Research Projects Detailed 2
In recent years, Chinook salmon returns to AYK drainages did not hold up to pre-season expectations and spawner-recruit models. In response to poor returns, fisheries management in Alaska resorted to unprecedented restrictions to subsistence users, such as 50% reduction in fishing time and a no-buy policy for Chinook salmon during summer chum commercial openings in the lower Yukon River. Such unpredictability causes economic hardship for residents dependent upon these fisheries; thus there is keen interest in understanding the processes that govern recruitment variability in AYK chinook salmon populations (AYK SSI 2006). Freshwater growth is thought to be a critical determinant of survival of juvenile survival (Holtby et al. 1990, Henderson and Cass 1991). In general, larger juvenile salmon are better able to use and compete for resources, are vulnerable to fewer predators, and are able to migrate to the resource-rich marine environment earlier and at larger size (reviewed in Quinn 2005). The consequences of freshwater growth for survival in the marine phase are less clear, with some studies reporting positive effects of juvenile size on marine survival (Parker 1968, Beamish and Mahnken 2001) and other studies finding marine survival to be decoupled from freshwater growth (e.g., Holtby et al. 1990, Ward 2000). Thus, a better understanding of the processes that link freshwater conditions to recruitment from egg or spawning adult are needed.
This study will relate infection with Ichthyophonus to a variety of indicators of reproductive success. The biomass of gametes, sperm viability, and egg quality (as measured by proximate analysis) and hatching rate of fertilized eggs will be compared between infected and non-infected Chinook salmon. Offspring of infected fish will be compared to those of non-infected fish to determine whether growth, development, and condition differs. Finally, blood chemistry and cortisol levels will be investigated as indicators of detrimental effects of infection, and for their potential as non-lethal assays of infection. This study connects the quality of the spawning adults to its effects on their juvenile offspring, including their size and potential for growth. To augment the resources requested from the PCCRC, we are asking for $50,000 from the Restoration and Enhancement fund of the US and Canada Yukon River Panel. This proposal, entitled, "Ichthyophonus in Chinook salmon – Continuation of a baseline in Emmonak and Eagle, Alaska and potential links to fecundity and blood chemistry". To augment the resources requested from the PCCRC, we are asking for $50,000 from the Restoration and Enhancement fund of the US and Canada Yukon River Panel. This proposal, entitled, "Ichthyophonus in Chinook salmon - Continuation of a baseline in Emmonak and Eagle, Alaska and potential links to fecundity and blood chemistry" is to support field sampling at these two locations, and the involvement of three undergraduate fisheries students in the project.
This study will use archived scales to construct time series of freshwater growth of Chinook salmon from the Yukon and Kuskokwim rivers. These time series will be used to assess the overall effect of freshwater growth on survival to the age of reproduction. Additionally, juvenile Chinook salmon will be reared and monitored in a laboratory to validate relationships between scale and otolith characteristics and juvenile growth and body size. These studies will provide a context for interpreting field observations of juvenile fish size and condition, and connect the processes affecting size and growth examined in the previous studies to their overall effect on the recruitment of adult fish.
Diet and nutrition in harbor seals
Oscillating cool and warm climatic periods have the ability to alter the basic structure and components of an ecosystem, which can impact the dietary base of a predator. Changes to diet can have significant impacts on predator populations.
A time series of harbor seal scat samples were collected from Tugidak Island, Alaska, during the summer from 2001 to 2009. Hard-part remains from scats were identified to the lowest possible taxon and approximate prey composition of the diet was determined from frequency of occurrence (FO) and biomass (BM) calculations. The nutritional profile of estimated diets was determined using a prey nutritional database developed from proximate analyses of various prey found in Alaskan waters.
Diet profiles constructed by BM estimations appear to provide a more realistic representation of actual diets due to biases associated with FO data. BM prey contribution of salmon species correlated with sea surface temperature (SST; 0.703, p < 0.10) and cephalopod (-0.663, p < 0.10), gunnel (-0.722, p < 0.05), and Gymnocanthus spp. (-0.753, p < 0.05) correlated negatively with SST. The plane of nutrition was calculated by BM estimations; protein (13.47-17.49% of diet), lipid (1.57-4.90% of diet), and gross energy (0.65-1.37kcal/g of diet) of the average diet varied across collection years. Lipid content and gross energy of diets fluctuated within a collection year relating to pupping and molting periods.
