Pacific Spirit Marine Institute
Size Does Matter! Conventional Wisdom Proves Wrong when it comes to fish. Size limits have backfired!
Thursday, April 17, 2008
Sport fishermen have always tossed back the little fish they caught. In theory the young ones are released back into the water so they can fully mature. But, little fish make more little fish.
“It’s not the young ones that should be thrown back, but the larger older fish that should be spared.” says George Sugihara of the Scripps Institution of Oceanography at UCSD. “Not only do the older fish provide stability…to the population, they provide more and better quality offspring.”
In a four-year study that was released back in 2002 that was headed by David O. Conover at the Marine Sciences Research Center at State University of New York at Stony Brook, harvesting the largest of a population leaves only the smaller fishbehind to breed which practically ensures more small fish in the long run.
Science magazine published Conover and a graduate student’s findings in July 2002. When the smallest fish in a group were removed the remainder became individually larger. (4.5 grams) When the largest in a group were removed the mean weight of individuals left was decreased. (2.5grams) In a third group where random sized fish were removed the remaining fish stayed similar to the size they started out at which was about 3.5 grams.
A member of the Atlantic States Marine Fisheries Commission said when striped bass were protected up to 36 inches, the fish of that size were depleted until the minimum limit was lowered to 28 inches.
Taking only the larger older population of fish creates an age-imbalanced population. A lack of older fish induces early maturation in the younger fish.
Young fish left behind, thought to be too small to bring to market, are also more vulnerable to suffering from changes in their environment.
The absence of only the larger fish being harvested must have a ripple effect on the whole ecosystem.
It’s a tangled web we weave. There is one bit of conventional wisdom that remains constant…It’s not wise to fool with Mother Nature…
Labels: Environment, Fish, Ocean, Size limit, ecosystems
© 2009, Pacific Spirit Marine Institute.
Size Does Matter! Conventional Wisdom Proves Wrong when it comes to fish. Size limits have backfired!
