NOTE Wells et a!.: Entanglement and mortality of Tursiops truncatus 
649 
removed suggested that it had been removed from a 
reel and discarded, rather than it had been actively 
involved in fishing at the time of entanglement. 
Recreational fishing activities pose a largely ig- 
nored threat to bottlenose dolphins near Sarasota. 
Of 11 carcasses of resident Sarasota Bay dolphins 
recovered during 1993-1996, monofilament fishing 
line was implicated as a contributing factor in three 
deaths (27%). Large quantities of fishing line were 
found around two dependent calves (MML 9314=1.5 
yr old and MML 9417=0.3 yr old). In one of these 
cases (MML 9314), growth of invertebrates on the 
line indicated that the line had been discarded prior 
to entanglement. The third case involved ingestion 
of line by an adult female (MML 9514) that had con- 
sumed a hooked sheepshead ( Archosargus probato- 
cephalus), as reported by Gorzelany (in press). 
Wells and Scott (1994) reported that a dispropor- 
tionately large number of subadult Sarasota Bay 
resident dolphins involved in entanglements of all 
kinds had been recorded through 1989 on the basis 
of scars observed during veterinary examinations as 
part of a capture-release program. More than half of 
the cases involved subadults; the balance were re- 
corded from adults, but the entanglement events had 
occurred at an undetermined younger age. Dolphin 
FB03, a subadult at the time of entanglement; and 
the two dependent calves described above lend fur- 
ther support to this pattern. Similarly, Mann et al. 
(1995) reported on four cases of infant bottlenose 
dolphins becoming entangled in Shark Bay, Austra- 
lia. In three of these cases, it was possible to remove 
the line from the semiprovisioned calves; in the fourth 
case, the line came free from the dolphin without 
human assistance. For many young animals, curios- 
ity, inexperience, and unrefined motor skills place 
them at greater risk of entanglement through play- 
ful and exploratory behavior, the occurrence of which 
declines as the animal matures. Play may be strongly 
related to foraging behavior, for example, and may 
allow younger animals to practice, learn, and develop 
other behaviors that will be essential to their sur- 
vival. Such behaviors may have an important role in 
the development of adult behaviors, but they may 
also be a costly practice for newborns or subadults 
who lack the experience of an adult. 
In many parts of the world, dolphins are killed in 
gillnet and other fisheries (Perrin et ah, 1994). It is 
interesting to note that in Sarasota Bay, Florida, an 
area of heavy recreational fishing activity, the num- 
bers of deaths or serious injuries resulting from rec- 
reational fishing could exceed historical levels from 
small-scale gillnet fisheries. Gill nets were used ex- 
tensively in this area prior to a state-wide ban, July 
1995. Three deaths and one rescue of Sarasota resi- 
dent dolphins entangled in recreational fishing gear 
occurred during 1993-96, but only one death (FB20 
in 1976) and one rescue from gill nets (FB11 in 1985) 
were recorded during the 20 years prior to the 1995 
gillnet ban. It should be noted, however, that strand- 
ing response coverage was uneven prior to the mid- 
1980s: not all deaths resulted in recovered carcasses, 
and not all possible entanglement events could 
be clearly identified as a direct cause of death, nor 
could they necessarily be distinguished as net or line 
entanglements. 
Mortality and serious injury to dolphins from rec- 
reational fisheries have been largely overlooked in 
management, yet such mortality and injury may be 
important. Management actions to reduce human- 
related dolphin mortality are needed to address such 
issues, particularly in regard to the practice of dis- 
carding fishing line. Discarded line poses a risk that 
is somewhat analogous to that of “ghost-fishing” by 
commercial nets. Increased education of fishermen, 
through clear descriptions of the documented conse- 
quences of discarded gear is a logical, important, 
approach to the issue. 
Acknowledgments 
We thank the Center for Field Research ( Earthwatch), 
the Chicago Zoological Society, Dolphin Quest, Dolphin 
Biology Research Institute, Mote Marine Laboratory, 
the Henry Foundation, and the dedicated efforts of 
our field team members for the rescue, monitoring, 
and subsequent examination of FB03. Observations 
were conducted under National Marine Fisheries 
Service Scientific Research Permit 805; physical ex- 
amination was conducted under National Marine 
Fisheries Service Scientific Research Permit 945. 
Finally, we thank M. Scott, A. Read, K. Urian, and J. 
Gorzelany for comments on the manuscript. 
Literature cited 
Gorzelany, J. F. 
In press. Unusual deaths of two free-ranging Atlantic bottle- 
nose dolphins ( Tursiops truncatus ) related to ingestion of rec- 
reational fishing gear. Marine Mammal Science 14(3). 
Irvine, A. B., M. D. Scott, R. S. Wells, and J. H. Kaufmann. 
1981. Movements and activities of the Atlantic bottlenose 
dolphin, Tursiops truncatus, near Sarasota, Florida. Fish. 
Bull. 79:671-688. 
Mann, J. , R. A. Smolker, and B. B. Smuts. 
1995. Responses to calf entanglement in free-ranging bottle- 
nose dolphins. Mar. Mamm. Sci. 11:100-106. 
Perrin, W. F., G. P. Donovan, and J. Barlow (eds.). 
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