Combining the prey database and plane of nutrition across years provides insight regarding the role of nutrition in evaluating changes in pinniped populations. Identification of the components of harbor seal diets allows for detection of potential competition for fish resources.
Walleye pollock maturity
Maturation rate is an important parameter for determining the optimum exploitation strategy for a fish stock. For eastern Bering Sea walleye pollock (Theragra chalcogramma) maturation rates were developed in the late 1970s by the National Marine Fisheries Service (NMFS). These rates were updated by a study conducted by the University of Alaska Fairbanks (UAF) in 2002-2004; similar estimates for maturity-at-age were found, although interannual and geographic variations were identified. In a follow- up analysis of the UAF results, NMFS examined interannual variation and found that younger pollock may contribute to the spawning stock at a rate that is higher than currently assumed in the eastern Bering Sea. For the Gulf of Alaska, estimates of maturity-at-age are generated from data collected by the NMFS echo-integration trawl surveys in winter. The average age-at-maturity is used for stock assessment modeling for the Gulf of Alaska, despite interannual variability in maturity. This UAF-NMFS proposal seeks to more fully explore the maturation of eastern Bering Sea and Gulf of Alaska pollock by analyzing maturity data collected by at-sea fisheries observers and from NMFS survey trawls throughout the spawning season over the geographic range occupied by these stocks. Analyses will include the estimation of a pollock sexual maturation schedule, including temporal and spatial variation in pollock maturity. The proposed study will also carefully evaluate the current visual key used to classify maturity stages using histology. Finally, the implications of our findings on annual stock assessment (e.g., estimation of spawning stock biomass) and implications on fishery management will be analyzed.
Skates injuries in longline fisheries
PI: Terrance J. Quinn II
Project #: 12-02
Skates (Rajidae), long-lived and late-maturing species, are caught in large numbers in the Eastern Bering Sea, especially by demersal longline vessels targeting Pacific cod (Gadus macrocephalus). The majority of these are discarded alive, though with injuries ranging in severity from minor to fatal. The mortality rate of these skates, an important component of models used to determine allowable catch, is currently unknown and roughly estimated, causing catch limits to be exceeded and retention prohibited. In order to address this lack of data, the study proposed here will describe those injuries sustained and classify them into a system of discrete injury codes, following a methodology similar to previous studies conducted on Pacific halibut (Hippoglossus stenolepis). A key will also be established to consistently classify caught skates with one of the codes, from which the rate that each code occurs can be accurately determined. The injury code rates will also be used to address the hypothesis that vessels will exhibit different rates of each code as an extension of different crew handling procedures, with more severe injuries resulting from less careful handling. This difference will illustrate the ability of management to effect a reduction in the discard mortality of skates through policies that encourage careful handling. Future studies will combine tag-and-release efforts with the foundation of injury codes established by this study in order to accurately establish mortality rates and gauge the effectiveness of future management policies and regulations.
Augmenting current Steller sea lions projects with additional field time
PI: Greg Walker
Project #: 12-03
Steller sea lions
This project funds a third week of a research cruise designed to: 1) assess the feasibility of using hip- based unmanned aircraft (UAS) to conduct Steller sea lion (SSL) surveys and 2) collect scat/spew samples over a larger section of the Aleutian Islands. With this additional time, the ideal cruise could originate in Adak where it will head west to Attu and then return to Dutch Harbor. The extended cruise will allow for the ship to reach virtually all the areas of interest for SSL research in the Western Aleutian Islands. This extension will provide National Marine Mammal Laboratory’s (NMML) NPRB Project with the needed additional week of ship time to adequately collect samples throughout the Western Aleutian habitat to improve the geographic diversity of the collected samples thereby increasing the overall value of the effort. Additionally, the joint cruise will allow NMML researchers to gain first hand exposure to the potential for UAS to assist them in their surveys while giving the UAS researchers ideal opportunities for learning about SSL research needs and how the UAS can be used to study and sustain the SSL population.
