Monday, February 21, 2005
Big is better.... for fish
World fish stocks are shrinking - literally. Fish are becoming smaller as the largest ones are caught for food. Because bigger, older fish are the most fertile, this also reduces the chance that stocks will recover, scientists warn.
Steven Berkeley, of the University of California Santa Cruz, said that older specimens were more highly prized by fishers - and produced more larvae. A 50cm (20in) rockfish produces 200,000 larvae, an 80cm (30in) one would produce 2m.
After testing rockfish larvae he found that survival rates were three times higher, and growth rates were 3.5 times faster, for larvae from older mothers. "Fishing very quickly removes older fish from a population," he said.
"By eliminating old fish we not only shorten the spawning season, we also eliminate the best spawners, the very fish we need to allow populations to recover."
