Widespread distribution in polar oceans of a 16S rRNA gene sequence with affinity to Nitrosospira-like ammonia-oxidizing bacteria
The northwest Atlantic population of smooth dogfish (Mustelus canis) ranges from Cape Cod, Massachusetts, to South Carolina. Although M. canis is seasonally abundant in this region, very little is known about important aspects of its biology, such as growth and reproductive rates. In the early 1990s, commercial fishery landings of smooth dogfish dramatically increased on the east coast of the United States. This study investigated growth rates of the east coast M. canis population through analysis of growth patterns in vertebral centra. Marginal increment analysis, estimates of precision, and patterns in seasonal growth supported the use of vertebrae to age these sharks. Growth bands in vertebral samples were used to estimate ages for 894 smooth dogfish. Age-length data were used to determine von BertalanfFy growth parameters for this population: K = 0.292/yr, L-infinity = 123.57 cm, and t(0) = -1.94 years for females, and K = 0.440/yr, L-infinity = 105.17 cm, and t(0) = -1.52 years for males. Males matured at two or three years of age and females matured between four and seven years of age. The oldest age estimate for male and female samples was ten and sixteen years, respectively.