339 
Surface mucous as a source of genomic DNA 
from Atlantic billfishes (Istiophoridae) 
and swordfish (Xiphiidae) 
Abstract — Procedures for sampling 
genomic DNA from live billfishes 
involve manual restraint and tissue 
excision that can be difficult to carry 
out and may produce stresses that 
affect fish survival. We examined 
the collection of surface mucous as 
a less invasive alternative method for 
sourcing genomic DNA by comparing 
it to autologous muscle tissue samples 
from Atlantic blue marlin ( Makaira 
nigricans), white marlin ( Tetraptu - 
rus albidus), sailfish {Istiophorus 
platypterus), and swordfish ( Xiphias 
gladius). Purified DNA from mucous 
was comparable to muscle and was 
suitable for conventional polymerase 
chain reaction, random amplified poly- 
morphic DNA analysis, and mitochon- 
drial and nuclear locus sequencing. 
The nondestructive and less invasive 
characteristics of surface mucous col- 
lection may promote increased sur- 
vival of released specimens and may 
be advantageous for other marine fish 
genetic studies, particularly those 
involving large live specimens des- 
tined for release. 
Manuscript submitted 26 November 2008. 
Manuscript accepted 26 March 2009. 
Fish. Bull. 107:339-342 (2009). 
The views and opinions expressed 
or implied in this article are those 
of the author and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
John P. Hoolihan 1 
Nerida F. Perez 2 
Ronald M. Faugue 2 
Andrea M. Bernard 3 
Understanding genetic variation and 
identifying evolutionary lineages are 
important considerations for conser- 
vation management of large pelagic 
fishes (Palumbi, 1994; Ward, 2000). 
Some methods used for genetic sam- 
pling of billfishes (families Istiophori- 
dae and Xiphiidae) require excision 
of muscle, skin, or fin tissue, and 
excision requires manual restraint 
or killing of the animal. Some non- 
destructive sampling methods, such 
as fin and scale collection, exist that 
avoid the need to kill the fish (Yue 
and Orban, 2001; Wasko et ah, 2003; 
Hoolihan et al., 2004). Tissue exci- 
sion from very large live specimens is 
problematic because of personal safety 
concerns for handlers, and injuries to 
fish that may reduce survival. Most 
recreational billfish caught in the 
United States are released (Prince 
et al., 2007), whereas possession of 
billfish by U.S. pelagic longline ves- 
sels and sales of Atlantic billfishes 
have been prohibited since 1988. This 
regulation eliminates opportunities to 
obtain DNA samples from landed spec- 
imens, warranting a need for alterna- 
tive methods. To sample genomic DNA 
with nondestructive techniques and 
Rebekah L. Horn 3 
Derke Snodgrass 1 
Duane R. Schultz (contact author ) 2 
with minimal handling would promote 
the survival of released individuals 
and increase the opportunities to con- 
duct genetic studies. 
One alternate potential source of 
genomic DNA is the epidermal cells 
found in billfish and swordfish sur- 
face mucous. Successful extractions of 
sufficient quantities of genomic DNA 
from surface mucous of freshwater 
fishes have been reported for Salmo 
trutta fario (brown trout), Esox lucius 
(northern pike) (Livia et al., 2006) 
and Scleropages formosus (Asian 
arowana) (Chansue, 2006), provid- 
ing an experimental model for large 
pelagic species. 
The present study compares DNA 
extractions from surface mucous and 
autologous skeletal muscle tissue from 
billfishes and swordfish to determine 
the suitability of DNA extracted from 
surface mucous for random amplified 
polymorphic DNA (RAPD) and DNA 
sequencing analyses. 
Materials and methods 
Surface mucous and autologous skel- 
etal muscle samples were collected 
Email address for contact author: dschultz@med.miami.edu 
1 NOAA Fisheries 
Southeast Fisheries Science Center 
75 Virginia Beach Drive 
Miami, Florida 33149 
2 Department of Medicine 
University of Miami 
Miller School of Medicine 
Miami, Florida 33136 
3 Guy FHarvey Research Institute 
Nova Southeastern University 
Oceanographic Center 
8000 North Ocean Drive 
Dania Beach, Florida 33004 
