Applying Fishery Catch Data to Population Trends and Community Structures in Atlantic Pelagic Species
Abstract
Recent studies have shown that fishing can influence marine trophic networks, as larger,
higher trophic level species are preferentially targeted by fishers. In this study,
we investigate US Pelagic Longline catch dynamics of twenty-nine Atlantic species
from 1986 to 2008 using information provided by the fishermen’s logbook data program.
Two different analyses were performed on the data for this study. Data were cleaned
and monthly catch per unit effort (CPUE) for each species within each of five fishing
effort regions – the Mid Atlantic Bight and Northeast Costal area, The Caribbean area,
the Florida East Coast and South Atlantic Bight area, the Gulf of Mexico area, and
the Northeast Distant area – were calculated to examine trends in catch rates. Annual
CPUE graphs were made for all areas combined, correcting for changes in fishing dynamics
to examine changes in relative abundance of species over time. A regression was run
through these annual graphs of CPUE over the study period in order to estimate increases
or decreases in relative population abundance for each species. The slopes from these
annual abundances regressions were further regressed versus trophic level, average
generation length, and resiliency to test for significant correlations between these
ecological factors and trends in population size. Though trends matched our predictions
(species with higher trophic level, lower resiliency, and longer generation length
showed greater declines in abundance), no significant p-values were found. It seems
likely that ecosystem structural shifts similar to those seen in other recent studies
are occurring, but the lack of significance makes it difficult to draw strong conclusions.
The lack of significance between ecological factors and population trends observed
in this study may be due to trophic shifts in fishing are not occurring or may be
due to issues with the data used for regressions. Future studies using different methods
of obtaining demographic factors and incorporating additional years of catch data
could bring more clarity to this work.
Type
Honors thesisDepartment
Environmental SciencePermalink
https://hdl.handle.net/10161/14291Citation
May, Eva (2017). Applying Fishery Catch Data to Population Trends and Community Structures in Atlantic
Pelagic Species. Honors thesis, Duke University. Retrieved from https://hdl.handle.net/10161/14291.Collections
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