U.S. North Pacific Groundfish Observer Program
Training, Briefing, and
During the third quarter of 2002, 194 observers were trained, briefed,
and equipped for deployment to fishing and processing vessels and shoreside
plants in the Gulf of Alaska, Bering Sea, and Aleutian Islands. They sampled
aboard 227 fishing and processing vessels and at 14 shoreside processing
plants. These observers were trained or briefed in various locations.
The University of Alaska Anchorage Observer Training Center trained 25
first time observers and briefed another 59 observers with prior experience.
The AFSC Observer Program in Seattle trained 20 first-time observers and
briefed another 67 observers who had prior experience. Twenty-three observers
were excused from briefing because they had just completed a cruise successfully
and were returning immediately to the field. The third quarter 2002 observer
workforce thus comprised 23% new observers and 77% experienced observers.
The Observer Program conducted a total of 110 debriefings during the second
quarter of 2002. Thirty-three debriefings were held in Anchorage, 1 in
Kodiak, and another 75 in Seattle.
NMFS issued a proposed rule on 16 September 2002 that would extend the
Observer Program through 2007 and amend the current regulations implementing
the Observer Program. The existing regulations for the Observer Program
would otherwise expire at the end of this year. (See AFSC Quarterly Report,
April-May-June 2002 issue, for details.) After the public comment period
ends on 11 October 2002, staff will be working on the Final Rule to implement
the proposed regulatory changes with a planned effective date of 1 January
The Observer Advisory Committee (OAC) of the NPFMC met 18-19 July 2002
at the AFSC to discuss ways of restructuring the Observer Program to better
meet the needs of NMFS, the fishing industry, observer provider companies
and observers themselves. Conclusions drawn from the OAC discussion are
- The funding mechanism for the Observer Program dictates to a large degree,
the overall structure of the Observer Program and its service delivery
model (SDM). Therefore, creating real change in the Observer Program must
first involve changing the funding arrangements.
- Full Federal funding of the Observer Program should be sought by NMFS
and the Council as their preferred plan with a blend of Federal funding
and fee collections as a secondary option.
- The goal for restructuring the Observer Program should be collection
of better scientific data to support fishery management rather than eliminating
the conflict of interest inherent in the current Observer Program SDM.
To achieve this goal, changes need to be made to the observer coverage
requirements with particular attention to the vessels requiring 30% observer
coverage and those vessels that carry no observers.
By Bob Maier.
Age and Growth Program
Estimated Gulf of Alaska production figures for January to September 2002.
Northern rock sole
Southern rock sole
Pacific ocean perch
Light dusky rockfish
Total production figures were 23,057 with 5,880 test ages and 127 examined
and determined to be unageable.
Alexander Buslov, a fishery biologist from Kamchatka, Russia, (KamchatNIRO),
visited the Age and Growth Program 11-25 September to share knowledge
concerning the ageing of teleost fish using vertebrae. Because of the
difficulty of acquiring known-age fish for age validation, the program
is looking for other methods to corroborate otolith ages. Preliminary
results indicate that vertebrae can be useful in supplying corroborative
evidence in some species.
By Dan Kimura.
Status of Stocks and
Multispecies Assessment Program
Atka Mackerel Tagging
The fishing vessel Pacific Explorer was chartered from 10 June to 9 July
2002 for tag and release studies of Atka mackerel in the Seguam Pass and
Tanaga Pass areas of the Aleutian Islands, Alaska. The cruise represents
the third consecutive year of work by the AFSC on Atka mackerel in Seguam
Pass and the first year of work in Tanaga Pass. The objective of these
studies is to determine the efficacy of trawl exclusion zones as a management
tool to maintain prey abundance and availability for Steller sea lions
at local scales. The purpose of the Pacific Explorer cruise in June-July
2002 was to tag and release Atka mackerel inside and outside the trawl
exclusion zones in Seguam and Tanaga Passes. Trawl exclusion zones were
established around sea lion rookeries as a precautionary measure to protect
critical sea lion habitat, including local populations of prey such as
Atka mackerel. Localized fishing may affect Atka mackerel abundance and
distribution near sea lion rookeries. Tagging experiments are being used
to estimate abundance and movement between areas open and closed to the
Atka mackerel fishery.
A feasibility study was conducted in 1999 at Seguam Pass. In summer 2000,
approximately 8,000 tagged Atka mackerel were released in Seguam Pass,
and in 2001 approximately 1,000 were released during a truncated cruise.
Recovery of tagged fish is supplied by the fishery in the open areas outside
the trawl exclusion zone. Recoveries in the closed areas are provided
by chartered recovery cruises.
Approximately 28,000 fish were tagged with plastic T-bar (spaghetti)
tags in the Seguam Pass area; 21,000 were released inside the trawl exclusion
zone, and 7,000 were released outside. Approximately 14,520 were tagged
near Tanaga Pass 8,520 were released inside the trawl exclusion zone
and 6,000 were released outside. In addition to T-bar tags, several Atka
mackerel were tagged with electronic archival tags, which record depth
and time continuously. The data can be downloaded from tags recovered
from fish caught by commercial vessels or AFSC charters. A total of 200
Atka mackerel were tagged with archival tags in the Seguam Pass area
60 inside and 140 outside the trawl exclusion zone. A total of 200 fish
were tagged with archival tags in the Tanaga Pass area 120 inside and
80 outside the trawl exclusion zone.
