[env-trinity] Research: What Is The Impact of Prolonged Fish Harvest on Fish Population Genetics?

Sari Sommarstrom sari at sisqtel.net
Wed Sep 16 17:28:13 PDT 2009

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 
depend on?

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 
Evolutionary Applications.

Articles from Toward Darwinian Fisheries Management, a special issue of 
Evolutionary Applications (2:3), can be freely downloaded at 
or http://www3.interscience.wiley.com/journal/119423602/home

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 
protected areas,
-- protect late-maturing and slow-growing individuals,
-- fish less.
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