11th ICRS Abstract book - Nova Southeastern University

22-9
Comparative Evaluation Of Reef Fish Resources Adjacent To Densely-Populated
South Florida, Usa: Anthropogenic Impacts And Implications For Management
Todd KELLISON* 1 , Vanessa MCDONOUGH 2 , Doug HARPER 1 , James TILMANT 3
1 Southeast Fisheries Science Center, NOAA Fisheries, Miami, FL, 2 Biscayne National
Park, National Park Service, Homestead, FL, 3 Water Resources Division, National Park
Service, Ft. Collins, CO
Assessing temporal and spatial trends in reef resources is important for ecosystem and
fisheries management in coral reef ecosystems. Biscayne National Park (BNP), FL,
USA, encompasses the northern portion of the FL Keys coral reef tract and is adjacent to
a local human population of ~2.5 million (regionally ~ 6 million) in a county that has
experienced considerable increases in human population (47%) and recreational fishing
vessels (48%) over the past 25 years. Despite being a national park, commercial and
recreational fishing is allowed in BNP. We compared the status of reef fish resources in
BNP with (1) historical data and (2) data from reefs adjacent to less-populated areas
along the FL Keys to assess the relative condition of reef fish resources in BNP. For the
historical comparison, we repeated a study to compare current (2006-2007) reef fish
community structure in BNP with that observed during 1977-1981. Reef fish
communities changed considerably over time with significant declines in species richness
and frequency-of-occurrence of fishery targeted and non-targeted species. For the spatial
comparison, we used three data sources to compare trends in abundance and lengthfrequency
distributions of multiple fishery-targeted species along the FL Keys.
Regardless of data source, species-specific proxies for abundance and length-frequency
distributions were predominantly lowest and smallest, respectively, in and around BNP.
The historical trends and spatial patterns observed are consistent with those expected in
heavily utilized reef systems and may continue given predicted increases in human
population and fishing pressure in southern FL. Results are discussed in terms of
prospects for adaptive ecosystem and fisheries management in BNP.
22-10
Revealing Patterns Of Impact Of Fishing On Fish Resources From A Large Scale
Regional Program
silvia PINCA* 1 , ribanatake AWIRA 1 , pierre BOBLIN 1 , melba WHITE 2
1 spc, noumea, New Caledonia, 2 MIMRA, majuro, Marshall Islands
A large scale program was conducted in the Pacific region to assess the status of
commercial resources and support countries in managing fisheries. Underwater visual
censuses and socio-economic interviews were carried out for 5 years to collect resource
status information from 17 countries. One of the main difficulties in evaluating the
condition of a fishery is the lack of knowledge of the conditions that existed before
fishing began. Moreover, records of changes over time are often missing, especially on a
large scale. The alternative choice to understanding variation in resource availability is to
compare resource status at different sites of similar environmental conditions (location,
geomorphology, habitat) but under different fishing pressures. Taking into account one
specific but localized historical data set along with acquired knowledge from frequent
underwater observations, we decided to focus on comparing records of size and size ratio
(ratio between average size and maximum size of a species) together with biomass of
target commercial species to identify responses in fish populations. By analyzing groups
of sites of similar geomorphogical and environmental conditions, but different levels of
fishing pressure, we could find significant negative relations between in situ total
commercial fish stock, carnivore mean size, specific commercial families and species
size ratio and selected indicators of fishing pressure: values of extrapolated catch per
village, density of fishers per area and percentage of population practicing fishing as
source of income rather than simply sustenance. Such results give a noteworthy
contribution to the search for indicators of fishing status which can be used when
assessing fish stocks for the purpose of management.
Oral Mini-Symposium 22: Coral Reef Associated Fisheries
22-11
Where Have All The Big Fish Gone? Distribution Of Remaining Large Reef Fishes in The
Hawaiian Archipelago
Benjamin RICHARDS* 1 , Emily LUNDBLAD 1 , Brian ZGLICZYNSKI 2 , Marc NADON 1 ,
Robert SCHROEDER 1 , Russell BRAINARD 2
1 NOAA Coral Reef Ecosystems Division, Joint Institute for Marine and Atmospheric Research,
University of Hawaii, Honolulu, HI, 2 Coral Reef Ecosystems Division, NOAA National Marine
Fisheries Service, Honolulu, HI
This study represents one of the first and most comprehensive efforts to investigate habitat
preference of large reef fishes in the Hawaiian Archipelago. Physical characteristics of the
coral reef including depth, slope, rugosity, and habitat type have been shown to play a critical
role in the distribution of many reef fishes. However, research has generally focused on small
spatial scales and on species living in tight association with the reef (e.g., Chaetodontidea,
Pomacanthidea, Pomacentridea). While it stands to reason that similar relationships should
exist, little work has focused on quantifying the effects of these habitat parameters on larger
reef fishes (e.g., Carcharhinidea, Carangidea, Lutjanidea, Scaridea), many of which contribute
to the highest trophic levels, are wide ranging, have extended ontogenies, and are most
vulnerable to exploitation, habitat degradation and ecosystem change. This study synthesizes
data collected biennially (2000-2006) along 700 surveys covering approximately 1500 hectares.
Biomass and numeric density distributions of large reef fish (>50 cm TL) were analyzed with
respect to depth, slope, rugosity and habitat type in a GIS framework. Bathymetric data were
derived from multibeam sonar, IKONOS and LIDAR surveys. Habitat type was determined
using published benthic habitat maps. Initial analyses support earlier research showing a less
dense large fish population in the main Hawaiian Islands compared to the Northwestern
Hawaiian Islands. Significant correlation was found between overall biomass of large reef
fishes and average depth, slope, and rugosity along each transect. These results provide the
scientific basis for efficient and targeted habitat-based management strategies for large reef fish,
begin to define essential fish habitat for these species, and lay the foundation for similar
investigations across the wider Pacific Region.
22-12
Historical Photos Document Changing Reef Fish Communities
Loren MCCLENACHAN* 1
1 Scripps Institution of Oceanography, La Jolla, CA
The importance of historical data in marine management has been demonstrated, particularly for
species whose populations were reduced significantly prior to the onset of ecological data
collection. Coral reef fisheries are frequently small-scale and affected by overfishing over long
time periods, so that data on long-term trends are lacking. Photographs from historical archives
contain information on the species composition and size structure of landings before fisheries or
ecological data are available. Using photographic data from the recreational fishing industry in
the Florida Keys, I quantified changes in size structure of large reef fish over the past half
century (1956-2007). This extensive data set provides temporal trends in the community
composition of exploited reef fish and offers baseline information on natural abundance and
body size. The average size of individual trophy fish declined from 91.7 cm (SE 2.4) to 42 cm
(SE 1.2) and from 19.9 kg (SE 1.5) to 3.8 kg (SE 0.3) between 1956 and 2007. The size of
sharks, the largest fish targeted, dropped from 204 cm in 1956 to 87 cm in 2007. Shifts in the
species and size of individuals caught demonstrate a loss of the largest predators from the reef
environment. The goliath grouper (Epinephelus itajara), with an average size of 135.3 cm (SE
3.2), was the most commonly caught trophy fish in the 1950s, but was rare by 1965. The largest
fish frequently caught by recreational fisheries in 2007 were snappers (Lutjanus spp. and
Ocyurus chrysurus), with an average size of just 34.4 cm (SE 2.4). This remnant fishery based
on increasingly small individuals underscores the depletion of reef fish communities, and the
overall degradation of Florida’s coral reef ecosystem. The results of this study illustrate the
need to consider long term data in assessing the conservation status of exploited animals.
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