Behavior of transient killer whales
Killer whales have been implicated in the decline of the western stock of Steller sea lions. Killer whales are known to prey on Steller sea lions in other parts of the North Pacific but no observations have been made of predation on Steller sea lions in the western and central Aleutians, though observation effort has been relatively sparse. During National Marine Mammal Laboratory (NMML) surveys (from 2001-2010) ‘transient’-type killer whales have been regularly seen in two areas in the central and western Aleutians: (1) the Delarof Islands-Tanaga Island and (2) Kiska and the Rat Islands, with abundance estimated at ~90 whales. A population of killer whales of this size could easily cause the decline or prevent the recovery of Steller sea lions in this region if they were a primary prey of transient killer whales there. Therefore, it is crucial to determine if transient killer whales in that region routinely prey on Steller sea lions. We have been conducting three lines of research on transient killer whales in the Aleutian Islands –stable isotope analysis of biopsy skin samples, satellite tagging, and acoustic recorders deployed at Steller sea lion rookeries. Nitrogen stable isotope values of transient killer whales in the central and western Aleutians show two dramatically different patterns – some whales have values consistent with substantial predation on Steller sea lions while other whales show values too low for that to be possible. Location-only satellite tags (N=4) have also elucidated two dramatically different foraging strategies, with some whales moving ~1000nm south of the Aleutians (far outside the range of Steller sea lions), and with other whales remaining in a single location over deep-water at the head of a submarine canyon for an entire month. Both foraging strategies suggest transient killer whales may spend considerable time not foraging for Steller sea lions in this region. With other funding, NMML will be deploying acoustic recorders at three Steller sea lion rookeries in the central and western Aleutians to monitor killer whale occurrence. In this proposal we are asking for funding to deploy Mk10-A satellite-linked depth tags on transient killer whales in the western and central Aleutians to track their movements and, importantly, record their diving behavior. We will be able to keep costs down (by a significant amount) by taking advantage of an opportunity to piggy-back on a NMML Steller sea lion pup branding and condition cruise scheduled for late June/early July of 2013. We are also requesting funding for travel costs in order to participate in the cruise. With information provided by the satellite tags, we can estimate what proportion of the time transient killer whales stay within the range of Steller sea lions. Diving information will allow us to estimate what proportion of the time transients in the region are pursuing a deep-diving foraging strategy, which we assume is time not spent foraging on Steller sea lions. The location information will inform us about what proportion of time transients spend foraging in proximity to Steller sea lion rookeries and haul-outs. Finally, with additional biopsy samples, we will also improve our estimate of what fraction of transient killer whales have stable isotope values consistent with diets containing a substantial proportion of Steller sea lions. Collectively these data will provide substantial information for quantifying killer whale predation on Steller sea lions in the central and western Aleutians.
Vital rates in Russian Steller sea lions rookeries
The endangered western Distinct Population Segment (DPS) of Steller sea lions (SSL) has declined by almost 90% through its range, reaching its nadir in 2000. By the late 1990s and early in the 21st century the decline had slowed and in some areas populations appeared be on the increase. This is not the case for SSL in the Western and Central Aleutians and in the nearby Commander Islands (Russia), where abundance continues to decline. This may be due in part to low reproductive rates, which has led to new fishing regulations in the Aleutian Islands that may cause significant economic consequences. Unfortunately, there presently are no empirical data available on the vital rates of sea lions in the western or central Aleutian Islands. However, just across the border into Russia, lie the Commander Islands, less than 200 miles from the westernmost United States SSL rookery. Steller sea lions from the Commander Islands are genetically similar to Aleutian Islands SSL and are also part of the Western SSL “stock”, and SSL abundance on the Medny Island (Commander Islands) rookery has shown similar instability as in the western Aleutians. We have conducted observations on Medny for over 10 years, and unlike in the Aleutian Islands, we have direct measurements of SSL vital rates at this and 7 other rookeries in Russia. Studies of SSL from the Medny Island rookery (Commander Islands) may provide valuable insights for comparison to the western Aleutians because the Commanders have been protected by a 30-mile no- fishing zone since the late 1950s. We propose to use demographic data collected in the Commander Islands (where SSL pup counts have been decreasing) and in the Kuril Islands (where SSL populations are increasing) over the years 2000 to 2012 to compare and contrast areas of differing population trends. We will utilize multiple hypothesis testing and model-based inference to investigate the relationships between SSL abundance trends and vital rates and prey, fishing activity and environmental conditions as well as presence of potential competitors (e.g. northern fur seals) and predators (killer whales). Our results should lead to insights about the causes of declining populations and the potential for fisheries interactions, and should be very applicable to the search for an understanding of the SSL situation in the western and central Aleutian Islands.
Modeling multilayered fisheries management
We propose to develop and apply ecological and economic modeling tools for Bering Sea fisheries, by (a) building on NOAA’s current multi-fishery stock model by increasing its spatial and temporal resolution, (b) modeling fleet fishing choices based on costs and revenue opportunities, given ecological conditions and regulatory constraints; and (c) using the models to examine ecological and economic implications of alternative combinations of management regulations. The project team has unique ecological and economic expertise and capacity to accomplish these complex interdisciplinary objectives.
