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Published byTamsyn Weaver Modified over 9 years ago
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Population Size, Growth, Mortality and Movement Patterns of Yellowtail Snapper (Ocyurus chrysurus) in the U.S. Virgin Islands CRP Funded Project NMF4540114 Funding : Federal=$132,850 CFMC=$20,000 STFA in-kind=$11,200
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# STT/STJ Yellowtail Fishing Trips
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Yellowtail lbs/Trip
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Yellowtail Snapper Annual STT/STJ Landings # lbs
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Annual Yellowtail Landings # Fish
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Average Monthly Handline & SeineTrips (1997-2008 Average)
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Yellowtail per Trap /Haul
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Pit Tags
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Scanner for Port Sampling
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Weight Calculations
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Study Status TaggingTrips
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Port Sample Locations
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Length at First Reproduction (FISHBASE) 188 mm Male, 224 mm Female CFMC Size Limit304.8 TL, 244.7 FL Length at First Capture (FL in mm) Traps228 mm Hand Line208 mm Nets198 mm Length at Full Recruitment Traps270 mm Hand Line290 mm Seine Nets260 mm
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Calculation of Total Mortality Rate (Z)
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Hand line Size Frequency
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Fish Trap Size Frequency
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Tagging/Port Sampling Summary
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Summary of Mortality 2005 Size/Frequency Distribution=0.174 (0.0154/month) 2011-12 Size/Frequency Distribution=0.249 (0.0208/Month) Coral World – Initial “Fishing/Transport” Mortality=9.6% Heavy stress from transport to tanks analogous to additional mortality from predators. – Tag Loss= 1.6% – Pre “Catastrophic” Mortality=2.1% (matches 2011-2012 rate)
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Gear Selectivity
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Selectivity Analysis: Fish Traps
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Selectivity Analysis: Hand Line
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Assess rate of tag loss (1.7%) Assess mortality – 9.6% initial “fishing/transport” mortality – Mortality following initial mortality almost exactly that indicated from size/frequency analysis. – Catastrophic mortality after 3 weeks. – Necropsy revealed that 60% had small livers when compared to fish from market and 69% had liver fluke infestation. Coral World Studies
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Survivorship at Coral World
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Recaptures None so far Comparison with Rick Niemeth’s tagging. All tagging done on aggregation site. To date Niemeth has tagged – 751 Nassau (2004-2010) and have recaptured 187 back on the aggregation site. In addition 3 have been captured by fishermen and reported to UVI by STFA members (0.5/year). – 661 yellowfin grouper and recaptured 25. All tags and recaps were on the aggregation site. – 3644 red hind (1999-2006) and recaptured 99. 47 Red hind were recaptured off the aggregation site (6.7/year).
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Next Steps Finish Coral World Studies Double Tagging with Floy and Pit tags. Started 8/15) Floy Tagging of remainder Continue Port Sampling. Data from DFW.
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