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Notes
- Abstract:
- Yellowfin grouper (Mycteroperca venenosa) form transient fish spawning aggregations (FSAs) on the Grammanik Bank, St. Thomas, United States Virgin Islands (USVI), from January to May. Intense fishing of yellowfin grouper led to a seasonal closure from February 1st to April 30th on the Grammanik Bank. To determine the closures effectiveness and study FSA behavior passive acoustic telemetry data of 21 yellowfin grouper was collected from 2007 to 2010. The data was
analyzed and modeled to determine what proportion of time fish were spending inside the closed area. Both sentinel and boat range tests were conducted on the Grammanik Bank acoustic array to determine what environmental factors affect the detection range of the acoustic transmitters. Temperature and time of day had the greatest influence on detection ranges due to the presence of a thermocline and ambient noise levels, respectively. The 80% detection probability was used and calculated by fitting a logistic curve to the data after temperature gradients and the time of day were corrected. The variable detection range was then applied to the yellowfin grouper passive acoustic data. A model was created using the average cruising speed of yellowfin grouper to assign all of the time the fish was absent from the array to a
spatially explicit area. A grid was overlaid and the proportion of time spent in each grid cell was calculated. The time yellowfin grouper spent in each grid cell were compared by years 2007, 2008, and 2010 (Repeated Measure ANOVA, F=1.39, p=0.25) and between the sexes (Hotelling T2, T2=2.12, p=0.145). No significant differences were found so all instances of movement were averaged together. The results show yellowfin grouper only spent 24.9% of their time inside the current boundary of the Grammanik Bank closure. Two proposed changes, the first reshaping
the current 1.5 km2 area and the second increasing it to 8.2 km2, would improve the time spent in the closed area to 33.1% and 50.5% respectively. The results and methodology used in this study are applicable to other sets of passive acoustic data, and may be used to assess protected areas effectiveness or to examine movement behaviors exhibited by other species.
- General Note:
- In the series University of the Virgin Islands Digital Collections.
Record Information
- Source Institution:
- University of the Virgin Islands
- Holding Location:
- University of the Virgin Islands
- Rights Management:
- Copyright Jonathan Jossart. Permission granted to the University of the Virgin Islands to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
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