Steller sea lion reproduction and survival
This proposal to the PCCRC/NPRB is for Phase 2 of a 3‐phase project to determine reproduction, survival, and depredation in Steller sea lions in the western Aleutian Islands (WAI) in relation to the eastern Gulf of Alaska (eGOA). Phase 1 was a very successful, collaborative twelve‐year endeavor that included LHX tag development, refinement of capture, holding and surgical implantation techniques specifically for Steller sea lions, extensive physiological and behavioral impact assessments, and ultimately deployment of LHX tags in 36 individuals. We will deploy second generation implanted Life History Transmitters (LHX‐ 2 tags) into up to 10 pre‐reproductive female western Steller sea lions (Eumetopias jubatus) captured and implanted at the Chiswell Island rookery (eGOA) and transported to the Alaska Sea Life Center for temporary captivity. LHX‐2 tags record data throughout the host’s life, record parturition events in females, and after death of the host and extrusion from decomposing, dismembered, or digested carcasses transmit stored data via satellite. Post‐mortem data will yield age at primiparity and lifetime births in females, as well as age and cause of death (predation vs non‐predation), and body mass in case of non‐predation deaths. All animals will be monitored after release via external satellite transmitters and through direct video‐based observations at the Chiswell Island rookery to determine pupping in subsequent years. Phase 2 objectives are to (1) validate LHX‐2 temperature‐based parturition detection against direct visual observations; (2) add to the eGOA sample size for animals >=3 years to increase the statistical power of a regional comparison to the WAI; (3) facilitate the transition to remote LHX tag deployments in the WAI by validating less invasive surgery enabled by smaller LHX‐2 tags and by commencing ship‐board surgeries immediately after capture – here still combined with recovery monitored under controlled conditions. The objectives of Phase 2 will be essential to enabling Phase 3. In Phase 3 (not requested here) we will quantify survival, depredation and reproduction in the WAI to determine: (1) do survival and predation schedules differ between stable and declining regions? (to allow testing recently proposed density‐dependent age structured predation rates); (2) does age at primiparity differ between regions? (3) do birth rates differ between regions?
Replacing ethoxyquin in fishmeal
PI: Charles Crapo
Project #: 13-05
Ethoxyquin is the standard antioxidant used to stabilize fishmeals. While it has been used successfully for several decades, its safety has been called into question. Aquaculture users of fishmeal are often required to withdraw feeds two weeks before harvest to purge ethoxyquin from edible tissues. Dog foods virtually ban the use of ethoxyquin in their manufacture effectively excluding Alaska fishmeals from being an ingredient source. This project will investigate potential replacements for ethoxyquin from the range of natural antioxidants currently used in the food industry. Antioxidants such as mixed tocopherols, rosemary extracts, ascorbic acid and combinations will be used to treat freshly produced at-sea fish meals. Untreated, ethoxyquin treated and the natural antioxidant containing meals will be stored at ambient and abuse temperatures for up to 8 months. At two-month intervals, meals will be evaluated for quality. Lipid and protein stability will be measured. Proximate composition, amino acid composition and color will be determined. A cost analysis will be completed to compare relative benefits of the various antioxidants.
Interactions among groundfish predators
Pacific halibut (Hippoglossus stenolepis) is among the most important fishery resources in Alaska, supporting valuable commercial, sport, and subsistence fisheries throughout the Gulf of Alaska. Troubling indicators of declining biological productivity over the past two decades, including downward trends in halibut spawning stock biomass and size-at-age, have led to increased restrictions for commercial and sport fisheries. One of the prevailing hypotheses to explain observed declines in growth and size-at-age of halibut is competition for shared resources with a burgeoning population of arrowtooth flounder. In the early 1990s, arrowtooth surpassed walleye pollock as the dominant groundfish species in the GOA. The nearly 8-fold increase in arrowtooth biomass over the past 30 years has led to concern about their impact as both predator and competitor. The proposed project will examine resource partitioning between arrowtooth flounder and Pacific halibut to better understand their potential competition for shared prey, including walleye pollock. We will (1) quantify the distributions and spatial overlap of arrowtooth, halibut, and pollock in relation to demographic and environmental variables; (2) quantify diet composition, including the contribution of pollock prey, and diet overlap of arrowtooth and halibut in relation to demographic and environmental variables; (3) describe spatial and temporal variation in resource partitioning between halibut and arrowtooth to evaluate their potential for competition; and (4) determine whether relationships between spatial overlap and diet overlap are consistent across regions and spatial scales in the GOA. Patterns in distributions and diets of arrowtooth and halibut across the GOA will be quantified using two complementary approaches. First, we will use existing diet data from NOAA to evaluate resource partitioning between halibut and arrowtooth across the western and central GOA. We will couple the analysis of existing data with a focused field study that contributes new, high-resolution diet data for halibut and arrowtooth in inshore waters of the eastern GOA, which are important feeding and nursery grounds for numerous groundfish species. The proposed study focuses on halibut, identified by the PCCRC as a priority incidental species caught in groundfish fisheries, thereby addressing PCCRC Research Priority 1. In addition, by providing an in-depth analysis of patterns of pollock prey in diets of arrowtooth and halibut, our project is relevant to PCCRC Research Priority 4e, “impact of predation on pollock recruitment and abundance.”
