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Society for Conservation Biology 16th
Annual Meeting July 14-July 19 2002
co-hosted by DICE and the British Ecological Society
Abstracts for Marine Conservation
Session Two
Tuesday 16th July, 15.30 - 17.30, Grimond
Lecture Theatre 3
Chair: Andy Dobson
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timetable
(BLOCK CAPITALS indicate the presenting author)
15.30 - 15.45
KRISTINSSON, Kristjan and Ransom A. Myers, Department of Biology, Dalhousie University,
Halifax, Nova Scotia, Canada B3H 4J1 ( kristjan@mscs.dal.ca
)
IS ATLANTIC HALIBUT (HIPPOGLOSSUS HIPPOGLOSSUS) GOING EXTINCT?
Examination of data over the past two centuries shows drastic decline of Atlantic
halibut (Hippoglossus hippoglossus) throughout its range in the North Atlantic
and virtual elimination in many areas. One explanation for this decline is that Atlantic
halibut is a long-lived and late maturing species and often harvested as bycatch
many years before reaching maturity. To determine the current status of Atlantic
halibut, we reconstructed its historical abundance in the North Atlantic using landing
statistics and data from fishery-independent surveys. Our results indicate that Atlantic
halibut, which was once so common that cod fishermen considered it a pest, is now
at critically low abundance levels. Fishery independent survey indices also indicate
that Atlantic halibut has continued to decrease in abundance in the North Atlantic
over the past two decades, even though there was little directed halibut fishing.
It is likely that abundance of Atlantic halibut will continue to decline, as there
is currently no management plan for it. A simple ban on halibut landings or designation
of protected areas is not likely to allow Atlantic halibut to recover. Any recovery
and perhaps survival will depend on reducing Atlantic halibut bycatch in other highly
exploited fisheries such as for cod.
15.45 - 16.00
BAUM, JULIA K., Daniel Kehler, and Ransom A. Myers. Department of Biology, Dalhousie
University, Halifax, Nova Scotia B3H 4J1, Canada, <baum@mscs.dal.ca>.
COLLAPSE OF PELAGIC AND LARGE COASTAL SHARKS IN THE NORTHWEST ATLANTIC
Pelagic and large coastal sharks are caught incidentally in considerable numbers
in pelagic longline fisheries. While generally assumed to be vulnerable to exploitation,
determining the status of shark populations is hindered by the lack of direct research
surveys, and it is consequently unknown for most species. To address this problem,
we analysed logbook data from pelagic longline fishing vessels from the U.S. Atlantic,
the Gulf of Mexico and the Caribbean between 1986 and 2000. Since zeros were not
recorded in these data, we examined an approach for obtaining unbiased estimates
of trends in abundance for shark species, when missing values cannot be distinguished
from real zeros. We used generalized linear models (GLMs) with truncated negative
binomial distributions, assuming only that if the sharks caught in a set were recorded
that it was the true number. The observed trends in abundance were robust to models
based on different distributions. Our results indicate that almost all recorded shark
species recorded, including thresher, great white, tiger and mako sharks, have declined.
In particular, the substantial declines in hammerhead sharks (Sphyrna mokarran,
S. lewini, S. zygaena) represent critical conservation concerns that had been
previously overlooked.
16.00 - 16.15
BEEMER, SHANA, and Merry Camhi. National Audubon Society, Scully Science Center,
550 South Bay Avenue, Islip, NY 11751, USA, <sbeemer@audubon.org>.
ICCAT & BIG FISH: RECOVERY OR EXTINCTION IN THE 21ST CENTURY?
Highly migratory, large pelagic fish populations in the Atlantic Ocean have been
reduced to as little as 15% of sustainable levels by fishing over the past two decades.
This decline has occurred under the watch of the International Commission for the
Conservation of Atlantic Tunas (ICCAT). A comprehensive review of historical catch
data and management actions shows that ICCAT has failed to prevent overfishing and
rebuild overfished stocks, as its treaty mandates. There are two main reasons for
this breakdown: 1) ICCAT has failed to implement management measures recommended
by its own scientific committee; and 2) ICCAT has been unable to enforce compliance
with fishing quotas and data collection among its member countries. Case studies
on Atlantic bluefin tuna, Thunnus thynnus, and white marlin, Tetrapturus
albidus, will exemplify these problems. ICCAT set the bluefin tuna quota in the
East Atlantic at a level 140% higher than recommended by ICCAT scientists. Inability
to reduce bycatch in pelagic longline fisheries may lead to the extinction of white
marlin. ICCAT must develop new strategies or be reorganised to allow for necessary
quota cuts, time/area closures, and bycatch reduction measures.
16.15 - 16.30
STOKES, DAVID L. and P. Dee Boersma. Department of Environmental Studies and
Planning, Sonoma State University, Rohnert Park, CA 94928, USA, <stokes@sonoma.edu>
(DLS), Department of Zoology, Box 351800, University of Washington, Seattle, WA 98195-1800,
USA (PDB).
