[env-trinity] Research: What Is The Impact of Prolonged Fish Harvest on Fish Population Genetics?
sari at sisqtel.net
Wed Sep 16 17:28:13 PDT 2009
THE COLUMBIA BASIN BULLETIN:
Weekly Fish and Wildlife News
September 11, 2009
Issue No. 499
* Research: What Is The Impact Of Prolonged Fish Harvest On Fish Population
What are the long-term evolutionary implications of prolonged fishing for
the fish that humans and, perhaps more importantly, diverse ecosystems
Researchers say that for many of the types of fish bought in stores or
ordered in restaurants, the chance that an individual fish dies from
fishing is several times higher than dying of natural causes.
This may seem obvious to most (they had to get to the table somehow), but
what may not be apparent is that the pursuit of consumer-friendly fish
products is having a massive impact on fish populations around the world.
By repeatedly choosing only the biggest fish, or only those found in
certain habitats, the fisheries industry may be permanently altering the
genetic composition of fish populations, researchers say.
A group of international scientists convened at the 2008 American Fisheries
Society Annual Meeting to address this issue, and contributions to the
symposium are now available online in an August 2009 special issue of
Articles from Toward Darwinian Fisheries Management, a special issue of
Evolutionary Applications (2:3), can be freely downloaded at
Several groups of scientists focused on teasing apart how much of the shift
in fish morphology, development and behavior that has been documented over
the years is due to genetic versus non-genetic changes. Long-term genetic
changes may be more problematic since these may not be reversible and they
make predicting the composition of fish stocks in the future very
difficult. Equally contentious among scientists was distinguishing between
changes that were caused by artificial selection due to fishing per se,
versus environmental influences such as habitat destruction or climate change.
The articles in the special issue use multiple approaches to address these
concerns and together come to the conclusion that in many cases, fish
stocks are indeed evolving in response to the artificial selection pressure
imposed by fishing. Shifts in yield-determining traits such as growth and
maturation are evident, and how quickly these changes manifest depends on
the type of fishing gear and the rate of harvest.
Given the uncertainty surrounding the future sustainability of wild fish
stocks, fisheries evolution scientists in the August 2009 Evolutionary
Applications issue make several key recommendations, including:
-- protect a portion of the stock through the creation of non-fished marine
-- protect late-maturing and slow-growing individuals,
-- fish less.
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