Multiple studies have revealed the importance of predation to pollock population dynamics in the Gulf of Alaska; however, natural mortality is set at a fixed value in the pollock stock assessment, which could lead to inaccurate biomass and yield projections. A recent Center for Independent Experts (CIE) external review of the Gulf of Alaska walleye pollock stock assessment recommended development of approaches that account for changes in predation mortality as a high priority for improving the assessment. The CIE identified simple methods, such as augmenting the single species assessment, as likely providing a more immediate benefit than multispecies or ecosystem modeling approaches. We propose to develop an index of predation that accounts for spatial and temporal variation in groundfish consumption of walleye pollock for application to the Gulf of Alaska (GOA) pollock stock assessment. Importantly, predator-prey interactions may vary in time and space in response to environmental conditions such as temperature; therefore, a useful index of predation needs to account for potential environmental drivers. In a collaboration among ecologists, fisheries oceanographers and stock assessment scientists, we will (1) develop an index of predation that measures the intensity of pollock consumption by major groundfish predators across four spatial scales in the GOA, (2) quantify spatial and temporal variation in the predation index related to environmental and demographic factors, and (3) develop and evaluate an analytical framework for incorporating the predation index into the GOA pollock stock assessment as a modifier of constant natural mortality. The project outcomes will directly address information needs for pollock assessment by improving estimates of natural mortality.
Effects of Asian pink and chum salmon on Alaskan chum and Chinook salmon growth
Ongoing declines of Alaskan stocks of Chinook and chum salmon have prompted concern statewide, particularly in western Alaska where these species are important resources. While a number of potential causes have been hypothesized for these declines, it is suspected that processes associated with the marine phase of the salmon life history play an important role. These include natural (e.g., climate cycles) and anthropogenic (e.g., climate warming, overharvest in target and non-target fisheries) factors. The large number of hatchery fishes released into the North Pacific have prompted concern that competition for marine resources has contributed to these declines. Here, we address this issue by conducting both a synthesis of existing data and novel analyses of growth indicators (insulin-like growth factor and scale data) to examine the potential role that Asian populations of pink and chum salmon negatively influence growth of western Alaskan populations of Chinook and chum salmon in the Bering Sea.
Shelf-stable pet treats from pollock skins
Pollock skins will be used to develop shelf-stable pet treats formulated with a blend of natural antioxidants. Two production processes, rolled and sliced, will be evaluated, for two blends of commercially available natural antioxidants and a control. The products will be evaluated for their nutritional value and shelf life with the goal of developing a pet treat product with a minimum shelf life of six months. The successful development of a pollock skin pet treat would create an additional market for pollock skins with potential of generating additional revenue to Alaska pollock processors. Test products (rolled pet treats and sliced pet treats) will be manufactured from 7.5 kg blocks of pollock skins frozen at sea. The findings of this project would be readily applicable to the utilization of Pacific cod skins for production of pet treats and, perhaps with few modifications, to development pet treats using skins from other commercially important whitefish species harvested in Alaska.
