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Potential interactions between commercial fishing vessels and Steller's and spectacled eiders in Alaska.

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Abstract

Spectacled eiders breeding in Alaska were listed as threatened in 1993, followed by the listing of the Alaska-breeding population of Steller’s eider in 1997. Primary reasons for concern for both eider species were the near disappearance of the species from the Yukon-Kuskokwim Delta and the low numbers of breeding birds on the North Slope. Causes of the declines in the Alaska-breeding birds are unknown. The larger Russian component of both eider species is more abundant and mixes with the Alaska breeding population during the late-summer molt and on the wintering grounds. Spectacled eiders molt in both northwestern Alaska and eastern Siberia, and have been only recently discovered wintering in leads in the pack ice south of St. Lawrence Island. Steller’s eiders move to locations in southwestern Alaska during the summer molt, and the mixture of Asian and Alaskan breeding populations winters from the eastern Aleutian Islands to Lower Cook Inlet and Kodiak Island, with Izembek Lagoon being the center of molting and wintering abundance. The potential impacts of fisheries on these eider species has been unknown. The current project was undertaken to describe which commercial fisheries occur in space and time near habitat used by the threatened Alaska components of the two eider populations. Steller’s and spectacled eiders could be envisioned to interact with fisheries in four possible ways: 1) entanglement, 2) competition for prey, 3) collisions or other interference with fishing vessels or fishing-related structures, and 4) habitat exclusion or avoidance because of fishing-related activity. Entanglement of Steller’s and spectacled eiders has not been reported to be a problem to date, but effort distributions were investigated as one way to get a handle on the potential risk from this source. Prey competition is unlikely because commercial fisheries do not directly take the shallow-water mollusk and crustacean species in the Steller's eider diet. Vessel strikes have been reported by observers and are investigated in this report. Habitat exclusion is difficult to quantify, but knowledge of nearby fishing effort distributions is essential for a first step. Seventeen records of collisions between fishing vessels and Steller's eiders appeared in fisheries observer reports which also had reliable time-of-day information, along with nineteen king eider strikes. Plotting the date and time of day of these observations revealed that all Steller's eider collisions except one had occurred at night during the winter and spring, along with all nineteen of the King eider observations. The collisions occurred in light levels well below astronomical twilight. As a result, the vessel collision problem is framed by the annual light regime for further analyses. Combining the presence of substantial numbers of eiders along the Alaska peninsula with the annual light regime, the time period September 1 through April 30 likely represents the greatest risk of collisions between eiders and fishing vessels. Between May 1 and August 30 there is little or no deep darkness in these areas and bird strikes are highly unlikely. Commercial catch records were examined from ADFG fish tickets and NMFS observers to determine the location and time of catch for salmon, herring, shellfish and groundfish fisheries. Very little fishing effort occurs near Spectacled eider critical habitat so detailed analysis of fishing distributions was organized around Steller's eider distributions. In addition to active fishing operations, there is potential for vessel collisions and habitat exclusion when vessels are offloading, anchored up, or transiting to or from fishing grounds. No direct records are kept of these activities. However, port of landing can serve as proxy for fishing-related activities such as offloading catch, fueling and staging areas. For the September through April period, Kodiak and Dutch Harbor/Unalaska were by far the busiest fishing ports, with landings dominated by shellfish and groundfish vessels. Along the Alaska Peninsula, King Cove was ranked 5th, and Port Moller 7th for the number of September through April landings. However, Port Moller landings consisted of late-season salmon, almost all in the early part of September. There were no other landings reported from the north Alaska Peninsula during the September through April period. The locations, timing, and gear used in Pacific herring fisheries are described but nearly all of the fishing effort occurs during the well-lit period of the year when vessel collisions are unlikely. Pacific herring fisheries occur at herring spawning locations throughout the coastal migration route of Steller's eiders. Very little Dungeness crab are harvested from areas near Steller's eider critical habitat; in addition, what Dungeness fishing effort occurs is mostly during the well-lighted summer months. Shrimp landings have been minimal in recent years. Scallop harvests occur offshore in the Bering Sea, but most effort occurs during the summer months. Bristol Bay and the Red King Crab savings area are closed to scallop dredging. The Bristol Bay red king crab fishery, with its brightly lit vessels, could well have the most potential for interactions with late-migrating eiders or overwintering eiders while anchored up or transiting nearshore areas. This fishery has occurred from late October through early December in recent years. Salmon fisheries occur during the summer period with minimal periods of darkness, so that there is very low potential for eider-vessel collisions. No eider collisions with salmon fishing vessels have been reported. Although gillnet entanglements with Steller's eiders have never been reported, other diving seabirds do become entangled in gillnets, so it is conceivable that there is some entanglement risk. Drift gillnet fishing occurs along the north Alaska Peninsula, primarily from Port Moller to Port Heiden. The largest amount of set gillnet effort near the general Steller's eider molting/summering areas occurs at Nelson Lagoon. During the spring migration, no groundfish effort occurred in Bristol Bay when it was open to trawling from April 1 to June 15. Bristol Bay is closed to groundfish trawling during the fall Steller's eider migration. The only groundfish fishing found near areas used by Steller's eiders was the yellowfin sole fishery along the northern shore of Kuskokwim Bay. However, this fishery occurs in May, past the time when astronomical twilight has disappeared from the fishing grounds so that the risk of vessel collisions is minimal. Eider-vessel collisions appear to involve bright lights during periods of darkness, so that it may be possible to detect the distribution of fishing vessels at sea using low-light satellite-borne sensors. NOAA archives of DMP/OLS satellites, which have been used to detect squid fleets at sea, were screened for cloud free periods when Bering Sea fishing fleets might be detected. Among other possibilities, the opening of the 1997 Bristol Bay red king crab fishery on November 1 coincided with a satellite pass over the fishing grounds when cloud cover was less than 10%, providing an ideal opportunity to determine whether crab vessel lights can be detected. However, time constraints precluded examining the imagery from that date. Further advancements in our knowledge of eider migration routes, from telemetry and other sources, could be used to further narrow the scope of analyses of potential conflict between fishing vessels and eiders. Observer records of vessel-eider collisions provided by far the most valuable information in this analysis. However, the seabird collision data is obtained anecdotally in field notes of fishery observers whose primary mission is to estimate groundfish and shellfish catches. A more dedicated, directed, effort to document seabird encounters would greatly enhance our knowledge of how fisheries and seabirds interact.
POTENTIAL INTERACTIONS BETWEEN COMMERCIAL FISHING
VESSELS AND STELLER’S AND SPECTACLED EIDERS IN ALASKA
By
Fritz Funk
Final Report
Federal Aid Project E-5-HP
Alaska Department of Fish and Game
Division of Commercial Fisheries
P.O. Box 25526
Juneau, AK 99802-5526
June 2008
_________________________
1The Regional Information Report Series was established in 1987 to provide an information access
system for all unpublished divisional reports. These reports frequently serve diverse ad hoc
informational purposes or archive basic uninterpreted data. To accommodate timely reporting of
recently collected information, reports in this series undergo only limited internal review and may
contain preliminary data; this information may be subsequently finalized and published in the
formal literature. Consequently, these reports should not be cited without prior approval of the
author or the Division of Commercial Fisheries.
NOTE: This document is
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making black and white copies,
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POTENTIAL INTERACTIONS BETWEEN COMMERCIAL FISHING
VESSELS AND STELLER’S AND SPECTACLED EIDERS IN ALASKA
By
Fritz Funk
Final Report
Federal Aid Project E-5-HP
Alaska Department of Fish and Game
Division of Commercial Fisheries
P.O. Box 25526
Juneau, AK 99802-5526
June 2006
_________________________
1The Regional Information Report Series was established in 1987 to provide an information access
system for all unpublished divisional reports. These reports frequently serve diverse ad hoc
informational purposes or archive basic uninterpreted data. To accommodate timely reporting of
recently collected information, reports in this series undergo only limited internal review and may
contain preliminary data; this information may be subsequently finalized and published in the
formal literature. Consequently, these reports should not be cited without prior approval of the
author or the Division of Commercial Fisheries.
TABLE OF CONTENTS
LIST OF TABLES.....................................................................................................................................
LIST OF FIGURES...................................................................................................................................
EXECUTIVE SUMMARY.....................................................................................................................
INTRODUCTION...................................................................................................................................
CRITICAL HABITAT AND MIGRATION ROUTES............................................................................
Steller’s Eider
.......................................................................................................................................................
16
Spectacled Eider
.......................................................................................................................................................
16
REPORTED VESSELS STRIKES BY EIDERS....................................................................................
SOURCES OF FISHING EFFORT AND DISTRIBUTION INFORMATION......................................
Commercial Catch Records
.......................................................................................................................................................
18
Satellite Low-Light Sensors
.......................................................................................................................................................
18
DISTRIBUTION OF FISHING ACTIVITY BY PORT OF LANDING................................................
DISTRIBUTION OF FISHING EFFORT NEAR STELLER’S AND SPECTACLED EIDER
CRITICAL HABITAT AND MIGRATION ROUTES...........................................................
Herring Fisheries
.......................................................................................................................................................
20
Shellfish Fisheries
.......................................................................................................................................................
21
Dungeness Crabs ..................................................................................................................21
Shrimp Fisheries ..................................................................................................................23
Weathervane Scallops ..........................................................................................................24
Red and Blue King Crab Pot Fisheries ................................................................................26
Salmon Fisheries
.......................................................................................................................................................
27
Set Gillnets.............................................................................................................................28
Drift Gillnets..........................................................................................................................28
Groundfish Fisheries
.......................................................................................................................................................
28
LITERATURE CITED ...........................................................................................................................
LIST OF TABLES
Table 1. Average number of landings for Bering Sea and northern Gulf of Alaska ports over the
period 1998-2002 by port of landing, from ADF&G fish
tickets...........................................................................................................................33
Table 2. Current Bering Sea groundfish fishery classifications and catch levels by species
group............................................................................................................................34
LIST OF FIGURES
Figure 1. Breeding (spring/summer) and winter distribution of Steller’s eiders. .................................
Figure 2. Critical habitat designated in federal regulations for Steller’s eiders in Alaska....................
Figure 3. Range map for spectacled eiders breeding in Alaska and eastern Russia..............................
Figure 4. Critical habitat designated in federal regulations for spectacled eiders in Alaska.
(Federal Register 2001)..........................................................................................................
