Alaska Fisheries Science Center Auke Bay Laboratory Report for April-May-June 1998 Quarterly Report

Salmon Survey in the North Pacific Ocean and Southeastern Bering Sea

A 30-day survey of the ocean distribution of immature and mature Pacific salmon and associated marine species was made in coastal waters off Alaska and Washington and the high seas of the Gulf of Alaska and central North Pacific Ocean during April and May 1998 by Auke Bay Laboratory (ABL) staff. The work is part of a cooperative international research effort coordinated through the North Pacific Anadromous Fish Commission to examine distribution, growth, and survival of Pacific salmon during their ocean life.

The survey was conducted on the chartered fishing vessel Great Pacific, a 38-m-long stern ramp trawler. The survey focused on nearshore and oceanic distribution of salmon off the eastern Aleutian Islands, Alaska Peninsula, and Washington coast and on the high seas of the central Gulf of Alaska (GOA) from lat. 50ºN to 55°N and along long. 145°W from the northern GOA (lat. 50°-59°N) to the central North Pacific Ocean (lat. 38°-55°N). Sampling gear was a midwater rope trawl towed at 5 knots at surface with typical spread to 18 m depth and 52 m width. The survey included three oceanographic transects at Scotch Cape, Cape Chiniak, and Cape St. Elias. Plankton tows and conductivity-temperature-depth (CTD) casts were conducted with surface trawl effort on the high seas.

Total catch of salmonids was 1,493 fish, including 881 immature and 612 maturing adult salmon. Immature salmon were 602 sockeye, 184 chum, and 95 chinook. Maturing adult salmon were 322 chum, 141 sockeye, 107 pink, 6 chinook, and 36 coho. Most immature salmon were sockeye taken in the Bering Sea, and most maturing adult salmon were chum taken in the northern Gulf of Alaska and in high seas tows. Catches of maturing salmon on the high seas varied between chum and sockeye with one species predominate, the other few or none. Noteworthy were catches of immature sockeye salmon, 20-30 cm fork length (FL), off Cape Cheerful in the southeastern Bering Sea and immature chinook salmon, 31-35 cm FL, off Foggy Cape in southwestern Shelikof Strait. Other fishes taken included juvenile sablefish, adult and young walleye pollock, Pacific herring, Pacific mackerel, jack mackerel, juvenile shad, and 18 oarfish over Juan de Fuca Canyon. Sea surface temperatures ranged from 3.6°C in the Bering Sea to 12.5°C in the central Pacific Ocean. Storms and heavy seas limited early sampling off the Aleutian Islands and efforts offshore in the central Gulf of Alaska.

By Richard Carlson and Ed Farley.

Kuroshima Oil Spill Response

The freighter Kuroshima grounded in Summer Bay near Dutch Harbor, Alaska, in November 1998 during a violent, 90-knot wind. Although some cleaning and oil removal on beaches was accomplished in the first few weeks, winter weather and winds hampered the response effort, and except for salvaging the vessel, all response activities ceased during the winter. The vessel was refloated in early March, and cleanup efforts were renewed in early April 1998. The strong winds causing the grounding also caused leaking oil to contaminate the nearby shoreline and Summer Lake, a salmon lake separated from the marine environment by a sand barrier beach. About 75% of the lake shoreline was contaminated. After the winter ice cover melted divers confirmed bottom sediments were also contaminated. In April, ABL divers sampled the lake sediments in a grid pattern over the entire lake. Chemical analyses of these samples confirmed sediment contamination throughout the entire lake with a concentration of oil globs in the north end. Most sediments were in the low hundreds of parts per billion (ppb) of polynuclear aromatic hydrocarbons (PAH), with some samples ranging as high as 24,000 ppb of PAH. The damage to salmonid populations is unknown. Pink salmon fry and smolts of sockeye and coho salmon have left the lake system through a weir operated by the Alaska Department of Fish and Game (ADF&G), indicating that total year-class failure is not a problem.

By Jeep Rice.

