Title page for ETD etd-07102009-105825

Type of Document Dissertation
Author Brown, Harmon
URN etd-07102009-105825
Title Assessing Linkages between Petroleum Platforms and Pelagic Fishes Using Telemetry, with Emphasis on Blue Runner (Caranx crysos)
Degree Doctor of Philosophy (Ph.D.)
Department Oceanography & Coastal Sciences
Advisory Committee
Advisor Name Title
Benfield, Mark C. Committee Chair
Baltz, Donald Committee Member
Galvez, Fernando Committee Member
Powers, Sean Committee Member
Rouse, Lawrence Committee Member
Hughes, Richard Dean's Representative
  • vertical movement
  • home range
  • schooling
  • Gulf of Mexico
  • petroleum platforms
  • telemetry
  • Caranx crysos
Date of Defense 2009-04-07
Availability unrestricted
Petroleum platforms number greater than 4,200 in the Gulf of Mexico and Caranx

crysos (blue runner) is one of the most abundant fish species around these

platforms. Forty-six blue runner were tagged with acoustical transmitters in

August 2005, though the study was terminated prematurely due to the impending

arrival of Hurricane Katrina. Nineteen blue runner were tagged in September

2006 and tracked for up to two months. Blue runner exhibited limited site fidelity

around the platforms in 2005. The home range of twenty-three blue runner was

calculated in 2005. A significant difference was found between the fork length of

the fish and their overall 50% range, but their overall 95% range. The reverse

was true when comparing mean daily ranges and fork length. The daytime core

ranges were generally larger than the nighttime core ranges, though not

significantly so. In 2006 tagged fish were released at unmanned platforms and all

but one returned to the main complex and remained there over the course of the

study period. The size of blue runner schools was estimated to be 36m. They

were found to school more during the day than at night and moved between

schools showing no preference for schooling with a particular fish. The blue

runner showed a distinct diel vertical migration pattern with a marked descent to

about 25m at night and ascent to the surface in the morning. The rate of ascent

was significantly greater than the rate of descent. There was no relationship

between these rates, the amplitude of migrations and maximum nightly depths

with the lunar periodicity. There was a significant difference between the

nighttime distribution of blue runner at the unmanned platforms and the manned

platforms with fish at the unmanned platforms having a greater mean depth. The

swimming speeds of tagged blue runner were greater during the day than at

night and were indicative of passive foraging behavior. The lighted manned

platforms appear to allow for greater foraging opportunities at night than the

unmanned platforms.

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