Figure 5. Annual light regime at Cold Bay, Alaska, and reported eider strikes by species and
time of day..............................................................................................................................
Figure 6. Average (1998-2002) landings by port and fishery for September through April from
ADF&G fish ticket landing receipts in the general wintering area of Steller’s eiders...........
Figure 7. Average number of landings by day and fishery, 1998-2002, for the top 5 ranked ports,
with stippled area representing landings from May through August when eider
collisions are least likely.........................................................................................................
Figure 8. Average number of landings by day and fishery, 1998-2002, for the ports ranked 6
through 10, with stippled area representing landings from May through August when
eider collisions are least likely................................................................................................
Figure 9. Average number of landings by day and fishery, 1998-2002, for ports ranked 11
through 15, with stippled area representing landings from May through August when
eider collisions are least likely................................................................................................
Figure 10. Number of vessels by day and fishery delivering to Kodiak, averaged over 1998-
2002, from ADF&G fish ticket landing receipts....................................................................
Figure 11. Number of vessels by day and fishery delivering to Dutch Harbor, 1998-2002, from
ADF&G fish ticket landing receipts.......................................................................................
Figure 12. Number of vessels by day and fishery delivering to Sand Point, 1998-2002, from
ADF&G fish ticket landing receipts.......................................................................................
Figure 13. Number of vessels by day and fishery delivering to Akutan, 1998-2002, from ADF&G
fish ticket landing receipts......................................................................................................
Figure 14. Number of vessels by day and fishery delivering to King Cove, 1998-2002, from
ADF&G fish ticket landing receipts.......................................................................................
Figure 15. Locations of Pacific herring fisheries in central and western Alaska....................................
Figure 16. Light regime and temporal distribution of herring catch, 1990-99, at the locations of
three herring fisheries along the Steller’s eider spring migration route.................................
Figure 17. Harvests of Dungeness crabs in western Alaska, 1970–2001................................................
Figure 18. Temporal distribution of Dungeness crab harvest in western Alaska, 1997–2001................
Figure 19. Spatial distribution of average Dungeness crab harvest along the western Alaska
Peninsula, 1985–2001.............................................................................................................
Figure 20. Harvest of all species of shrimp in western Alaska, 1958–2001...........................................
Figure 21. Spatial distribution of average shrimp harvest, for the years 1985–2001..............................
Figure 22. Harvests of weathervane scallops in Alaska, 1970–2001......................................................
Figure 23. Temporal Distribution of scallop harvest, 1970–2001...........................................................
Figure 24. Spatial distribution of average scallop harvest, 1997–2001, showing areas closed to
scallop fishing.........................................................................................................................
Figure 25. Harvest of red king crabs in the Bering Sea and Aleutian Islands, 1950–2001.....................
Figure 26. Spatial distribution of average red king crab harvests in the eastern Bering Sea, 1985–
2001........................................................................................................................................
Figure 27. Timing of the Bristol Bay red king crab fishery (2001-2005 average number of
landings by day), with respect to the light regime at Cold Bay..............................................
Figure 28. Large-scale distribution of the average number of salmon setnet landings by statistical
area, 1970–2001, for southwestern Alaska.............................................................................
Figure 29. Detailed distribution of average annual setnet landings by statistical area along the
north Alaska Peninsula, 1998-2003........................................................................................
Figure 30. Distribution of average annual drift gillnet landings by statistical area along the north
Alaska Peninsula, 1998-2003.................................................................................................
Figure 31. March 2003 groundfish fleet distribution and effort by target fishery, March 31 sea ice
coverage (maximum extent), groundfish closure areas in effect for March, and March
29-April 11, 2003 Steller's eider distribution from aerial surveys (Larned 2003)..................
Figure 32. April 2003 groundfish fleet distribution and effort by target fishery, April 11 sea ice
coverage, groundfish closure areas in effect for April, and March 29-April 11, 2003
Steller's eider distribution from aerial surveys (Larned 2003)...............................................
Figure 33. May 2003 groundfish fleet distribution and effort by target fishery, May 9 sea ice
coverage, groundfish closure areas in effect for May. Also shown are the locations of
the Togiak and Goodnews Bay herring fisheries, which were ongoing in early May,
2003........................................................................................................................................
EXECUTIVE SUMMARY
Spectacled eiders breeding in Alaska were listed as threatened in 1993, followed by the listing of
the Alaska-breeding population of Steller’s eider in 1997. Primary reasons for concern for both
eider species were the near disappearance of the species from the Yukon-Kuskokwim Delta and
the low numbers of breeding birds on the North Slope. Causes of the declines in the Alaska-
breeding birds are unknown. The larger Russian component of both eider species is more
abundant and mixes with the Alaska breeding population during the late-summer molt and on the
wintering grounds.
Spectacled eiders molt in both northwestern Alaska and eastern Siberia, and have been only
recently discovered wintering in leads in the pack ice south of St. Lawrence Island. Steller’s
eiders move to locations in southwestern Alaska during the summer molt, and the mixture of
Asian and Alaskan breeding populations winters from the eastern Aleutian Islands to Lower
Cook Inlet and Kodiak Island, with Izembek Lagoon being the center of molting and wintering
abundance. The potential impacts of fisheries on these eider species has been unknown. The
current project was undertaken to describe which commercial fisheries occur in space and time
near habitat used by the threatened Alaska components of the two eider populations.
Steller’s and spectacled eiders could be envisioned to interact with fisheries in four possible
ways: 1) entanglement, 2) competition for prey, 3) collisions or other interference with fishing
vessels or fishing-related structures, and 4) habitat exclusion or avoidance because of fishing-
related activity. Entanglement of Steller’s and spectacled eiders has not been reported to be a
problem to date, but effort distributions were investigated as one way to get a handle on the
potential risk from this source. Prey competition is unlikely because commercial fisheries do not
directly take the shallow-water mollusk and crustacean species in the Steller's eider diet. Vessel
strikes have been reported by observers and are investigated in this report. Habitat exclusion is
difficult to quantify, but knowledge of nearby fishing effort distributions is essential for a first
step.
Seventeen records of collisions between fishing vessels and Steller's eiders appeared in fisheries
observer reports which also had reliable time-of-day information, along with nineteen king eider
strikes. Plotting the date and time of day of these observations revealed that all Steller's eider
collisions except one had occurred at night during the winter and spring, along with all nineteen
of the King eider observations. The collisions occurred in light levels well below astronomical
twilight. As a result, the vessel collision problem is framed by the annual light regime for further
analyses. Combining the presence of substantial numbers of eiders along the Alaska peninsula
with the annual light regime, the time period September 1 through April 30 likely represents the
greatest risk of collisions between eiders and fishing vessels. Between May 1 and August 30
there is little or no deep darkness in these areas and bird strikes are highly unlikely.
Commercial catch records were examined from ADFG fish tickets and NMFS observers to
determine the location and time of catch for salmon, herring, shellfish and groundfish fisheries.
Very little fishing effort occurs near Spectacled eider critical habitat so detailed analysis of
fishing distributions was organized around Steller's eider distributions.
In addition to active fishing operations, there is potential for vessel collisions and habitat
exclusion when vessels are offloading, anchored up, or transiting to or from fishing grounds. No
direct records are kept of these activities. However, port of landing can serve as proxy for
fishing-related activities such as offloading catch, fueling and staging areas. For the September
through April period, Kodiak and Dutch Harbor/Unalaska were by far the
busiest fishing ports, with landings dominated by shellfish and groundfish vessels. Along the
Alaska Peninsula, King Cove was ranked 5th, and Port Moller 7th for the number of September
through April landings. However, Port Moller landings consisted of late-season salmon, almost
all in the early part of September. There were no other landings reported from the north Alaska
Peninsula during the September through April period.
The locations, timing, and gear used in Pacific herring fisheries are described but nearly all of the
fishing effort occurs during the well-lit period of the year when vessel collisions are unlikely.
Pacific herring fisheries occur at herring spawning locations throughout the coastal migration
route of Steller's eiders.
Very little Dungeness crab are harvested from areas near Steller's eider critical habitat; in
addition, what Dungeness fishing effort occurs is mostly during the well-lighted summer months.
Shrimp landings have been minimal in recent years. Scallop harvests occur offshore in the
Bering Sea, but most effort occurs during the summer months. Bristol Bay and the Red King
Crab savings area are closed to scallop dredging.
The Bristol Bay red king crab fishery, with its brightly lit vessels, could well have the most
potential for interactions with late-migrating eiders or overwintering eiders while anchored up or
transiting nearshore areas. This fishery has occurred from late October through early December
in recent years.
Salmon fisheries occur during the summer period with minimal periods of darkness, so that there
is very low potential for eider-vessel collisions. No eider collisions with salmon fishing vessels
have been reported. Although gillnet entanglements with Steller's eiders have never been
reported, other diving seabirds do become entangled in gillnets, so it is conceivable that there is
some entanglement risk. Drift gillnet fishing occurs along the north Alaska Peninsula, primarily
from Port Moller to Port Heiden. The largest amount of set gillnet effort near the general
Steller's eider molting/summering areas occurs at Nelson Lagoon.
During the spring migration, no groundfish effort occurred in Bristol Bay when it was open to
trawling from April 1 to June 15. Bristol Bay is closed to groundfish trawling during the fall
Steller's eider migration. The only groundfish fishing found near areas used by Steller's eiders
was the yellowfin sole fishery along the northern shore of Kuskokwim Bay. However, this
fishery occurs in May, past the time when astronomical twilight has disappeared from the fishing
grounds so that the risk of vessel collisions is minimal.
Eider-vessel collisions appear to involve bright lights during periods of darkness, so that it may
be possible to detect the distribution of fishing vessels at sea using low-light satellite-borne
sensors. NOAA archives of DMP/OLS satellites, which have been used to detect squid fleets at
sea, were screened for cloud free periods when Bering Sea fishing fleets might be detected.
Among other possibilities, the opening of the 1997 Bristol Bay red king crab fishery on
November 1 coincided with a satellite pass over the fishing grounds when cloud cover was less
than 10%, providing an ideal opportunity to determine whether crab vessel lights can be
detected. However, time constraints precluded examining the imagery from that date.
Further advancements in our knowledge of eider migration routes, from telemetry and other
sources, could be used to further narrow the scope of analyses of potential conflict between
fishing vessels and eiders. Observer records of vessel-eider collisions provided by far the most
valuable information in this analysis. However, the seabird collision data is obtained anecdotally
in field notes of fishery observers whose primary mission is to estimate groundfish and shellfish
catches. A more dedicated, directed, effort to document seabird encounters would greatly
enhance our knowledge of how fisheries and seabirds interact.