DYNAMIC MEASURES ARE REQUIRED TO CONSERVE DYNAMIC SYSTEMS: MAGELLANIC PENGUINS AND
THEIR MARINE ENVIRONMENT
Wide-ranging species and variable systems present challenges to traditional reserve-based
conservation strategies. Dynamic approaches have the potential to effectively protect
these species and systems; however extensive information is required. The Magellanic
penguin in the Southwest Atlantic Ocean is an example of a wide-ranging species inhabiting
a variable environment. The species is currently declining because of factors in
its marine environment. Nineteen years of breeding biology data, six years of satellite
tracking, and remote-sensing data indicate that this species responds to oceanic
variability at several temporal and spatial scales. Foraging movements and activity
are correlated with ocean productivity patterns, which change within and between
years. Migration movements also are related to variable oceanic conditions. The relationships
between oceanic conditions and the penguin's use of its marine environment ultimately
determine reproductive success and colony population trends. Our emerging understanding
of the interaction between this species and its variable environment allows the design
of conservation measures to protect this species. These measures must be dynamic
at scales consistent with the variability of the marine system. They also must be
responsive to future novel changes in the system that are likely to result from climate
change.
16.30 - 16.45
ANDRIANARIVELO, N. Institut halieutique et des Sciences Marines, Univerity of
Toliara P.O. Box 141, Toliara (601), Madagascar, <ihsm@syfed.refer.mg>.
PROBLEM OF DOLPHINS IN THE REGION OF ANAKAO (SOUTHWESTERN MADAGASCAR)
Malagasy fishermen exploit many marine species including marine mammals. We initiated
the preliminary studies in 1999 in Anakao, a village situated in the southwest of
Madagascar in order to obtain more knowledge about small cetaceans of Madagascar.
The information concerning dolphin fisheries was gathered through interviews with
fishermen and the data on the dolphin populations, their abundance, distribution
and behaviour was collected using boat surveys. Three dolphin species Tursiops
truncatus, Stenella longirostris and Sousa chinensis were recorded
from the boat. The socio-economic survey enabled us to identify several stresses
on the dolphin population: fishing, stranding and by-catch. Two types of fishing
methods (harpoons and gill nets) are used in the region to catch dolphins. At least
4000 small cetaceans were caught between 1974 and 1999 and 1300 dolphins have been
stranded. The use of shark nets or "jarifa" can also lead to by-catches
of dolphins. The dolphins caught are used for local consumption and are sold locally
as well as in others regions. The meat has been sold in the market places and served
at restaurants in western Madagascar. Cetaceans are amongst the least studied zoological
groups in Madagascar, particularly with regards to research on the conservation of
biodiversity.
16.45 - 17.00
DOBSON, ANDY, Linda Lowenstein and Frances Gulland. EEB, Princeton University,
NJ 08544, USA, <andy@eno.princeton.edu> (AD), School of Veterinary Sciences,
UC-Davis, Davis, CA, USA (LL), Marine Mammal Center, Marin Headlands, Sausalito,
CA, USA (FG).
POPULATION ECOLOGY OF PINNIPED HERPESVIRUS INFECTIONS AND CANCER IN CALIFORNIA SEA
LIONS
Herpes virus are endemic in California sea lions (Zalophus californianus),
while infection with these pathogens is by itself harmless, the presence of organic
pollutants leads to aggressive carcinomas. In this talk we will present an age- and
sex-structured model for California sea lions that incorporates both herpes transmission
and the presence of environmental pollutant. As female sea lions forage in more polluted
waters than males they carry higher doses of the pollutant and this interacts with
the herpes virus to increase their risk of mortality. The model is used to examine
the long-term impact of organic pollutants on the sea lion population. The expected
mortalities are compared with the observed patterns along the coast of California.
17.00 - 17.15
HATCH, LEILA T., Leah R. Gerber, and Phillip J. Clapham. Department of Ecology
and Evolutionary Biology, Corson Hall, Cornell University, Ithaca, NY 14853-2701,
USA <lth5@cornell.edu> (LTH), Department of Biology, College of Liberal Arts
and Sciences, Arizona State University, P.O. Box 871501, Tempe, AZ 85287-1501, USA
(LRG), Large Whale Biology Program, Northeast Fisheries Science Center, 166 Water
Street, Woods Hole, MA 02543, USA (PJC).
MIGRATORY SPECIES, METAPOPULATIONS, AND MARINE RESERVE DESIGN: LESSONS FROM WHALING
Currently, most marine reserves are coastal and small in area. Thus, wide-ranging,
pelagic species are protected only in small, inshore portions of their ranges. We
develop a simple metapopulation model for testing the effect of reserves that target
feeding, breeding, and migratory corridors for baleen whales within a single ocean
basin. We use this model to evaluate the relative importance of population growth,
harvest, migration, carrying capacity and reserve area for two populations: a portion
that is protected in a reserve and an unprotected remainder. We apply the model to
case studies in which subpopulations of whales were extirpated by whaling activities,
and where no significant repopulation of those areas has occurred on a management
timeframe. A substantial fraction of simulations representing different harvest rates
and life history attributes went extinct in the absence of a reserve, and these scenarios
leading to extinction could be predicted accurately (79% aptly classified) on the
basis of harvest and migration. These results suggest that severely depleted subpopulations
may preclude recolonisation from other populations. This work has implications for
managing large whales based upon discrete population segments which, if extirpated,
would not be repopulated on a decadal timescale by immigration from other areas.
17.15 - 17.30
ANGEL, MARTIN. Southampton Oceanography Centre, Empress Dock, Southampton, SO14
3ZH, UK, <mva@soc.soton.ac.uk>.
BIODIVERSITY, AN UNHELPFUL CONCEPT FOR MARINE CONSERVATION
Assessments of biodiversity vary so much with time and space, and are so prone to
subject bias that biodiversity per se cannot be considered a rational basis for scientific
evaluation of conservation priorities in the marine environment.
The SCB2002 pages are maintained by Christine Eagle
email: C.M.Eagle@ukc.ac.uk
Conference email: scb2002@ukc.ac.uk
Last updated: 30.06.02