Maturing giant grenadier eggs from a histology slide.

Although giant grenadier have generally not been fished commercially, they are frequently taken incidentally in the sablefish longline fishery. NOAA trawl surveys in Alaskan waters indicate that giant grenadier are the most abundant species in terms of biomass at depths 400-1,000 m on the continental slope, and therefore are an important component to the slope ecosystem. Very little is known about grenadier life history, including basic biology such as their age and size of maturity, the number of eggs they spawn (fecundity), and the time of year they release their eggs. More knowledge about grenadier biology will enhance their management in the future.

Maturing giant grenadier eggs.

Giant grenadier ovaries and otolith samples were collected on the Alaska Fishery Science Center Alaska sablefish longline survey to determine fecundity, size- and age-at-maturity, and to describe their ovarian development. Ages from otoliths indicate maximum age of 58 years, but these ages have not been validated. Reproductive stages that have been determined from histology slides are currently being compared to onboard visual stages to develop an accurate maturity stage scale for giant grenadier that can be used in the field. Histology is currently being analyzed for the development of maturity-length and maturity-age relationships.

Contact:
Cara Rodgveller
Auke Bay Laboratories
Alaska Fisheries Science Center, NOAA Fisheries

Ted Stevens Marine Research Institute
17109 Pt Lena Loop Rd
Juneau AK 99801
Cara.Rodgveller@noaa.gov