Sablefish Longline Survey Completed
Personnel from the ABL and the Centers RACE Division recently completed
the twenty-third annual longline survey of the upper continental slope
of the GOA of Alaska and eastern Bering Sea (EBS). The survey consisted
of six legs of 12-14 days each from the Bering Sea to Dixon Entrance in
Southeast Alaska and one special experiment. One hundred fifty-three longline
hauls (sets) were completed between 2 June and 3 September 2001 by the
chartered fishing vessel Ocean Prowler. Sixteen km of groundline containing
7,200 hooks baited with squid were set each day.
Sablefish (Anoplopoma fimbria) was the most frequently caught species,
followed by giant grenadiers (Albatrossia pectoralis),
Pacific cod (Gadus macrocephalus), and arrow-
tooth flounder (Atheresthes stomias). A total
of 94,033 sablefish were caught during the survey. A total of 4,170 sablefish,
626 shortspine thornyhead (Sebastolobus alascanus), and 128 Greenland turbot
(Reinhardtius hippoglossoides) were tagged and released during the survey.
Length-weight data and otoliths were collected from approximately 2,500
fish. Sperm whales (Physeter macrocephalus) and killer whales (Orcinus
orca) took fish from the longline at several stations as in previous years.
Data have been processed and reports are being prepared for the North Pacific
Fishery Management Council.
By Chris Lunsford
Tags From Seamount Sablefish Appear in Commercial Fishery
Tagging of sablefish near seamounts began in 1999 in an effort to determine
the extent, if any, of emigration from and exchange of sablefish between
seamounts in the Northeast Pacific Ocean. To date, about 2,700 tagged
fish have been released on five seamounts: Giacomini, Surveyor, Pratt,
Welker, and Dickens. Eight tags have been recovered in the commercial
fishery so far, verifying that seamount to continental slope migration
does occur. Although a number of tagged fish have been recaptured on the
same seamounts where they were released, none have been recovered on different
seamounts. Four of the slope recoveries were of fish tagged on Giacomini
Seamount in 1999. Three of these were recovered in the central Gulf of
Alaska between long. 147º and 149ºW. Time at liberty ranged from 329 to
452 days. Recovery data for the fourth Giacomini-area tagged fish were
missing. Recoveries of fish released on Surveyor Seamount were made in
the western, central, and eastern Gulf of Alaska . Time at liberty ranged
from 300 days for the central gulf recovery to nearly 2 years for the eastern
gulf recovery. One fish tagged on Welker Seamount in 2000 was recovered
283 days later in the central gulf.
By Nancy Maloney.
Trawl Survey Design for Rockfish Studied
ABL staff are examining ways to improve trawl survey design for slope rockfish,
including methods for efficiently increasing sample size and precision.
One way to increase sample size with minimal effort is to collect hydroacoustic
signals, both during trawl hauls and between trawls. Raw data were collected
during the AFSC Gulf of Alaska groundfish trawl survey in summer 2001 with
a Simrad ES60 echosounder. On the chartered fishing vessel Morning Star,
a split-beam transducer was used, and data were collected during and between
trawls. On the chartered fishing vessel Vesteraalen, a single-beam transducer
was used, and data were collected only during trawl hauls. Global Positioning
System (GPS) coordinates and time-stamps were recorded with the raw data.
The data collected for the entire survey are on 55 CDs and will be analyzed
as part of a doctoral dissertation at the University Alaska Fairbanks,
Juneau Center for Fisheries and Ocean Sciences.
By Jon Heifetz.
Multibeam Echosounder Surveys Conducted in Gulf of Alaska
Portions of the seafloor in the Gulf of Alaska were surveyed using multibeam
echosounder technology during summer 2001 aboard the chartered survey vessel Davidson. The surveys were designed to enable production of detailed bathymetric
and habitat maps in support of ongoing research on the effects of fishing
gear on seafloor habitat, identification of Habitat Areas of Particular
Concern, and stock assessment of rockfish. In cooperation with the ADF&G,
the surveys were conducted off Southeast Alaska in the vicinity of Cape
Ommaney and in the central GOA near Portlock Bank. The Cape Ommaney site
is the locality of extensive colonies of red-tree coral (Primnoa willeyi).
The Portlock Bank site is an important commercial fishing area. Approximately
1,200 km2 of seafloor were mapped during 12 survey days. To aid in habitat
classification, dives were conducted using the submersible Delta to
collect video data of the seafloor. Benthic grab samples were also collected in the vicinity of the dive
By Jon Heifetz.
quarterly Jul-Sept 2001 sidebar
Auke Bay Lab