They need to congregate to breed. They need to meet each other. The scientists want to attach satellite transmitters to several whales in hopes of tracking them to their breeding lagoons, believed to be in the South China Sea. They have raised some funds and built transmitters, but so far the Russian government has refused to approve permits to bring the transmitters to Pil'tun. It's uncertain whether the Western Pacific gray whales can reproduce fast enough to stem the tide pushing them toward extinction.
Gray whales tend to calve every other year.
In 1998, seven females returned to Pil'tun with calves. Researchers expected that at least some of the seven would arrive in 2000 with calves. All seven came back to Pil'tun, but they came without calves, preliminary reports indicate. Four of the seven returning mothers were also tentatively identified as unusually thin in 2000. Some of those whales are repeats from 1999 to 2000.