Intragravel Exposure of Pink Salmon Embryos to Crude Oil

Research following the Exxon Valdez oil spill in 1989 continues to suggest the negative impacts of oil exposure on pink salmon eggs intertidally exposed to crude oil. Researchers at the ABL have attempted to simulate intragravel exposure by incubating pink salmon embryos under three exposure conditions: 1) in direct contact with oil-coated gravel, 2) in effluent from oil-coated gravel, and 3) in direct contact with gravel coated with very weathered oil (VWO). Embryo mortalities and PAH accumulation in embryo tissues during the direct-contact and effluent exposure experiments were not significantly different, indicating that PAH accumulation was mediated by aqueous transport. Mortality rates for embryos exposed initially to a total PAH concentration (TPAH) of 1.0 ppb were significantly higher than mortality rates for controls when the PAH were derived from VWO. The same aqueous TPAH concentration failed to increase mortality rates when the PAH were derived from less weathered oil, indicating that toxicity of effluents from the VWO was primarily associated with the greater PAH concentration. We conclude that water quality standards for TPAH above 1.0 ppb may fail to protect fish embryos. Further, pink salmon embryos incubating in Prince William Sound (PWS) after the Exxon Valdez oil spill may have accumulated lethal concentrations of PAH from interstitial water that was contaminated when it percolated through oil reservoirs located upstream from salmon redds. There are two significant issues with this research effort. First, it corroborates the oil toxicity mechanism of elevated egg mortalities observed by the ADF&G through 1993, 4 years after the spill. Second, along with the larval herring study (see below), these are the lowest effective oil concentrations showing negative effects from an oil spill ever reported.

By Ron Heintz.

Low-level Exposure of Pacific Herring Eggs to Weathered Crude Oil

Malformations were observed in Pacific herring (Clupea pallasi) larvae in PWS following the Exxon Valdez oil spill. In an effort to understand the role oil exposure might have played in these observed changes, ABL researchers exposed two groups of Pacific herring eggs for 16 days to weathered Alaska North Slope crude oil in the laboratory in spring 1995. The composition of the oil to which eggs were exposed was closely similar to oil compositions observed in PWS after the spill. Oil-contaminated water used in our experiment contained the same PAH compounds observed in PWS, including naphthalenes through chrysenes. The ratios of these compounds change as weathering occurs, both in the environment and in the laboratory, and can be described by first-order loss-rate kinetics. Our experiments included a less-weathered oil with relatively more naphthalenes and fewer larger compounds such as phenanthrenes, and more weathered oil with relatively fewer naphthalenes and more large compounds. Weathering effects observed in PWS encompassed those of the laboratory study, thus our methods simulated conditions observed in PWS following the spill. Exposure to an initial aqueous concentration of 0.7 ppb PAH caused malformations, genetic damage, mortality, and decreased size, and inhibited swimming ability. Total aqueous PAH concentrations as low as 0.4 ppb caused sublethal responses such as yolk-sac edema and immaturity consistent with premature hatching. Responses to less weathered oil, which had relatively lower proportions of high molecular weight PAH, generally paralleled responses to more weathered oil, but lowest observed effective concentrations (LOECs) were higher (9.1 ppb), demonstrating the importance of composition. The LOEC for more weathered oil (0.4 ppb) was similar to that observed for pink salmon (1.0 ppb), a species with a very different development rate. By inference, other species may be similarly sensitive to weathered oil. Biological effects including temporal and physical evidence of premature hatching, small size, edema, and genetic damage were identical to those observed in larval herring from PWS in 1989 and support the conclusion that the Exxon Valdez oil spill caused significant damage to herring in PWS. Previous demonstration by our laboratory in 1990 that most malformed or precocious larvae die corroborates the decreased larval production measured after the spill.

By Mark Carls.

