Live Pacific Halibut Projects in the United
States, Year 2001
Compiled by
Loh-Lee Low (email: Loh-Lee.Low@noaa.gov) Alaska Fisheries Science
Center, NMFS, Seattle
1. Commercial Culture Activity
There was no commercial culturing activity of Pacific Halibut in the west coast
of the United States and Alaska.
There were, however, some live Pacific halibut projects conducted for research
purposes in the U.S. These research activities were not focused on breeding and
propagation of the species; rather, they were conducted for diet, growth, mortality, habitat, and effect of fishing and tagging studies. The following
summaries are descriptions of the projects.
2. Research with Live Pacific Halibut at Alaska Fisheries Science Center (National Marine Fisheries Service) in Newport, Oregon (Reported by
Al Stoner, (email: Al.Stoner@noaa.gov))
Research emphasis with Pacific halibut in the Fisheries Behavioral Ecology
Program during 2001 was placed on age-0 and age-l fish. Age-0 fish (~500 individuals, 3-7 cm TL) were collected in August 2001 in near-shore waters of
Kodiak and shipped live to Newport with zero mortality. Age-l fish result from
fish grown out from collections made in 2000. Approximately 20% of Program
effort was devoted to research with live halibut in 2001 in the following
research themes:
Habitat
It is increasingly apparent that groundfish depend upon certain habitat conditions, particularly during the first year of life. Laboratory
experiments begun during the latter part of 2000 to determine habitat requirements sediment preferences of
age-0 halibut (3 to 15 cm) have been completed and two papers for publication are currently in draft form, to be
submitted early in 2002. Tentative titles are provided below. Sediment preferences shift rapidly with fish size within the first few months of life. These
preferences are related to burial capabilities and shelter, also tested in the
laboratory. Laboratory experiments were combined with data from beam trawl
collections made over a six-year period in Kachemak Bay (AK) to provide field verification of the associations observed in the laboratory.
We have also learned that age-0 halibut have a very strong affinity for physical structure on the bottom provided by sand waves, bivalve shells, and
sessile invertebrates such as sponges and bryozoans. One paper is currently in
draft on this subject (see below). Preliminary predation experiments in laboratory mesocosms conducted during 2001 revealed that survivorship of
small halibut increases substantially with physical structure. The same was not
true for rock sole. These experiments will be expanded in 2002. Because of
behavioral associations and increased survivorship, we hypothesize that habitats with structure provide important
nursery sites for halibut in the Bering Sea and Gulf of Alaska.
Growth
Experiments were initiated in the summer 2001 to examine growth rates of age-0 halibut over a temperature range
of 2-15°C. Growth was close to zero at 2°C and increased with temperature to 10°C, while growth rates at
10°C and 15°C were relatively similar. Locomotion and feeding motivation
were also associated with temperature. We are currently testing for the ability
of compensatory growth in fish. We hypothesize that low summer temperature
in the Bering Sea may have a significant effect on the contribution of Bering
Sea nurseries to the halibut population because of effects on growth and recruitment. The fish from these studies will be used in a collaborative effort
being planned with the IPHC to examine relationships between temperature, growth rate, and otolith microchemistry.
Bait Detection
Many factors affect the attraction and capture of halibut and other species on long-line gear (in stock assessment surveys and in the
fishing industry). Laboratory investigation of chemosensory abilities in adult
halibut (70-90 cm) were begun in 2000 to test different bait types (e.g., squid,
herring, and salmon) and halibut feeding history. Methods for experiments with
halibut have been developed, and we have initiated new experiments with age-1 halibut to explore the development of olfactory capabilities.
Bycatch Stress
The first paper from the Fisheries Behavioral Ecology Program on capture-related stress was published during 2001 (see below). The
levels of stress and mortality in halibut (70-85 cm) that resulted from simulated
capture by hooking or towing in a net, followed by exposure to elevated seawater and air, were determined in the laboratory. Exposure to 16°C
temperature magnified stress, with mortality at 33% for hooked fish and 78%
for towed fish. These deaths occurred up to 30 days after experimental treatment, suggesting that delayed mortality needs to be considered in any
study of by catch mortality. The results showed that seasonal increases in
temperature associated with thermoclines and deck conditions have the potential for markedly increasing mortality of halibut that might otherwise
survive capture and release.
Halibut collected in 2000 are now approaching two years old and 25-35 cm TL. These fish will be used to initiate new experiments on stress associated
with trawl capture (e.g., air exposure, etc.) when they reach larger size in 2002.
Citations:
Davis, M.W. and B.L. Olla. Stress and delayed mortality induced
in Pacific halibut by exposure to hooking, net towing, elevated sea water temperature and air: implications for management of bycatch. N. Amer. J. Fish.
Manag. 21:725-732.
Stoner, A.W. and A.L. Abookire. Sediment preferences
and distribution of young-of-the-year Pacific halibut in an Alaska nursery. (in
draft)
Stoner, A.W. and R.H. Titgen. The role of biological and bedform
structures in habitat choices made by Alaska flatfishes: potential for fishing
gear impacts. (in draft)
Stoner, A.W. and M.L. Ottmar. Relationships between size-specific sediment
preferences and burial capabilities in juveniles of two Alaska flatfishes. (in
prep.)
Current holdings of live Pacific halibut in Newport
(approximate numbers as of 9 January 2002):
Age-0 (2001 year class): 100
Age-1 (2000 year class): 60
3. Research with Live Pacific Halibut at Northwest Fisheries Science Center
(National Marine Fisheries Service) in Manchester, Washington (Reported by
Ken Massee, (email: Ken.Massee@noaa.gov))
Halibut tagging study
In summer of 2001 a pilot study conducted by IPHC researchers investigating tag location and retention was done using adult
Pacific halibut at the Manchester field station. Placement and retention of PIT
(Passive Integrated Transponder) tags were evaluated over a 2 month period.
The goal of the study was to develop tagging methods, using captively held
halibut, and use the developed methodology to apply to wild fish.
Nutrition research
Digestibility of various diets was investigated on several fish species including Pacific halibut at the Manchester field station. This study is
part of a masters thesis by Kate Guthrie at the University of Washington, School of Fisheries. Results will be published in fulfillment of her degree
requirements.
Current holdings of live Pacific halibut in Manchester
Adult halibut: 45