Freshness and nutritional value of Alaska pollock products and byproducts
The seafood industry is a vital source of revenue for the state of Alaska. Within this industry, the pollock fishery accounts for ~$343 million in annual revenue with ~2.8 billion pounds of pollock harvested. Pollock production accounts for ~54% of Alaska’s total fish harvest and it is important that quality products be delivered to insure maximum monetary returns. One aspect of pollock quality and changes to quality that has not been well defined is how postmortem changes occurring between catching and processing affect the quality and nutritional value of pollock products. In addition, a comprehensive data set on the nutritional composition of pollock products does not exist and could provide additional value to pollock products. Therefore, the objectives of this proposal are to determine the postmortem changes occurring to pollock fillets at time intervals of 0, 24, 48 and 96 hours between harvest and processing. Nutritional composition of pollock products is also needed. For this reason fatty acid, vitamin, mineral, and amino acid content will be determined for pollock products. To accomplish this, a variety of analytical techniques will be employed to determine the nutrition and chemical composition of pollock fillets, milt and roe. This research will also result in a comprehensive data set defining the contributing factors of quality loss in pollock fillets occurring between times of harvest and processing. A data set encompassing the nutritional components of pollock products will also be obtained. For all data sets, comparisons will be made between fish harvested in the fall and fish harvested in the spring.
Skate discard mortality
Skates (Rajidae) are caught as bycatch in significant numbers, on the order of tens of thousands of tons, each year in the North Pacific and Bering Sea, primarily via longline and with the majority discarded. Presently unknown is the rate of mortality amongst these discarded skates, though management authorities employ the precautionary approach of assuming the rate to be 100%. Currently, a study is being conducted in which the injuries sustained by these skates and the parameters that effect the severity are being evaluated. The study proposed here builds on those research efforts to further investigate discard mortality as well as provide estimates, with handling regime in mind, of both short- and medium- term mortality. This study will charter a longline vessel to capture skates, under both careful and normal commercial handling regimes, which will subsequently be held in captivity for a period of three months, during which mortality will be recorded. Furthermore, injury recovery during the holding period will be documented. Feeding trials to gauge impairment due to injury to mouthparts will be conducted as well as analysis of blood constituents to compare stress at time of capture to that during the holding period. These efforts aim to not only provide a first-of-its-kind skate discard mortality estimate for these species, but also further our understanding of discard mortality in general.
Drivers of AYK Chinook salmon survival
Dramatic recent declines in the productivity of many populations of the Western Alaska Chinook salmon (Oncorhynchus tshawytscha) stock complex have jeopardized commercial, subsistence, and recreational fishing opportunities for United States and Canadian stakeholders. Similarly, rapid and broad scale global climate change may be outpacing the adaptive potential of Alaska Chinook populations, potentially influencing their future viability. However, it yet remains unclear what combination of the simultaneously occurring natural and anthropogenic factors are driving variation in Chinook salmon survival over time. Moreover, it is unknown which stages of the complex Chinook lifecycle are most sensitive to environmental change. We propose to address these fundamental knowledge gaps by tailoring and applying a pre-existing life stage-structured statistical population dynamics model to evaluate the direction and magnitude of influence that a range of hypothesized environmental factors have on realized survival for Chinook salmon populations in Western Alaska. Estimation of the influence of each environmental covariate will be informed by available adult abundance, juvenile abundance, and age composition data. Our proposed approach has three key benefits relative to alternative analytical methods. First, we will use a statistical model that will estimate the relationships between survival and environmental covariates directly from the available data, rather than a priori specifying relationships defined for other systems, pulled from the literature, or from laboratory experimentation. Second, this would be the first attempt, to our knowledge, to simultaneously evaluate both natural and anthropogenic stressors in a common estimation framework, using available juvenile and adult abundance data as the arbitrator. Third, estimated values for coefficients describing the influence of environmental factors on survival may be used to forecast future abundance trends under alternative climate and management scenarios. Taken together, we are confident that this approach will be greatly beneficial in illuminating the key freshwater, marine, and fishery factors most associated with Chinook survival in Western Alaska.
Decline in Pacific halibut size at age
Size-at-age of Pacific halibut has declined significantly since the 1990s. For instance, the average weight of a 20-year-old halibut declined from more than 100 pounds in 1993 to less than 40 pounds in 2011. The decline in size-at-age corresponds to a period of declining halibut recruitment and spawning biomass, reductions in catch limits for the directed commercial halibut longline fishery, and declines in recreational and subsistence catches of halibut in Alaska. Also associated with these declines are increasing concerns about bycatch of halibut taken in other groundfish fisheries in the Gulf of Alaska and Bering Sea. The causes of changes in halibut size-at-age are very poorly understood. We seek PCCRC funding to allow us to test hypotheses about (1) the effects of environmental and ecological variability on halibut growth, and to (2) quantify the implications of fishery effects, such as size-selective fishing, bycatch, and wastage on changes in size-at-age, which have implications on biological reference points used in the halibut stock assessment, as well as harvest policy. Our proposed PCCRC project builds off a multi-investigator study funded by the North Pacific Research Board (NPRB) in which we are involved. The two-year NPRB study funds our investigation of the effects of environmental and ecological variability on growth. The proposed one-year PCCRC study would allow us to fully incorporate findings from our NPRB collaborators into our growth models, and would fund our research to examine the cumulative effects of size-selective fishing.
