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North Pacific Research Board Research Series

FISH & INVERTEBRATES Alaska’s Ocean Bounty 2002-2008 research summary

Patrick Endres | Alaska Stock.com 2 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

The North Pacific Research Board (NPRB) was established by Congress in 1997 to develop a comprehensive science program of the highest caliber that provides a better understanding of the North Pacific, Bering Sea, and Arctic Ocean ecosystems and their fisheries.

The NPRB carries out science planning, prioritizes pressing fishery management and ecosystem information needs, coordinates with other ocean science programs, competitively selects research projects, and communicates research results to diverse audiences.

Since its founding, the North Pacific Research Board has developed a comprehensive program of marine research. The Science Plan, developed with guidance from the National Research Council of the U.S. National Academies of Sciences, serves as the foundation for annual requests for proposals organized by major research themes, including:

• Lower Trophic Level Productivity • Fish Habitat • Fish and Invertebrates • Marine Mammals • Seabirds • Humans • Other Prominent Issues • Integrated Ecosystem Research • Other Research and Partnerships

The annual requests for proposals result in the majority of the funded projects, which are numbered by the year they were funded (e.g., #201 funded in 2002). The Board also supports integrated ecosystem research programs that look in-depth at Alaska’s major ocean ecosystems, with a program ongoing in the Bering Sea and in development for the Gulf of Alaska.

This research summary describes research funded from 2002 through 2008. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 3

fish and invertebrates

major goal of the Board is to improve our ability to manage and protect the healthy, sustainable fish and wildlife populations that comprise the ecologically diverse marine Aecosystems of the North Pacific, and provide long-term, sustainable benefits to local communities and the nation. This is a very large task, considering that the marine regions off Alaska support rich and vast assemblages of fish and invertebrates, and the largest fisheries in the U.S. These assemblages are extremely important not only economically, but also ecologically and socially. If fishing is the human activity that has the greatest impact on both targeted and non- targeted populations in the North Pacific, as the National Research Council contends, resource managers must know how the ecosystem functions, and understand the life histories and distributions of the fish stocks themselves and how they are influenced by fishing and changes in their environment.

Studies funded in this category fall within five broad topics which together address pressing fishery management issues and marine ecosystem information needs:

• stock assessment research and development • bycatch reduction • causes of major species decline • implications of ecosystem change on fishery management • management tools

Through 2008, the Board supported 76 fish and invertebrate projects for just under $14 million, of which 47 have been completed. Researchers have studied a variety of forage species, jellyfish, squid, crab, sculpin, skates, sharks, salmon, rockfish, halibut, pollock, cod, Atka mackerel, and other groundfish species. Projects are split fairly evenly between the Gulf of Alaska and the Bering Sea, with a few projects taking place in the Arctic Ocean, reflecting the different degrees of importance of commercial fisheries throughout Alaska.

The complex factors that influence the behavior of fish and drive the fluctuations of their populations require all four research approaches described in the NPRB Science Plan (monitoring, modeling, process, and retrospective studies). The majority, however, have focused on processes in order to increase our understanding and ability to forecast future changes. Several involve cooperative research projects with industry and/or communities, and draw upon local and traditional knowledge. 4 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

Fish and invertebrates projects

202 Application of new sonar technology to reducing salmon bycatch in 420 Interannual and spatial variation in population genetic composition of pollock fisheries. C. Rose northeastern Gulf of Alaska young-of-the-year Pacific ocean perch. A. Gharrett 204 NPAFC salmon tagging. V. Fedorenko, J. Helle 502 Integration of ecological indicators for the North Pacific with emphasis 205 Genetic stock identification of W. AK sockeye salmon. J.Seeb, R. Wilmot on the Bering Sea: A workshop approach. A. Bychkov, J.Overland 208 Environmental cues for herring spawning. G. Kruse, D. Musgrave 503 Arctic Ocean synthesis. R. Hopcroft 209 Two species of rougheye rockfishes in the northern Gulf of Alaska. 504 Analysis of ongoing salmon programs. E. Knudsen A. Gharrett 505 Walleye pollock in the Eastern Bering Sea: A spatially explicit model. 210 Nutritional quality of Alaska fish for predators. M. Castellini T. Quinn 303 North Pacific Anadromous Fish Commission Cooperative Research: 506 Factors influencing the mortality of tagged walleye pollock captured Use of genetic stock ID to determine the distribution, migration, early using a trawl net. R. Foy marine survival, and stock abundance of sockeye and chum salmon in the Bering Sea. S.Abe, J. Seeb, S. Urawa, R. Wilmot 508 Female reproductive output of snow crab in eastern Bering Sea. D. Armstrong, B. Ernst, T. Essington, P. Livingston, L. Orensanz 305 Monitoring and modeling predator-prey relationships. P. Livingston 509 Retrospective analysis of Kodiak red king crab. G. Kruse 306 Species identity and life history of Hematodinium, the causative agent of bitter crab syndrome in northeast Pacific snow (opilio) and Tanner 510 Skate life history and demography. G.Cailliet, D. Ebert (bairdi) crabs. L. Hauser, P. Jensen, F. Morado, D. Woodby 511 Spiny dogfish in Alaska. V. Gallucci, G. Kruse 308 Forage fishes in the western Gulf of Alaska: Variation in productivity. 512 Juvenile Pacific Ocean perch genetics, phase 2. A. Gharrett K. Bailey, J. Duffy-Anderson, J. Napp, J. Paakkonen, M. Wilson 521 A profiling echosounder for North Pacific monitoring. D. Mackas, S. Vagle 310 Estuaries as essential fish habitat for salmonids: Assessing residence time and habitat use of coho and sockeye salmon in Alaska estuaries. 522 Reproductive biology of Atka mackerel. S. Atkinson, M. Canino, N. Hillgruber, M. Bishop, S. Powers, G. Reeves S. McDermott 311 Establishing a statewide data warehouse of salmon size, age, and 523 Pollock recruitment and stock structure. M. Dorn, A. Hermann, S. Hinckley, growth records. B. Agler J. Horne, B. Megrey, C. Parada 314 Thermal habitat preferences of Pacific halibut and the potential influ- 524 Productivity of capelin and pollock. J. Duffy-Anderson, P. Livingston, ence of hydrographic variability on a local coastal fishery. E. Logerwell, M. Wilson T. Loher, H. McCarty 525 Modeling multispecies groundfish interactions. P. Livingston 317 Pre-season forecast of Bristol Bay sockeye salmon migration timing 531 Seabird-fish models. W. Sydeman based on oceanographic and biological variables. G. Ruggerone 605 Modeling growth and survival of early life-stages of Pacific cod in 319 Retrospective study of pigmented macrophage aggregates as markers response to climate-related changes in sea ice conditions in the Bering of Pacific herring population health. G. Marty Sea. M. Behrenfeld, L. Ciannelli, M. Davis, T. Hurst, B. Laurel, A. Stoner 321 Evaluation of alternative hypotheses to explain the collapse of the 606 Modeling climate effects on interdecadal variation in southeastern Kvichak sockeye salmon: A project to catalyze a comprehensive, Bering Sea jellyfish populations. M. B. Decker hypotheses-driven research program. M. Link, G. Ruggerone 610 Adaptation to a changing world: Molecular evidence for selective 325 Video monitoring aboard Bering Sea factory trawlers—a pilot study. mortality in walleye pollock larvae. K. Bailey, M. Canino, L. Hauser S. Anderson, M. Buckley 617 Migration patterns of Pacific halibut in the southeast Bering Sea. 327 Early marine ecology of juvenile chum salmon in Kuskokwim Bay, Alaska. T. Loher, B. Norcross L. Haldorson, N. Hillgruber, C. Zimmerman 618 Spatial and temporal patterns in Pacific cod reproductive maturity in 401 Survey strategies for assessment of Bering Sea forage species. the Bering Sea. El. Logerwell, S. Neidetcher M. Benfield, E. Brown, J. Churnside, N. Hillgruber, J. Horne, S. Parker Stetter, M. Sigler 619 Connectivity between Greenland halibut (Reinhardtius hippoglossoides) 404 Alaska Marine Information System. D. Kiefer, K. Stocks spawning and nursery areas in the eastern Bering Sea: A paradigm for 407 Kelp-grazer interactions in Kachemak Bay, Alaska: grazing activity, offshore spawning flatfish species. K. Bailey, L. Ciannelli, J. Duffy-Anderson, chemical defenses and resource allocation. K. Iken A. Matarese 417 Reproductive ecology of Atka mackerel, Pleurogrammus monopterygius, 620 Estimating movement rates of Pacific cod (Gadus macrocephalus) in the in Alaska. S. Atkinson, N. Hillgruber, R. Lauth, S. McDermott Bering Sea and the Gulf of Alaska using mark-recapture methods. 418 Abundance, life history, and population demographics of Spiny Dogfish, D. Gunderson, P. Munro, D. Urban Squalus acanthias. V. Gallucci, G. Kruse 621 Diet and trophic ecology of skates in the Gulf of Alaska (Raja and 419 Modeling of multispecies groundfish interactions in the eastern Bering Bathyraja spp.): Foundational ecological information for ecosystem- based management of demersal resources. G. Cailliet, D. Ebert Sea. P. Livingston NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 5