INTRODUCTION
The portion of the Spectacled eider (Somateria fischeri) population breeding in Alaska was listed
as threatened in 1993 (Federal Register 1993), followed by the Alaska-breeding population of
Steller’s eider (Polysticta stelleri) in 1997 (Federal Register 1997). Primary reasons for concern
for both eider species were the near disappearance of the species from the Yukon-Kuskokwim
Delta and low numbers of breeding birds on the North Slope. Causes of the declines in the
Alaska-breeding birds are unknown. The larger Russian component of the Pacific population of
both eiders mixes with the Alaska breeding population during the late-summer molt and on the
wintering grounds. Spectacled eiders molt in both northwestern Alaska and eastern Siberia
(USFWS 1996), and have been only recently been discovered wintering in leads in the pack ice
south of St. Lawrence Island (Petersen et al. 1999). Steller’s eiders move to locations in
southwestern Alaska during the summer molt, and the mixture of Asian and Alaskan breeding
populations winters from the eastern Aleutian Islands to Lower Cook Inlet and Kodiak Island
(USFWS 2002a).
The potential role of fisheries in the decline of these eider species has been unknown. The
current project was undertaken to describe which commercial fisheries occur in space and time
near habitat used by the threatened Alaska components of the two eider populations.
Comprehensive views of the distribution of fisheries in Alaska is hampered by the complex
mosaic of federal and state jurisdictions. Generally, fisheries inside of 3 miles from shore are
managed by the State of Alaska, while those further offshore are managed by the U.S. National
Marine Fisheries Service. Some species, such as Pacific cod, which are distributed in both State
and Federal waters, are technically managed separately but with close coordination between
State and Federal agencies. For some other species, such as crab and salmon, whose distribution
also transcends state and federal boundaries, federal agencies have delegated management
authority to the State of Alaska, usually because there had been a precedent for State
management before jurisdictional boundaries were extended by the Fishery Management and
Conservation Act of 1976. From a research standpoint, it is sometimes difficult to derive a
comprehensive view of Alaska fisheries. State and Federal management agencies have different
data collection programs to describe the distribution of catch and effort. Confidentiality
restrictions on both State and Federal data can make it difficult to share information among
agencies, or to release the data required for comprehensive fishery overviews to the public. This
project attempted to provide such comprehensive overviews of fisheries that might affect
Steller’s and spectacled eiders, using confidentiality agreements to share data among agencies,
and judicious editing of confidential information to meet both state and federal requirements.
Steller’s and spectacled eiders could be envisioned to interact with fisheries in four possible
ways:
1. Entanglement
2. Competition for Prey
3. Collisions or other interference, likely related to lighting, with fishing vessels or fishing-
related structures
4. Avoidance (habitat exclusion) because of fishing-related activity
Entanglement of Steller’s and spectacled eiders has not been reported to be a problem to date.
However, self-reporting rates of any such encounters might not be expected to be very high.
Observers are one possible source of such information, but to date catch-monitoring observers
have mostly only been placed aboard larger crab and groundfish vessels. The National Marine
Fisheries Service (NMFS) Marine Mammal Observer Program has gathered information from
the small set gillnet operations around Kodiak Island, and the drift gillnet fleet in Cook Inlet.
Spectacled eiders do not occur in these areas and Steller’s eiders were not found to be entangled
in either of those observer programs. While entanglement of Steller’s and spectacled eiders is
not thought to be a problem, the effort distributions in this report would help to identify where
the potential for entanglement interactions might exist.
On the molting and wintering grounds where contact with fisheries is most likely, Steller’s eiders
forage on marine invertebrates such as mollusks and small crustaceans (Petersen 1980, 1981).
Commercial fisheries do not directly take the shallow-water mollusk and crustacean species in
the Steller's eider diet.
Vessel strikes are a potential problematic impact of fisheries on eider populations during low
light and storm conditions (USFWS 2002b), and will be one focus area of this report.
Avoidance (habitat exclusion) because of fishing-related activity would be very difficult to
quantify. A first step, would be to examine the proximity of fishing activities described in this
report to Steller’s and spectacled eider critical habitat and migration routes.
There have been little or no reports of direct entanglement of Steller's eiders in fishing gear but it
is thought there may be more substantial risk from collisions with lighted fishing vessels during
darkness and stormy weather.
This project was undertaken to review the potential risks to Steller’s and spectacled eiders from
fisheries along their migration paths in the Bering Sea and Alaska Peninsula. The available
information on eider migration and distribution is reviewed to narrow the time and space where
potential interactions may occur. Darkness emerged as a key feature to be considered in these
analyses. The light regime in the eider critical habitat was examined and used to further narrow
the window where potential interactions between fisheries and eiders might occur.
CRITICAL HABITAT AND MIGRATION ROUTES
Critical habitat is specified in the ESA as Critical habitat is defined in section 3(5)(A) of the ESA
as:
(i) the specific areas within the geographical area occupied by the species...on which
are found those physical or biological features (I) essential to the conservation of
the species and (II) which may require special management considerations or
protection; and
(ii) specific areas outside the geographical area occupied by the species...upon a
determination by the Secretary of Commerce (Secretary) that such areas are
essential for the conservation of the species.
The U.S. Fish and Wildlife Service (USFWS) designated critical habitat for both eider species in
2001 (Federal Register 2001a,b).
Steller’s Eider
After breeding along the Arctic coastal plain, mature male eiders depart southward in early July
for molting areas along the Kuskokwim delta and Alaska Peninsula (Figure 1). Less is known
about the migratory timing or locations of the relict Yukon-Kuskokwim delta breeding
population. The mature males remain in these molting areas until October or November, when
they disperse broadly along both sides of the Alaska Peninsula, with the major concentrations
remaining in Izembek and Nelson Lagoons. Based on limited telemetry data, mature females
depart the Arctic coastal plain in late August for the same molting areas used by the mature
males (USFWS 2002a).
The critical habitat designation (Federal Register 2001a) for Steller’s eider (Figure 2), protects
these molting areas, as well as the breeding and overwintering grounds. Telemetry data do not
have sufficiently fine scale to determine whether Steller’s eiders migrate directly across Bristol
Bay, or follow a coastal route, however it is suspected that they fly directly across (P. Martin,
USFWS, Anchorage, Alaska, personal communication).
Spectacled Eider
In Alaska, spectacled eiders are known to breed in low-lying arctic and sub-arctic wetlands along
the margins of the Yukon-Kuskokwim delta, and the arctic north slope (Figure 3). Limited
nesting may also occur on St. Lawrence Island (USFWS 1996). Molting occurs in adjacent
nearshore waters, particularly eastern Norton Sound and Ledyard Bay. Males depart the nesting
areas for the molting grounds by late June, with females and offspring molting in early
September. While moving between nesting and molting areas, spectacled eiders travel along the
coast up to 50 km offshore. During the winter months of October through March, they move far
offshore to waters up to 65 m deep, where they sometimes gather in dense flocks in openings of
nearly continuous sea ice USFWS 1996, Petersen et al. 1999).
The critical habitat designation for spectacled eiders (Federal Register 2001b) protects the
Ledyard Bay and eastern Norton Sound molting areas, the Yukon-Kuskokwim delta spawning
area, and the St. Lawrence Island offshore wintering grounds (Figure 4).
REPORTED VESSELS STRIKES BY EIDERS
Lighting aboard fishing and cargo vessels has increased greatly in the last three decades. During
the 1970s, high intensity sodium deck lights became commonplace on crab fishing vessels,
which allowed fishing activity to occur around the clock (Brennan 2002). Subsequently,
development of the domestic groundfish fishery increased the number of heavily lit fishing
vessels using the nearshore Alaska Peninsula area. Although the primary fishing grounds for the
brightly lit fishing vessels occurs offshore, these vessels use the nearshore areas for anchoring
during storms, other respites from fishing, deliveries to coastal communities, and transiting
nearshore areas such as False Pass.
The attraction of seabirds to lighted vessels at night is well known (Dick and Donaldson 1978),
but the extent of mortality from night collisions with vessels and shore facilities is unknown.
There have been documented cases of Steller’s and other eiders striking vessels (USFWS
2002b):
In December 1980, 150 eiders of unknown species were found on the deck of the M/V
Northern Endeavor after the vessel anchored at False Pass to weather a storm with its
crab lights on.
In 1991, three Steller’s eiders fatally struck the Alaska patrol vessel P/V Wolstad,
operating with crab lights on.
In February 1997, two eider strikes were reported in two days, with one fatal strike,
aboard a trawler anchored in False Pass.
Steller’s eiders have been reported striking lighted structures along the shoreline around
Cold Bay.
Observers aboard crab and groundfish vessels have begun systematic collection of seabird
mortality information. The observations are not comprehensive, but provide the only available
at-sea information on seabird strikes. Onboard observer records of seabird strikes from 1993
through 2003 were obtained from the NMFS observer program, which gave the date and time of
impact. Only records where the approximate time of impact was recorded were used, so that the
relationship between eider strikes and the degree of darkness could be examined. A total of 17
Steller’s eider strikes were reported with reasonable time of day information, along with 19 king
eider strikes. Because most of the fishing effort in the winter occurs in the southern part of the
Bering Sea, the light regime at nearby Cold Bay was applied to the seabird impact information as
a reasonable proxy for the light regime on the fishing grounds. Almost all of the reported eider
impacts occurred during hours of complete darkness (Figure 5), in the late winter and early
spring.
SOURCES OF FISHING EFFORT AND DISTRIBUTION INFORMATION
Commercial Catch Records
Available records of fishing activity were examined to determine where and when fishing
activity might be in close proximity to eiders during their migrations or at times when they use
the designated critical habitat. Fishing records examined included State of Alaska fish ticket
landing receipts, which note both port of landing and fishing location, and observer records from
the NMFS North Pacific Groundfish Observer program. Annual management reports and other
management-related publications from the Alaska Department of Fish and Game (ADF&G) were
consulted to summarize the locations of herring fisheries, and to determine details for other
fisheries.