Tagged fish were randomly selected and placed into tanks to assess mortality
rate following capture, handling, and tagging. Experiments were conducted
over two different durations, 48 hours and 4 days (96 hours). Sixteen
experiments were conducted over the course of the cruise. Of the 315 fish
included in the experiments, a total of 13 died, for a mortality rate of
In addition to tagging and releasing Atka mackerel, AFSC scientists collected
length-frequency data and took biological samples that will provide information
on age, growth, reproductive condition and diet. Otoliths, gonads, and
stomachs were collected from 10 males and 10 females from every successful
haul for a total of 210 fish of each sex. In addition to these samples,
approximately 30 whole fish of each sex were frozen for future proximate
analysis (fat, protein, water, and ash content). These data provide information
on the caloric value of Atka mackerel as prey for Steller sea lions.
AFSC scientists also collected physical oceanographic data with the goal
of examining the water column characteristics of Atka mackerel habitat.
Continuous temperature and salinity data were collected with a sensor
plumbed to receive water from near the surface. Temperature-depth data
were also collected with a microbathythermograph (MBT) mounted on the net
used to catch fish for tagging.
By Libby Logerwell.
Fishery Interaction Experiment
REFM scientists participated in a fishery interaction experiment which
was completed between 14 August and 5 September off the east side of Kodiak
Island in the Gulf of Alaska. The cruise was part of an ongoing collaborative
effort between RACE and REFM scientists. The work is part of a larger
program designed to evaluate the effect of commercial fishing activity
on the prey availability of walleye pollock and other forage fish species
to endangered Steller sea lions. For more information on this cruise see
the complete report in the RACE/MACE section.
By Chris Wilson and Anne Hollowed.
Stock Assessment Modeling Changes:
An application of a NOAA Fisheries Toolbox stock assessment model to Aleutian
Islands Atka mackerel was presented for review at the September Bering
Sea/Aleutian Islands groundfish plan team meetings. The Stock Assessment
Toolbox is the result of an initiative by the NMFS Office of Science and
Technology dating back to 1998 and has been adopted in a number of stock
assessment settings on the U.S. East Coast. The Toolbox provides a user-friendly
interface which facilitates construction of stock assessment models with
AD Model Builder software and provides many improvements. The conceptual
model is similar to the stock synthesis application first developed for
Aleutian Islands Atka mackerel in 1991. Motivation for changing the software
is primarily to use improved algorithms for estimation and better evaluations
of assessment uncertainty. A key feature is that the Toolbox readily calculates
standard errors for model output. The change from the stock synthesis
application to the Toolbox application provides more flexibility in the
estimation of the survey catchability coefficient, selectivity, and natural
mortality. Previously, these model parameters were difficult to explore
in stock synthesis. The Bering Sea/Aleutian Islands Plan Team concurred
with the development and recommendation to use the Toolbox stock assessment
model for this years Atka mackerel stock assessment.
By Sandra Lowe and Jim Ianelli.
Stock Assessment Modeling Changes: Arrowtooth Flounder
The arrowtooth flounder stock assessment for the year 2003 fishing season
in the eastern Bering Sea and Aleutian Islands region will be conducted
with a change of implementation software. The AD Model Builder language
is used to rewrite the established population dynamics model (used since
1995) in C++ computer language. The model is a length-based approach where
survey and fishery length composition observations are used to calculate
estimates of population numbers-at-age by the use of a length-age (growth)
Motivation for changing to the AD Model Builder language comes primarily
from a past attempt at modeling the shelf and slope survey population estimates
which indicate that females are consistently estimated to be in higher
abundance than males. Females were also found in higher proportions in
the Gulf of Alaska from triennial surveys conducted from 1984 to 1996.
This information was incorporated into the synthesis model by adjusting
the size composition data inputs by the sex ratio proportion observed in
shelf and slope trawl surveys and fishery data. Unsatisfactory low estimates
of male selectivity were obtained from these model runs which had the undesirable
effect of artificially increasing population estimates. These results
were due to the assumption of equal proportions of males and females implicit
in the synthesis model. The AD Model software allows more flexibility
in modeling sex-specific natural mortality. The stock assessment for the
2003 fishing season will attempt to provide separate estimates of natural
mortality for males and females.
By Tom Wilderbuer.
Adak Island Rockfish
Figure 1. A shortraker rockfish photographed during the REFM Divisionís Adak
Island rockfish submersible study.
REFM scientists conducted a study of shortraker (Sebastes borealis )and
rougheye (Sebastes aleutianus) rockfish near Adak Island, Alaska, with
the submersible Delta during 27-30 July. Moss Landing Marine Laboratory
assisted with the data collection. The goal of the study was to use line
transects to estimate shortraker and rougheye densities and characterize
habitat. A total of 12 dives and 39 transects were completed during the
4 days of sampling. Each dive consisted of approximately three 20-minute transects during which an observer collected data on species identification,
distance of fish from submersible, habitat type, and size of specimen.
The dive locations were identified as shortraker and rougheye habitat from
historical bottom trawl research surveys. Line transects were then conducted
at depths of 300-350 m. The four sampling days were divided between the
north and south side of the Aleutian Islands. A variety of habitats were
encountered, ranging from flat, sandy areas to steep rocky outcrops. An
example of the latter type of habitat was the eastern portion of Adak Canyon
(Fig. 1 above), where three dives were conducted. Each dive was videotaped using
two cameras, and these tapes will be analyzed in order to estimate rockfish
densities within the different habitat types.
By Paul Spencer and Rebecca Reuter.
quarterly July-Sept 2002 sidebar
Auke Bay Lab