622 Analysis of fall, winter, and spring predation of key Bering Sea and Gulf 811 Development of a quantitative PCR assay for simultaneous identi- of Alaska groundfish through food habits and stable isotope analysis. fication and enumeration of planktonic red king crab (Paralithodes K. Aydin, B. Miller camtschaticus) larvae. G. Eckert, P. Jensen, J. Morado 623 Tools to assess Hematodinium life history and impacts on Tanner crabs. 812 Reproductive indices of male snow crabs (Chionoecetes opilio) from C. Friedman, L. Hauser, F. Morado the Bering Sea: Analysis of hormones, reproductive structures, and behavior. S. Tamone 624 Modeling transport and survival of larval crab: Investigating the contraction and variability in snow crab stocks in the eastern Bering Sea 813 Determining the implications of uncertainty in snow crab recruitment using individual-based models .D. Armstrong, B. Ernst, A. Hermann, S. Hinckley, using management strategy evaluation. A. Punt, B. Turnock G. Kruse, B. Megrey, J. Napp, J. M. (Lobo) Orensanz, C. Parada 814 Recruitment mechanisms for tanner crabs in the eastern Bering Sea. 625 Assessment of Bristol Bay red king crab resource for future management E. Curchitser, A. Hermann, G. Kruse, J. Napp action—a new approach. G. Conan, S. Hughes 815 Pacific cod (Gadus macrocephalus) migration and distribution related to 627 Identifying life history characteristics of squid in the Bering Sea. spawning in the eastern Bering Sea: A mark-recapture experiment on a N. Bickford, B. Norcross large geographic scale. M. Conners, P. Munro 628 Understanding the population dynamics of an abundant non-target 816 Estimating source contribution and dispersal histories of Pacific cod species group: Life history and demographics of large sculpin species in recruits using otolith elemental composition. T.Hurst, J. Miller, J. Moss the Bering Sea large marine ecosystem. K. Aydin, A. Hollowed, R. Reuter 817 A landscape genetics approach to Pacific cod (Gadus macrocephalus) 629 Assessment of female reproductive effort and maternal effects in Pacific population structure in the Bering Sea and Aleutian Islands; investiga- Ocean perch: Do big old females matter? tion of ecological barriers to connectivity between potentially distinct S. Heppell, S. Heppell, P. Spencer population components. I. Spies 630 Food web linkages: Forage fish distribution and ecology in core areas of 825 Assessment of Bristol Bay red king crab resource for future management predator distribution in the Aleutian archipelago. M. Arimitsu, J. Piatt , V. Byrd action: Implementing a cooperative approach. S. Hughes

704 *Developing the Alaska Marine Information System. M. Johnson 711 Quantification of unobserved injury and mortality of Bering Sea crabs due to encounters with trawls on the seafloor. M. Davis, J. Gauvin, J. Munk, C. Rose, A. Stoner 712 Bycatch characterization in the Pacific halibut fishery : A field test of electronic monitoring technology. J. Cahalan, W. Karp, B. Leaman, J. Watson, G. Williams 713 Predicting snow crab growth and size with climate warming in the northern Bering Sea. J. Lovvorn 714 Developing biological reference points for crustacean fisheries: Reproductive potential of Bristol Bay red king crab and eastern Bering Sea snow crab. G. Eckert, G. Kruse, K. Swiney 715 Life history and population dynamics of four endemic Alaska skates: Determining essential biological information for effective management of bycatch and target species. G. Cailliet, D. Ebert

716 Evaluating acoustics for squid assessment in the Bering Sea. J. Horne 728 Herring synthesis: Documenting and modeling herring spawning areas within socio-ecological systems over time in the southeastern Gulf of Alaska. V. Butler, M. Moss, T. Thornton 731 Temperature data collections on Bering Sea groundfish vessels to evaluate temperature at depth and catch rates for target and bycatch species in order to reduce bycatch and increase knowledge of how ecosystem variables affect fishing. J. Gauvin, J. Ianelli, P. Stabeno 809 Evaluation of echosign data in improving trawl survey biomass estimates for patchily-distributed rockfish. D. Hanselman, P. Spencer 810 Assessment of rockfish species in untrawlable habitat using advanced acoustic, optical, and trawl technologies. D. Demer, M. Martin, C.Rooper, T.s Weber, M.Wilkins, C. Wilson, M. Zimmermann

* discussed in Other Research Partnerships

Jack Helle 6 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

Stock Assessment Research and Development

Some of the most challenging issues for fisheries management involves the accurate assessment of fish populations.

The National Marine Fisheries Service annually reports to species, squid, rockfish and planktonic stages of commer- Congress on the status of fisheries under a federal fishery cially important species, to improving existing assessment management plan and identifies their status – overfished, technologies, integrating ecosystem indicators into assess- not overfished, approaching an overfished condition, or ment models, making these models more spatially explicit, unknown. These conditions do not distinguish if a stock has and better understanding the general foraging, behavioral, declined due to natural or human factors. and population ecology of the species of interest.

We need to understand how these factors interact and New Methods for Assessing Difficult Species influence populations so resource management can adapt. State and federal management agencies routinely assess Fishery councils place stocks into different tiers depending stocks of exploited fishes and invertebrates, but some spe- on how much information they have, with fewer data result- cies are difficult to study. We lack information on forage ing in more cautionary considerations. Given the varying species, including myctophids, euphausiids, sandlance, amounts of information known about different species and capelin, and gadids, which are important prey for large the uncertainty in resulting stock assessments, scientists are fishes, seabirds, and mammals. continually gathering more information about target and bycatch species, as well as improving upon stock assess- Forage species occur in sometimes dense patches in space ment techniques, methods, and models. and time, and these ephemeral hotspots influence the structure and function of marine ecosystems. Yet survey The Board has funded 49 projects (29 of which are com- methodologies do not yet accurately measure these prop- pleted) for over $9.3 million related to stock assessment erties, nor have different types of surveys been compared research and development, ranging from the development to each other to determine which approaches or combina- of new methodologies to assessing a variety of forage tion would provide the best information. Christopher Kenaley Christopher Photograph of a hot spot with large concentrations of seabirds and marine mammals. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 7

FISH & INVERTS :: Stock Assessment Research & Development FISH & INVERTS :: Stock Assessment Research & Development Testing Techniques for Finding Testing ProfileE co-Sounder Forage Species Project 521 Project 401

In project 401, researchers evaluated different techniques to characterize forage species in the slope, shelf, and nearshore regions of the southeast Bering Sea using ship-based (acoustics, midwater trawls, MultiNet, beach seine, jig, ROV) and aerial remote-sensing technologies, including LIDAR. Aerial surveys can rapidly cover large areas and are cheaper than ship-based surveys, but cannot provide information deeper than 20-50 meters.

During ship-based surveys, acoustics profile the water Life cycle of Neocalanus plumchruus (left) and breakdown by size and depth of its column to the seafloor and direct sampling provides bio- predation mortality (right). logical information, such as species composition, but the survey is comparatively slow and may not capture ephem- Scientists most frequently use acoustics to eral events. Ship surveys detected patchy prey at middle measure and monitor the vertical biomass distribution of depths of 100–300 meters along the slope and nearshore, key forage species, validated by vertical net tows. Nearly all but dispersed prey at shallow depths of less than 100 of the food for Pacific salmon, pollock, and other important meters and in deep water of more than 300 meters over pelagic predators funnels through either large calanoid the slope, indicating that eastern Bering Sea slope and copepods (mostly Neocalanus spp.) or through midwater shelf regions differ in forage species composition, distri- micronekton, which are primarily myctophid fishes and bution, and abundance. Ship-based surveys also identified small squids about 5-10 centimeters long. unique types of aggregations as well as several intense surface foraging events involving many birds, fish schools, Both groups live primarily in waters between 400 and 1200 whales, and zooplankton. A typical event measured about meters deep. Copepods migrate seasonally to deeper ten kilometers across and lasted for about three days. water for a prolonged deep dormancy, while the fishes and squids migrate twice a day between the surface and the Both LIDAR and acoustics recorded similar spatial patterns mesopelagic depths occupied by the dormant copepods. in forage species distribution, but most of the forage species remained below the LIDAR penetration depth at more When they migrate up to the sea surface to feed on cope- than 24 meters, even at night. pods, the micronekton in turn are a major source of food for Pacific salmon and other top predators. Knowing Given these findings, a compromise between the advan- the biomass and distribution of these zooplankton and tages and limitations of each approach appears to be that micronekton is key to understanding variations in food sup- shelf, slope and nearshore regions should be surveyed ply for their predators, especially in autumn and winter, separately, and that broad-area aerial surveys can direct when upper ocean food sources are scarce. ship-based surveys to regions of interest. Year-round monitoring of both large copepods and micronekton is problematic. For most of the year, nearly all of the monthly total biomass occurs at depth, where sampling with nets is difficult, time consuming, and expensive. Project 521 focused on adapting a moderate-cost, high- frequency echosounder to allow in situ profiling to ocean depths of at least 1000 meters. Researchers modified existing sonar technology to target the size, power consumption, data-compression, and depth requirements and attached it to Argo profiling floats.

A series of unexpected technical problems in 2006 and early 2007 prevented full field testing of the new profiling eco-sounder, but information suggests that this technology On June 17, fish schools reappear and reform the hot spot as well as a secondary hot spot between Unalaska and Akutan Islands. will deliver very useful biological data from mesopelagic layers of the subarctic Pacific. 8 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Stock Assessment Research & Development Using Acoustic Technology to Survey Squid Project 716

Squid are another important, but poorly understood component of the Bering Sea. Prevalent in the diets of northern fur seals, Steller sea lions, and other marine mammals, squid represent significant bycatch in the Bering Sea walleye pollock fishery. Gaps in our knowledge of squid life history and distribution data limit our ability to effectively manage squid stocks, although we do know that squid populations are generally volatile and strongly tied to environmental conditions, such as temperature.

