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Auke Bay Laboratory

(Quarterly Report for April-May-June 2000)

Dispersant Effectiveness Testing Begins at ABL

The environmental repercussions of not treating an oil spill were amply demonstrated by the damage that ensued from the Exxon Valdez oil spill.  Research conducted by the Auke Bay Laboratory following the spill demonstrated decade-long persistence of the oil in nearshore sediments.  This persistent source of petroleum hydrocarbons is bioavailable and toxic to nearshore and estuarine fish eggs at parts per billion concentrations.  Dispersal of the oil in the water column is viewed as a possible means of eliminating this threat to the productive nearshore environment.  It remains to be seen, however, if dispersants are chemically effective in dealing with Alaskan spills.

While dispersants are often the primary method used in Europe for treating a spill, in the United States dispersants are used only when certain stringent conditions are met.  The decision to use dispersants following an oil spill is contingent on balancing the obvious advantages of using dispersants against the potential for acute damage, both from the dispersant and from the synergistic interactions of oil and dispersant. Evaluating  these difficult tradeoffs is one of the most challenging jobs facing an on-site coordinator.  The decision to use dispersants will hinge initially on whether the stockpiled dispersant in Alaska (Corexit 9527) will prove effective in dispersing the oil under regional conditions.  Initial research suggests that both Corexit 9527 and its likely replacement Corexit 9500 may be less effective in dealing with Alaska North Slope Crude oil than against other types of oil.  The ABL is conducting a series of effectiveness tests to determine what percentage of the oil is dispersed at combinations of cold temperatures (4°-15°C),  reduced salinities (15‰-25‰), and a variety of weathering states (fresh, 26% weathered, and mousse).

By Adam Moles.

Army Corps of Engineers Proposes Aquatic Habitat Restoration for Duck Creek

National recognition of efforts to restore aquatic habitat in Duck Creek has prompted the U.S. Army Corps of Engineers (COE) to propose up to $4.0 million in aquatic habitat restoration projects for the Duck Creek watershed.  That funding is contingent on a 35% match from sponsors such as the City/Borough of Juneau (CBJ), Mendenhall Watershed Partnership, and Trout Unlimited.

Awards to the Duck Creek Advisory Group (DCAG) from Coastal America and the Federal Interagency Stream Restoration Working Group (FISRWG) led to the Corp’s involvement.  In 1999, the DCAG received a partnership award from Coastal America, and Duck Creek was selected by the FISRWG as one of 12 national demonstration watersheds.  The Coastal America award was for facilitating Federal agency cooperation in state and local efforts to address specific environmental problems along our Nation’s coasts. As part of the Clean Water Action Plan, the FISRWG is promoting Duck Creek as one of 12 watersheds in the Nation that best demonstrate the principles and practices of stream corridor restoration.

Federal agencies involved in the project include National Marine Fisheries Service, the Environmental Protection Agency (EPA), and U.S. Fish and Wildlife Service (USFWS). The AFSC  provided personnel and secured grant funding for several Duck Creek projects through the NOAA Community-Based Restoration Program.  The EPA provided nearly $450,000 in funding for research and demonstration of nonpoint source pollution treatment in the Duck Creek watershed.  The USFWS provided personnel and grant funding through Partners for Wildlife and other programs.

The City/Borough of Juneau is the primary local sponsor of the proposed COE projects.  The CBJ has agreed in principle to support the projects by matching up to 35% of the COE expenditure.  Most of that match will likely be “in-kind” services such as providing rights-of-way, construction materials, or engineering services.

The proposed projects are being designed primarily to restore aquatic habitat for fish and wildlife.  In Duck Creek’s urban location, however, those projects will also address a number of other issues such as public health and safety, water quality, and flooding.  ABL scientists K Koski and Mitch Lorenz are currently being funded by the COE to complete a feasibility study for the eight projects proposed for COE funding by the end of FY 2000.

By Mitch Lorenz.

