Egg Deposition in Sponge Bed and Deepwater Coral Habitats by Bigmouth Sculpin (Hemitripterus bolini) and Goldeneye Snailfish (Allocareproctus unangas) in Alaska with Descriptions of Eggs

In this talk we present two examples of marine fishes that deposit eggs in or attached to benthic invertebrates in Alaska and provide descriptions of the eggs. In both cases, late stage embryos were dissected from eggs for examination, then cleared and stained to obtain counts of meristic features. Bigmouth sculpin, Hemitripterus bolini, is a cottoid fish in the family Hemitripteridae. Female H. bolini deposit their eggs into four species of sponges we collected in the Gulf of Alaska and Bering Sea at depths of 108–522 m: barrel sponge (Halichondria lambei), clay-pipe sponge (Aphrocallistes vastus), boot sponge (Acanthascus dawsoni), and tree sponge (Mycale loveni). Mean diameter of H. bolini eggs is 4.73 mm, and the range is relatively large (3.81–5.40 mm). Eggs are usually deposited in an adhesive mass; eggs adhere to each other, but not to the inner surface of the sponges. Egg surfaces may be somewhat flattened, but most are spherical.  The progression of developmental stages of eggs collected in spring and winter when hatching eggs and newly-hatched larvae were found suggests an incubation duration of at least 10 months.

Four unusual masses of adhesive fish eggs surrounding limbs of the octocoral Primnoa sp. were collected in Seguam Pass in the Aleutian Island Archipelago at a depth of 419 m. The eggs contained embryos in the flexion stage of development. Counts of meristic features identified the eggs as those of Allocareproctus unangas Orr and Busby, a newly described snailfish species. Egg masses of A. unangas are nearly spherical in shape. Diameters of the egg masses measured 34.0–41.0 mm along the deposition axis and 36.3–42.5 mm along the perpendicular axis. Live coloration of the eggs varied from beige to light rose; the stalks of Primnoa sp. were a bright reddish orange. One mass contained 267 eggs. Individual eggs of A. unangas are slightly aspherical and noticeably flattened or have a slightly cup-shaped depression on the outer chorion at points of contact with adjacent eggs. Mean egg diameter is 5.7 x 6.3 mm (range 5.2–6.0 x 5.8–6.8; n = 241). This represents the first report of snailfishes of the genus Allocareproctus, and of liparids other than those in the genus Liparis, depositing eggs outside of lithodid crabs. We conclude that sponge grounds and areas inhabited by deepwater corals constitute essential fish habitat for these species.