Impacts on marine turtles - The Great Barrier Reef: An Environmental History - page 72

Impacts on marine turtles
Introduction
Of the seven extant species of marine turtle, six occur in Queensland waters: green
( Chelonia mydas ), hawksbill ( Eretmochelys imbricata ), loggerhead ( Caretta caretta ),
flatback ( Natator depressus ), olive ridley ( Lepidochelys olivacea ) and leatherback
( Dermochelys coriacea ) turtles. Most are defined by the IUCN (2013) as critically
endangered, endangered or vulnerable (Table 6.1) . As a result of many natural
and anthropogenic pressures - including predation of nests by feral foxes and
pigs, incidental catches in fishing and shark control nets, ingestion of litter, boat
strikes, Indigenous hunting, habitat destruction and tourism - declines in many
marine turtle populations have been documented. Marine turtles are vulnerable
to those impacts as a result of their life histories, which involve very high natural
mortality of hatchlings and of small juvenile turtles, the use of a limited number
of nesting beaches, high fidelity to nesting sites and feeding grounds, limited
interaction between genetic stocks and long maturation periods. Mature female
turtles come ashore at nesting sites on specific beaches to lay several large clutches
of eggs in a single nesting season - a life history that requires high survivorship
of adults. Yet many human impacts on turtles - including those described in this
chapter - have affected female turtles disproportionately at that critical life stage.
Since European settlement in Queensland, various human activities have
exploited marine turtles in the Great Barrier Reef and adjacent areas: the production
of tortoise-shell, the commercial marine turtle fisheries, the 'sport' of turtle-riding
at tourism resorts and the traditional hunting of turtles by Indigenous people.
This chapter presents documentary and oral history evidence of the scale of those
exploitative - and largely unsustainable - industries and activities. That evidence
indicates that some intensive exploitation of those long-lived, slow-maturing
animals - especially of green and hawksbill turtles - occurred. Consequently,
observable declines in the numbers of those animals were reported. The account
presented below indicates the scale of the exploitation that can occur in the
absence of effective regulation or protection of vulnerable species and populations.
The commercial marine turtle fisheries in Queensland, which worked during
the period 1867-1962, had a particularly severe impact on marine turtles because