Stock Origins of Illegally Captured Salmon on the Drift-Net Vessel Arctic Wind

(view "Origins of Salmon Seized From the F/V Arctic Wind" file (.pdf format))
On 1 May 2000 the U.S. Coast Guard (USCG) spotted the 177-ft fishing vessel Arctic Wind illegally driftnet fishing about 600 miles southwest of Adak Island.  The Honduran-registered, Korean-owned, Russian-crewed vessel was stopped and boarded by the USCG on May 8.  Two nets from the vessel were retrieved on 10 May, approximately 300 miles from Adak Island.  The vessel was escorted to Adak and samples of the catch were sent to the ABL for stock identification and other analyses.  Samples included 492 chum salmon, 217 sockeye salmon, and 55 chinook salmon.  The remaining approximately 1,000 chum salmon were delivered by the USCG to the food bank in Anchorage.

Of the sampled chum salmon, 464 whole and 28 gutted, 301 were processed for genetic analysis (whole fish only), 474 for otoliths, and all 492 for scales.  Of the sampled sockeye salmon, 61 were whole, 146 were gutted, and 10 were headed and gutted.  The headed-gutted sockeye salmon were not sampled; all the remaining fish were sampled for genetic, scale, and brain parasite analysis.  The gutted fish had been sprinkled with rock salt, which may have been an attempt to firm up the flesh, and may interfere with the genetic analysis.  All of the 55 chinook salmon, 24 whole and 31 gutted, were sampled for genetic, scale, and brain parasite analysis.

Age determination of fish by scale analysis, presence of brain parasites in sockeye and chinook salmon, and genetic stock identification analysis by protein electrophoresis will be used to identify the region(s) of origin of these fish.  The genetic analysis is ongoing and so far sample quality has been very good.  The chum salmon otoliths will be examined for hatchery thermal marks by the Alaska Department of Fish and Game (ADF&G) Otolith Processing Laboratory.

By Jon Poll, Chris Kondzela, and Chuck Guthrie.

Southeast Alaska Coastal Monitoring

The Southeast Alaska Coastal Monitoring (SECM) project is a cooperative effort of the ABL Ocean Carrying Capacity and Marine Salmon Interactions Programs, which examines environmental relationships of juvenile salmonids as they leave natal waters of northern Southeast Alaska and progress through Icy Strait to the outer coastal waters off Cross Sound.

Two cruises were completed this quarter for the SECM.  Joseph Orsi (Marine Salmon Interactions) was Chief Scientist for the May 2000 John N. Cobb Cruise JC00-05 and James Murphy (Ocean Carrying Capacity Program) the Chief Scientist for the June 2000 Cruise JC00-09. Bruce Wing (Ocean Carrying Capacity Program) participated on both cruises.  Besides ABL staff, Craig Chisolm (Northern Southeast Regional Aquaculture Association) and Robert Spevic (biology instructor from a private high school in San Francisco, California) were volunteer assistants during the June cruise.

The May cruise was restricted to oceanographic sampling, during which temperature and salinity profiles and zooplankton samples were obtained at 21 stations, and surface nutrient and chlorophyl samples were taken at 15 stations.  Because juvenile salmon are usually either very rare or not present at the sampling stations in May, we did not conduct surface trawling.

A coordinated oceanographic, rope trawl and acoustic survey for juvenile salmon aboard the NOAA research vessel John N. Cobb and the research vessel Quest was conducted between 26 June and 2 July 2000.  Sampling locations included four stations along an offshore transect at Icy Point, four stations along a transect in Cross Sound, nine stations along a transect in Icy Strait, four stations along the upper Chatham transect, and four stations in the inshore waters. Zooplankton settled volumes (SVs) were highest at the Icy Strait stations and coincided with the highest catches of juvenile salmon. Zooplankton consisted primarily of small copepods and euphausiids. The increase in zooplankton SVs at the Icy Point Station 40 miles offshore was primarily due to the abundance of Limacina.

