes- 

 tis have almost doubled in length, to 11% and 19% 

 DML, respectively, and the accessory and ovi- 

 ducal glands of females or the spermatophoric 

 organ/Needham's sac complex of males becomes 

 evident. The ovary appears as a fine-grained 

 band of tissue. 



Stage 3: This is a transitional stage between 

 immaturity and maturity. The NGI and AGI 

 have approximately doubled again (24% and 5% 

 DML), and the translucent white immature ova 

 give the ovary a distinctly granular appearance 

 ( AEO = 2 or 3). TheTLI averages31% DML(Fig. 

 3b; Table 3), and immature spermatophores may 

 be visible as small white specks in Needham's sac 

 ( ASN = 2). No gametes can be found in the penis 

 or oviduct, however. 



Stage 4: In these mature squid (Fig. 3b), 

 much of the mantle cavity is occupied by the 

 bulging ovary and oviduct or by the testis. Ripe 

 eggs fill the oviduct and appear as amber spheres 

 1-2 mm in diameter (AEO>3, AEOVM). Elon- 

 gate mature spermatophores (ca. 5 mm long) are 

 visible both in Needham's sac and in the penis 

 (ASN, ASP>1). Immature ova are also found 

 beneath the ripe eggs in the ovary, and usually 

 the spermatophore receptacle is packed with 

 spermatophores. A few virgin females were 

 seen, however. 



An Application of the Method 



Insights into the usefulness and relevance of 

 the new classification system can be provided by 

 a brief examination of several findings of the 

 overall population study of which this was a part 

 (Macy 1980). Vovk ( 1972) distinguished between 

 ripe/mature squid and spent squid, but through- 

 out 1975 when the Vovk method was routinely 

 employed, no spent squid were positively identi- 

 fied. Subsequent statistical analysis also failed to 

 make this distinction. Laboratory observations 

 (Macy 1980), however, suggest a reasonable ex- 

 planation: Isolated females spawned repeatedly 

 over 2-3 wk, but still contained significant num- 

 bers of immature eggs; neither sex ceased feed- 

 ing after mating; and no evidence of nutrient 

 depletion was found. Thus no truly spent individ- 

 uals might be expected. 



Maturing squid, on the other hand, were abun- 

 dant in late winter prior to the onset of inshore 

 migrations. In the March 1978 Argus samples, 

 stage-3 squid constituted 35-40% of the popula- 

 tion, while only 8% of the females and 21% of the 

 males had yet reached maturity (stage 4). About 

 1 mo later (late April) large mature squid began 

 to arrive and spawn in Narragansett Bay. By 

 late July most spawning activity was completed, 

 but already stage-1 individuals from early 

 spawnings were becoming numerically domi- 

 nant. By the time of arrival offshore, in late fall 

 and early winter (Cryos and Argus 1977 sam- 

 ples), fewer than 6% of either sex were mature or 

 maturing, but over 50% of the population was 

 composed of stage-2 squid. 



These early winter stage-2 squid seem to repre- 

 sent two distinct age/maturity groups: Smaller 

 developing young of the year, and larger and pre- 

 sumably older squid whose gonads appear to be 

 resorbing or regressing. The 1976 Cryos sample, 

 for example, consisted of three groups of males 

 with modal lengths of 8.2, 11.6, and 19.1 cm. Only 

 4.5% of these males (n — 287) were mature (stages 

 3, 4), but 71.4% were at stage 2. The modal size of 

 the stage-2 squid lay between 10 and 12 cm, but 

 individuals ranged from 8 to 23 cm. The remain- 

 ing stage-1 squid had a modal length of only 8-9 

 cm. Regressing stage-2 individuals belonged to 

 both the 11.6 and 19.1 cm size classes. Their go- 

 nads had the coloration and approximate length 

 of more mature individuals, but were distinctly 

 thin and lacked eggs or spermatophores of any 

 size. 



453 



