
TY  - JOUR
A1  - Carlson, John K. 
A1  - Baremore, Ivy E. 
T1  - Changes in biological parameters of Atlantic sharpnose shark <emph type="2">Rhizoprionodon</emph> <emph type="2">terraenovae</emph> in the Gulf of Mexico: evidence for density-dependent growth and maturity?
JF  - Marine and Freshwater Research
JO  - Mar. Freshwater Res.
Y1  - 2003
VL  - 54
IS  - 3
SP  - 227
EP  - 234
KW  - age, compensatory, exploitation, small coastal shark.
UR  - https://doi.org/10.1071/MF02153 
N2  - Biological parameters of the Atlantic sharpnose shark Rhizoprionodon terraenovae in the northern Gulf of Mexico were re-examined to test for potential changes due to density dependent responses. Biological data from published studies in the Gulf of Mexico collected during the period 1979&#8211;1984 were compared with data collected during the period 1998&#8211;2001. For combined sexes, the von Bertalanffy growth parameters were L&#8734; = 110.8 cm total length, K = 0.39 year&#8211;1 and to = &#8211;0.86 year during 1984 and L&#8734; = 94.0 cm total length, K = 0.73 year&#8211;1 and to = &#8211;0.88 year during 1998&#8211;2001. Median size for males and females at maturity decreased from approximately 78.3 and 80.2 cm total length (TL), respectively, in 1979&#8211;1980 to 72.6 and 75.8 cm TL, respectively, in 1998&#8211;2001. Age at maturity for combined sexes also decreased from 2.3 years in 1979&#8211;1980 to 1.4 years in 1998&#8211;2001. Litter size was similar between periods (5.0 embryos), as was the average size of embryos close to parturition (32 cm TL; 130&#8211;150 g). Growth rates using observed mean size-at-age data were higher from 1998&#8211;2001 for early ages (0&#8211;2.5 years). The observed decrease in maturity and increased growth rate lends support to the hypothesis of a compensatory response, although it could not be fully determined whether the response was due to differences in methodology among studies, anthropogenic influences or natural causes. 
ER  -