The National Marine Fisheries Service acknowledges that a directed squid fishery in the Bering Sea and Aleutian Islands ecosystem could quickly develop, but to set catch and bycatch rates for squid, they need quantitative stock information. No one has comprehen- sively surveyed squid in the Bering Sea and so there are no reliable biomass estimates.

Squid are difficult to assess with conventional trawling. Acoustics provide an alternate approach, surveying large distances over short time periods and providing snapshots of organisms throughout the water column. Project 716 is evaluating the potential of using acoustic technology to assess Bering Sea squid by examining methods used to charac- Works courtesyReprinted Stuff of How terize acoustic energy from squid assemblages in the waters north of the Aleutian archipelago and along the southern portion of the shelf break near Unimak Island, called the horseshoe region. Specimens collected through midwater or bottom trawls will be used to verify the identity of species of squid in the area and will provide life history information. Scientists expect to calculate a squid density index and a catch per unit effort based on the systematic acoustic data and the trawl catches, respectively.

FISH & INVERTS :: Stock Assessment Research & Development Counting Rockfish in Untrawlable Habitats Project 810

The habitat preferences of certain fishes make instruments to estimate abundance, including an EK60 stock assessment surveys problematic. Rockfish aggregate echosounder operating at five frequencies, a multibeam in untrawlable rocky areas, yet constitute an important com- echosounder (ME70) to identify school characteristics, ponent of marine ecosystems and commercial fisheries in and an autonomous underwater vehicle (AUV) with a 38 Alaska with an ex-vessel value exceeding $11 million in 2006. kHz echosounder, and a stereo drop camera to measure length. A semipelagic trawl will be fished near the sea- A constant problem in estimating groundfish biomass floor to verify species identification and size. Results will using trawl surveys is the unknown, but presumed signifi- be used to develop a methodology that will scale up to cant amount of the continental shelf that is not fishable with entire surveys of the untrawlable areas of the Gulf of Alaska the survey trawl. To estimate the total biomass for a spe- and Aleutian Islands, allowing scientists to compare species, catch per unit effort data from a survey are generally cies composition, abundance, and size between trawlable expanded across entire regions regardless of the propor- and untrawlable areas. tion of untrawlable ground within the area. There is some evidence that untrawlable areas can have different species assemblages and different size classes or abundances of the same species than trawlable areas, potentially resulting in significant effects on the accuracy and precision of bottom trawl survey biomass estimates.

Project 810 is comparing rockfish abundance between trawlable and untrawlable areas to improve assessments of rockfish abundance. The study aims to evaluate the abil- The NOAA Fisheries AUV is configured with a 38 kHz split-beam echosounder, stereo ity of using advanced remote sensing acoustic and optical cameras, CTD, and 300 kHz ADCP. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 9

FISH & INVERTS :: Stock Assessment Research & Development Detecting Patches of Rockfish Project 809

Even within trawlable areas, surveys do not count everything everywhere and scientists extrapolate the data to a larger region, making a series of assumptions about the nature of the fish distribution.I n the case of rockfish, these estimates are often highly variable and thus less precise, in part, because of the patchy distribution of these fish. Project 809 is using improved acoustic technology (specifically echosign data) to better allocate sampling effort during stock assessment surveys so as to better represent high-density rockfish patches and thus decrease

biomass estimate variability. Darin Trobaugh

FISH & INVERTS :: Stock Assessment Research & Development Identifying Red King Crab Larvae Project 811

A key component to developing accurate stock Crab larvae are patchily distributed in time and space, assessments and predicting year-class strength is to under- requiring extensive sampling efforts to track larval disper- stand the dynamics governing early life history stages. The sal and understand larval dynamics. A major impediment Alaska red king crab fishery was one of the most economi- to analyzing large numbers of plankton samples is the time cally important, single-species fisheries in the world with required to sort and individually identify zooplankton via a landed value of US $265 million in 1980, before its col- light microscopy. Identification is tedious and not always lapse in 1981-82 that led to a total closure of the Bristol reliable, making large-scale plankton surveys cost-prohib- Bay fishery in 1983. Stocks have not shown any substantial itive due to the time and expertise required per sample. recovery, and researchers believe that the planktonic larval dispersal and recruitment for red king crab, like that for To tackle this problem, Project 811 is developing a DNA- many other species, are major determinants of the struc- based assay (QPCR) for the simultaneous identification ture and dynamics of its population. and enumeration of red king crab larvae in plankton samples. The assay will advance sampling techniques, which will facilitate comprehensive studies of red king crab larval dynamics. If successful, such an assay should support development of similar protocols for Tanner, snow, and blue king crab larvae. Brad Stevens Brad 10 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Stock Assessment Research & Development Improving Existing Assessment Technologies Projects 625, 825

Improving population estimates involves more the National Marine Fisheries Service and the Alaska than just developing new technologies for assessing dif- Department of Fish and Game in 2005, a full survey of ficult species, but also ensuring the accuracy of current 241 random site tows was conducted over approximately methodologies, especially in light of significant uncertain- 24,000 square nautical miles in 2007. ties about gear selectivity and catchability. Such is the case for the Bristol Bay red king crab, which for more than The new survey gear, sampling methodology, and geo-sta- 30 years has been annually assessed by trawl surveys to tistical approach proved highly effective and lowered the determine crab densities, biomass estimates, guideline uncertainty of the abundance estimates for large male Bristol harvest levels, and biological parameters for sustained Bay red king crab of about 37% from the standard NMFS yield management. survey over the past ten years to about 13%. Results also showed significantly higher estimated mean abundance and Project 625 developed and conducted an alternative, reduced variance from the Bering Sea Fisheries Research cost-effective survey for Bering Sea crab resources that Foundation survey for all sizes and sexes as compared to eliminates or greatly reduces bias and uncertainty in the National Marine Fisheries Service survey. Recognizing the estimates of crab biomass for all relevant life stages that one survey season, although promising, does not set a of crab. Based on a successful pilot study by the Bering new standard, Project 825 continues this effort with another Sea Fisheries Research Foundation in cooperation with full-scale side-by-side assessment in 2008. Steve Hughes Steve Photos from the 2007 BSFRF trawl showing footrope configuration along wing sections (upper) and the throat section (lower). NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 11

Ecology

Counting and estimating the number of any given species at a specific point in time and place is complex. Determining why a given number of these species are there, or perhaps more critically, why they may not be there, may be even more complicated as it requires in-depth knowledge of their behavioral, foraging, and population ecology. Understanding these aspects, however, is crucial to properly assessing and predicting population status.

Behavioral Ecology The Board has funded a variety of behavioral ecology studies focused mostly on salmon, Pacific halibut, and Pacific cod.

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Behavioral Ecology Salmon on the High Seas Project 204

Project 204 tagged almost 1,500 salmon in the Bering Sea to determine where they go in the open ocean and what factors affect their survival. Better understanding of the distribution patterns, habitat use, and movements of Asian and North American salmon migrating in the Bering Sea and North Pacific Ocean helps determine which competitive feeding dynamics between different stocks and species may be negatively affecting the growth, maturation rates, and survival of salmon in the Bering Sea.

The tags employed in this study recorded sea temperature, depth, salinity, and daily position. Almost 8% of the tags have been recovered to date, and the recorded information suggests that different species preferred different Researchers concluded that fish choose depth over temper- depth ranges. Chum and chinook prefer deeper water (58– ature and that these depths may remain relatively constant 130 meters) than sockeye, while pink and coho salmon are across water masses and ocean areas. Whether warming found in waters 22–46 meters deep. Temperatures of the ocean temperatures will lead to increases in depths pre- water, on the other hand, varied widely. ferred by both salmon and their prey remains to be seen.

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Behavioral Ecology Young Salmon in Estuaries Project 327

Project 327 focused on chum salmon and their behavior in estuaries in the last stage of their migration from fresh to salt water, in this case, Kuskokwim Bay. During this period, young fish undergo the energetically costly process of physiologically

adapting from fresh to marine water and often experience high mortality rates. Gansemer Edward

This project studied the patterns of estuarine distribution, diet, body condition, and growth of juvenile salmon in Kuskokwim Bay to better understand the factors regulating this population at this life stage. Scientists found that the timing of outmigration and spatial distribution of juvenile chum salmon in the bay are critically important to their feeding success, and hence to their growth patterns and subsequent chances of survival. As sea surface temperatures increased from 7˚C in May to 16˚C in June, fish lost energy density with size and season, and models indicated that the lowest growth potential for juvenile chum salmon occurred in inshore habitats. Combined, these factors illustrate the delicate balance between different environmental factors needed to properly prepare young salmon for the ocean period of their life, thus influencing how we may assess these stocks at sea. 12 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Behavioral Ecology Migration Patterns of Pacific Halibut Projects 314, 617

Pacific halibut support one of the strongest fisheries in the Gulf of Alaska and Bering Sea and Aleutian Islands. Landings between 2000–2006 averaged over 71 million pounds annually, and are worth approximately $170 million ex-vessel. The halibut fishery is especially important to small communities in western Alaska, where they harvest approximately 2.5 million pounds per year. Around the

Pribilof Islands, harvest shortfalls led to speculation that the Guild Gillespie/www.chartingnature.com © B. harvest and changing environmental conditions impacted local abundance and/or accessibility to small vessels that fish close to the shore. Projects 314 and 617 focused on water temperature preferences and migration patterns of Pacific halibut.

