Strict fishing limits along New England’s coast, imposed since 1994, have contributed to rebounds in a dozen species, according to a report released this week. But tight fishing restrictions are likely to remain in place for a few years because some fish, including Gulf of Maine cod, are still at record low levels. The New England Fisheries Management Council projects that fish populations should be fully recovered within 10 years. In less happy fish news, 7.6 million fish in California’s Salton Sea died in a single day last week, the largest one-day death toll ever recorded in the lake. Some scientists say the die-off indicates that the lake’s ecosystem is in serious trouble.