Hoff: A nursery site of Bathyra/a parmifera in the eastern Bering Sea 
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Figure 4 
Length frequency for embryos of the Alaska skate ( Bathyraja parmifera) collected during 
each sampling date at the nursery index site in the eastern Bering Sea. Embryos were 
assigned to cohorts 1, 2, or 3 (separated by diagonal lines) following mode frequencies. 
A fourth cohort was evident that was detected in the November 2004 sampling and persisted 
through July 2005 (graph left) but was not used for growth-rate estimates. 
Analysis of published developmental periods 
Developmental period for the Alaska skate was the lon- 
gest period yet observed for any oviparous elasmobranch 
species. Embryonic developmental periods were highly 
correlated with the rearing temperatures for the other 
oviparous elasmobranchs included in this review (Fig. 7). 
Most studies were conducted in >8°C water tempera- 
tures and developmental periods were one year or less. 
However, a single study conducted on the thorny skates 
( Raja radiata ) (Berestovskii, 1994) in water tempera- 
tures near those found for the Alaska skate revealed 
that the developmental periods of these two species to 
be comparable (thorny skate, 4.6°C, 912 days; Alaska 
skate, 4.4°C, 1290 days). 