The ADF&G fish ticket database is the primary means of collecting data on commercial fisheries
landings in Alaska. A fish ticket is basically a bill of sale that indicates the quantity of fish of
each species that was delivered and purchased by a processor from a particular fishing permit
holder on a given date. Note that landing enumeration by fish tickets differs from the product
recovery rate methods of estimation used in many federally-managed groundfish fisheries. The
record includes other information, such as gear type, statistical area, management area, and port
of landing. A fish ticket is produced for each shoreside delivery. Catches made in a federally-
managed groundfish fishery are included only if the vessel happened to deliver the catch to a
shoreside plant. Therefore, deliveries made to a floating or catcher-processor vessel outside of
state waters are not contained in the database. On the other hand, all landings in state-managed
fisheries are included in the fish ticket database. For example, catches made in the high seas crab
fishery in the Bering Sea that are delivered to an offshore processor are included in the database
because it is a state-managed fishery in which fish tickets are required.
The ADF&G fish ticket system has been compartmentalized into different database systems,
defined by species group. For this report, information was compiled from the “Venus” (shellfish),
“Zephyr” (salmon), “Neptune” (groundfish), and “Triton” (herring) fish ticket database systems.
Satellite Low-Light Sensors
Eiders appear to collide with vessels at sea because the vessels are displaying bright lights which
either confuse the seabirds or attract them. The bright lights themselves could prove a useful tool
for describing the distribution of vessels at sea. For example, the distribution of squid fishing
vessels, which use particularly intense lights has been captured by DMP/OLS satellite sensors
(Maxwell et al. 2004, Waluda et al. 2004). Cloud cover over Alaskan fisheries would likely
prove problematic for routine effort detection using these methods, but opportunistic sampling
during cloud-free days could be an inexpensive and comprehensive method of describing fleet
distributions, particularly for concentrated fishing effort as in the Bristol Bay red king crab
fishery. NOAA archives of DMP/OLS satellite images were screened for relatively cloud-free
days occurring during the time frame and in the location of the Bristol Bay red king crab fishery.
Among other possibilities, opening of the 1997 fishery on November 1 coincided with a satellite
pass over the fishing grounds when cloud cover was less than 10%. Time constraints precluded
examining the imagery from that date. For future work, the Bristol Bay imagery from the 04:55
GMT satellite pass on November 1, 1997 over Bristol Bay should determine whether high-
intensity crab lights are detectable from satellite platforms.
DISTRIBUTION OF FISHING ACTIVITY BY PORT OF LANDING
ADF&G fish ticket records from the general eider wintering location were summarized for the
five-year period 1998 through 2002. Viewing fishing records by port of landing serves as a proxy
for general vessel activity in nearshore areas around ports of landing. This view could be
relevant to quantifying the risk of eiders striking vessels, which can occur at anchor, or tied to
docks, particularly if the vessels are brightly lit. Landings are examined both annually, and for
the September 1 through April 30 period when darkness is more prevalent on the fishing
grounds. Combining the presence of substantial numbers of eiders along the Alaska peninsula
with the winter darkness regime, the time period September 1 through April 30 likely represents
the greatest risk of collisions between eiders and fishing vessels. Between May 1 and August 30
there is little or no deep darkness in these areas and bird strikes are highly unlikely.
The port of Kodiak has by far the most landings, either on an annual basis or from September 1
through April 30 (Table 1). For the September through April period, Kodiak averaged 3,474
deliveries, followed by Dutch Harbor/Unalaska with 1,757 deliveries. In the September through
April period, most of the vessel landing activity occurs on the south side of the Alaska Peninsula,
and is dominated by groundfish deliveries (Figure 6).
For the top 15 ports of landing, ranked by number of deliveries, salmon fisheries by far dominate
the vessel activity in most ports (Figures 7-9). Groundfish and shellfish vessels dominate
deliveries during the winter, when long hours of darkness increase the potential for vessel
collisions.
Among the top 5 ports, groundfish, salmon, and herring deliveries followed fairly similar
patterns among the years 1998-2002 (Figures 10-14). Shellfish fisheries show the most
variability among years.
DISTRIBUTION OF FISHING EFFORT NEAR STELLER’S AND
SPECTACLED EIDER CRITICAL HABITAT AND MIGRATION ROUTES
Herring Fisheries
Herring fisheries occur at a number of locations that potentially overlap Steller’s eider migration
routes and critical habitat (Figure 15). For spectacled eiders, the only potential overlap with
herring fisheries would occur at Norton Sound and Cape Romanzoff, if the eiders spend time in
coastal waters before moving ashore to nest. Most Alaskan herring fisheries are for sac roe and
occur in the spring, just before herring begin to spawn. The only non-sac roe herring fishery in
the Bering Sea is the Dutch Harbor food and bait fishery, which occurs in the waters around
Unalaska Island in mid-July.
During Bering Sea herring fisheries, from 15 to approximately 500 catcher vessels are on the
fishing grounds, along with smaller numbers of tenders (typically 18-30m in length), and several
large transport vessels (typically 50 to 100+m in length). These vessels, particularly the larger
ones, would be brightly lit during hours of darkness and anchored in inshore waters where
Steller’s eider strikes are a potential hazard. However, reported eider strikes have almost all
occurred during very deep darkness, at light levels below astronomical twilight (Figure 5).
Almost no herring fishing occurs during the time of year when light levels are extremely low
(Figure 16). North Peninsula (Port Moller) sac roe herring fisheries have opened only four times
from 1995-2005, with maximum effort levels at only 12 permits fished (Jackson 2006). Port
Moller herring fisheries occur when there are about 4 hours or less with light levels below
nautical twilight, and no periods below astronomical twilight (Figure 16).
Gillnet gear is used in all Bering Sea herring sac roe fisheries, with purse seine gear also used at
Togiak and Port Moller. Beach seines are legal gear in Norton Sound, but harvest only a small
percentage of the overall catch.
A food and bait herring fishery using purse seines and gillnets occurs in the vicinity of Dutch
Harbor, with a current regulatory opening date of noon on July 15 annually, with most of the
harvest completed within one to several days, and the full length of the fishery averaging 12 days
from 1994-2004 (Jackson 2006). Since 1997, fishing has occurred during daylight hours using
spotter aircraft. Almost all of the harvests have occurred in Unalaska Bay itself, with catcher and
support vessels retiring to port when not fishing. An average of 21 catcher vessels participated
from 1994-2004 (Jackson 2006).
Alaska’s largest herring fishery occurs along the north shore of Bristol Bay near the village of
Togiak (Figure 15). From 1995 through 2004, an average of 190 gillnet vessels and 123 purse
seine vessels participated in this fishery (Westing et al. 2006). The earliest opening date for this
fishery is April 25, with the latest closure date May 26, although the average duration was only
71 hours of fishing for gillnet vessels and 33 hours of fishing for purse seine vessels over the
1995-2004 period. No developed harbors are near the Togiak fishing grounds, so all vessels
anchor in what protection they can find. The Togiak herring fishery occurs during periods of
very limited darkness, with less than four hours with light levels below nautical twilight, and no
periods below astronomical twilight (Figure 16), minimizing the potential for bird strikes.
Several small fisheries occur along the Kuskokwim delta, at Security Cove, Goodnews Bay,
Cape Avinof, Nelson Island, Nunivak Island and Cape Romanzof. From 2000 through 2003 the
effort at any of these areas ranged from 12 to 86 vessels (Whitmore et al. 2005). The daylight
regime in these areas ranges between that at Togiak to the south, and Norton Sound, to the north.
A sizable herring biomass (20,000 to 50,000 tons) spawns in Norton Sound that in past years has
attracted over 500 fishermen. Fishing is limited to gillnet vessels and small beach seine
operations only, hence average vessel size is small (6 to 11m). In recent years, effort in the
Norton Sound fishery has dwindled because of poor markets for herring roe. In addition, Norton
Sound herring sometimes spawn before ice-free conditions are present, increasing the risk of
preparatory investment for fishermen and processors. As a result, an average of only 52 vessels
participated in the Norton Sound herring fishery from 2000 through 2005 (Alaska Department of
Fish and Game, Nome Office 2005). During the period 1990 through 1999, when fishing was
less limited by processing capacity, dates of herring catches ranged from May 20 through June
22 , with the mode of herring catch occurring on May 25. This fishery occurs during well-lit
periods, with darkness never dropping below nautical twilight levels, and with less than 5 hours
below civil twilight (Figure 16), resulting in very low risk of bird strikes.
Shellfish Fisheries
Dungeness Crabs
Dungeness crabs (Cancer magister) are widely distributed in bays, estuaries, and along the
nearshore coast of Alaska from Dixon Entrance out into the Aleutian Islands. Dungeness crab
abundance is lower in the islands of the Aleutian Chain, which are separated by deep passes with
swift currents and are closely bordered by steep depth contours. Dungeness crabs primarily
inhabit bays, estuaries, and other shallow water habitats that are more common east of the
Aleutian Islands.
Dungeness crabs are usually captured in circular pots baited with herring, squid, or clams,
individually tethered to floating marker buoys. The pots are about 40 inches in diameter and 14
inches high, constructed of 3/4-inch round, steel frames wrapped in rubber tubing then covered
with stainless steel wire mesh woven in 2-inch squares. Two 4⅜" diameter escape rings are
required to be built in each pot to allow undersize crabs to leave the pot. The number of pots that
can be set by a vessel and the fishing season varies by management area
Dungeness crab fisheries in Alaska use a “3-S” management strategy, setting seasons, size limits
(based on carapace width, CW), and sex of harvest in lieu of harvest quotas:
_______________________________________________________________________
Season Sex Size Limit
Kodiak District, South End June 15 - December 31 Males Only 6.5 in CW
Kodiak District, All Other May 1 - December 31 Males Only 6.5 in CW
N. Alaska Peninsula District May 1 - October 18 Males Only 6.5 in CW
S. Alaska Peninsula District May 1 - December 31 Males Only 6.5 in CW
Aleutian District May 1 - December 31 Males Only 6.5 in CW
_______________________________________________________________________
This harvest policy is predicated on the assumption that the fishing gear is does not cause
significant injury so that crabs may be identified, measured, and sexed, with non-legal crabs
returned unharmed to the ocean. The minimum legal size is set one molt increment above the
size at maturity.
Harvest of Dungeness crabs has fluctuated widely since 1970, a combination of fluctuating
abundance and changing market interest (Figure 17). Most of the harvest has occurred in the
area around Kodiak Island, with small amounts out on the Alaska Peninsula. Around Kodiak
Island, Dungeness crabs were first harvested commercially in 1962, with harvests escalating
rapidly to the maximum recorded catch of 3,098 mt in 1968. The number of vessels participating
in this fishery varied from as low as four to as high as 125, but less than 25 vessels have been
operating since 1995. Harvest declined through the 1970s as both stock levels and market value
for Dungeness crabs decreased (Jackson 1997).
