Impacts on dugongs - The Great Barrier Reef: An Environmental History - page 110

management issues for dugongs in Queensland, and the hunting of dugongs
probably now occurs at unsustainable rates in Torres Strait and the northern
GBRWHA (Marsh et al., 2004, 2005, 2011).
Summary
This chapter has described some of the historical impacts on dugongs that have
occurred in Queensland waters. Commercial dugong fishing in the Moreton
Bay area resulted in the reported local scarcity of the animals by 1888; by
that year, the methods of catching dugongs were considered to have caused
excessive destruction of the animals and restrictions had been introduced. In
1923, concerns about the survival of the species were reiterated. Nonetheless,
commercial dugong fishing expanded in the 1930s and persisted until 1969, when
the dugong received legal protection from commercial fishing; during the latter
period, however, a single dugong fishing operation in Hervey Bay was responsible
for a reported annual harvest of about 200 animals. Dugong populations were
depleted by such commercial operations for more than eighty years after concerns
for their numbers had first been expressed, and the surviving dugong population
in the Toogoom-Burrum Heads Bay in 2003 was estimated by one dugong fisher
to be about 200-300 animals: approximately the size of the annual harvest of the
dugong fishery at Burrum Heads. However, in 1999, the dugong population of
Hervey Bay was estimated by Marsh and Lawler (2001, p125) to be approximately
1,650 animals.
In addition to the impacts of the commercial fishery, dugong numbers were
also reduced in order to supply dugong oil to Indigenous settlements, between
1928 and 1976. That activity apparently took fewer dugongs from the more robust
northern Great Barrier Reef population and produced smaller quantities of oil
than the commercial industries, servicing local communities rather than the larger
markets that were supplied by the commercial fisheries; nonetheless, that smaller
fishery represented another layer of impact on the same stock that had already
been depleted in the southern Great Barrier Reef. The effects of both fisheries
were compounded by Indigenous hunting of dugongs, which still continues and
is of cultural as well as economic significance to Aboriginal and Torres Strait
Islander people. The degradation of some seagrass beds as a result of terrestrial run-
off associated with extreme climatic events, the prevalence of accidental dugong
mortality due to boat strikes, and the drowning of dugongs in shark control nets
set for bather protection since the 1960s now form serious threats to the species.
Furthermore, Indigenous hunting, which now represents the largest single impact
on dugong populations in the GBRWHA, is largely unchecked (Preen and Marsh,
1995; Heinsohn et al., 2004). Any additional activity that increases the mortality
of this vulnerable, long-lived and slow-reproducing species now conflicts with the
World Heritage values of the ecosystem.
Since the formation of the GBRMP, scientific knowledge of dugongs has
greatly improved, however, placing the narrative presented above in a broader