POWELL, M/L; KAVANAUGH, S/I; SOWER, S/A; University of New Hampshire, Durham; University of New Hampshire, Durham; University of New Hampshire, Durham: Seasonal Gonadal Development in the Atlantic Hagfish, M. glutinosa

Hagfish are an important part of the benthic community in the deep ocean, consuming decaying animal material and recycling nutrients. In recent years they have become the focus of a growing fishery in the North Atlantic despite a lack of basic knowledge on their growth and reproduction. There are currently no regulations on the fishery despite an increase of hagfish landings, increasing from 2 million lbs in 1993, to 12 million lbs in 2000. The goal of our studies is to further understanding of growth and reproduction by testing the hypothesis that M. glutinosa exhibit seasonal reproductive growth. The specific objective of this study was to determine gonadal development by histological analysis in relation to maturity based on weight and length. M. glutinosa were trapped at a depth of 100-150m, 25 miles off the New Hampshire coast. Hagfish have no external secondary sexual characteristics that can be used for sex determination, therefore, identification requires histological examination of gonad tissues. Female hagfish with large eggs (15mm+) were identified in the July 2001 and 2002 samples. In January 2002 male tissue was observed in the posterior region of over 90% of the hagfish between 35-45cm total length and female tissue was present in the anterior portion. It is not known if these hermaphroditic hagfish were functional. Hagfish containing only male tissue were rare and were always identified in the 35-45 cm size class. Hagfish greater than 45 cm in length contained only female gonad tissue. These data support the hypothesis of a seasonal reproductive cycle in M. glutinosa with spawning occurring in mid- to late summer. Supported by UNH/UME NOAA Sea Grant R/FMD-168.