Apex Predators Program
28 Tarzwell Drive
Narragansett RI 02882-1152 USA
NEFSC Apex Predators Program
Knowledge of the reproductive life history of a species is an essential component in understanding a species' ability to withstand both natural and manmade pressures. Estimates of maturity combined with age are fundamental to proper management, particularly at the species level.
The APP conducts basic biological studies on the reproduction of sharks to gain a comprehensive picture of the reproductive cycle of a given species.
- Biological sampling takes place at shark tournaments and on research and commercial fishing vessels.
- A variety of measurements are taken of the reproductive organs including, but not limited to: female - length and width of ovaries, uterus, oviducal gland; male - length and width of testis and clasper length.
- Tissue samples are collected for histological analysis.
- Females are examined for numbers and sizes of eggs, maturity of eggs and number, sizes and maturity of pups if pregnant.
Once samples of all sizes are obtained, a graph of the relationship of body length to organ length or width will generally show an inflection at the point of maturity - this should show up at approximately the same point for all organs measured for a species and sex.
- Obtain size at 50% maturity for each sex
- Determine seasonality of mating
- Determine frequency of mating
- Calculate gestation time
- Determine number of pups per litter
- Determine size at parturition
Goals in combination with age data:
- Determine age at first maturity by sex
- Calculate number of pups produced over the lifetime of the individual (reproductive potential)