Scientists participating in Project 314 supplied mem- bers of the local fishing fleet with recorders that could be attached to their longline gear during normal fishing operations to measure bottom temperature and fishing depth. Researchers compared these data with daily catch rates, using logbook information and the total weight of fish landed after each trip.

The data did not demonstrate a direct relationship between temperatures and catch within-season, although fleet-wide catch was lowest in 2003, which was warmer on average than 2002 and 2004. The results suggest that halibut do not respond strongly to temperatures within the observed range over short periods, but that local abundance may be influenced by spring temperature prior to commencement Location of major known spawning grounds for Pacific halibut.From St. Pierre, 1984. of the fishery, with warmer water yielding fewer fish or fish that are harder to capture. The data also revealed geographically localized groups of Project 617 investigated the question of harvest and the Pacific halibut along theA leutian Island chain. All of the fish movement of fish. If fish range widely, then the current tagged there displayed residency, with their movements large area management approach (one stock extending possibly impeded by passes between islands. Mid-winter from California through the Bering Sea) may be adequate. aggregation areas of Pacific halibut are assumed to be If, on the other hand, movement of individual halibut is spawning grounds, of which two were previously unidenti- relatively limited, as suggested by local depletion in the fied and extend its presumed spawning range about 1000 Bering Sea, then areas may be self-recruiting and local area kilometers west and about 600 kilometers north of the management plans may more accurately reflectP acific hali- nearest documented spawning area. but population structure. Overall, halibut seemed to follow three general behavioral Researchers tagged 24 adult Pacific halibut with externally patterns, including dispersal to the continental slope, con- attached pop-up archival transmitting tags in summer, and tinental shelf residency, and feeding site fidelity. Several released them on the southeastern Bering Sea continental additional research projects conducted by the International shelf/slope area. In February of the following year, the tag PacificH alibut Commission and others are currently under- released from the fish, floated to the surface of the ocean, way to help better understand the seasonal movements and transmitted the stored data to overhead satellites. and population structure, and this behavioral information Results showed that none of the Pacific halibut moved out will help refine some assumptions ofP acific halibut biology of the region during the winter spawning season, support- and ecology. ing the concept that fish in this region may belong toa separate group from those in the Gulf of Alaska. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 13

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Behavioral Ecology Movements of Pacific Cod Project 620

Projects 620 and 816 focus on the movement of Pacific cod and implications for stock structure and management. In 1996, the cod fishery caught a record 240,590 metric tons, but catches as of 2005 have declined to about 170,000 metric tons. Pacific cod are harvested almost year-round with the concentrated trawl fishery in winter off Unimak Island called “cod alley” and steady longline and pot fishery over the slope and southeastern Bering Sea. © B. Guild Gillespie/www.chartingnature.com

Besides their economic importance, Pacific cod also play Although movement could be presented graphically, the an important ecosystem role as a major predator of other four original datasets were too disjointed, either in time marine organisms and as winter prey for marine mammals, or space, to allow a quantitative representation of move- such as Steller sea lions. To adequately balance ecological ment rates among regions of the Bering Sea or between needs and commercial wants, we need to accurately assess the Gulf of Alaska and the eastern Bering Sea. The model the size and boundaries of stocks. Resource managers cur- produced estimates of survival and exploitation rates, but rently identify two stocks of cod in Alaska, one in the Gulf these were considered “not very precise and biased due of Alaska and one in the Bering Sea and Aleutian Islands. to the non-controlled nature of the tagging studies in all Project 620 was a modeling study in which four existing four datasets.” A well-designed mark-recapture study is Pacific cod tagging datasets were compiled into oneto needed to fill these gaps, so the Board fundedP roject 816. quantify Pacific cod movement and to estimate survival and exploitation rates.

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Behavioral Ecology Distribution of Juvenile Pacific Cod Project 816

The graphic representation of the compiled movement data discussed in Project 620 and other previous research indicated that the Unimak Pass–Alaska Peninsula area may likely represent the primary source for dispersal of Bering Sea cod larvae. Fish spawned in this region, or transported through Unimak Pass from Gulf of Alaska spawning areas, would be carried into Bristol Bay by the Bering Coastal Current with possible transport northward toward the Pribilof Islands.

Determining this connectivity and dispersal behavior has great implications for management, yet it is still unknown if larvae and early juveniles follow spatially discrete dispersal pathways depending on the location and timing of spawning, or if individuals from different A graphical presentation of minimum distance traveled and direction of movement of tagged Pacific cod in the eastern Bering Sea. Data presented here were based on FIT study only. Each arrow represents three or regions are intermixing throughout their devel- more recoveries, except the one fish captured in Russian waters. opment phases.

Project 816 is attempting to solve this puzzle by using otolith elemental composition to quantify and visualize spatial and temporal patterns in the distribution of juvenile Pacific cod collected in the eastern Bering Sea in relation to known spawning distributions, major current fields, and other gadid species. 14 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Behavioral Ecology Capturing Live Walleye Pollock Project 506

Tagging studies help scientists assess move- Overall survival rates of the ten trawl samples were not ment and stock structure, but only if the results properly sufficiently strong to endorse a full-scale tagging sur- represent the natural processes. If care is not taken, vey without further testing. However, information gained tagged fish may be impaired in ways that alter their natural from this study indicated that satisfactory survival may be behavior, and thus provide faulty information. Project 506 achievable by targeting dense aggregations of large fish, evaluated the feasibility of capturing live walleye pollock and carefully de-gassing any individuals with symptoms of with a closed-codend trawl net, which researchers hoped disorientation or swimbladder distension. to use for large-scale tagging surveys of pollock in the Bering Sea and Gulf of Alaska.

A closed-codend trawl net pools fish in calm water as the net is brought on deck. Live pollock from ten trawl samples were placed in laboratory holding tanks for 30 days to ana- lyze survival rates as a function of trawl depth, fish length, and catch density.

From nine of these samples, survival after 30 days was low, with pollock suffering significant scale loss during capture. But from one sample, the survival rate was nearly 50% after the codend unexpectedly overfilled with fish, plugging the codend pool.

This outcome suggested that captured pollock benefit from being within dense aggregations of fish, preventing them from harmful contact with the sides of the net or swimming to exhaustion. Fish length also positively correlated with survival rates. The effects of depth resulted in some pollock displaying persistent symptoms of barotrauma, suggesting that pollock caught in deep water adjust poorly once brought to the surface. Shannon Hanna The NOAA trawl net with chafing gear attached, being lifted onto the survey vessel deck after a tow.

Mark Rauzon NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 15

Foraging Ecology The Board funded two foraging ecology projects—one project studies how oceanography, prey distribution, and competition can determine foraging success, survival, and productivity of capelin and juvenile pollock, and the other project focused on the diet and ecosystem role of skates in the Gulf of Alaska.

Walleye pollock is a key species in the Alaska groundfish complex and a target species for one of the world’s largest fisheries. Juvenile pollock are prey for other groundfish, such asP acific cod, arrowtooth flounder andP acific halibut, as well as for marine mammals and seabirds. Capelin, while not important commercially, are an important forage fish inA laska, serving as important prey for seabirds, groundfish, and marine mammals.

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Foraging Ecology Foraging Success of Capelin and Juvenile Pollock Project 524

For both ecological and commercial reasons, Project 524 looked at the forage requirements and interac- tion between pollock and capelin to better understand their productivity. Using mid-water trawls, researchers collected fish for stomach contents analysis off of Kodiak Island, and recorded physical (CTD) and biological (zooplankton) data. The previous year, investigators found spatial overlap between capelin and pollock, with both species foraging on euphausiids, suggesting the potential for competition.

In 2005, however, only juvenile (age-0) pollock were distributed in the cool, high-salinity waters coincident with the distribution of the bulk of their preferred prey, euphausiids, whereas capelin distribution was more wide-spread and coincident more with the distribution of copepods, their dominant prey that year.

Although capelin and pollock ate different prey in 2005, capelin occurring with pollock often had reduced foraging success compared to capelin occurring alone. This suggests that juvenile pollock were the superior competitor of the two species and that the exclusion of capelin from foraging on euphausiids has negative consequences for their Distribution of euphausiids(S m2 nm-2) in August 2004 based on 120-38kHz acoustic growth, and perhaps even their survival. We still need to A differencing overlaid on water temerature (˚C) at 75 meters. further examine the potential for resource limitation and to study in more detail the interactions been capelin and juvenile pollock and its effects on their respective productivity.

Population Ecology The study of how populations interact with the environment, and the dynamics and demography of species populations makes population ecology a large and important field of research that provides critical life-history information needed to build accurate population and stock assessment models. Its importance is reflected in the $4.3 million the Board dedicated to 23 projects focused on this subject through 2008, spread across numerous species of commercial and ecological importance, including skates, dogfish, squid, sculpin, crab, herring, salmon, pollock, cod, Atka mackerel, halibut, and rockfish.

