The future of
stock enhancements: lessons for hatchery practice from conservation biology
C. Brown, R.L. Day-2002
Fish and
Fisheries, 3
(2): 79-94
Abstract:
The world's fish species are under threat
from habitat degradation and over-exploitation. In many instances, attempts
to bolster stocks have been made by rearing fish in hatcheries and releasing
them into the wild. Fisheries restocking programmes have primarily headed
these attempts. However, a substantial number of endangered species recovery
programmes also rely on the release of hatchery-reared individuals to ensure
long-term population viability. Fisheries scientists have known about the
behavioural deficits displayed by hatchery-reared fish and the resultant
poor survival rates in the wild for over a century. Whilst there remain
considerable gaps in our knowledge about the exact causes of post-release
mortality, or their relative contributions, it is clear that significant
improvements could be made by rethinking the ways in which hatchery fish are
reared, prepared for release and eventually liberated. We emphasize that the
focus of fisheries research must now shift from husbandry to improving
post-release behavioural performance. In this paper we take a leaf out of
the conservation biology literature, paying particular attention to the
recent developments in reintroduction biology. Conservation reintroduction
techniques including environmental enrichment, life-skills training, and
soft release protocols are reviewed and we reflect on their application to
fisheries restocking programmes. It emerges that many of the methods
examined could be implemented by hatcheries with relative ease and could
potentially provide large increases in the probability of survival of
hatchery-reared fish. Several of the necessary measures need not be
time-consuming or expensive and many could be applied at the hatchery level
without any further experimentation.
(Sub-department of Animal Behaviour, Department of Zoology,
University of Cambridge, Madingley CB3 8AA, UK, Tel.: +44 1223 741803,
Fax: +44 1223 741802, E-mail: culumbrown@yahoo.com)