Endocrinological investigation into the reproducti

Authors: Jeff Kneebone Darren E Ferguson James A Sulikowski Paul C W Tsang

Publish Date: 2007/02/17

Volume: 80, Issue: 2-3, Pages: 257-265

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Abstract

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 E2 and progesterone P4 concentrations were determined using radioimmunoassay RIA In female M senta and A radiata monthly T concentrations ranged from 4522 pg ml−1 to 1373 pg ml−1 and 31940 pg ml−1 to 14428 pg ml−1 E2 concentrations from 831 pg ml−1 to 60  pg ml−1 and 8515 pg ml−1 to 2902 pg ml−1 and P4 concentrations from 3027 pg ml−1 to 20 pg ml−1 and 3264 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 23146 to 12660 pg ml−1 and from 57500pg ml−1 to 24737 pg ml−1 while E2 concentrations ranged from 75 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 MaineWe 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

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