Vertical Distribution, Diet, and Reproduction of the Velvet Dogfish in Waters off Hawaii
A study on the velvet dogfish (Zameus squamulosus) shark species in the Hawaiian longline fisheries.
The velvet dogfish (Zameus squamulosus) is a wide-ranging species of shark that is captured as bycatch in bottom and pelagic longline fisheries in the Atlantic, Pacific, and Indian oceans from near the surface to depths as great as 2000 m. Here we provide information on the vertical distribution, diet, and reproduction of the velvet dogfish based on examination of 21 specimens captured in Hawaiian longline fisheries. Only females (576–839 mm in total length [TL]) were captured in waters off Hawaii and this finding may indicate sexual segregation for this species. All individuals were captured in epipelagic and pelagic oceanic waters at estimated target hook depths between 24 and 400 m. Stomach and intestinal contents consisted of squid, fish, and shrimp. Females were immature at 576–729 mm TL and mature at 715–839 mm TL. Mature females contained 6–10 uterine eggs and 4–8 embryos. On the basis of results from a pregnant female (715 mm TL), the size of ovarian ova, and the width of the uteri of slightly larger individuals, female maturity was estimated to occur at 715–730 mm TL. No reproductive seasonality was detected; however, our sample size was small. Reproductive data from published records for size of near-term embryos and smallest free-swimming specimens with umbilical scars indicate that size at birth is 245–270 mm TL.
Gerald L. Crow, Bradley M. Wetherbee, Robert L. Humphreys Jr., and Richard Young. Published in the Fishery Bulletin 116(2).