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Disease in Herring Populations Project 319

Increased knowledge about critical life-history but the population has abundant year-classes only every parameters is not only crucial for commercial species, but few years, likely connected to environmental factors, nutri- also for those that support valuable resources and play tional stress, exposure to contaminants, and disease. important roles in subsistence. Pacific herring encompass all of the above. Our understanding of the detailed ecological and evolutionary impacts of disease in marine systems is very Herring range throughout coastal regions of the North general, and for herring is particularly poor. As a result, Pacific. They are a critical source of high-energy food for Project 319 focused on identifying a biological “marker” other fish and marine mammals, such as Steller sea lions, that could show if Pacific herring were affected by disease and are highly valued in commercial and subsistence fish- in the past, so that scientists could determine the existence eries. Pacific herring first spawn as three- to five-year olds of disease before populations decrease in the future, and and live as long as 15 years. Mature herring spawn yearly, thus shed light into one of the parameters affecting herring population trends.

Researchers used 1,300 historic fish liver samples collected in Prince William Sound from 1988 and 1994 to study how age, gender, season, and disease affected the amount of small round structures called pigmented macrophage aggregates (PMA) normally found in fish organs. The study showed that PMA are excellent permanent biomarkers of population level stress in Pacific herring that remain with a year class until the fish die. Differences in PMA volume between the 1988 and 1994 fish supported the idea that a stress-related population decline of herring occurred sometime between 1992 and 1994 due to a disease out- break, and not immediately following the 1989 Exxon Valdez oil spill.

Clupea pallasii. Pigmented macrophage aggregates in the livers from two, six-year-old male Pacific herring sampled in 1994. Micrographs within a column are from serial sections of the same liver; micrographs within a row were stained with the same reagents. Magnification is the same for all images. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 17

F ea t u re P R O J E C T

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Skates in Alaska’s Seas Projects 510,621,715

Skates are common, bottom-dwelling cartilaginous fishes that serve important ecological functions as top predators and compete with other groundfish. Four species inhabit the outer continental shelf and upper continental slope environ- ments of the Gulf of Alaska—big, longnose, Aleutian, and Bering skates.

We know little about what skates eat in Alaska waters, which severely limits effective management of skates and co-occurring species. Project 621 aimed to provide quantitative information on their feeding ecology by collecting individuals caught during the fishery independent trawl surveys of the National Marine Fisheries Service and Alaska Department of Fish and Game in the western Gulf of Alaska in the summers of 2005-2007.

All skates of the four study species were identified, sexed, measured, and stomach contents were preserved for identification and analysis. All skates ate primarily shrimp and crab, although Aleutian and Bering skate diets differed among years, with euphausiids comprising a much greater proportion during 2007, and relatively fewer shrimp.

This first systematic quantification of skate diets in this region provided crucial information for multispecies trophic models, ultimately allowing more effective ecosystem-based management plans. Stomach samples from 2,060 skates were collected in the Gulf of Alaska during 2005–2007. Researchers continue to investigate the sources of variability, such as body size or location and depth of capture, in skate diets. Combined, these three Life Histories of Skates Using the skates collected as part of Project 621, Projects 510 and 715 derived informa- projects have provided tion on their age, longevity, growth, and reproductive biology. Skates are commonly taken as bycatch in groundfish fisheries in the Gulf of Alaska and eastern Bering Sea, the first quantitative and in 2005, approximately 620,000 pounds of skates were caught as bycatch but information on age, mostly discarded. growth, and reproductive While skate susceptibility to fishing pressure has been well documented, we lack enough knowledge of their life histories to assess stocks and implement sustainable manage- biology of eight Alaska ment plans. Knowing more about skates has recently become even more important with skate species, none the emergence of directed fisheries for big and longnose skates in the Gulf of Alaska. of which had been These two projects revealed maximum age estimates for Aleutian and Bering skates of 17 and 13 years, respectively, with no significant differences between the growth of previously studied in females and males for either species. Researchers estimate that Aleutian skates reach Alaska waters. maturity at ten years, and Bering skates become mature at seven years, with resulting demographic models projecting annual population growth rates of 25% for Aleutian skates, 36% for Bering skates, 33% for big skates, and 20% for longnose skates.

Project 715 continues these research efforts as it studies the age, growth, and reproductive biology of four additional Alaska skate species (commander skate, whiteblotched skate, whitebrow skate, and mud skate). Combined, these two projects have provided the first quantitative information on age, growth, and reproductive biology of eight Alaska skate species, none of which had been previously studied in Alaska waters. 18 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Life Histories of Dogfish Projects 418, 511

Because many elasmobranchs, including skates Using dogfish samples, investigators analyzed predomi- and sharks, grow slowly, mature late, and have few nant prey species and regional variability in the diet, and, young—characteristics that make them especially vulner- using the catch-per-unit-effort data, established a stan- able to fisheries exploitation—we need details on these dardized index of relative abundance. This index, coupled species-specific traits to develop realistic stock assessment with a surplus production model, allowed them to calculate models and establish sustainable management. Projects the potential risk of fishing to spiny dogfish. 418 and 511 investigated the abundance, life history, and population demographics of spiny dogfish to conduct a The studies found that dogfish primarily eat herring, smelt, preliminary stock assessment based on bycatch data. and other forage fishes, with shrimp being the most abundant non-fish portion of their diet. Male and female spiny In the Gulf of Alaska, dogfish have long faced fishing pres- dogfish showed similar growth rates until 30 years of age, sure in significant quantities as bycatch in commercially after which females grew faster and larger than males and valuable sablefish, salmon, halibut and other fisheries. No lived longer. Dogfish catch rates varied with year, area, one knows the impact of this fishing mortality on dogfish depth and vessel, and models estimated that dogfish may populations in the Gulf of Alaska, and no stock assessment be at 80%-90% of their theoretical population carrying had been completed prior to these studies. capacity in the Gulf of Alaska.

Researchers collected dogfish through targeted sampling Given our current life-history knowledge, it appears that cruises, state and federal assessment surveys, and oppor- the population would decline under relatively low rates of tunistic fishery bycatch samples between 2004 and 2007 fishing mortality, with harvest strategies targeting juveniles across the Gulf of Alaska. They also drew on observer data, and subadults leading to the greatest risks to sustainability. survey catch per unit effort (CPUE) and logbook informa- These results are currently being folded into the forth- tion, then used ageing technologies validated in the lab coming NPFMC stock assessments for spiny dogfish and to model the most appropriate age and growth curves for provide the critical tools needed to build a full population spiny dogfish. dynamics model. Mickey Darden Mickey Life history studies reveal that dogfish grow slowly, mature late, and primarily eat herring, smelt, other forage fishes, and shrimp. Dogfish face fishing pressure as bycatch in commercial fisheries. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 19

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Squid Life Histories Project 627

The North Pacific Fishery Management Council also used chemical signatures embedded within the stato- manages squid and sculpin as part of their “other species” lith to estimate the degree of squid movement between category, which has an aggregate quota that also includes hatching and capture locations. taxonomically and biologically dissimilar groups such as sharks and octopi. Researchers assume that squid biomass Although limited sample sizes did not permit detailed diet is huge and mostly concentrated in the Bering Sea basin analysis, it appears that in summer, Berryteuthis magister waters. Squid play an integral role in the trophic web as mainly ate euphausiids and gadids, whereas B. anonychus predators of larval fish and zooplankton, and as prey for ate arrow worms, fish, and euphausiids,Boreoteuthis bore- larger fish and marine mammals, with as much as 1,000,000 alis ate fish, euphausiids, and amphipods, and Gonatus metric tons of squid consumed as prey. kamtschaticus ate squid, fishes, crabs, and euphausiids. This is the first diet baseline information for these species. Despite squid’s ecological importance, and extremely high Scientists found that B. magister, which made up most of abundance in the Bering Sea, we know little about their the available samples, complete their life cycle in about life histories. Project 627 filled in some of these gaps by one year. Juveniles and adults appear to occupy different collecting gonatid squid from research cruises, and oppor- parts of the water column, indicating that the hatching and tunistically from commercial fisherman, then removing capture locations are not the same and that B. magister stomachs for diet analysis, and inner ear bones (statolith) for hatch at three or more different hatching locations along determining age by counting the daily rings. Researchers the Bering Sea slope.

