560 
Fishery Bulletin 95(3), 1997 
The Eymard BRD was developed to reduce the 
catch of larger hardhead catfish, particularly in Loui- 
siana waters east of the Mississippi River. Hardhead 
catfish reductions were 6% in terms of numbers, but 
51% in biomass, resulting from the loss of larger cat- 
fish. Overall, the Eymard BRD caught 26% more fish, 
but fish biomass was 19% less than that caught by 
the control net. This finding was the result of the 
BRD catching more fish smaller than 80 mm and 
fewer large fish than the control nets. The Eymard 
BRD caught significantly more numbers and bio- 
mass of shrimp, particularly smaller shrimp. The 
Eymard BRD design contained a webbing funnel, 
designed to carry shrimp and fish into the codend 
with accelerating water flow (Watson 5 ). Because 
swimming speed of a fish is a function of size (Blaxter 
and Dickson, 1958), smaller fishes may not be able 
to swim in increased water flow, with the result that 
fewer shrimp and small fish can escape from the 
Eymard BRD than from a control net. However, dye 
released into the Eymard indicated that the water 
flow was not perceptibly increased by the funnel, 
probably because the funnel diam- 
eter was only slightly smaller than 
the net diameter. However, the 
Eymard BRD had a 21.6-cm greater 
net spread than that of the control 
net; this greater net opening may 
have resulted in the higher catches 
of many species. Because the nets 
were otherwise constructed identically, 
we suspect this difference was most 
likely due to the presence of the hoop. 
The polyethylene webbing may have 
increased the incidence of anchovy be- 
ing gilled, particularly during haul- 
back. Numerous small bay anchovies 
were found, upon retrieval, to be gilled 
in the polyethylene webbing of the 
Eymard BRD, and the device caught 
83% more bay anchovy than the con- 
trol net. In a subsequent study, a poly- 
ethylene net caught 245% more ancho- 
vies than a nylon net (Rogers et al. 6 ). 
Fish were observed escaping from 
several of the BRD’s during diver 
evaluations in Florida. Divers ob- 
served several large juvenile pinfish 
(Lagodon rhomboides ) escaping from 
the bottom openings of the Eymard 
BRD and numerous juvenile pinfish 
escaping the Authement-Ledet BRD 
5 Watson, J. W. 1988. Fish behaviour and 
trawl design: potential for selective trawl 
development. In S. G. Fox and J. Hunting- 
ton (eds.), Proceedings of the world sympo- 
sium on fishing gear and fishing vessel de- 
sign, p. 25-29. Newfoundland and Labra- 
dor Institute of Fisheries and Marine Tech- 
nology, St. John’s, Newfoundland. 
6 Rogers, D. R., B. D. Rogers, J. A. de Silva, 
and V. L. Wright. 1994. Evaluation of 
shrimp trawls designed to reduce bycatch 
in inshore waters of Louisiana. School of For- 
estry, Wildlife, and Fisheries, Louisiana 
State Univ. Agricultural Center. Final re- 
port submitted to NMFS, St. Petersburg, FL. 
NOAA Award No. NA17FF0375-01, 230 p. 
Available from LSU library. 
