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Study Shows Eastern Tropical
NOAA Study Shows Eastern Tropical Pacific Ocean Dolphin Populations Improving
Two Dolphin Stocks May Be Recovering from Tuna Fishing Practices
June 5, 2008
 The
numbers of northeastern offshore spotted
and eastern spinner dolphins in the eastern
tropical Pacific Ocean are increasing after being severely
depleted because of accidental death in the tuna purse-seine
fishery between 1960 and 1990, according to biologists from
NOAA's Fisheries Service.
"These
estimates are encouraging because they are consistent with
what we would expect to see if these stocks are recovering,
now that reported fishery mortality has been dramatically
reduced," said Dr. Lisa Ballance, director of NOAA's
Southwest Fisheries Science Center protected resources
division. "However, we have to be careful not to jump to final
conclusions. We need to resolve the uncertainties around these
estimates before we can definitively say these stocks are
recovering."
Between
1960 and 1990, the northeastern offshore
spotted and eastern spinner dolphin populations dropped to
20 percent and 30 percent, respectively, of their pre-fishery
levels when dolphins were caught and died in tuna purse-seine
nets. Since the early 1990s, however, the number of reported
dolphin deaths has been very low because of severe restrictions
on the fishery.
"We
expected to see these populations begin their recovery years
ago, because fishermen have been so successful at reducing
dolphin deaths," said Tim Gerrodette of NOAA's Fisheries Service.
"The new data are the first to indicate the beginning of a
recovery, but these initial indications are not enough to
be confident that the populations will continue to grow."
 Researchers
emphasize the need to continue to monitor dolphin populations
at sea through comprehensive ecosystem research cruises, and
to conduct an updated dolphin stock assessment that will include
not only these most recent abundance estimates, but also additional
information on dolphin life history, fishery mortality, and
the ecosystem. This assessment will enable a more definitive
interpretation of whether these abundance estimates indicate
Eastern Tropical Pacific dolphins are recovering and the degree
to which the fishery and other factors affect the conservation
of these stocks.
Today's
report stems from a series of research cruises conducted since
1986. It presents new estimates of abundance for 10 dolphin
stocks for each survey year between 1986 and 2006. These estimates
may be found at http://swfsc.noaa.gov/prd-etp.aspx.
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National Oceanic and Atmospheric Administration, an agency
of the U.S. Commerce Department, is dedicated to enhancing
economic security and national safety through the prediction
and research of weather and climate-related events and information
service delivery for transportation, and by providing environmental
stewardship of our nation's coastal and marine resources.
Through the emerging Global Earth Observation System
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to develop a global monitoring network that is as integrated
as the planet it observes, predicts and protects.
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