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Ecological Role of Sculpin Project 628

Project 628 focuses on sculpin, which represent a significant portion of fishery bycatch in Alaska, with an average of 6,658 metric tons or 22% of the “other species” catch total from 1997–2004. The study focuses on determining age, growth, reproductive biology, food habitats, and other life history parameters to improve stock assessments models and to better understand the ecological role of four abundant large sculpin species (bigmouth sculpin, great sculpin, plain sculpin, and the yellow Irish lord) in the Bering Sea. Samples were collected during the summer 2006 NOAA eastern Bering Sea continental shelf and the Aleutian Islands survey conducted by the Alaska Fisheries Science Center, as well as during the fall, spring, and winter of 2007-2007 using field contractors. Photographs of plain sculpin otoliths aged using the surface and the break and bake method. A shows large early years on the surface and the break and bake method. B shows a small 1st year on the surface, but normal size on the break and bake. 20 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology The Reproductive Biology of Female Snow Crabs Project 508

By 2004, the recommended guideline harvest The cyclical signal in the abundance of recruitment to the level for the snow crab fishery dropped to 6% of the 1991 mature female and male populations appears to have a historical maximum of 328 million pounds. The geographic pervasive effect on virtually every aspect of snow crab life range of snow crabs in the eastern Bering Sea has con- history and population ecology—female size at maturity, tracted substantially towards the northwest, but no one egg clutch fullness, sex ratios, and average age past-termi- knows how this reduced range is affecting recruitment. nal molt among others. The research suggests that using Project 508 analyzed existing data from trawl surveys aggregate indices of spawning biomass…as a surrogate conducted between 1978–2003 by the National Marine for female effective reproductive output in conventional Fisheries Service, and from immature crab taken from cod stock assessment can be seriously misleading, obscuring stomachs. interpretable patterns in the case of stocks that, like snow crab in the eastern Bering Sea, show strong geographic Results showed that the early benthic life history for crabs structure. This is particularly so when biological process are at depths of 50 to 100 meters in the eastern shelf of the strongly governed by environmental gradients, geographic Bering Sea lasts for an average of six years—from settle- features, and patterns of circulation and other hydrographic ment to terminal molt when females reach maturity or processes, as is the case for this species. males reach adulthood. Towards the north shelf, life history events tend to be delayed due to colder temperatures, presumably because of a combination of biennial brood- The geographic range of snow crabs in ing and lower molting frequency at higher latitudes. the eastern Bering Sea has contracted Females live for up to 14 years, including six to seven years substantially towards the northwest. of reproductive life. Males may live up to 18 years. The study confirmed and expanded previous results showing that female recruitment over the last 25 years occurred in a regular cycle of four pulses, with a six- to seven-year period. © B. Guild Gillespie/www.chartingnature.com © B. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 21

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Male Snow Crabs Projects 812, 714

Project 812 is adding to our renewed under- Project 714 is also assessing egg quality and larval fitness standing of crab reproductive biology by focusing on male relative to female size and reproductive history to incor- snow crabs, particularly on the physiological difference porate these reproductive potential indices into stock between males that have reached terminal molt and are assessment models, which currently only use a crude mea- thought to be mostly responsible for mating, and indi- sure of reproductive output based on total female biomass. viduals in stages before the terminal molt that are already reproductively mature.

A more detailed understanding of the factors that contribute to successful mating and maximal fertilization of a clutch could support more refined population models. Project 812 is thematically synergistic with Project 714, which is examining the relationship between the amount of sperm in the spermathaeca (sperm load) of Bristol Bay king crab, and the percentage of the clutch that is fertilized. NOAA

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Tanner Crab Abundance Project 814

Project 814 focuses on Tanner crabs, and aims to investigate the causes of the wide swings in Tanner crab abundance over the last 15 years, seemingly due to extreme recruitment variability. Understanding the processes driving this variability would let fishery managers set sustainable biological catch and overfishing limits, and provide a basis for evaluating impacts of climate variability.

The study will apply a process-oriented, simulation model to explore the effects of stock biomass on recruitment through density-dependent relationships. Investigators will also look at how bottom temperature affects gonadal development of maturing adults, and how wind impacts the supply of nutrients leading to primary and second- Estimated male Tanner crab recruitment in Bristol Bay, during 1976-1996. Recruit- ary production favorable to larval crab feeding. The study ment occurs approximately seven years after egg hatching. also examines mixed-layer temperatures on productivity of copepod nauplii as prey of larval crab, and the advection of larval crabs to suitable nursery areas distant from the cold-pool predators such as Pacific cod, and cannibalistic subadult and adult crabs. 22 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

F ea t u re P R O J E C T

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Reproductive Biology of Atka Mackerel Projects 417, 522

Atka mackerel support a multi-million dollar commercial fishery and are important food for fish, seabirds, and marine mammals in the marine ecosystem of the Aleutian Islands. Resource managers need to know more about Atka mackerel life histories to best manage this valuable species.

Projects 417 and 522 proposed to learn more about how temperature affects the development of embryos, how maturity and fecundity differ and change among areas during the reproductive season, and to describe male guarding behavior of egg masses.

Using National Marine Fisheries Service Atka mackerel tag recovery cruises, researchers collected Atka mackerel and their egg masses from inside and outside Trawl Exclusion Zones, then mapped their distribution by reproductive condition. They determined female maturity and fecundity across different geographic areas, and used parentage analyses of embryos produced in both captive and natural populations to assess the mating system and patterns of egg cannibalism by adults.

The reproductive ecology of Atka mackerel turned out to be more complex than previously assumed. Atka mackerel spawn only in specific portions of their habitat, mostly inside the Trawl Exclusion Zones, with males, females, and immature fish living in different areas during the spawning season. Depending on water temperatures, eggs can take up to 100 days to hatch, meaning that adults could The 21 stages of embryonic development for Pleurogrammus monopterygius. Egg be spawning and guarding nests for up to six months a diameter = 2.66 millimeters. year. The study revealed that fecundity and maturity are dependent on growth patterns, with mature females (3-4 years old) in better body condition being more productive.

The study also found that although males mostly fathered the eggs they were guarding, sneaking behavior by other males resulted in egg batches produced by multiple parents.

Overall, variations in behavioral and environmental factors can lead to spawning systems with seasonal influences on the temporal and spatial distributions of the adult population, and it turns out that females are able to regulate their fecundity in response to area and year-specific variations in Bob Lauth Atka mackerel egg masses. the environment. Incorporating this information into stock assessment models and fishery management will greatly enhance our ability to successfully assess and manage this species and fishery. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 23

The reproductive ecology of Atka mackeral turned out to be more complex than researchers previously assumed.

Map of spatial Atka mackerel fishing controls, including the NMFS statistical areas, Steller sea lion critical habitat, and Trawl Exclusion Zones. Also includes three study sites of Amchitka Island. Clark James Mishler 24 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Reproduction of Pacific Ocean Perch in the Bering Sea Project 629

The idea that large females matter a great deal to the population due to their high reproductive potential applies to a variety of species, including Pacific ocean perch. In this long-lived and commercially important species of rockfish, age and size of females could potentially be mediating recruitment variability. Project 629 is investigating the size- and age-specific female reproductive effort of ocean perch and incorporating these data into age-structured population models to determine if and what maternal effects play an important enough role to be taken into account in stock assessment models. Lindsey Arnold Late stage Pacific ocean perch larvae.

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Life Histories of Pacific Cod Projects 618, 815, 817

Project 618 aims to identify the spatial and temporal patterns in spawning and maturity of commercially and ecologically valuable Pacific cod in the Bering Sea. Monthly maps of cod maturity stages, based on data collected by observers on commercial vessels, help determine the location and timing of cod spawning. Maturity data collected at St. Paul Island and from the National Marine Fisheries Service Bering Sea trawl surveys and fisheries observers, lets researchers assess the spatial differences in cod maturity schedules to better understand the potential for climate-driven shifts in fish distribution to impact cod life history parameters.

Distribution of Cod Following up on the recommendation made in Project Boundaries for Gene Flow 620, Project 815 will tag 12,000 fish and quantitatively esti- Using landscape genetics as an alternate approach to mate movement rates in the eastern Bering Sea between determining whether there are discrete populations of cod pre-spawning distributions in the fall to spawning distribu- with the Bering Sea and Aleutian Islands management area tions in the late winter and early spring. Understanding is the focus of Project 817. Landscape genetics is a rela- this movement is critical to adult life history. This project tively new approach for examining population structure, is the first study specifically designed to relate geographic but has the potential to identify and correlate clear physical distributions and movement on scales necessary for identi- boundaries, such as oceanic passes, deepwater canyons, fying potentially separate spawning stocks. Doing so gives and current systems, to gene flow (index for the amount of resource managers insight to harvest decisions that can individuals moving between areas). The complex and var- preserve the health of these cod stocks as components of ied physical environment of the Bering Sea and Aleutian a larger system. Islands lends itself to such a study and if successful, results would complement movement information inferred from the tagging study (Project 815), and substantially add to our understanding of the population dynamics of this species. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 25

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Greenland Halibut Collapse Project 619

Quantifying the important connectivity between differences, and for those leading to the ongoing recruit- spawning and nursery areas for Greenland halibut is the ment failure, remain poorly understood. focus of Project 619. Greenland halibut used to be one of the most important commercial flatfish species of the A critical aspect of the Greenland halibut life history Eastern Bering Sea, with landings in the late 1970s far appears to be the transport of eggs and larvae from exceeding the 2005 combined landings of all other com- their deepwater spawning areas across the slope to suit- mercial large flatfish species, such as Pacific halibut, able nursery locations on the shelf. It is the hope of this arrowtooth flounder, and flathead sole. project that understanding how evolving physical conditions of the Bering Sea affect this transport pathway will However, since the late 1970s when landings measured provide critical insight into the recruitment dynamics of 80,000 tons, a dramatic decline in recruitment resulted in Greenland halibut, and possible other deepwater spawn- landings of about 2,000-3,000 tons during the three years ing flatfish. Researchers are employing a combination of before the onset of this project. The collapse of this stock field and laboratory work as well as modeling to achieve is in strong contrast to the increase of other flatfish spe- these objectives. cies of the eastern Bering Sea and the causes for these

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Walleye Pollock in the Gulf of Alaska Project 523