Dungeness crab harvests along the south Alaska Peninsula have been recorded since 1968, but
landings have been sporadic. The highest landing was 571 mt achieved in 1968. In the 1980s,
catch and effort increased as a result of the decline in king crab harvest and stronger market for
Dungeness crab and the harvest rose to 545 mt. This harvest attracted 132 vessels to the fishery
and local fishermen became concerned about an excessive influx of effort. In subsequent years
the BOF designated the south Alaska Peninsula Dungeness crab fishery as “superexclusive”,
meaning that vessels that fished Dungeness crab in other management areas could not also fish
the Alaska Peninsula. The numbers of vessels operated during 1990s were low, varying from
less than 3 to 24.
Fishing effort for the North Peninsula Dungeness crab fishery has been sporadic, with few
vessels participating. Most effort has occurred north of Unimak Island. In 1995 six vessels made
19 deliveries for a harvest of 61 mt. Catch information from 1996 to 1998 is confidential, as less
than three vessels participated in those years. The average annual harvest in the three-year period
from 1996–1998 was approximately 22 mt. No vessels registered to fish for Dungeness crabs in
the North Peninsula District in 1999. One vessel, for which landings are confidential,
participated in the 2000 fishery.
In the Aleutian District, the Dungeness crab fishery has occurred primarily as a small-vessel,
summer fishery in the vicinity of Unalaska Island. Some larger-vessel effort has occurred in
other locales within the district, but fishing in these areas has been sporadic throughout the
history of the fishery. Interest and activity in this fishery has been erratic from year to year, with
the first reliable reports of harvest made in 1970. Since 1974, deliveries have ranged from 0 in
several years, to a peak of over 40 mt in 1984–85.
Most of the Dungeness crab harvest occurs, in July, August, and September (Figure 18). The
prevailing light conditions when most effort occurs makes vessel strikes highly unlikely during
this fishery. In addition, only relatively small and trace amounts are harvested along the Alaska
Peninsula (Figure 19), in areas where Steller’s eiders would be found in the summertime. There
is no overlap of Dungeness crab fishing effort and spectacled eider distribution.
Shrimp Fisheries
Five species occur in Alaska shrimp fisheries: northern (formerly, pink) shrimp, Pandalus
borealis; sidestriped shrimp, Pandalopsis dispar; coonstriped shrimp, Pandalus hypsinotus; spot
shrimp, Pandalus platyceros; and humpy shrimp, Pandalus goniurus. Northern and sidestriped
shrimp now comprise almost all the landings from the areas west of long. 144° W.
The shrimp fishery in western Alaska has been prosecuted primarily with trawls, along with a
very small amount of pot effort. In recent years the Bering Sea has contributed most of the
harvest because of the decline of shrimp stocks in almost all other areas. Shrimp resources in
Alaskan waters have been exploited since 1915, but catch records are available only for the last
five decades. In almost all areas, the early exploratory fishing led to rapid escalation of effort,
overharvest, and closure. High effort levels coinciding with the oceanic regime shift of 1976–77
combined to reduce shrimp stocks to very low levels, and catches have been extremely low since
the early 1980s (Figure 20), with little or no catch along the outer Alaska Peninsula (Figure 21).
The fishery in the South Peninsula area has been closed since 1980. Although only offshore areas
in Chignik District have been open for fishing since 1982, no commercial harvests have been
reported since 1982–83.
Current shrimp populations remain well below long-term historic averages in most of the Kodiak
Area. Localized areas showed increases in shrimp densities during a survey conducted in 2001;
however, most commercial trawl shrimp fisheries remain closed. Most of the nearshore areas
where shrimp abundance has increased and where the historic trawl fishery once occurred are
now within the areas closed to non-pelagic trawl gear by the BOF.
No vessels have registered for the North Peninsula District pot or trawl shrimp fishery since
1994. Currently, shrimp fishing is not permitted in this district due to a lack of data concerning
the shrimp stocks.
In the Bering Sea-Aleutians Area, limited shrimp harvests resumed in 1999, but the fishery was
then closed because of very limited management and assessment information. Subsequent effort
will only be allowed when consistent with the Alaska Board of Fisheries “Management Plan for
High Impact Emerging Fisheries”.
Because shrimp fishing effort is extremely low, and most of the areas traditionally trawled for
shrimp are within areas closed to non-pelagic trawl gear by the BOF or fall within the extensive
closure areas for Steller sea lions, the potential for interactions with Steller’s eiders is extremely
low. Shrimp fishing effort does not overlap the distribution of spectacled eiders.
Weathervane Scallops
The primary commercially fished scallop species in Alaska, the weathervane scallop
Patinopecten caurinus, occurs offshore aggregated in elongated beds that lie parallel to Alaska's
coastline from Southeast Alaska to the Aleutian Islands. Weathervane scallop beds occur on
mud, silt, sand, gravel, and to a lesser extent, rocky bottoms at depths of 60–220m.
The scallop fishery is prosecuted using a standard “New Bedford style” scallop dredge. On
average, a 15-foot dredge weighs approximately 1.2 mt and a 6-foot dredge weighs about 0.4 mt.
The frame design provides a rigid, fixed dredge opening. Attached to and directly behind the
rigid frame, is a steel ring bag consisting of 4-inch (inside diameter) rings connected with steel
links. A sweep chain footrope is attached to the bottom of the mesh bag. The top of the bag
consists of 6-inch stretched mesh polypropylene netting. The mesh netting helps hold the bag
open while it is towed along the ocean floor. A club stick attached at the end of the bag helps
maintain the shape of the bag and provides for an attachment point to dump the dredge contents
on the deck. Steel dredge “shoes” are welded onto both lower corners of the rigid frame. The
dredge shoes bear most of the weight and act as “sled runners” permitting the dredge to move
easily along the substrate. Each dredge is attached to the boat by a single steel wire cable
operated from a deck winch. Vessels fishing inside the Cook Inlet Registration Area are limited
to operating a single dredge not more than 6 feet in width. Vessels fishing in the remainder of
the state are limited to operating no more than 2 scallop dredges at one time and the scallop
dredges may not be more than 15 feet wide. Vessels used in the weathervane scallop fishery
range in size from 18 to 40m in length, with a maximum of 1,200 horsepower.
After the scallop fishery began to develop in 1967, increased participation led to several boom-
and-bust cycles from 1967–1992 (Figure 22). Details of specific management actions over the
history of the fishery are given in Barnhart (2000a). Currently, 100% onboard observer coverage
is required in the fishery, along with regulations that limit efficiency and slow the pace of catch.
The statewide regulatory season was established as July 1 through February 15, excluding the
Cook Inlet Registration Area. Although the season dates were established to protect molting and
mating crab they have the added benefit of not disturbing scallops prior to and during their
spawning period. T Most fishing occurs in late summer to early fall (Figure 23).
The federal government has delegated authority to the state of Alaska to manage all aspects of
the scallop fishery, except limited access, in federal waters (Barnhart 2000b).
Over the last five years, scallop harvest has come principally from upper Shelikof Strait, the east
side of Kodiak Island, and the Bering Sea (Figure 24). Large areas of the central and western
Gulf of Alaska and Bering Sea are now closed to scallop fishing as a conservation measure.
Commercial scallop fishing activities in the Alaska Peninsula Area have been documented since
1975. Closed areas included waters within three miles of shore and the offshore waters of
Unimak Bight (to protect king crab stocks) and around Mitrofania Island (to protect Tanner crab
stocks). The fishery has been sporadic and most catches prior to 1993 are confidential because
too few boats fished in the area. Harvest peaked in 1982 when six vessels delivered 93 mt.
In the Bering Sea, significant commercial harvests have occurred since 1993, with harvests
peaking at 229 mt in 1994–95. The principal fishing area is near the outer edge of the continental
shelf, north of Unimak Island. Large areas of the Bering Sea, including the Pribilof Islands area,
the red king crab savings area, and all waters east of long. 162º W. are closed to scallop fishing.
Because the large closed area includes all of Bristol Bay and remaining scallop effort occurs well
offshore in the Bering Sea, vessel collisions with Steller’s eiders are not likely while vessels are
fishing. The only risk would appear to be from vessels at anchor or in port. Additionally, in the
Bering Sea, most of the fishing effort occurs in July through September when the fishing grounds
are relatively well lit.
Red and Blue King Crab Pot Fisheries
Red king crabs, Paralithodes camtschaticus, and blue king crabs, P. platypus, are distributed in
Alaska from the southeast panhandle throughout the Aleutian Islands, and Bering Sea.
Southwestern Bristol Bay and Kodiak Island have been historical centers of abundance for red
king crab, with blue king crab being most abundant around St. Matthew and the Pribilof Islands.
Red and blue king crabs can occur from the intertidal zone to more than 200 m. Adults move
into shallower waters in the late winter and spring for mating and molting, followed by
movements to feeding areas in deeper water, and may range up to 150 km in annual movements.
King crabs are commercially fished using large 250-300 kg steel-framed pots covered with
nylon-webbing. Each pot is baited, usually with chopped herring, lowered to the bottom and
allowed to soak, typically for one to two days when fishing red or blue king crabs. Buoys are
attached to the pots with heavy line and pots are retrieved and lifted onto the vessel with a
hydraulic puller. The catch is sorted on deck and all females and undersize males are tossed
overboard. The retained catch of large males is held in large recirculating seawater tanks for live
delivery, or are processed and frozen onboard the small fleet of catcher-processor vessels. King
crab vessels fishing the Bering Sea usually exceed 30m in length, although smaller vessels have
participated in Gulf of Alaska fisheries.
Fishing regulations for king crab were initially grounded in the concept of season, sex, and size
limit (“3S”) harvest policies which allowed only the harvest of large males. However, this
harvest policy has been criticized in recent years because of the potential handling mortality on
female and sublegal crabs. In addition, research on the reproductive capabilities of male king
crabs now indicates that large males are more important to the brood stock than small males
(Paul and Paul 1990). In the few areas where king crab fishing is still allowed, quota and
sometimes threshold-based harvest policies are now used, in addition to the 3S harvest policy.
Biodegradable escape mechanisms are required on crab pots so that if the pot is lost it will soon
stop fishing, and pot limits are imposed on fishing vessels in an attempt to control fishing effort.
