Vol. 53 - Alaska Resources Library and Information Services

(1983b), the same volume of oil
is mixed to 20-30 m and 0.05-0.1 mg
1[superscript]-1
is considered toxic to crab larvae, then an area of 15,000 km 2
might be affected.
Curl and Manen (1982) predicted that a 50,000 barrel
spill in the St. George Basin would be lethal over a 100-300 km 2 area
(0.2 mg 1[superscript]-1
threshold; mixed to 50 m).
In a worst-case scenario, mixing
oil less deeply and considering oil concentrations of 0.05-0.1 mg 1[superscript]-1
water soluble fraction (WSF) to be toxic, then water over an area of
10,000-15,000 km 2 might contain concentrations toxic to crab larvae
following a large spill.
In order to study the direction of surface oil trajectory following oil
spills from lease sale areas in the SEBS (Figure 4.5-1), Leendertse and
Liu (1981) ran computer simulations based on average wind events in
winter and in summer (Figure 4.5-2).
During summer and fall, oil from
spills in the St. George Basin and along the NAS would be moved by
prevailing winds east over the middle shelf and south to the North
Aleutian Shelf coast at Unimak Island eastward for 200 km (Figure
4.5-2A). In the winter, oil would be transported northwest off the
shelf or towards the Pribilof Islands (Figure 4.5-2B).
Most sigificantly,
the rate of movement in summer is predicted to be about 8.5
km day[superscript]
-1 , much faster than the net current transport of crab larvae
along the NAS, which is estimated to be between 1.4 and 3.4 km day[superscript]
-1.
Further, surface borne oil can be moved east by winds over the surface
of the middle shelf domain to the coastal domain, even though the water
masses exchange very little water through advective processes.
Easterly
movement of oil from the NAS lease sale area in late spring and summer
would move hydrocarbons towards major population centers of all red king
crab life history stanzas.
4.5.2 Oil Toxicity to Red King Crab Life History Stanzas
The king crab life history stanzas covered in this analysis are: 1)
sexually mature females; 2) developing eggs; 3) pelagic larvae; and 4)
young juveniles as O+ (including young-of-the-year) to 2+ age groups.
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