Overfishing and Global Warming Killing Billfish and Tuna

ScienceDaily — Billfish and tuna, important commercial and recreational fish species, may be more vulnerable to fishing pressure because of shrinking habitat, according to a new study published by scientists from NOAA, The Billfish Foundation, and University of Miami Rosenstiel School of Marine and Atmospheric Science.

An expanding zone of low oxygen, known as a hypoxic zone, in the Atlantic Ocean is encroaching upon these species' preferred oxygen-abundant habitat, forcing them into shallower waters where they are more likely to be caught.

During the study, published recently in the journal Fisheries Oceanography, scientists tagged 79 sailfish and blue marlin with satellite tracking devices in the western North Atlantic, off south Florida and the Caribbean; and eastern tropical Atlantic, off the coast of West Africa. The pop off archival satellite tags monitored horizontal and vertical movement patterns. Researchers confirmed that billfish prefer oxygen rich waters closer to the surface and will actively avoid waters low in oxygen.

While these hypoxic zones occur naturally in many areas of the world's tropical and equatorial oceans, scientists are concerned because these zones are expanding and occurring closer to the sea surface, and are expected to continue to grow as sea temperatures rise.

"The hypoxic zone off West Africa, which covers virtually all the equatorial waters in the Atlantic Ocean, is roughly the size of the continental United States, and it's growing," said Dr. Eric D. Prince, NOAA's Fisheries Service research fishery biologist. "With the current cycle of climate change and accelerated global warming, we expect the size of this zone to increase, further reducing the available habitat for these fish."

Less available habitat can lead to more fish being caught since the fish are concentrated near the surface. Higher catch rates from these areas may give the false appearance of more abundant fish stocks. The shrinking availability of habitat and resulting increases to catch rates are important factors for scientists to consider when doing population assessments.

Researchers forecast that climate change and its associated rise in ocean temperatures will further increase the expansion of hypoxic zones in the world's oceans. As water temperature increases, the amount of oxygen dissolved in water decreases, further squeezing billfish into dwindling available habitat and exposing them to even higher levels of exploitation.

Source: http://www.sciencedaily.com/releases/2010/12/101222162402.htm

The oceans are in a crisis. Greenpeace has a plan to save them. A global network of marine reserves can restore the world’s oceans to health

Our oceans are an absolute marvel - but they are also in a deep, deep crisis. If we don’t act fast, our oceans will continue to deteriorate and vital food sources and essential functions provided to our planet and its people by the oceans could be lost forever. Since healthy oceans underpin our very survival, Greenpeace is today releasing an “Emergency Oceans Rescue Plan” aimed at world leaders, which sets out the best way to save our oceans- something that can and should be done at the Convention on Biological Diversity (CBD) which takes place later this month in Japan.



Our plan shows how to create a global network of marine reserves- wildlife parks at sea- to cover 40% of the world’s oceans. As scientists keep telling us, that’s exactly the kind of large-scale protection we need if we are to maintain living oceans. Our “Emergency Oceans Rescue Plan” is a call for policy-makers to implement it.
The benefits are obvious. Large-scale marine reserves will not just protect the full diversity of marine life and ensure healthy fisheries. They will also help us to alleviate food insecurity and poverty and build the resilience of our oceans to the impacts of climate change and, ultimately, allow us to sustain life on Earth for future generations.

If we want our oceans to thrive and to continue to support human and animal life, then we need marine reserves now. Marine reserves are off-limits to fishing, fossil fuel extraction and other industrial activities. Establishing marine reserves effectively puts a massive ‘STOP’ sign right in the front of those destructive bottom trawlers and dirty oil exploration ships that roam our oceans so freely right now, and says “yes” to healthy oceans and fish for the future.’

Last month, UN Secretary-General Ban Ki-moon told politicians gathered in New York that a “rescue package similar to that introduced after the global financial crisis is urgently needed to halt the worldwide loss of biodiversity, which is resulting in a heavy human cost.”

Well, with respect to our oceans, world leaders preparing for the CBD meeting need look no further than the Emergency Oceans Rescue Plan. The CBD meeting is a chance for world leaders to halt the massive loss of marine biodiversity and ensure the survival of the millions dependent on the oceans for food and their livelihoods - all that is needed is political will.

Please spread the word and join the call for marine reserves.