In most of Alaska, king crab may only be taken with pot gear. Pots must be no more than 10 feet
long by 10 feet wide by 42 inches high with rigid tunnel eye openings that individually are no
less than five inches (13 cm) in any one dimension, with tunnel eye opening perimeters that
individually are more than 36 inches (91.4 cm), or pots must be no more than 10 feet long by 10
feet wide by 42 inches high and taper inward from the base to a top consisting of one horizontal
opening of any size. King crab pots may be stored submerged under certain conditions, if they
are unbaited and the doors are secured fully opened.
Pot limits are in effect in most king crab fisheries to attempt to control fishing effort and allow
fishery managers to constrain the rate of harvest so that GHLs are not exceeded. The pot limit
requirements vary by vessel size, area, and GHL level, and range from 75 pot limits in Cook
Inlet (may be reduced to 40-pot limit with GHLs less than 680 mt) to 250 pot limits in Bristol
Bay when GHLs are high.
The red king crab fishery can be described as a brief pulse of extremely intensive fishing activity
in the 1960s and 1970s. Red king crab stocks crashed in almost all areas in the early 1980s,
likely due to overfishing, with a lesser role played by the regime shift of 1977 (Kruse et al. 1996)
and periods of high natural mortality (Zheng et al. 1997).. A relatively low level of catch
continues in the Bering Sea areas (), primarily the Bristol Bay red king crab fishery. Advances in
technology greatly increased the efficiency of the crab fishing fleet, which originally started out
primarily as converted wooden salmon seine vessels. Vessel size increased, allowing more and
larger pots to be carried, and hydraulic launchers and pullers allowed efficient handling of the
large pots. LORAN navigation and chart plotters allowed pot locations to be precisely tracked
and large numbers of pots to be managed. Bright sodium deck lights became available in the
1970s, allowing fishing around the clock.
Most of the king crab fishing effort and catch since 1985 has occurred in southwestern Bristol
Bay (Figure 26), with king crab harvests are concentrated in a very small number of statistical
areas. The top 15 of the 93 statistical areas in the EBS reporting some catch account for 93% of
the king crab harvest over the period 1985 to 2001. The remaining statistical areas averaged 30
mt or less from 1985–2001 and are shown as “trace” amounts in Figure 26. Catch and effort
occurs well offshore in Bristol Bay.
In recent years, the Bristol Bay red king crab fishery has been opening in mid-October. The bulk
of the catch and effort occurs within 5 days of the initial opening (Figure 27), with a much lower
level of catch and effort stretching into December from the Community Development Quota
(CDQ) segment of the fleet.
A separate fishery for blue king crab has occurred just south and east of St. Matthew Island. The
St. Mathew Island blue king crab fishery has been closed since 1998 due to low stock abundance,
and the stock has not yet recovered.
Salmon Fisheries
Salmon fisheries nearly all occur during the well-lit period of summer (Figures 7-8) and
therefore present minimal collision risk for eiders. However, eiders that summer along the
Alaska Peninsula could possibly be subjected to some entanglement risk from gillnets in certain
bays. Although net entanglement of eiders has not been reported, because other diving seabirds
are ensnared in nets, the distribution of salmon fishing effort along the north Alaska Peninsula
molting/summering areas was examined. Gillnets are the primary type of net fishery of concern
for bird entanglements. Two types of gillnets are used along the Alaska Peninsula: set gillnets
(setnets) and drift gillnets. Both types of gillnets are hung in panels with corks on the top and a
leadline on the bottom (Figure 28) . The net does not sink; if water depth is sufficient, there is
sufficient floatation in the corkline to float the leadline off of the bottom. Maximum gillnet size
is limited by state regulations, which vary by region.
Set Gillnets
Set gillnets have been commercially fished for salmon in Alaska for at least a century, with some
techniques dating back to millennia of subsistence utilization by indigenous cultures. Unlike
most other fisheries in Alaska, set gillnet fisheries operate from specific sites, with the same
location often being fished for generations within an extended family.
A salmon “setnet” is an anchored gillnet. Some setnets have a “lead” comprised of very large
mesh seine webbing at the inshore end of the set gillnet to channel the fish toward the net during
high tide periods. The inshore end of most set gillnets is anchored on the beach and the offshore
end is secured to anchors and buoys. However, some setnets are not anchored to the shoreline,
but held stationary with anchors on each end of the net. Set gillnets can be simply set in a straight
line, or set to have a v-shaped hook at the end. Salmon become caught in the nets by their gills
when they attempt to swim through the net. Fishermen may use small skiffs to tend the nets and
pick the salmon, or the nets can be accessed by motor vehicles and picked at low tide in some
shallow areas such as Bristol Bay. Running lines are sometimes used for setting out and
retrieving the setnet, with a line manually dragged from the beach straight out to a pulley and
screw anchor, and back to the beach. Setnet sites are often run as family operations, supported
by fixed shore-based facilities. The State of Alaska Department of Natural Resources manages a
permit system for shore fishery leases on the tidelands, which grants up to 10 years use for first
priority access to the site. Many setnet sites are located in remote areas, accessibly only by boat
or airplane.
For the three decades from 1970-2001, setnet landings in southwestern Alaska were concentrated
primarily in Bristol Bay (Figure 29). Expanded detail for the north Alaska Peninsula for 1998-
2003 shows significant setnet effort only in Nelson Lagoon (Figure 30).
Drift Gillnets
Drift gillnets are similar to setnets but may not be anchored to the bottom or fixed to the shore.
Usually a larger vessel than the typical setnet tender is used to tend the net, which is set and
retrieved entirely from the fishing vessel. Gillnet vessels tend to be relatively small, and are
limited to a maximum length of 32 feet in Bristol Bay. Catch is delivered to tenders or nearby
ports.
Most drift gillnet fishing along the north Alaska Peninsula occurs from Port Moller to Port
Heiden (Figure 31). Relatively low numbers (less than 50 per statistical area) drift gillnet
landings occur in statistical areas near the primary Steller's eider molting/summering area of
Izembek lagoon.
Groundfish Fisheries
Groundfish fisheries in the Bering Sea are managed by the NMFS and the North Pacific
Fisheries Management Council, currently regulated with target fisheries for ten different species
groups (Table 2). Groundfish fishery distributions as they may intersect eider distributions are a
complex interaction of optimal effort patterns for each of the groundfish target species groups,
ice movements (in late winter and spring) which may constrain fishing activities, closures (for
prohibited and protected species), and the timing and location of eider movements. The potential
for groundfish vessel-eider interactions was examined by superimposing groundfish fleet
distributions, closure areas, ice movements, and eider surveys. This report focuses on the spring
2003 eider migration period.
To examine groundfish fleet distributions in detail, groundfish observer information was
obtained from the National Marine Fisheries Service. These voluminous records list the location
and duration of each observed tow, and catch by species. Tows were classified by "target
fisheries", based on the predominant species in the catch. For the spring eider migration period
in the general vicinity of Bristol Bay, fishery classifications by "cod", "pollock", "yellowfin
sole", "arrowtooth flounder and other flatfish", and "flatfish" were sufficient to characterize the
targeting nature of the groundfish fishery. At other times of the year or in other locations the
targeting classifications describing the groundfish fisheries could be considerably more complex,
reflecting all the species in Table 2. Fishing effort by target class was summarized by the
number of unique vessels fishing, hours fished, and location and month. Locations given for
individual tows are both confidential and voluminous. To better summarize the pattern of fishing
and protect confidentiality, smoothed fishing effort contours were created by target fishery for
each month.
A number of fishery closure areas constrain the locations where groundfish fisheries can operate.
The two most significant are the "Red King Crab Savings Area", a year-round closure from 56 to
57 degrees latitude and 162 to 164 west degrees longitude, and the Bristol Bay Nearshore Area.
The Bristol Bay Nearshore Area includes all waters east of 162 degrees west longitude, and is
closed year-round except for April 1 to June 15. A number of smaller closures are also extended
outward from Steller sea lion haulouts and rookeries, and additional closures are possible if
prohibited species catch limits for herring, crab, or salmon are reached during the season.
Groundfish management measures can also be amended on an annual basis. Tables showing the
current status of groundfish management measures are maintained by the Alaska Region of the
NMFS at their website: http://www.fakr.noaa.gov.
Sea ice patterns vary dramatically from year to year. During years of extensive southerly ice
movements, sea ice constrains the operating area of the groundfish vessels, as well as likely
influencing the timing of the northward eider migrations. Sea ice information was obtained from
the National Ice Center, summarized by amount of ice cover in ten percent increments and
entered as a GIS layer as described in Tojo et al. (2007).
Eider distributions from spring aerial surveys given by Larned (2003) were digitized and entered
as a GIS layer. The 2003 surveys were flown beginning on March 29 at Nunivak Island and
proceeded clockwise and southward, with the final surveys completed April 9-11 at Izembek
Lagoon and Cold Bay. While not comprehensive throughout the migration, these surveys
provide a valuable "snapshot" of eider distributions as the spring migration is beginning.
By late March of 2003, sea ice had extended south of Cape Newenham and appears to have
limited the northern extent of the small fleet (11 vessels) fishing for flatfish (Figure 32). A much
larger fleet of approximately 150 vessels was fishing for cod and pollock off the north Alaska
Peninsula, north and west of False Pass. Both the Red King Crab and Bristol Bay nearshore
closure areas constrained the operating areas of the groundfish vessels. Eider aerial surveys
began on March 29 at Nunivak Island, and located some eiders already moving northward in
open areas within the mostly ice-covered Kuskokwim Bay.
At the April 11 completion of the eider aerial surveys, sea ice had mostly receded to the northern
half of Kuskokwim Bay (Figure 33). Bristol Bay opened to trawling on April 1 through June 15,
although trawl effort has not shifted eastward at all into Bristol Bay. The red king crab savings
area remained closed to trawling. Off of the Alaska Peninsula north and west of False Pass the
groundfish effort has shifted to Pacific cod, with similar overall effort levels to the mixed cod-
pollock fleet in the same area in March. The flatfish fleet has shifted northward slightly, likely
allowed by the northward retreat of the sea ice.
By May 9, the sea ice has almost completely retreated from the area (Figure 34). Trawl effort
remains well outside of Bristol Bay. Near Kuskokwim Bay, a 13-vessel fleet is now targeting
yellowfin sole, and has moved close to the northern shore of Kuskokwim Bay in areas that are
used by Steller's eiders for migration. However, by May the daylight hours have extended
substantially such that there is no longer any period of astronomical twilight (Figure 5).
