Bulletin of the Sea Fisheries Institute 1 (155) 2002 - CEEMaR

Fecundity of walleye pollock (Theragra chalcogramma Pallas) .. 35
fecundity
800000
700000
600000
500000
400000
300000
200000
100000
0
25 30 35 40 45 50 55 60 65
length [cm]
present data Bering Sea (Hinckley [1987])
Aleutian Basin (Teshima et al. [1989]) Gulf of Alaska (Miller et al. [1986])
Kronotskyi Gulf (Balykin [1986]) SE Kamchatka (Balykin [1986])
Sea of Japan (Zverkova [1977])
Fig. 5. Walleye pollock length-absolute maturity regression curves for selected regions of the North Pacific.
the Bering Sea and from the Kronotskiy Gulf were longer at 42.0 and 41.0 cm, respectively,
when 50% of them achieved sexual maturity (Balykin 1986). In turn, the results of the current
study were nearly identical with those recorded for females spawning off the eastern coast of
Kamchatka at 37.0 cm (Balykin 1986).
The results presented by Shuntov (1998) indicate that in the mid 1990s a change occurred
in the quality of the ecosystem of the northern region of the Sea of Okhotsk. The principal
symptom of this was an increase in the biomass of herring at the cost of that of walleye
pollock. Studies of the directions of walleye pollock migrations throughout the Sea of Okhotsk
described by Fadeev (1995) and Kotenev et al. (1998) indicated that changes in patterns also
affected the walleye pollock which spawn off the southwest coast of Kamchatka.
In light of the results of walleye pollock fecundity studies conducted in 2000 and those
previously obtained by Zverkova (1969), it can be concluded that changes in the ecosystem of
the Sea of Okhotsk has not affected the fecundity of walleye pollock.