Relationship of Shrimp Trawl Bycatch

1
Relationship of Shrimp Trawl Bycatch Derived Red
Snapper F-values to Effort and Catch, and the
Number of Samples (trawl tows) Required to
Estimate Red Snapper Bycatch Rick A. Hart and
James M. Nance NOAA Fisheries Service SEFSC Galves
ton Laboratory
2
Shrimp trawl bycatch F-value (red snapper)
Shrimp trawl bycatch F- values (red snapper) vs.
offshore effort, 1960 2005.
3
Shrimp trawl bycatch F-value (red snapper)
Shrimp trawl bycatch F- values (red snapper) vs.
brown shrimp catch, 1960 2005.
4
Shrimp trawl bycatch F-value (red snapper)
Shrimp trawl bycatch F- values (red snapper) vs.
red snapper bycatch estimates, 1972 2003.
5
Shrimp trawl bycatch F-value (red snapper)
Shrimp trawl bycatch F- values (red snapper) vs.
total finfish bycatch estimates, 1972 2004.
6
Effort (24 hour days fished)
Shrimp trawl offshore effort vs. year, 1960
2005.
7
Sample Size (n)
Gulf of Mexico number of observer sampled tows
required at the 0.05 and 0.01 alpha levels with
varying precision levels to estimate the number
of red snappers.
8
Sample Size (n)
Eastern Gulf of Mexico number of observer sampled
tows required at the 0.05 and 0.01 alpha levels
with varying precision levels to estimate the
number of red snappers.
9
Sample Size (n)
Western Gulf of Mexico number of observer sampled
tows required at the 0.05 and 0.01 alpha levels
with varying precision levels to estimate the
number of red snappers.
10
Sample Size (n)
Gulf of Mexico number of observer sampled tows
required at the 0.05 and 0.01 alpha levels with
varying precision levels to estimate the weight
of red snappers.
11
Sample Size (n)
Eastern Gulf of Mexico number of observer sampled
tows required at the 0.05 and 0.01 alpha levels
with varying precision levels to estimate the
weight of red snappers.
12
Sample Size (n)
Western Gulf of Mexico number of observer sampled
tows required at the 0.05 and 0.01 alpha levels
with varying precision levels to estimate the
weight of red snappers.
13
Estimation of Sample Sizes (trawl tows) under
Varying Levels of Precision Based on the Mean
Number of Red Snappers
14
Eastern Gulf of Mexico Estimation of Sample
Sizes (trawl tows) under Varying Levels of
Precision Based on the Mean Number of Red Snappers
15
Western Gulf of Mexico Estimation of Sample
Sizes (trawl tows) under Varying Levels of
Precision Based on the Mean Number of Red Snappers