A total of 5,396 fish and squid were captured with the rope trawl, representing 15 different species.  Juvenile lingcod appeared to be more abundant in June than in previous years in trawls taken over the continental shelf.  About three dozen pelagic stage lingcod were taken, compared with previous years when usually less than 10 juvenile lingcod were taken during a cruise.  Salmon catches were predominately juveniles (n = 1,544): juvenile chum salmon was consistently the most abundant fish species captured (n = 917) and was considerably more abundant than the other species of juvenile salmon (sockeye salmon (n = 272), pink salmon (n =  253), coho salmon (n = 93), and chinook salmon (n = 9)).  Juvenile salmon were most abundant in Icy Strait.  Mean fork lengths of juvenile salmon varied by species.  Coho salmon had the largest mean length (165 mm), followed by chinook (157 mm), sockeye (114 mm), chum (106 mm), and pink (95 mm).

Hydroacoustic surveys were conducted along several transects near the Icy Strait stations.   Hydroacoustic data were collected with a Biosonics DT4000 system with a 150 kHz narrow beam (6E) transducer mounted in a fin and towed along the side of the vessel. The transducer was mounted in a side scanning configuration with a downward tilt of 4E.  The hydroacoustic data will be processed to provide mean backscattering area per unit of horizontal area and then will be compared to the zooplankton and trawl data.

By Bruce L. Wing.

Auke Bay Environmental Monitoring

Daily sea surface temperature and weather observations at the Auke Bay Laboratory continued through the winter and spring of 1999-2000.  Sea surface temperatures were about average compared with the long-term mean (1978-2000).  Air temperatures were warmer than average and precipitation was about average for the first half of the year.

By Bruce L. Wing.

Monthly Mean Sea Surface Temperature (EC)

Monthly Midrange Air
Temperature (EC)
Year 1999 2000 Mean Year 1999 2000 Mean
January 4.1 3.9 3.6 January -2.9 -2.9 -4.1
February 4.0 3.4 3.2 February -1.2 0.5 -1.1
March 3.7 3.7 3.8 March -1.4 2.9 1.34
April 6.0 6.3 6.2 April 4.8 5.1 5.1
May 9.1 10.4 10.0 May 7.9 9.5 7.63
June 13.7 13.3 13.4 June 13.2 13.1 12.5

Monthly Precipitation (cm)


Monthly Snowfall (cm)

Year 1999 2000 Mean Year 1999 2000 Mean
January 18.8 5.6 11.7 January 104.6 26.7 70.1
February 6.0 3.2 10.0 February 67.6 3.6 45.3
March 5.6 11.6 8.5 March 4.3 0 44.1
April 14.0 14.1 7.5 April 3.1 Trace 5.0
May 14.8 10.1 10.0 May 0 0 1.0
June 8.0 16.1 10.5 June 0 0 0


2000 Longline Survey Under Way

The twenty-second standard longline sablefish survey conducted by the Center’s ABL and Resource Assessment and Conservation Engineering (RACE)  Division began 1 June in Dutch Harbor aboard the survey charter vessel Alaskan Leader.  The survey covers the Gulf of Alaska annually and the Bering Sea and Aleutian Islands region in alternate years.   The survey catch rates are critical in determining the annual allowable biological catch of sablefish.  In addition to indexing sablefish abundance, sablefish, shortspine thornyheads, and Greenland turbot will be tagged and released with Floy anchor tags during the survey.  Length data are collected on all major species, including rockfish and grenadiers, and weight data and otoliths are collected from sablefish. Also, a small-mesh surface gillnet is deployed at night to sample juvenile sablefish (ages 0 and 1), genetic tissue samples are taken from rougheye rockfish, and sightings of short-tailed albatross are recorded.