Female walleye pollock spawn millions of eggs, but 99% of these die before the end of their first Map A: Regions where year, due to high levels of predation, transport by ocean modeled pollock eggs currents out of their preferred habitat, and a lack of food. were released for the Project 523 developed and used a physical-biological years 2000-2004. model to simulate the physical environment and the early life history of walleye pollock in the Gulf of Alaska for a better understanding of the processes that influence walleye pollock recruitment, and how recruitment may fluctuate as climate changes. Part of this study also looked at the relationships between spawning locations and nursery areas of walleye pollock in the North Pacific. Map B: Positions of particles (correspond- The study showed that young pollock that were spawned ing to eggs, yolksac in outer Cook Inlet, Shelikof Strait, the Semidi Islands, larvae, feeding larvae, as well as in the Shumagin region, may all be using the and juveniles) during Shumagin Island region as a nursery area. Contrary to pre- the simulation on vious assumptions, the model indicated that many young August 1, 2000. pollock hatched in the Gulf of Alaska may eventually end up in the Bering Sea, especially if they were spawned on the outer edges of the continental shelf or slope or in the Shumagin region. Shumagin Island region a self-sustaining population, or This result raises two important ecological and manage- are all the young fish produced in this region “lost” to the ment questions. Are the Gulf of Alaska and Bering Sea Bering Sea? Results from this modeling effort need to be walleye pollock populations really separate, as reflected in validated with field observations, but if they are, the pre- the current management scheme, or is recruitment in the dicted survivorship and transport from the model could be Bering Sea affected by spawning in the Gulf? And is the added to the annual stock assessments of walleye pollock. 26 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Tracking Juvenile Sockeye Salmon Project 205

Determining the geographical boundaries of different fish populations and quantifying the connectivity between different areas are important aspects of population ecology and species management, and help in determining population trends. Researchers traditionally relied on tagging individual fish and receiving tag returns from fisheries. In recent years genetics, specifically microsatellite loci and single nucleotide polymorphism (SNP, pronounced “snip”, a small genetic change or variation in the DNA), have been increasingly used to track migration, survival, and stock structure of commercially important fish species.

Using these genetic markers, Project 205 tracked the migration and relative survival of juvenile sockeye salmon populations exiting Bristol Bay and the eastern Bering Sea. Data were collected from across the entire eastern Bering Sea using the National Marine Fisheries Service Ocean September stock distributions (except R1-Aug) in the Bering Sea for immature Carrying Capacity (OCC) surveys of 1999-2002, and com- sockeye salmon collected in 2002 and 2003. Sample sizes of successfully genotyped fish are indicated. pared to juvenile reference samples. Unfortunately, the OCC experimental design for sampling juvenile sockeye salmon differed every year in both sampling locations and Some data suggested that the more northerly-derived fish, time of year, precluding a systematic analysis of the data. along with all the other stocks, can migrate northeasterly in some years, but given the single sampling observation Results showed that these genetic techniques could be suc- period it is difficult to predict where these fish migrated cessfully applied to these types of studies and confirmed later in the season. A comprehensive analysis of the interplay that stocks originating from throughout Bristol Bay head between ecological and oceanographic factors became the out into the bay at about the same time and migrate along focus of Project 303. the northern Alaska Peninsula in a southeasterly direction.

Dustin Pillips NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 27

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Where Do Pacific Ocean Perch Go? Projects 420, 512

Pacific ocean perch described as part of project 629 were also the subject of projects 420 and 512, which used genetics to determine interannual and spatial variation in northeastern Gulf of Alaska young-of-the-year perch. An important question for this species and other rockfishes is how far individuals move between the release from their mothers until they reproduce about six years later, and how this relates to the size of current management areas. If these areas are much larger than the dispersal distances, uneven harvests may erode potential production and must be carefully considered in stock assessments and management regimes.

Between 1998 and 2003, researchers collected young- Map of collection sites and geographic groupings of adult POP (Palof 2008). Geographic groupings are: Queen Charlotte Islands (QCI), Cross Sound (CSS), Yakutat of-the-year Pacific ocean perch opportunistically during (YAK), Cordova (COR), Kodiak (KOD), Shumagins (SHU), Akutan (AKU), Central Aleu- surveys of juvenile salmon in the Gulf of Alaska and Bering tians (ALE), Western Aleutians (WAL), Southern Bering Sea (SBS), and Central Bering Sea. They genotyped each fish at the same 14 microsatellite Sea (CBS). Solid black lines delineate management areas. loci used during a previous adult ocean perch study, which served as a reference. The genetic composition of the col- where they are caught. Noted differences between years lections of the young ocean perch was compared within at the same geographic locations suggest that the month and among sampling areas within a collection year, as well of capture or differences in oceanographic conditions can as among years for a particular sampling areas. Areas dif- produce differences in distribution patterns from year to fered from each other within a year, confirming that Pacific year. Clearly, the sampling scale of adult fish at about 400 ocean perch in Alaska have a strong localized population kilometers was much larger than the scale of the population structure. Although they have the opportunity and abil- structure, and it appears finer-scale sampling is needed to ity to disperse long distances during their life times, they build accurate models that can evaluate the effects of dif- do not, which means that harvested fish originate close to ferent management approaches.

FISH & INVERTS :: Stock Assessment Research & Development :: Ecology :: Population Ecology Identity of Rougheye Rockfish Project 209

Project 209 employed genetics to determine whether rougheye rockfish is really two different species currently managed as one. Fishermen target commercially valuable rougheye rockfish, often harvesting to the maximum level allowed in bycatch guidelines. If two distinct species exist and scientists could identify visual cues for telling them apart, it would be a substantial contribution to conservation and management. The population genetic survey did show that one species Using two independent types of genetic markers to dis- dominated along the Aleutian Chain and in the Bering tinguish between species, the study confirmed that there Sea, but that both were present in the northeastern Gulf are two distinct species, with very few naturally occurring of Alaska. Scientists are continuing this work to develop hybrids between them. Although one type generally had molecular methods which may be more rapidly applied lighter coloration, there was too much visual and mor- in the field in the future. In the meantime, we still know phological overlap to currently allow for a quick and easy little about the ecological differences between these two distinction in the field. closely related species. 28 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

Improving Stock Assessment Models

The number, size, age, location, condition, fecundity, behavior, and many other parameters eventually end up in a stock assessment model that calculates the amount of fish that may be caught the following year. Traditional stock assessment models focus on a single species and in the past did not explicitly take the influence of environmental variability on life history parameters into account. Those impacts were implicitly integrated by the updated biological information, such as counts, being used.

Environmental Issues In recent years, however, and with increased concern about changing climate ocean conditions, the explicit examination of environmental factors driving population dynamics has received more attention, and the Board funded three projects that fall into this category through 2008.

FISH & INVERTS :: Stock Assessment Research & Development :: Improving Stock Assessment Models :: Environmental Issues Forecast Model for Bristol Bay Sockeye Salmon Project 317

Project 317 developed a pre-season forecast showed that the migration of Bristol Bay sockeye salmon model for Bristol Bay sockeye salmon based on oceano- can be predicted from sea surface temperature in the graphic and biological variables that influence the timing North PacificO cean if coupled with one or more other vari- of returning adults. The run of Bristol Bay sockeye salmon ables, such as length of adult salmon, river temperature, occurs within a narrow time span, typically between late or harvest rate. The observed runs were consistent with in- June and late July, so migration timing has a significant season projections made from pre-season migration timing effect on the interpretation of in-season abundance of estimates and historical cumulative daily run size data. The Bristol Bay sockeye salmon. The run size entering the fish- study showed that migration timing forecasts can be used ing districts during this one month has ranged from 2.2 to adjust in-season forecasts of sockeye salmon abun- to 61 million sockeye salmon. Researchers developed a dance returning to each fishing district, which represents statistical model to relate historical migration timing to an improved tool for harvest management of Bristol Bay environmental, biological, and fishery information. Results sockeye salmon. Greg Ruggerone Greg NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 29

FISH & INVERTS :: Stock Assessment Research & Development :: Improving Stock Assessment Models :: Environmental Issues Can Seabird Diets Predict Fish Returns? Project 531

Another project aimed at improving Bristol Bay sockeye salmon returns used seabird diets as biological indices. Some seabirds eat the same food as fish of commercial interest, potentially responding to changes in the marine environment in similar ways, and thus could be useful in understanding and forecasting fish abundance. Seabirds are the most conspicuous of all marine organisms, which makes them easier to study than fish.

Project 531 employed statistical methods to relate when seabirds breed and their reproductive success on St. Lazaria Island in Southeast Alaska, and the Pribilof archipelago in the Bering Sea, with the biomass of Pacific herring in Sitka Sound and sockeye salmon returns to Bristol Bay, respectively.

Scientists set out to see whether the bird data could predict the fish/fisheries. In Southeast Alaska, the breeding time of common murres related positively to Sitka herring spawning biomass four years later, explaining 61% of the variation in herring biomass and thus substantially improving forecasting abilities. The study speculated that murres may breed later in years when conditions are more favorable for larval and juvenile herring growth and survival, which in turn affects recruitment.

In the eastern Bering Sea, researchers found that the hatching dates of eggs of red-legged kittiwakes on St. Paul Island and the number of young raised to fledging per breeding pair varied relative to prey availability and explained 42% of the sockeye returns three years later.

The study concluded that this link indicates that both the birds and salmon are responding to changes in the availability and/or quality of available prey and that variation in seabird breeding parameters is affected by the same parameters as those affecting salmon survival at sea. The three-year lag between the bird and salmon information supports previous evidence that the first and/or second year at sea is important in determining sockeye year-class strength.

FISH & INVERTS :: Stock Assessment Research & Development :: Improving Stock Assessment Models :: Environmental Issues Environmental Effects on Snow Crab Populations Project 813

Project 813 will integrate an analysis of the effects of environmental variables on recruitment directly into the stock assessment model for snow crab. This study is developing scenarios for future recruitment of snow crab and evaluating management strategies based on existing control rules given uncertainty in future recruitment success.

