Publisher :
Place of publication :
Publication year : 2009
Thematic : Sea Turtles
Language : English
Note
This paper reviews the gear parameters
responsible for loggerhead sea turtle (Caretta caretta)
capture and mortality while taking into account the
mitigation measures tested in the Mediterranean Sea.
Incidental catch is considered as one of the major
threats for turtle survival; however, the loggerhead
bycatch estimated in different areas seems to be
unrealistic, which highlights the need of a method for
homogenising the estimates. Drifting longlines and
bottom trawls have the greatest impact on Mediterranean
turtle populations, respectively in pelagic and
demersal phase, while passive nets (gillnets and
trammel nets) seem to be responsible for the highest
direct mortality, due to drowning. Most of the
experiments available for the Mediterranean are
focused on drifting longline. The longline parameters,
hook shape and size, bait type, setting position and
the reaction to sensory stimuli, strongly affect the sea
turtle bycatch and mortality. Circle hooks have the
potential to reduce turtle mortality only in certain
fisheries and areas; larger hooks are less likely to be
swallowed by turtles due to physical constraints of
the mouth, reducing the mortality rate and the catch
of juveniles; branchlines, once ingested, appear to be
one of the major causes of sea turtle mortality; squid
bait, which consistently catches more turtles than
mackerel, and lightsticks, which strongly attract
turtles, should be banned, at least in some areas and
seasons. On the contrary only two bottom trawl
studies are available from the Mediterranean. Turtle
excluder devices have been tested with promising
results in Turkey and Italy, even if the loss of large
fish should be carefully investigated. For set nets no
practical solutions are available at this time. The
analysis allows the conclusion that technical parameters
affecting turtle bycatch and mortality should
only be studied one at a time, in order to avoid
inconclusive results, studies on post-release mortality
should be implemented and finally fishermen cooperation
is paramount in reducing turtle bycatch and
mortality.
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Keywords : Paulamys naso
Encoded by : Pauline Carmel Joy Eje
