In order to address critical gaps arising from limited available data on
historic shark catches in the Atlantic Ocean, a method was developed to
estimate shark removals using shark fin trade data. A characterization of
the global fin trade as of 2000, including number and biomass by shark
species, was used as the basis of the methodology. A first step involved
scaling Hong Kong trade-derived estimates for 2000 to annual global values
for 1980-2006 based on the observed quantity of imports to Hong Kong and an
approximation of Hong Kong's share of the global trade in each year. The
resulting global fin trade figures for each year were then scaled to
Atlantic-specific values using three different factors: (1) area of the
Atlantic range relative to the global range of pelagic sharks; (2) Atlantic
catches of tunas and billfishes relative to global catches of tunas and
billfishes; and (3) Atlantic longline effort relative to global longline
effort. The strengths and weaknesses of each scaling factor and the
assumptions inherent in the methodology are discussed. These estimates are
not intended to replace reliable fisheries dependent catch data compiled by
ICCAT from submissions of members and cooperators, but can serve as one of a
variety of useful cross-validation tools when historic catch data are
missing or uncertain.