Maternal foraging of northern fur seals
Numerous studies have demonstrated a link between maternal foraging trip durations (MFTD) of fur seals in the Bering Sea and various indicators of prey abundance, particularly of walleye pollock. MFTD is also correlated with the transfer of energy to growing pups and their rate of growth, which is an important determinant of post-weaning pup survival. We propose to monitor MFTD as an index of foraging conditions for northern fur seals in 3 colonies known to forage in 3 different oceanic domains around the Pribilof Islands: the middle shelf, outer shelf, and shelf break/basin. This study will establish VHF data- logging receiver stations and deploy 75 pulse-coded, multiyear VHF flipper tags on lactating fur seals at 3 rookeries to estimate maternal foraging trip durations in late season 2016, and full breeding seasons in 2017 and 2018. The length of the foraging trips will be examined with respect to metrics of environmental and oceanographic conditions, prey availability from NMFS surveys and fisheries data, and pup mass. This will allow us to characterize the spatial and temporal variability in these relationships and test hypotheses about how environmental changes may influence northern fur seal reproductive success. In addition, by establishing the validity and utility of MFTD as a monitoring tool for processes operating at the rookery scale, we will provide a new tool for assessing the health of Northern fur seal populations beyond the temporal frame of this grant.
Gel enhancement of Alaska pollock surimi
The purpose of our proposal is to recover Alaska pollock fish bone and upgrade the value of this solid waste as a natural source of functional and nutritional nano-scale calcium for use in Alaska pollock fillet and surimi block. Recovery of Alaska pollock fish bone for use as a natural and nutritional source of highly bioavailable calcium is a new approach to reduce fish processing solid waste and upgrade the value of Alaska pollock surimi and fillet. By recovering fish bone of Alaska pollock harvest, overall resource utilization will be improved. After recovery, the fish bone will be ground into nano-scale, which has a high bioavailability and could be used to reincorporate nutritional calcium to fish fillets that is lost during processing. In addition injecting nano-scale fish bone when prepared in a marinade with Alaska pollock surimi protein in salmon fillets has been shown to improve the eating quality of frozen fillets; maintaining more fresh-like qualities of cooked frozen fillets than untreated fillets. The researchers hypothesize that similar quality improvements are possible when injecting nano-scale fish bone into Alaska pollock fillets. Nano-scale fish bone (NFB), if included before freezing, could also improve gel texture as well as calcium enrichment of Alaska pollock surimi. Processors from Unalaska or Bering Sea will be interviewed to determine production-scale feasibility of upgrading fish bone from a discarded solid waste product to utilization as a nutritional and functional ingredient. If successful, the annual harvest value of the Alaska pollock fishery could be significantly improved.
Pollock roe R&D
Traditional markets for pollock roe are in Japan and South Korea and the prices for walleye pollock roe received by producers have been declining. Our objective is to develop alternative pollock roe product forms for markets in East Asia, including Hong Kong, China, Japan, Korea and elsewhere, using Asian and Asian-Americans in Kodiak and Washington State that favor traditional seafood dishes as proxy for prototype product development and testing. The methods employed follow well-established market research and food product development procedures including engaging industry and conduct secondary data search to understand market conditions, the use of focus groups to define appropriate product attributes, conduct both consumer taste panels and surveys to learn potential consumer views, and report our findings to the industry, to consumers and to peers. Anticipated results from this work will provide information and options to pollock roe producers for expanding existing opportunities in Asian markets.