Genetic Stock Identification of Chum Salmon Caught in Bering Sea Trawl Fishery

Laboratory analysis of Southeast Alaska hatchery chum salmon has been nearly completed for addition to the North Pacific chum salmon genetic baseline. Recoveries of thermally-marked chum salmon in the Bering Sea trawl fishery indicate that significant numbers of Southeast Alaska hatchery chum salmon are caught in this fishery. The expanded genetic baseline should allow us to quantify the presence of these hatchery fish in the bycatch. The genetic samples from the 1996 Bering Sea trawl fishery chum salmon bycatch (the last year samples were collected from this fishery) are nearly finished, and genetic stock identification analysis will begin in the fourth quarter.

By Richard Wilmot.

Yukon River Fall-Run Chum Salmon Radio Tagging Study

The major components for installation of satellite radio-tag tracking towers were obtained and shipped to the Yukon River for installation on the upper section of the river in Canada, and on the Chandalar and Sheenjek Rivers on the U.S. side of the border. As part of this cooperative international project between Canada and the United States, tagging and tracking of fall chum salmon will begin next quarter when the fish arrive in the river.

By John Eiler.

Chinook Salmon and Hatchery-Wild Stock Interaction Studies

Increasing concern about the effects of cultured salmonids on wild salmon populations prompted the initiation of studies designed to measure the effects (if any) of hatchery practices on the behavior, growth, and survival of chinook salmon in Southeast Alaska. These studies, begun in 1996, are examining interactions of progeny from fourth generation hatchery chinook salmon and the undisturbed, parental wild population from which they were derived.

Gametes from wild Chickamin River stock chinook salmon and the NMFS Little Port Walter (LPW) Chickamin River stock were collected in 1996. The LPW stock originated from a small founder population of gametes collected from the Chickamin River in 1976, with no subsequent introduction of wild gametes. The LPW stock has been maintained by the culture and release of coded-wire tagged age-1 smolts as part of a long-term ocean ranching, stock enhancement research program. In 1996, the wild and hatchery gametes were used to create four groups of progeny: wild × wild, hatchery × hatchery, wild × hatchery and hatchery × wild. Each group was incubated and cultured separately. The ability of fry from these groups to avoid predation was tested by a series of exposure trials to fish predators during May 1997. In May 1998, the predation ability of the smolts from these groups was evaluated by exposing pink salmon fry to the smolts in a variety of experimental conditions. A third experiment evaluated the freshwater culture performance of the groups in a replicated design. Finally, smolts from each group were coded-wire tagged and released from LPW in May 1998 to evaluate marine survival, fishery contribution, and age at maturation.

Knowledge gained from these studies will provide important data concerning the risks associated with hatchery selection and will aid in evaluating the impacts of straying and introgression of hatchery fish into wild populations. Pending adequate funding, further studies are planned using other hatchery stocks and the undisturbed wild populations from which they were derived. Different paired populations of wild and hatchery chinook salmon stocks in Southeast Alaska provide a unique opportunity to examine the potential impacts of hatchery selection without the confounding effects of a different stock history or severe habitat degradation.

By John Joyce.

Steelhead/Rainbow Trout Studies at Little Port Walter Field Station

In spring 1996 scientists at LPW initiated a study to begin examining the effects of long-term freshwater sequestration on progeny of anadromous steelhead trout. Over 60 years ago, wild steelhead trout (Oncorynchus mykiss) fry were collected from Sashin Creek, Alaska, and stocked into Sashin Lake, which until then had been without fish and separated by a barrier falls from the endemic anadromous run of steelhead trout in the lower creek. Round Lake, part of the Sashin Creek drainage, is also separated from Sashin Lake and the lower creek by a second barrier falls and was stocked 12 years later with fish from Sashin Lake. Both lakes now have healthy resident populations of steelhead trout that still produce migratory smolts, are reproductively isolated from each other, and are partially isolated from the anadromous steelhead population in the lower portion of the creek. In the intervening 60 years no other stocking into any of these populations has occurred.