Scientists on the Alaskan Leader sampled Aleutian Islands stations during the first leg, Western Gulf stations during the second leg, then transited the Gulf of Alaska for a port call in Ketchikan. During the Gulf of Alaska transit, three seamounts were sampled.  Two of the three seamounts fished, Surveyor and Pratt, were also sampled last year.  Sablefish catches were down slightly at Surveyor and about the same as last year at Pratt.  The third seamount sampled this year was Welker, about 100 miles southeast of Pratt.  Over 2,000 sablefish were caught on Welker.  About 300 sablefish were tagged and released and 50 sampled for otoliths at each of the three seamounts. Seven tagged fish were recovered from the same seamounts where they were released last year.  One tagged fish, released off Kodiak in 1989, was recovered on Welker Seamount.  The third leg of the survey began at Dixon Entrance and will progress north and west to complete the sixth leg in the Central Gulf Area around 3 September. Chief scientists were, for the first leg, Larry Haaga (RACE) and, for the second leg, Nancy Maloney (ABL).

By Nancy Maloney and Mike Sigler.

Sablefish Fishery Catch Rates

The number of sablefish caught during the annual longline survey helps determine trends of abundance over time.  In recent years, survey catch rates have steadily declined, indicating sablefish populations in Alaska have decreased.  Some fishermen have expressed concern about this trend because their catch rates have remained strong in some areas in contrast to the decline indicated by the NMFS survey. Since changes in abundance estimates directly affect fishermen’s individual fishing quotas (IFQs), survey trends are an important issue to fishermen.  To address these concerns and to determine if the fishery and survey are showing similar trends, the ABL is utilizing commercial fishery data.  The addition of fishery data along with survey data will expand the time frame during which CPUE is represented in the assessment model.

Several sources of fishery data are now available to ABL assessment scientists.  Extensive fishery information is available through data collected by the domestic observer program since 1990.  In 1997, a cooperative effort by the ABL and fishing industry representatives established a volunteer sablefish logbook program for vessels under 60 feet. These vessels typically do not carry observers on board and represent a large proportion of the vessels operating in the eastern Gulf of Alaska.  Skippers of these vessels voluntarily supply data which are provided to NMFS by their fishing associations. Data include catch locations, composition, and amounts and gear specifications essential for standardization.  In addition to the volunteer logbook program, a required logbook program was initiated in March 1999, which requires vessels over 60 feet in length to maintain a logbook documenting sablefish catch.  The recent addition of these logbook programs provides a large amount of information which we can now use to accurately estimate trends in fishery catch rates.

Using the fishery data, a standardized fishery catch rate for each management region and year is computed for comparison to survey catch rates.  Catch rates are standardized by set to account for differences in hook spacing which can vary greatly between vessels and gear.  Standardizing the data allows the analysts to compare the fishery data to the survey data in different regions and years.  Catch rates are expressed as the number of pounds caught per hook.

catch per unit effort as described in figure caption
Figure 1.  Average CPUE (pounds/hook) by region for survey and
sablefish directed longline fishery data, 1990-1998.

The highest catch rates for both fishery and survey data are in the West Yakutat and East Yakutat/Southeast areas (Figure 1 above). The fishery and survey catch rate trends from 1995 to 1998 are similar in all Gulf of Alaska areas except in West Yakutat.  In West Yakutat, the survey catch rate has declined steadily since 1996.  Fishery catch rate, however, increased in 1997 followed by a decrease in 1998.  In other areas, the survey catch rate has generally declined since 1995, whereas the fishery catch rate appears steady from 1995 to 1998. Fishery catch rates increased dramatically from 1994 to 1995 in all Gulf of Alaska regions.  This increase in catching ability is  probably due to the change from a “derby” to an IFQ fishery.

After accounting for the change to the IFQ fishery, the results of this analysis indicate fishery and survey catch rate trends from 1995 to 1998 are similar in all Gulf of Alaska areas except West Yakutat. These results are an important step towards incorporating both survey and fishery data into the management process.  The establishment of two logbook programs indicates a strong commitment from the industry to help NMFS and increases the amount of fishery information available for management purposes.  The fishery catch rate data from this analysis has been added to the sablefish assessment model and will assist in better understanding the status of the sablefish population in Alaska.

By Chris Lunsford.