TY - JOUR
T1 - Endocrinological investigation into the reproductive cycles of two sympatric skate species, Malacoraja senta and Amblyraja radiata, in the western Gulf of Maine
AU - Kneebone, Jeff
AU - Ferguson, Darren E.
AU - Sulikowski, James A.
AU - Tsang, Paul C.W.
N1 - Funding Information:
Acknowledgements We thank Joe Jurek of the F/V Mystique Lady for all skate collections. Further thanks are extended to Scott Elzey and Suzie Biron (UNH Department of Zoology) for their help in processing of skates. This project was supported by a grant from the Northeast Consortium (NA16FL1324) to PCWT and JAS.
PY - 2007/10
Y1 - 2007/10
N2 - The smooth skate, Malacoraja senta, and thorny skate, Amblyraja radiata, are two commercially exploited batoids found within the Gulf of Maine. During the past five years, we conducted a large study to accurately describe important biological life history parameters previously lacking for these species. As part of that project, the current study reports our findings on the hormonal profiles associated with the reproductive cycles of M. senta and A. radiata. Blood samples were obtained from mature M. senta and A. radiata of both sexes from all months of the year, and plasma testosterone (T), estradiol (E 2) and progesterone (P4) concentrations were determined using radioimmunoassay (RIA). In female M. senta and A. radiata, monthly T concentrations ranged from 4,522 pg ml-1 to 1,373 pg ml-1 and 31,940 pg ml-1 to 14,428 pg ml-1, E2 concentrations from 831 pg ml-1 to 60 pg ml-1 and 8,515 pg ml-1 to 2,902 pg ml-1, and P4 concentrations from 3,027 pg ml-1 to 20 pg ml-1 and 3,264 pg ml -1 to 331 pg ml-1, respectively. No statistical differences were detected between any months for any hormone. Estradiol concentrations were not correlated with ovary weight, shell gland weight, or diameter of the largest follicles in either species. Monthly T concentrations in male M. senta and A. radiata ranged from 23,146 to 12,660 pg ml-1 and from 57,500pg ml-1 to 24,737 pg ml-1, while E 2 concentrations ranged from 7.5 pg ml-1 to undetectable and 103 to 30 pg ml-1, respectively. No statistical differences were observed between months for either steroid. Testosterone concentrations were weakly correlated with testes weight and percent of stage VI spermatocysts in A. radiata, however, no correlation was detected between T and stage VI spermatocysts in M. senta. Collectively, these data support the previous conclusion that M. senta and A. radiata of both sexes are capable of reproducing year round in the western Gulf of Maine.
AB - The smooth skate, Malacoraja senta, and thorny skate, Amblyraja radiata, are two commercially exploited batoids found within the Gulf of Maine. During the past five years, we conducted a large study to accurately describe important biological life history parameters previously lacking for these species. As part of that project, the current study reports our findings on the hormonal profiles associated with the reproductive cycles of M. senta and A. radiata. Blood samples were obtained from mature M. senta and A. radiata of both sexes from all months of the year, and plasma testosterone (T), estradiol (E 2) and progesterone (P4) concentrations were determined using radioimmunoassay (RIA). In female M. senta and A. radiata, monthly T concentrations ranged from 4,522 pg ml-1 to 1,373 pg ml-1 and 31,940 pg ml-1 to 14,428 pg ml-1, E2 concentrations from 831 pg ml-1 to 60 pg ml-1 and 8,515 pg ml-1 to 2,902 pg ml-1, and P4 concentrations from 3,027 pg ml-1 to 20 pg ml-1 and 3,264 pg ml -1 to 331 pg ml-1, respectively. No statistical differences were detected between any months for any hormone. Estradiol concentrations were not correlated with ovary weight, shell gland weight, or diameter of the largest follicles in either species. Monthly T concentrations in male M. senta and A. radiata ranged from 23,146 to 12,660 pg ml-1 and from 57,500pg ml-1 to 24,737 pg ml-1, while E 2 concentrations ranged from 7.5 pg ml-1 to undetectable and 103 to 30 pg ml-1, respectively. No statistical differences were observed between months for either steroid. Testosterone concentrations were weakly correlated with testes weight and percent of stage VI spermatocysts in A. radiata, however, no correlation was detected between T and stage VI spermatocysts in M. senta. Collectively, these data support the previous conclusion that M. senta and A. radiata of both sexes are capable of reproducing year round in the western Gulf of Maine.
KW - Amblyraja radiata
KW - Estradiol
KW - Malacoraja senta
KW - Progesterone
KW - Radioimmunoassay
KW - Testosterone
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U2 - 10.1007/s10641-007-9215-8
DO - 10.1007/s10641-007-9215-8
M3 - Article
AN - SCOPUS:34948888642
SN - 0378-1909
VL - 80
SP - 257
EP - 265
JO - Environmental Biology of Fishes
JF - Environmental Biology of Fishes
IS - 2-3
ER -