Therefore there is likely minimal risk of collisions between migrating eiders and lighted fishing
vessels. During May 2003 groundfish fishing effort was drastically reduced along the Alaska
Peninsula, with only a 6-vessel fleet targeting arrowtooth flounder and other flatfish offshore
from False Pass.
An animation of Figures 32-34 with additional frames showing twice-weekly ice coverage is
maintained at: http://www.backwater.org/eiders/.
LITERATURE CITED
Alaska Department of Fish and Game, Nome Office, 2005. Norton Sound herring season summary,
2005. Unpublished Memorandum, September 19, 2005., 6p.
Barnhart, J. P. 2000a. Weathervane scallop fishery in the Westward Region, 1967–1999: Report to
the Alaska Board of Fisheries. Alaska Department of Fish and Game, Division of Commercial
Fisheries, Regional Information Report 4K00-12, Kodiak.
Barnhart, J. P. 2000b. Annual Management Report for the weathervane scallop fisheries of the
Westward Region, 1999/00. In Annual Management Report for the shellfish fisheries of the
Westward Region, 1999. Alaska Department of Fish and Game, Division of Commercial
Fisheries, Regional Information Report 4K00-55, Kodiak.
Dick, M.H. and W. Donaldson. 1978. Fishing vessel endangered by crested auklet landings.
Condor 80: 235-236.
Federal Register. 1993. Final rule to list the spectacled eider as threatened. Federal Register
58(88):27474-27480.
Federal Register. 1997. Threatened status for the Alaska breeding population of the Steller's eider.
Federal Register 62(112): 31748-31757, June 11, 1997.
Federal Register. 2001a. Final Determination of Critical Habitat for the Alaska-Breeding Population
of Steller's Eider. Federal Register 66(23):8849-8884, February 2, 2001.
Federal Register. 2001b. Final determination of critical habitat for the spectacled eider. Federal
Register 66(25):9146-9185, February 6, 2001.
Hayes, S, and K. Clark.2006. Cape Romanzof district herring fishery. Unpublished memorandum,
March 2006, Alaska Department of Fish and Game, Anchorage.
Jackson, D. 1997. Westward Region Commercial Dungeness crab and shrimp fisheries: A report to
the Alaska Board of Fisheries. Alaska Department of Fish and Game, Division of Commercial
Fisheries, Regional Information Report 4K97-09, Kodiak.
Jackson, J. V. 2006. Alaska Peninsula-Aleutian Islands management area herring sac roe and food
and bait fisheries annual management report, 2005. Alaska Department of Fish and Game,
Fishery Management Report No. 06-20, Anchorage.
Kruse, G. H., Funk, F.C., and Zheng, J. 1996. Were Alaskan red king crabs overfished? Pages 295–
300 in: High Latitude Crabs: Biology, Management, and Economics. Alaska Sea Grant College
Program, AK-SG-96-02. University of Alaska, Fairbanks.
Larned, W. W. 2003. Steller's eider spring migration survey, southwest Alaska, 2003. U. S. Fish and
Wildlife Service, Unpublished report. 24pp.
Maxwell, M.R., A. Henry, C. D. Elvidge, J. Safran, V. R. Hobson, I. Nelson, B. T. Tuttle, J. B. Dietz,
J. R. Hunter, 2004, Fishery Dynamics of the California market squid (Loligo opalescens), as
measured by satellite remote sensing. Fish Bull, 102, pp. 661-670
Melvin, E., Dietrich, K., Van Wormer, K., and T. Geernaert. 2004. The distribution of seabirds on
Alaskan longline fishing grounds: 2002 data report. Washington Sea Grant publication WSG-
TA 04-02.
Paul, J. M., and A. J. Paul. 1990. Breeding success of sublegal size male red king crab Paralithodes
camtschatica (Tilesius, 1815) (Decapoda, Lithodidae). Journal of Shellfish Research 9:29–32.
Petersen, M.R. 1980. Observations of wing-feather moult and summer feeding ecology of Steller’s
eiders at Nelson Lagoon, Alaska. Wildfowl 31:99-106.
Petersen, M.R. 1981. Populations, feeding ecology, and molt of Steller’s eiders. Condor 83:256-262.
Petersen, M.R., W.W. Larned, and D.C Douglas. 1999. At-sea distribution of spectacled eiders,
Somateria fischeri: 120 year-old mystery resolved. Auk 116:1009-1020.
Tojo, N., G.H. Kruse, and F.C. Funk. 2007. Migration dynamics of Pacific herring (Clupea
pallasii) and response to spring environmental variability in the southeastern Bering Sea. Deep
Sea Research Part II, Topical Studies in Oceanography: 54: 2832-2848 .
U.S. Fish and Wildlife Service. 1996. Spectacled eider recovery plan. Fairbanks, Alaska.
U.S. Fish and Wildlife Service. 2002a. Steller’s eider recovery plan. Fairbanks, Alaska.
U.S. Fish and Wildlife Service. 2002b. Habitat conservation plan for coastal Alaska: has the time
come? Unpubl. Report. U. S. Fish and Wildlife Service, Ecological Services, Anchorage. 9pp.
Waluda, C.M. C. Yamashirob, C. D. Elvidge, V. R. Hobsond and P. G. Rodhouse. 2004. Quantifying
light-fishing for Dosidicus gigas in the eastern Pacific using satellite remote sensing. Remote
Sensing of Environment, 91(2): 129-133.
Westing C., T. Sands, S. Morstad, P. Salomone, L. Fair, F. West, C. Brazil, and K. A. Weiland. 2006.
Annual management report, 2005, Bristol Bay area. Alaska Department of Fish and Game,
Fishery Management Report No. 06-37, Anchorage. .
Whitmore, C., M. M. Martz, D. G. Bue, J. C. Linderman and R. L. Fisher. 2005. Annual
management report for the subsistence and commercial fisheries of the Kuskokwim Area, 2003.
Alaska Department of Fish and Game, Fishery Management Report No. 05-72, Anchorage.
Zheng, J., M. C. Murphy, and G. H. Kruse. 1997. Alternative rebuilding strategies for the red king
crab, Paralithodes camschaticus fishery in Bristol Bay, Alaska. Journal of Shellfish Research
16(1): 205–217.
Table 1. Average number of landings for Bering Sea and northern Gulf of Alaska ports over the
period 1998-2002 by port of landing, from ADF&G fish tickets (* indicates
confidential data).
Port Annual Landings
Landings:
Sept. 1 to April 30
Kodiak 10,414 3,474
Dutch Harbor 2,444 1,757
Sand Point 2,930 986
Akutan 1,207 897
King Cove 4,424 884
Homer 1,924 858
Port Moller 3,565 311
St. Paul Island 209 194
Adak 232 136
Chignik 2,370 88
False Pass 91 86
Naknek 5,874 47
Nome 91 28
Alitak Bay 140 27
Wasilla 240 27
Anchorage 69 16
Egegik 2,933 15
Kenai 3,069 13
Ninilchik 193 5
Atka 10 *
Port Bailey 100 *
Ekuk 693 *
Seward 14 *
Unalakleet 187 *
Kasilof 392 *
Dillingham 4,064 0
Kotzebue 16 0
St. George Island 0 0
Soldotna 0 0
Old Harbor 0 0
Togiak 790 0
Ugashik 411 0
Nikiski 235 0
King Salmon 74 0
Seldovia 4 0
Table 2. Current Bering Sea groundfish fishery classifications and catch levels by species
group (from National Marine Fisheries Service website:
http://www.fakr.noaa.gov/sustainablefisheries/2008_09hrvstspecs.htm, Table 1).
Figure 1. Breeding (spring/summer) and winter distribution of Steller’s eiders. a
a (Modified from http://www.seaduckjv.org/rangemaps/stellers_eider.pdf).
Figure 2. Critical habitat designated in federal regulations for Steller’s eiders in Alaska.
Figure 3. Range map for spectacled eiders breeding in Alaska and eastern Russia.b
b Figure source: USFWS).
Figure 4. Critical habitat designated in federal regulations for spectacled eiders in Alaska.
(Federal Register 2001).
Figure 5. Annual light regime at Cold Bay, Alaska, and reported eider strikes by species and
time of day.
Figure 6. Average (1998-2002) landings by port and fishery for September through April from
ADF&G fish ticket landing receipts in the general wintering area of Steller’s eiders.
Figure 7. Average number of landings by day and fishery, 1998-2002, for the top 5 ranked ports,
with stippled area representing landings from May through August when eider
collisions are least likely.
Figure 8. Average number of landings by day and fishery, 1998-2002, for the ports ranked 6
through 10, with stippled area representing landings from May through August when
eider collisions are least likely.
Figure 9. Average number of landings by day and fishery, 1998-2002, for ports ranked 11
through 15, with stippled area representing landings from May through August when
eider collisions are least likely
Figure 10. Number of vessels by day and fishery delivering to Kodiak, averaged over 1998-
2002, from ADF&G fish ticket landing receipts.
Figure 11. Number of vessels by day and fishery delivering to Dutch Harbor, 1998-2002, from
ADF&G fish ticket landing receipts.
Figure 12. Number of vessels by day and fishery delivering to Sand Point, 1998-2002, from
ADF&G fish ticket landing receipts.
Figure 13. Number of vessels by day and fishery delivering to Akutan, 1998-2002, from ADF&G
fish ticket landing receipts
Figure 14. Number of vessels by day and fishery delivering to King Cove, 1998-2002, from
ADF&G fish ticket landing receipts.
Figure 15. Locations of Pacific herring fisheries in central and western Alaska
Figure 16. Light regime and temporal distribution of herring catch, 1990-99, at the locations of
three herring fisheries along the Steller’s eider spring migration route.
0
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2,000
3,000
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9800
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Kodiak
Alaska Peninsula
Bering Sea/Aleutians
Figure 17. Harvests of Dungeness crabs in western Alaska, 1970–2001.
Figure 18. Temporal distribution of Dungeness crab harvest in western Alaska, 1997–2001.
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Figure 19. Spatial distribution of average Dungeness crab harvest along the western Alaska
Peninsula, 1985–2001.
Figure 20. Harvest of all species of shrimp in western Alaska, 1958–2001.
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Figure 21. Spatial distribution of average shrimp harvest, for the years 1985–2001.