Results of the LPW study are expected to provide scientific information on 1) the effects of long-term sequestration in fresh water on genetic variability; 2) the effects of small founder population size on genetic variability; 3) the effects of long-term sequestration on anadromous smolt production capability and marine survival; and 4) the effects of long-term sequestration on important life history parameters such as embryo survival, size of fry, and long-term growth, survival, and maturation rates. These results could have important implications in determining the potential role of resident rainbow trout to the genetic heritage of listed ESUs (evolutionary significant units) of steelhead and in determining the most effective restoration strategies for stocks in peril. Presently there are no salmonids in Alaska listed under the Endangered Species Act (ESA), and this research is designed to provide basic scientific data to aid in ESA salmonid recovery programs in the Pacific Northwest.

To date, the study has succeeded in producing 80 families of resident rainbow and steelhead trout and crosses between the types of the 1996 brood year. These crosses have been raised to smolt stage and resulted in the first release of anadromous smolts from the study in June 1998. In addition, 6,600 passive-integrated-transponder-tagged fish from the same families are being reared in captivity to maturity to determine which crosses provide the best genetic mix to use in captive brood programs for ESA recovery plans.

An additional 80 families were produced from the 1997 brood year and are currently under culture at LPW. Microsatellite DNA and mitochondrial DNA have been examined from the donor steelhead population and the current resident lake population, and allozyme analysis will be conducted this summer to compare variation between the populations. The first returning adults from the study are expected in the year 2000, at which time the second phase of the study, examination of outbreeding depression, will begin.

By Frank Thrower.

Juvenile Sablefish Studies

Off Southeast Alaska, sablefish spawn in deep waters (200-300 m) in late winter (January-February). During development, the buoyant eggs rise toward the surface, the larvae hatch and rise towards the surface and finally occupy the neuston layer, where they feed and grow rapidly to 120-130 mm by late summer. Studies conducted in recent years in conjunction with the NMFS annual sablefish longline survey found young-of-the-year (YOY) sablefish in surface waters along the continental slope of the Gulf of Alaska. In late summer, YOY sablefish move shoreward from their oceanic distributions and have been found along the coast and in nearshore bays. They have been taken in surface rope-trawls during juvenile salmon studies in the fall and found in the stomachs of silver salmon taken in the coastal troll fishery. At least some juvenile sablefish apparently overwinter in inshore locations such as St. John the Baptist Bay where they have been found throughout their first winter and the following summer. Tagging juveniles during this stage of their life cycle has provided valuable assessment information, such as the age of recruitment to the offshore fisheries, and has provided a valuable tool for validating ageing methods of sablefish.

Biologists from ABL and the AFSC’s RACE Division tagged juvenile sablefish in inshore waters of Baranof Island in Southeast Alaska during a cruise of the NOAA ship John N. Cobb during 5-11 May. Approximately 1,200 juvenile sablefish (age 1+) were tagged and released at St. John the Baptist Bay and Silver Bay, near Sitka. This was the fourteenth consecutive year of sampling at St. John the Baptist Bay. While juvenile sablefish have been found only sporadically in other nearshore areas, they are typically found in abundance at St. John the Baptist Bay. Strangely, only 50 juvenile sablefish (age 1+) were caught and tagged there in 1997.

By Jeff Fujioka and John Karinen.

Sablefish Longline Survey Under Way

The first two legs of the AFSC’s annual Sablefish Longline Survey have been completed; they covered the Aleutian Islands region and the western Gulf of Alaska. The survey is conducted by the ABL and RACE Divisions and covers the Gulf of Alaska annually and the Bering Sea and Aleutian Islands region in alternate years. The survey charter vessel Alaskan Leader completed Legs 1 and 2 (1-29 June) and transited the Gulf of Alaska from the western gulf to Dixon Entrance in the eastern Gulf of Alaska to begin the third leg of sampling at stations from Dixon Entrance to Yakutat. This sequence of coverage has been altered from past surveys to avoid interaction with major trawl fishery openings in the central and western gulf in July. The survey catch rates are critical in determining the annual allowable biological catch of sablefish, and the reduction of influences from fishery activities decreases the uncertainty in the assessment.

