Researchers find rare fish in Southeast Alaska

10/25/06

Juneau, Alaska

In April of 2003, NOAA Fisheries scientists conducting research with a mid-water trawl in Alaska found something unexpected inside their net: a juvenile bigmouth manefish, Caristius macropus.

After reviewing preserved specimens and the scientific literature of manefish from Alaska, Alaska Fisheries Science Center researchers believe the new find expands the biological knowledge of the rare fishes. More importantly, the find indicates a new habitat for the species and describes a wider distribution than previously known.

Manefish, which weren't known to science until 1903, appear unusual because they have a "mane" - a fragile, elongate dorsal fin originating on the head - and a fleshy sheath along the base of the dorsal and anal fin.

"Research cruises occasionally encounter rare fish species," said Doug DeMaster, Director of the Alaska Fisheries Science Center. "Capture of such specimens provides an opportunity to increase knowledge of their morphology, distribution and habitat."

"Manefish distribution in the North Pacific and the biology of this species and family are poorly understood," said NOAA Fisheries researcher David Csepp. "The capture of a manefish in protected inside waters could add much-needed information on the life history of this rare, poorly known family of fishes. More documented captures are needed, however, to verify southeast Alaska inside waters as a new habitat for this species. This is why publication of the capture and morphology of rare species is so important. While putting this find in context was not our top priority and took us a while, we are pleased to add knowledge to the body of science on a rare species."

This is not the first time an individual of this species has been netted in Alaskan waters. However, after examination of specimens and the locations where they were found, scientists at the Alaska Fisheries Science Center's Auke Bay Laboratory in Juneau and Resource Assessment and Conservation Engineering Division in Seattle believe this is the first known find in the Gulf of Alaska and in the coastal, inside waters of southeastern Alaska.

The juvenile manefish was netted in Lynn Canal north and west of Juneau at only 270 meters (about 820 feet). The research trawl was smaller than any commercial trawl, catching pounds of fish rather than tons, catching just enough for viable data while impacting the environment as little as possible.

Most of the other known Alaska bigmouth manefish specimens were collected by fishery observers in the Alaska Fisheries Science Center's North Pacific Groundfish Observer Program during mid-water commercial trawl fisheries targeting walleye pollock between 1983 and 2003. Before this find in Lynn Canal, the only bigmouth manefish collected in Alaska were from unprotected, open ocean waters near the western Aleutian islands or farther north in the Eastern Bering Sea. The largest Alaska specimen is 330 mm (about 13.5 inches). The Lynn Canal specimen is 152 mm (about 6 inches) and is the smallest of the 14 preserved Alaska manefish.

Two manefish have been reported caught off British Columbia, one near the Queen Charlotte Islands and another near Vancouver Island. Both of these were found in deep, open waters.