Figure 22. Harvests of weathervane scallops in Alaska, 1970–2001.
Figure 23. Temporal Distribution of scallop harvest, 1970–2001
Figure 24. Spatial distribution of average scallop harvest, 1997–2001, showing areas closed to
scallop fishing.
Figure 25. Harvest of red king crabs in the Bering Sea and Aleutian Islands, 1950–2001.c
c Pribilof Islands and foreign harvests include both red and blue king crabs. Effort in pot lifts does not include the
foreign fishery. Foreign harvest data from Otto (1990).
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Figure 26. Spatial distribution of average red king crab harvests in the eastern Bering Sea, 1985–
2001.
Figure 27. Timing of the Bristol Bay red king crab fishery (2001-2005 average number of
landings by day), with respect to the light regime at Cold Bay.
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Figure 28. Large-scale distribution of the average number of salmon setnet landings by statistical
area, 1970–2001, for southwestern Alaska.
Figure 29. Detailed distribution of average annual setnet landings by statistical area along the
north Alaska Peninsula, 1998-2003.
Figure 30. Distribution of average annual drift gillnet landings by statistical area along the north
Alaska Peninsula, 1998-2003.
Figure 31. March 2003 groundfish fleet distribution and effort by target fishery, March 31 sea ice
coverage (maximum extent), groundfish closure areas in effect for March, and March
29-April 11, 2003 Steller's eider distribution from aerial surveys (Larned 2003).
Figure 32. April 2003 groundfish fleet distribution and effort by target fishery, April 11 sea ice
coverage, groundfish closure areas in effect for April, and March 29-April 11, 2003 Steller's
eider distribution from aerial surveys (Larned 2003).
Figure 33. May 2003 groundfish fleet distribution and effort by target fishery, May 9 sea ice
coverage, groundfish closure areas in effect for May. Also shown are the locations of
the Togiak and Goodnews Bay herring fisheries, which were ongoing in early May,
2003.
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
Novel data on the spatial and temporal distribution of fishing effort and population abundance are presented for the market squid fishery (Loligo opalescens) in the Southern California Bight, 1992-2000. Fishing effort was measured by the detection of boat lights by the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). Visual confirmation of fishing vessels by nocturnal aerial surveys indicated that lights detected by satellites are reliable indicators of fishing effort. Overall, fishing activity was concentrated off the following Channel Islands: Santa Rosa, Santa Cruz, Anacapa, and Santa Catalina. Fishing activity occurred at depths of 100 m or less. Landings, effort, and squid abundance (measured as landings per unit of effort, LPUE) markedly declined during the 1997-98 El Niño; landings and LPUE increased afterwards. Within a fishing season, the location of fishing activity shifted from the northern shores of Santa Rosa and Santa Cruz Islands in October, the typical starting date for squid fishing in the Bight, to the southern shores by March, the typical end of the squid season. Light detection by satellites offers a source of fine-scale spatial and temporal data on fishing effort for the market squid fishery off California, and these data can be integrated with environmental data and fishing logbook data in the development of a management plan.
Article
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In the southeastern Bering Sea, Pacific herring (Clupea pallasii) migrate from the Pribilof Islands region where they overwinter, to the Alaska coast where they spawn in spring. The migration sustains a nearshore commercial fishery that targets roe-bearing females just prior to spawning. Herring also are taken as bycatch in groundfish trawl fisheries, where time and area closures in these fisheries are triggered by herring bycatch caps. Using herring bycatch data collected since the 1970s by National Marine Fisheries Service (NMFS) observers aboard groundfish fishing vessels, a retrospective analysis was conducted to describe the seasonal migration pattern of Pacific herring in the southeastern Bering Sea and to study its spatial and temporal variability. Observed changes in herring catch per unit of effort were compared with variability in climate and oceanographic conditions. The seasonal migration is complex, but annual shifts in migration routes and a possible northward shift of the overwintering grounds was identified. Pre-spawning herring aggregated in different areas depending on whether spawning occurred early or late in spring. The thermal structure of the ocean around the ice edge appears to influence herring migration timing and route as well as spawning date. Thus, on the basis of recent changes in sea-ice extent and duration, we suggest that the herring bycatch savings area that was developed from data collected in the 1980s should be revised to reflect prevailing conditions.
Article
The abundance of Bristol Bay red king crab Paralithodes camtschaticus has fallen to historically low levels in recent years. Concerns about depressed spawning stock levels and economic hardships associated with fishery closures in 1994 and 1995 prompted reevaluation of the status quo harvest strategy and investigation of alternative strategies to rebuild the stock. Using a length-based model initialized with the 1994 population abundance, we simulated future effects of seven alternative rebuilding strategies on this stock. Strategies ranged from the status quo strategy through increasingly restrictive harvest strategies culminating in complete fishery closure until the stock is rebuilt. Statistics on catch, variation in catch, effective spawning biomass, probability of rebuilding, probability of fishery closure, and present exvessel value were collected for comparisons. Sensitivities of the harvest strategies to natural mortality, handling mortality, stock-recruitment relationship, and measurement error were examined. Reducing the status quo harvest rate greatly shortened rebuilding time and enhanced long-term catch. The most conservative strategy achieved a 50% probability of rebuilding the stock to a target 25,000 t of effective spawning biomass in 12 y. In terms of catch and present exvessel value, the status quo strategy performed best among the seven strategies over a short-term (≤20 y) planning horizon, whereas strategies with a mature male harvest rate of 50-75% of the status quo level performed best over longer planning horizons. Scenarios with lower natural mortality, higher handling mortality, or a more density-dependent stock-recruitment relationship favor the implementation of more conservative strategies. Our analysis of population and fishery dynamics leads us to recommend a 25-50% reduction in harvest rate to rebuild this depressed stock.
Article
The at-sea distribution of the threatened Spectacled Eider (Somateria fischeri) has remained largely undocumented. We identified migration corridors, staging and molting areas, and wintering areas of adult Spectacled Eiders using implanted satellite transmitters in birds from each of the three extant breeding grounds (North Slope and Yukon-Kuskokwim Delta in Alaska and arctic Russia). Based on transmitter locations, we conducted aerial surveys to provide visual confirmation of eider flocks and to estimate numbers of birds. We identified two principal molting and staging areas off coastal Alaska (Ledyard Bay and eastern Norton Sound) and two off coastal Russia (Mechigmenskiy Bay on the eastern Chukotka Peninsula, and the area between the Indigirka and Kolyma deltas in the Republic of Sakha). We estimated that >10,000 birds molt and stage in monospecific flocks at Mechigmenskiy and Ledyard bays, and several thousand molt and stage in eastern Norton Sound. We further identified eastern Norton Sound as the principal molting and staging area for females nesting on the Yukon-Kuskokwim Delta, and Ledyard Bay and Mechigmenskiy Bay as the principal molting and staging areas for females nesting on the North Slope. Males marked at all three breeding grounds molt and stage in Mechigmenskiy Bay, Ledyard Bay, and the Indigirka-Kolyma delta region. Males from the Yukon-Kuskokwim Delta molt and stage mainly at Mechigmenskiy Bay. Equal numbers of males from the North Slope molt and stage at all three areas, and most males from arctic Russia molt and stage at the Indigirka-Kolyma delta region. Postbreeding migration corridors were offshore in the Bering, Chukchi, and Beaufort seas. In winter, eiders were in the Bering Sea south of St. Lawrence Island. Our estimates from surveys in late winter and early spring suggest that at least 333,000 birds winter in single-species flocks in the pack ice in the Bering Sea.
Article
This study considers the temporal and spatial distribution of Steller's Eiders (Polysticta stelleri) during molt along the north side of the Alaska Peninsula from Port Heiden to Bechevin Bay. Subadult eiders molted primarily at Nelson Lagoon, adult males at Nelson Lagoon and Izembek Bay, and adult females primarily at Izembek Bay. Only a few eiders used Bechevin Bay, Seal Islands, and Port Heiden. Although the flightless period overlapped among different age and sex classes, subadults were flightless first, then adult males, and last, adult females. Eiders maintained spatial and temporal separation during the flightless period, thereby reducing competition for food resources. Eiders at Nelson Lagoon were observed feeding only by head-dipping during the pre-flightless period in 1979, a significant change from 1977 when they fed both by diving and dipping. During both 1977 and 1979 eiders foraged for approximately equal amounts of time during each stage of molt. Foods consisted primarily of bivalve mollusks and amphipods. These foods were consumed in different proportions before and after the wing-feather molt, with mussels being most important when eiders were growing remiges. Comparisons between the amount of energy in blue mussels (Mytilus edulis), clams (Macoma balthica), and gammarid amphipods showed that mussels yield the most energy per gram of whole wet weight. Apparently Steller's Eiders have adjusted to the increased energy demands of molt by eating invertebrates with high caloric content, rather than by increasing the amount of time feeding.
Article
The distribution and abundance of the fleet targeting Jumbo flying squid (Dosidicus gigas) in the Eastern Pacific is examined during the 1999 fishery season. The commercial fishery consists of a multinational jigging fleet, which fish at night using powerful lights to attract squid. The emission of light from these vessels can be observed using satellite-derived imagery obtained by the United States Defence Meteorological Satellite Program-Operational Linescan System (DMSP-OLS). In order to quantify fishing effort using lights, data on the distribution and abundance of vessels were obtained via satellite tracking using the ARGOS system. The distribution of the fishery as derived from light signatures was found to closely resemble that derived from ship location data. By using ARGOS data to calibrate DMSP-OLS images, we are able to estimate fishing effort in terms of the ‘area illuminated’ by the fishing fleet. Light signatures derived from DMSP-OLS were successfully used to quantify fishing effort, estimating the number of vessels fishing to within ±2 in 85 out of 103 satellite images (83%). High seas fishing was also quantified, with light signatures corresponding to a single fishing vessel observed in 11 out of 103 satellite passes during the fishery season (July–December 1999). This study examines how much light (in terms of area) is emitted by a single squid fishing vessel, and may prove to be a valuable tool in assessing and policing fisheries using satellite remote sensing.
Report to the Alaska Board of Fisheries. Alaska Department of Fish and Game, Division of Commercial Fisheries
  • J P Barnhart
Barnhart, J. P. 2000a. Weathervane scallop fishery in the Westward Region, 1967-1999: Report to the Alaska Board of Fisheries. Alaska Department of Fish and Game, Division of Commercial Fisheries, Regional Information Report 4K00-12, Kodiak.