Smalltooth Sawfish (Pristis pectinata) |
Smalltooth
sawfish are a tropical marine elasmobranch that often utilizes estuaries as a
part of their habitat (NMFS 2009). They
have been found to tend to stay in coastal waters, spending most of their time
in shallow areas (Carlson et al. 2014). This
tendency could maybe explain their historic frequent encounters with humans,
and possibly why they have been affected so much by human development and
fishing activities. Their name comes
from their saw-like rostrum, with transverse teeth on both sides (NMFS 2009). The range of the smalltooth sawfish has
become highly restricted, contributing to the population collapse. Their range was once thought to extend all
the way up the eastern coast of the United States to New York, but now their
range is restricted to the southwestern waters of Florida (NMFS 2009). They have also been found to live near some
of the islands of the Bahamas (Guttridge et al. 2015).
Distribution of reported encounters with smalltooth sawfish along the US coast, 1998 to 2008 (Wiley and Simpfendorfer 2010) |
Declines
in smalltooth sawfish populations can be attributed to a number of factors,
most of them being anthropogenic causes.
The drastic declines in sawfish populations have been attributed mostly
to being bycatch in commercial and recreational fisheries and to the depletion
of suitable habitat (NMFS 2009). As
stated before, the main reason for the smalltooth sawfish’s decline is by bycatch. According to Seitz and Poulakis
(2006), one of the main reasons for the decline of the species is mortality
caused from bycatch in net fisheries. Their
low rates of population increase coupled with their high catchability (often
caused by their rostra being tangled in nets) has contributed to their decline
(Dulvy et al. 2016). The Recovery Plan
by NMFS (2009) also states that their slow reproductive rates are a limiting
factor in their overall recovery, so it could take a very long time for any
sort of positive change in population numbers to become evident. Recovery, or stage where managers could
delist the species, would require that there be strict adherence to regulations
protecting smalltooth sawfish from harm, as well as protecting their critical
habitats.
Because
of this decline, many plans have been put in place in attempt to recover the
smalltooth sawfish. Some of the data used
to direct the study of related to smalltooth sawfish was done through examining
the records of public encounters with the fish (Wiley and Simpendorfer
2010). Wiley and Simpendorfer found in
their study that most of the bigger fish were located towards the center of the
sawfish’s range in southern Florida, as well as that most fish were observed in
estuarine and nearshore habitat. It was
also found by Wiley and Simpendorfer that most of the smaller fish were found
in shallower waters. Many studies on smalltooth
sawfish reference these data that were collected via voluntary encounter
reports by the public, as they found some important habitat information. Norton et al. (2012) states that protection of
critical habitat would be an important step in smalltooth sawfish recovery,
especially in the protection of nursery areas for juvenile sawfish.
There
is a lot to be done if the smalltooth sawfish is to be delisted, let alone just
downlisted to simply “endangered” by the IUCN or to “threatened” on the
endangered species list. According to
the National Marine Fisheries Service’s Smalltooth Sawfish Recovery Plan, this
will involve programs to educate the public, establishment of guidelines for
safely releasing sawfish, and laws at the state and federal level (NMFS
2009). Carlson and Simpfendorfer (2015)
state that, optimistically, smalltooth sawfish can be recovered only if
fishing-related mortality is kept to an absolute minimum. As Seitz and Poulakis (2006) point out, many
of the reasons for declines, such as pollution and direct harm by humans, can
be decreased if the public becomes more educated on the topic of smalltooth
sawfish. It seems that this goal of
education could maybe be reached, considering all of the voluntary public
involvement that was used to generate much of the data used in many
studies. It is also important to note
the need for sound management involving development in areas where smalltooth
sawfish were known to live. But with
increasing populations, and so much development in areas where smalltooth
sawfish historically thrived, this may not be likely. For example, the areas in which the sawfish
have nurseries should be considered in decisions relating to freshwater
withdrawals and development on the coasts such as changing the shoreline
(Poulakis et al. 2012). If all of these
things are achieved, it is quite possible that the smalltooth sawfish can be
recovered, but whether all of these things can happen together for the benefit
of the sawfish is yet to be seen.
Carlson, J. K., Gulak, S. J. B.,
Simpfendorfer, C. A., Grubbs, R. D., Romine, J. G., & Burgess, G. H.
(2014). Movement patterns and habitat use of smalltooth sawfish, Pristis pectinata,
determined using pop-up satellite archival tags. Aquatic Conservation-Marine
and Freshwater Ecosystems, 24(1), 104-117. doi: 10.1002/aqc.2382
Carlson, J. K., & Simpfendorfer, C.
A. (2015). Recovery potential of smalltooth sawfish, Pristis pectinata, in the
United States determined using population viability models. Aquatic
Conservation-Marine and Freshwater Ecosystems, 25(2), 187-200. doi:
10.1002/aqc.2434
Chapman, D. D., Simpfendorfer, C. A.,
Wiley, T. R., Poulakis, G. R., Curtis, C., Tringali, M., . . . Feldheim, K. A.
(2011). Genetic Diversity Despite Population Collapse in a Critically
Endangered Marine Fish: The Smalltooth Sawfish (Pristis pectinata). Journal
of Heredity, 102(6), 643-652. doi: 10.1093/jhered/esr098
Dulvy, N. K., Davidson, L. N. K., Kyne,
P. M., Simpfendorfer, C. A., Harrison, L. R., Carlson, J. K., & Fordham, S.
V. (2016). Ghosts of the coast: global extinction risk and conservation of
sawfishes. Aquatic Conservation-Marine and Freshwater Ecosystems, 26(1),
134-153. doi: 10.1002/aqc.2525
Guttridge, T. L., Gulak, S. J. B.,
Franks, B. R., Carlson, J. K., Gruber, S. H., Gledhill, K. S., . . . Grubbs, R.
D. (2015). Occurrence and habitat use of the critically endangered smalltooth
sawfish Pristis pectinata in the Bahamas. Journal of Fish Biology, 87(6),
1322-1341. doi: 10.1111/jfb.12825
National Marine Fisheries Service. 2009.
Recovery Plan for Smalltooth Sawfish (Pristis pectinata). Prepared by
the Smalltooth Sawfish Recovery Team for the National Marine Fisheries Service,
Silver Spring, Maryland.
Norton, S. L., Wiley, T. R., Carlson, J.
K., Frick, A. L., Poulakis, G. R., & Simpfendorfer, C. A. (2012).
Designating Critical Habitat for Juvenile Endangered Smalltooth Sawfish in the
United States. Marine and Coastal Fisheries, 4(1), 473-480. doi:
10.1080/19425120.2012.676606
Poulakis, G. R., Stevens, P. W., Timmers,
A. A., Stafford, C. J., & Simpfendorfer, C. A. (2013). Movements of
juvenile endangered smalltooth sawfish, Pristis pectinata, in an estuarine
river system: use of non-main-stem river habitats and lagged responses to
freshwater inflow-related changes. Environmental Biology of Fishes, 96(6),
763-778. doi: 10.1007/s10641-012-0070-x
Seitz, J. C., & Poulakis, G. R.
(2006). Anthropogenic effects on the smalltooth sawfish (Pristis pectinata) in
the United States. Marine Pollution Bulletin, 52(11), 1533-1540. doi: 10.1016/j.marpolbul.2006.07.016
Wiley, T. R., Simpfendorfer, C. A.
(2010). Using public encounter data to direct recovery efforts for the endangered
smalltooth sawfish Pristis pectinata.
Endangered Species Research 12(1).
179-191.
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