Viducic et al.: Reproductive characteristics for Prionace glauca in the North Atlantic Ocean 
Table 2 
Ranges of measurements and descriptions of organs used to determine maturity stages of female blue sharks (Prionace glauca) 
captured in the western North Atlantic Ocean between New Jersey and the Flemish Cap during 1971-2016. Sharks in the size 
ranges associated with the juvenile and mature stages generally conform to those assignments (unless otherwise noted); whereas, 
sharks in the transitional size range can be either immature or mature and represent the size of the smallest mature and largest 
juvenile fish. The table format is adapted from Walker (2005). n=number of samples. 
Organ 
Ovary length 
(n=183) 
Ovary width 
(n=159) 
Egg diameter 
(n=296) 
Oviducal gland width 
(n=273) 
Uterus width 
(n=290) 
Uterus length 
(n=91) 
Range of organ 
measurement 
(mm) 
<136 
<136 to >240 
>240 
<42 
<42 to >80 
>80 
<4 
>4 to <16 
>16 
<22 
>22 to <35 
235 
<14 
>14 to <35 
235 
<260 
>260 to <540 
>540 
Description 
Enclosed in epigonal tissue, clear or no visible oocytes 
Thinning epigonal tissue, follicles become opaque 
Little epigonal tissue, oocytes range from new developing to turgid 
yolked oocytes 
Thin, difficult to distinguish from epigonal tissue 
Thinning epigonal tissue, widening with developing oocytes 
Thin epigonal tissue, defined shape, follicles range from new 
developing to turgid yolked oocytes 
Clear or non-visible follicles, contained in layer if generative tissue 
Follicles become opaque 
Yolked oocytes 
Thin, undifferentiated from the upper oviduct 
Begins to take shape, differentiated from the upper oviduct 
Plump, heart shaped 
Thin, undifferentiated from the oviduct 
Widens from the oviduct 
Tissue thickens, elastic or flaccid 
Thin, undifferentiated from the oviduct 
Differentiated from the oviduct, widening and elongated 
Elongated and flaccid 
Maturity 
stage 
Immature 
Transitional 
Mature 
Immature 
Transitional 
Mature 
Immature 
Transitional 
Mature 
Immature 
Transitional 
Mature 
Immature 
Transitional 
Mature 
Immature 
Transitional 
Mature 
55) Thin tube 
>5 to <12 
Upper oviduct width 
(n=182) 
212 Thickens, differentiated from oviducal gland 
birth to turgid, large oocytes (29.0 mm) that were ready for 
ovulation (Table 2, Suppl. Fig. 1 [online only]). In mature 
specimens, the oviduct was fully differentiated from the ovi- 
ducal gland, which was plump, heart shaped, and >35 mm in 
width. The status of mature females was further staged as 
gravid (n=32) and postpartum (n=11). 
Males Data collected from 1971 through 2016 were exam- 
ined to determine male reproductive condition (see the 
“Median maturity analysis” section). Sharp increases in 
organ size relative to FL for clasper length, testis length, 
and epididymis width indicate that they are good indica- 
tors of L;,) (Fig. 1, Suppl. Fig. 4 [online only]). In contrast, 
the siphon sac length, ampulla epididymis width, and tes- 
tis width had slower gradual growth when plotted against 
FL and are not adequate indicators of Lo. 
Immature males (n=148) ranged between 64.7 and 
220.5 cm FL and between 1.4 and 68.5 kg, and they 
were characterized externally by soft, uncalcified, or 
partially calcified claspers that resisted rotation and 
opening of the tip (Table 3). The siphon sacs of juvenile 
males were constricted and did not extend fully to the 
pectoral girdle. In this stage, the epididymis was thin 
and straight, and the testes were entirely encompassed 
Immature 
Transitional 
Mature 
in epigonal tissue. In some juvenile males, sperm was 
present. 
Immature males in the transitional size range were 
maturing, and their organs often had both mature and 
immature characteristics. Although most fish in this 
size range were staged as mature or immature, data 
collected on 5 specimens (180.5—191.2 cm FL) did not 
provide enough information to determine reproductive 
condition; therefore, these specimens were not assigned 
a condition and were not used in ogive analysis. Imma- 
ture sharks in the transitional range were found to have 
testes enclosed in thinning epigonal tissue, a coiled epi- 
didymis, and flexible claspers. In 5 cases, males with 
mature internal organs had partially calcified claspers. 
These individuals ranged in size between 188.5 and 
228.0 cm FL, overlapping the transitional size range 
that may indicate that clasper calcification is the best 
indicator of maturity. 
Mature males ranged between 181.0 and 300.0 cm 
FL and between 35.4 and 213.4 kg (n=331). Claspers of 
mature males (>220.5 cm FL) were elongated (£123 mm; 
Fig. 1), fully calcified, easily rotated, and opened at the tip. 
A mature epididymis was heavily coiled, and the mature 
testis was surrounded by a thin layer of epigonal tissue 
