11th ICRS Abstract book - Nova Southeastern University

22.821
Estimating Populations Of Two Rabbitfish Species (siganus Guttatus And
siganus Javus) in The Coral Reefs Of Singapore: A Pilot Study On The Use Of
Software-Assisted Photo-Id
Marco PERRIG* 1 , Beverly GOH 1
1 NSSE/NIE, NIE-NTU, Singapore, Singapore
The knowledge of population parameters and an understanding of the ecological
interactions are important for proper management and conservation of living resources
and ecosystems. Populations studies of fish species traditionally involve the use of
physical tagging of animals in a mark and recapture methodology. However, tagging
induced behavioural changes, stress, infection risks, and mortality are some undesired but
unavoidable side effects of the methodology. For rare and highly endangered species that
are susceptible to handling, or are difficult to trap, physical tagging is therefore
unsuitable. Photo-ID is a non-intrusive method used to identify individuals, and has been
utilized successfully in a wide range of species, especially marine mammals. However,
this method requires the labour-intensive work of manually comparing photographs, and
has found little application in fisheries where populations are commonly very large.
Advances made in information technology have resulted in software that can assist in
reducing the variability and time taken to compare digital images of individual
organisms. This paper presents the results of a pilot study that explores the use of
computer-assisted photo-ID in studying populations of two species of fish (Siganus
guttatus and Siganus javus), that are known to inhabit coral reefs of Singapore and
adjacent waters. The stability of colouration patterns and the uniqueness of individual
patterns within each species are examined. In addition, the use of the software
‘Interactive Individual Identification System (I3S)’ as a tool to reliably and efficiently
compare digital pictures of individuals of the two fish species will be tested.
22.822
Use of a Model Selection Approach to Estimate Effects of Age, Size, and Density on
Post-Settlement Survival of Yellow Tang in a Hawaiian MPA Network
Jeremy T. CLAISSE* 1 , Sarah A. MCTEE 1 , James D. PARRISH 1
1 Department of Zoology, University of Hawaii, Honolulu, HI
Major efforts have recently begun to manage the valuable and heavily harvested juvenile
yellow tang, Zebrasoma flavescens (Acanthuridae), in the commercial aquarium fishery
in the State of Hawaii. Perceived declines of fish populations led to the establishment of a
network of MPAs which now prohibit aquarium collecting along more than 30% of the
west coast of Hawaii Island. This led to the first serious life history studies of this species
in order to better interpret extensive population monitoring data and to model effects of
protection on yellow tang populations. Part of this effort included estimating natural
mortality rates through the juvenile size range targeted by the fishery. Furthermore,
because settlement rates are highly variable spatially and temporally in this system, it is
important to understand how survival rates change as a function of age or size and
density. We used a model selection approach implemented in Program MARK to
estimate survival and resight probabilities and evaluate the effects of density and age on
yellow tang recently after settlement and the effects of size in older juveniles. We found
that survival of recent settlers decreased with density and increased with age. In older
juveniles the effects of size varied between sites, but results were inconclusive, similar to
other studies that have found relatively constant rates of survival in fish of moderate age.
This approach may provide valuable insight for understanding the life history of a variety
of coral reef species, which could lead to broader understanding of how population
regulation occurs on coral reefs under both natural and fished conditions.
Poster Mini-Symposium 22: Coral Reef Associated Fisheries
22.823
The Coupling Of St. John, Usvi Marine Protected Areas Based On Reef Fish Habitat
Affinities And Movements Across Management Boundaries
Mark MONACO* 1 , Alan FRIEDLANDER 2
1 Biogeography Branch, NOAA National Ocean Service, Silver Spring, MD, 2 Biogeography
Branch, NOAA NOS and The Oceanic Institute, Waimanalo, HI
NOAA’s Biogeography Branch, the National Park Service and US Geological Survey are
quantifying spatial patterns and habitat affinities of reef fishes in the US Virgin Islands. The
objective of the study is to define the movements of reef fishes among habitats within and
between the Virgin Islands Coral Reef National Monument (VICRNM), adjacent to Virgin
Islands National Park (VIIS), and US Virgin Island Territorial waters. In order to better
understand species’ habitat utilization patterns and movement of fishes among management
regimes and areas open to fishing around St, John, we deployed an array of hydroacoustic
receivers and acoustically tagged reef fishes. A total of 123 fishes, representing 18 species and
10 families were acoustically tagged along the south shore of St. John from July 2006 to July
2007. Forty receivers with a detection range of approximately 350 m each were deployed in
shallow nearshore bays and across the shelf to depths of approximately 30m. Receivers were
located within reefs and adjacent to reefs in seagrass, algal beds, or sand habitats. Example
results include the movement of lane snappers and blue striped grunts that demonstrated diel
movement from reef habitats during daytime hours to offshore seagrass beds at night. Timing of
migrations closely coincided with changes in sunrise and sunset. Fish associated with reefs that
did not have adjacent seagrass beds made more extensive movements than those fishes
associated with reefs that had adjacent seagrass habitats. The array comprised of both nearshore
and cross shelf location of receives provides information on fine to broad scale fish movement
patterns across habitats and among management units to examine the strength of connectivity
between the marine protected areas and areas open to fishing.
22.824
Abundance Of Economically Important Fish Species Inhabiting Patch Reefs in Shallow
Water Near South Eleuthera, The Bahamas: Implications For Mpa Development
Annabelle ORONTI* 1 , Christina ELMORE 2 , Jill HARRIS 1 , Aaron SHULTZ 1 , Andrew
FIELD 2 , Andy DANYLCHUK 1
1 Cape Eleuthera Institute, Fort Lauderdale, FL, 2 The Island School, Fort Lauderdale, FL
Small patch reefs are common to the expansive shallow water banks of the Bahamian
archipelago and can provide essential transitional habitat for fish and invertebrates, such as the
Nassau grouper (Epinephelus striatus) and Caribbean spiny lobster (Panulirus argus). Given
the economic importance of these species, patch reefs are often the focus of small-scale
artisanal and moderate commercial fisheries. In recent years, evidence suggests that these fish
stocks are in decline, and the Bahamian government is responding by imposing regulations,
including size limits and a closed season when Nassau grouper aggregate to spawn. In 2000,
the Bahamian government also proposed a network of marine reserves in an attempt to protect
critical habitats for all life stages of commercially and ecologically important marine species,
one of which is proposed for the waters off South Eleuthera. The purpose of this study was to
establish a long-term monitoring program to assess the abundance of fish and invertebrates
inhabiting small patch reefs in the region of the proposed reserve. Timed visual surveys were
conducted on over 80 patch reefs in the spring and fall since 2004. Long-term trends indicate
that the abundances of Nassau grouper (0.97 ± 0.37 SD) and spiny lobster (0.48 ± 0.48 SD) are
relatively stable, and that only juvenile Nassau grouper inhabit these reefs. These results
provide the only baseline data on the abundance of commercially important species in South
Eleuthera and can assist the government with the planning and management of the proposed
marine reserve. Collectively, our results suggest that marine reserves in the Bahamian
Archipelago should include shallow water patch reefs as a way to provide protection for
economically important fish and invertebrates in transitional habitats.
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