Foraging behavior of "resident" killer whales
PI: Lorrie Rea
Project #: 16-04
The relatively high abundance of “resident”-type (fish-eating) killer whales in the western and central Aleutian Islands suggest that the consumption of fish by these killer whales is on the same order of magnitude as commercial fisheries in the region. We propose to study the foraging behavior of these whales to determine what species of fish they are consuming. Specifically, we propose to study their foraging movements and diving behavior using satellite-linked tags. We also propose to conduct stable isotope analyses of existing killer whale and fish samples to assess, in particular, whether killer whales are a major consumer of Atka mackerel, and therefore a potential competitor with Steller sea lions and commercial fisheries in this region. Our proposal is cost-effective because we can piggy-back on an existing research cruise, which we have successfully done for the previous three years. Our proposed research addresses research priority: “3. Habitat and Ecosystem Considerations c) Assess the impact of increases in whale populations on lower trophic energy pathways and implications for FMP species”. This research will improve our understanding of which commercially important prey species are dominant in the diet of resident-type killer whales and will assess the quantity of fish removed by resident type killer whales in the context of other upper trophic level members, including Steller sea lions and commercial fisheries. Stable isotope data generated for Aleutian prey species would also contribute to ongoing diet modeling studies for western and central Aleutian Island Steller sea lions.
Value-added market opportunities for pollock co-products
Our objective is to continue nutritional investigations on milt and roe that will provide processors with the information needed to support value-added product development and market diversification. Currently, milt does not have a well-developed market and although the market for pollock roe is developed, prices have been dropping. In the past few years research and markets have been developing around dietary nucleotide supplements. Nucleotide supplements are based on the basic building blocks of DNA and RNA which are comprised of the purines, adenine and guanine, and the pyrimidines, cytosine and thymine. Sperm cells have high contents of DNA. It is the purpose of this study to understand the content and composition of both DNA and RNA in pollock roe and milt. We also want to understand how the content and composition changes when exposed to different handling and preparation conditions. Nucleotide investigations will be conducted by OSU. Promotional and marketing materials will be developed from the outcomes from our previous proposal and the current proposal by University of Alaska and ASMI. Finally, an evaluation of potential markets will be conducted using a market survey by University of Alaska.
Zooplankton predation on first-year pollock
We propose to establish the relative magnitude of the three dominant predatory zooplankton components (Scyphozoans, Hydrozoans, Chaetognaths) in the Gulf of Alaska. We believe that the predatory potential of hydrozoans and chaetognaths is comparable to that of the more visible scyphozoans which receive the greatest attention in most ecosystems. We will document predatory species composition, spatial and temporal patterns and determine if any correlations exist between these, environmental variables, and the early life stages of pollock. This process will align several distinct time-series within the Gulf of Alaska. Establishing such linkages will help inform the needs for future sampling programs, and be of value to fisheries management. This collaborative effort between UAF and NOAA also seeks to train a graduate student with interest in zooplankton and fisheries.
Chum salmon genetic stock identification
Genetic stock identification is key to management of the harvest of mixed stocks of Pacific salmon, including those accidentally caught in other fisheries such as the Bering Sea pollock fishery. Application of this management tool has been hindered for chum salmon from western Alaska, where limited genetic divergence among populations across coastal western Alaska has made it impossible to accurately apportion stock mixtures to desired reporting groups (e.g., Lower Yukon River, Kuskokwim River) within the region. The proposed project focuses on leveraging previous work to identify a panel of ~500 informative genetic (SNP) markers that can be transferred across laboratory platforms to provide finer resolution of genetic stock identification of chum salmon from western Alaska. The proposed project responds directly to a research priority identified by the PCCRC. The proposed project will also expand genetic stock identification capacity at UAF, NOAA National Marine Fisheries Service, and the Alaska Department of Fish and Game.
Movement, behavior, and predation on Chinook salmon in the Bering Sea
Information about the spatial distribution, movement, vertical distribution, and predation of fishes can help in understanding a species’ population dynamics and in informing its management. To add to knowledge gained from a recently completed study on 17 Chinook salmon in the Bering Sea, we propose a continuation of our study in which another 10 large, immature Chinook salmon (>60 cm) will be captured near Dutch Harbor and tagged with pop-up satellite archival transmitting tags. While externally attached to the fish, the tags will measure and record ambient light (for daily geoposition estimates), depth and temperature data. On preprogrammed dates, the tags will release from the fish, float to the surface of the ocean and transmit the recorded data to overhead satellites, which will then be retrieved by project investigators. Spatial distribution, movement, depth distribution, thermal environment, and predation of the tagged Chinook salmon will be described and related to regional environmental factors. These analyses should provide a more complete understanding of oceanic phase of large, immature Chinook salmon in the Bering Sea, which may be useful for understanding its population dynamics and susceptibility to interactions with groundfish fisheries.