Effects of Trawling on Benthic Habitat—Studies With a Submersible

A description of the seafloor habitat in heavily trawled and protected regions of the central Gulf of Alaska near Kodiak Island was obtained during a cruise during 4-17 June aboard the State of Alaska research vessel Media using the submersible Delta as an observation platform. The objective of the cruise was to assess changes to the seafloor and organisms caused by chronic, long-term trawling in three areas of the central Gulf of Alaska. Specific objectives are to compare nontrawled areas to trawled areas to determine if changes have occurred to 1) infauna and associated demersal zooplankton, 2) epifauna, 3) fish populations associated with the seafloor, and 4) seafloor characteristics including grain-size composition, sorting of sediments, and total organic carbon content. Weather and sea conditions prevented diving on several days so only two areas were studied: near Chiniak Bay and the Trinity Islands. All videos taken on the transects over trawled and nontrawled areas were reviewed at sea to quantify benthic epifaunal assemblages, demersal fish, and physical characteristics of the seafloor. Sediment samples of the upper 10 cm of the bottom were obtained for all transects using a 0.04-m2 Shipek grab. Samples were sieved through 1-mm and 0.5-mm screens, and the biota obtained from the samples were preserved in 5% seawater-buffered formaldehyde containing 0.5 g/L Rose Bengal. Processing of samples and video data is currently under way. We thank Captain Wade Loofbourrow and the crew of the Media and the pilots and crew of the Delta for their assistance, dedication, and effort to make the cruise a success.

By John Karinen.

Internal Tags Will Tell Secrets of Sablefish Movements

Fifty-four electronic temperature-depth tags were surgically implanted in sablefish during the first two legs of the 1998 Sablefish Longline Survey. In all, approximately 200 of these tags will be released during the course of the survey. The data-logging life of the tags is dependent on user-specified sampling protocol. Maximum logging life is 11 years, and the data will be retained for up to 20 years. Data obtained from recovery of these tags are expected to provide useful information on diurnal movements and timing of inshore-offshore migration, and might help to refine estimates of movement rates between regulatory areas obtained from conventional tagging studies. There is a $100 reward for return of recovered tags.

By Nancy Maloney

Has El Niño 1997-98 Lost Its Punch?

As of 30 June 1998, sea surface temperature anomalies in the Gulf of Alaska and the Bering Sea are negative except for a warm core in the central gulf and slightly warmer water along Southeast Alaska. Positive anomalies still are present in surface waters occupying a large area north and south of the equator off South America but there as yet appears to be little northward movement of this warm core. The multivariate ENSO index (NOAA-CIRES Climate Diagnostics Center) sharply declined from March-April to June-July (2.5 to 1.0) as predicted by several models. The rate of decline is presently similar to El Niño events of 1972-73 and 1982-83, both of which reverted to a La Niña episode.

El Niño 1997-98 may be on the wane, but its effects are still evident in Southeast Alaska. Air, Auke Lake temperatures, and sea surface temperatures monitored at the ABL are above average from May 1997 through June 1998. Precipitation has been below average since December 1997. The combination of increased winter temperatures and lower precipitation resulted in a reduced snow pack and lower spring runoff to Auke Lake. We suspect that this contributed to the lower number of out-migrant sockeye salmon and coho salmon smolts observed at the Auke Creek weir.

By John Karinen and Bruce Wing.

Reference Collection

Dr. Bruce Wing, curator of ABL’s reference collections, collected specimens of three species of hoplonemerteans (ribbon worms) for Drs. Donald Jensen and G. Orti. The two University of Nebraska researchers are using biochemical and mitochondrial DNA genetic techniques to examine evolutionary trends and the nemertean theory of vertebrate origin. Wing also confirmed the identification of several species of fish and invertebrates for Habitat Investigation’s Essential Fish Habitat Task. Included were range extensions of the blackeye goby, Coryphopterus nicholsi, and kelp perch, Brachyistius frenatus, not previously known from Alaska. Finally, Wing received a roughtail skate, Bathyraja trachura, for the collections from Mr. William Razpotnik, Taku Fisheries. Juneau, Alaska. This rare skate was caught by a sablefish longline at about 600 fathoms west of Cross Sound, Alaska.