Ryan Kingsbery 30 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

Spatial Issues More species appear to have spatial stock structure than previously thought. Once spatial scales and the connections of populations between areas become more clearly defined, researchers need to integrate these considerations into the stock assessment models or they won’t weigh into the management decision process. The Board has funded two projects to this effect, one for pollock and one for snow crab.

FISH & INVERTS :: Stock Assessment Research & Development :: Improving Stock Assessment Models :: Spatial Issues Modeling Populations of Walleye Pollock Project 505

Before the start of project 505, the standard eastern Bering Sea walleye pollock stock assessment model had no spatial dimension. Currently there is only sparse information on the degree, size-dependent differences, and actual routes of seasonal migrations by eastern Bering Sea walleye pollock. During cold years, researchers hypothesize that walleye pollock tend to be more offshore as they get older and that there is a general movement from the northwest to the southeast. This project successfully extended the existing stock assessment model into a two-region (northwest and southeastern areas of the eastern Bering Sea), two-season (winter and summer), and age-specific movement model.

Movement between the two regions was estimated based The bottom trawl survey division between the northwest(NW) and southeast (SE) on sparse empirical data, and thus had low precision. The regions of the eastern Bering Sea. Areas 2, 4 and 6 are part of the NW and areas 1, 3 and 5 are part of the SE. study concluded that a mark-recapture study is needed before such a model has sufficient accuracy to be applied to management, but the successful development of the model structure is an important first step in that direction.

FISH & INVERTS :: Stock Assessment Research & Development :: Improving Stock Assessment Models :: Spatial Issues Modeling Snow Crab Population Dynamics Project 624

The commercial importance of snow crab, their Despite the contraction in range and decline in abundance recent population decline, and geographic range contrac- of the spawning female population, there have been tion were previously described under Project 508. Project some strong recruitment years based on a combination of 624 is working on coupling an individual-based model of changes in prevailing currents, expansion of the summer larval snow crab with an existing hydrodynamics and food cold pool, (which benefits post-settlement survival), and model, and integrating information on the distribution of less cod predation on early settlement juvenile crab due crab larvae in the eastern Bering Sea. These coupled mod- to fewer cod. Results from this study should provide new els help scientists investigate the spatial stock structure of insight into spatial and environmental population drivers female snow crab and its relationship to transport of larval and thus prove useful for management purposes. stages, as well as the relationship between the ice-edge phytoplankton bloom and larval and early settler survival. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 31

New Models Single-species stock assessment models, even if amplified to take into account environmental and spatial issues, do not include species interactions, such as competition, that can severely impact population dynamics. As a result, current stock assessment models are still far from the ecosystem approach to management required to deal with today’s challenges. Managing fisheries in the Bering Sea and Aleutian Islands with an ecosystem approach requires understanding the predator-prey relationships between fished and unfished marine resources, as well as resource overlap between different species of commercial interest. Continued monitoring of predator/prey relationships and the development and improvement of multispecies and ecosystem models will aid in these goals, and thus the Board has funded four interrelated studies which either support development of new multispecies models or enhancement of existing ones.

FISH & INVERTS :: Stock Assessment Research & Development :: Improving Stock Assessment Models :: New Models Predator/Prey Models for Pollock and Mackerel Project 305

Project 305 Proposed to improve estimates of The study revealed that major predators sampled in the predation mortality of walleye pollock and Atka mackerel, eastern Bering Sea tended to consume more walleye pol- both of which are eaten by other fishes, marine mammals, lock on the continental shelf than on the slope, and that and humans. Researchers analyzed more than 20,000 in the Aleutians, important prey for groundfish included stomachs from a variety of groundfish species in the Bering walleye pollock, Atka mackerel, and myctophids. Based on Sea and Aleutian Islands and added the information to a this new information, the updated multispecies statistical multispecies predator/prey model. model provided substantially more precise estimates of mortality due to predation, a crucial factor in stock assessment models.

FISH & INVERTS :: Stock Assessment Research & Development :: Improving Stock Assessment Models :: New Models Multispecies Models for Pollock Projects 419, 525

Project 419 followed up on the work of project 305 by integrating new diet information into the multispecies virtual population analysis and the multispecies forecast model. New estimates of pollock (age-1) predation mortality turned out to be larger than the previous estimates. For older age groups, the opposite trend was observed.

Preliminary results from the multispecies simulation also Comparison of the temporal trend of the predation mortality of age-1 walleye pollock. suggested that the estimates of average long-term walleye pollock spawning biomass are larger than the single-species This improved model creates a powerful new analysis tool estimates. Researchers agreed that they need to perform that will let researchers evaluate a broad range of implica- a more detailed review of the new stomach content data tions of alternative management policies within a complete and the modeling process before extensive forecasting with multispecies framework. Results from these models will pro- this updated model can be used in the management arena. vide advice to the North Pacific Fishery Management Council Project 525 is taking this process a step further, recognizing on how fisheries affect marine ecosystem dynamics through that these models need to consider not only predator-prey food web interactions and technological interactions. relationships, but also the impacts of the fishing on them. 32 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Stock Assessment Research & Development :: Improving Stock Assessment Models :: New Models Sampling What Predators Eat in Fall, Winter and Spring Project 622

A current key shortfall of multi-species and ecosystem models is that most of the diet information they depend on comes from fish collected during assessment surveys, which typically take place between May and September. Different key ecological processes occur during fall, winter and spring, which likely have strong impacts on fish populations and model results, as illustrated by the mismatch between production and consumption estimates of walleye pollock in the Gulf of Alaska. To address this shortfall, Project 622 is sampling predator stomach contents collected by observers during non-survey months from the period 2000-2006 and synthesizing the resulting data on a monthly and geographical scale to provide inputs for future model- Total production of Gulf of Alaska walleye pollock (lines and points) 1990-2005, accord- ing efforts. Particular emphasis will be placed on stable ing to the most recent stock assessment, compared with independent consumption isotope analysis that reveals diets over a longer period estimates of major predators on pollock. of time.

Bycatch Reduction

The incidental catch of fishes, marine mammals, sea turtles, seabirds, and other living marine resources has become a central concern of the commercial and recreational fishing industries, resource managers, conservation organizations, scientists, and the public, both nationally and globally

The Magnuson-Stevens Act defined bycatch as fish which increases the uncertainty concerning total fishing-related are harvested in a fishery, but which are not sold or kept for mortality, which in turn makes it more difficult to assess the personal use, and includes economic discards and regula- status of stocks. Also, concentrated discards can result in tory discards. Such term does not include fish released alive localized environmental degradation, and hampers growth under a recreational catch and release fishery management of that stock and limits future catch. program. In 1998, the National Marine Fisheries Service report “Managing the Nation’s Bycatch,” expanded the The bycatch problem is complex because actions taken definition to include “discarded catch of any living marine to reduce the bycatch of one species can increase that resource plus retained incidental catch and unobserved of another, and efforts to reduce bycatch mortality typi- mortality due to a direct encounter with fishing gear.” cally change the distribution of the net benefits from the fisheries. We need to improve mitigation measures designed to reduce the catch of unwanted species, or perhaps of cer- In its Science Plan, the Board stated that research priori- tain age groups of targeted species. Incidental harvests ties under this topic should include, but are not limited of endangered species, such as short-tailed albatross, or to, mitigation of seabird and marine mammal interactions bycatch of prohibited species, such as red king crab, Pacific with fisheries, new technologies, and methods to reduce herring, chinook and chum salmon, can curtail fisheries and bycatch, and studies of survival rates of discarded fish to elevate concerns for the effects of fishing on other living allow accurate estimation of total fishing mortality. From resources. 2002-2008, the Board funded five projects for $900,000 related to fish and invertebrate bycatch. Seabird and Incidental catch of undesirable species leads to increased marine mammal-related bycatch studies are expanded costs of fishing operations and decreases its sustainability. upon in their respective sections. If bycatch mortality is not adequately monitored, it NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 33

F ea t u re P R O J E C T

FISH & INVERTS :: Bycatch Reduction Development of New Salmon Bycatch Technologies Project 202

In 2002, the NPRB funded project 202 to examine the feasibility of using sonar technology to reduce salmon bycatch in the Alaska pollock fishery. Salmon are a prohibited species in groundfish fishery management plans and cannot be retained or sold if taken incidentally. Pollock fishermen try to avoid salmon “hotspots” to stay under bycatch caps, but the effort costs fishing time and fuel as they seek fishing grounds with lower salmon bycatch rates, which potentially also have smaller pollock concentrations.

Researchers developed and attached an Advanced Dual-frequency Identification SONar (DIDSON) to nets to provide higher-resolution images that distinguish between different species of fish entering the net.D uring capture, pollock con- tinuously moved toward the back of the net, with relatively infrequent, brief Orientation of the DIDSON sonar and the area that it imaged on efforts to hold position or move slightly forward. Salmon, by contrast, fre- the trawl net. quently moved forward, and swam nearer the top of the net than the pollock.

When the net slowed during retrieval, many salmon swam forward, away from the trawl’s codend, whereas pollock remained in the back of the net. This new The difference in salmon and information aided researchers in developing and testing a new type of salmon excluder that relies on the differences in body shapes and behavior to separate pollock behavior in nets lets animals during capture. researchers develop and test a By using DIDSON to identify species before catching them, chinook salmon bycatch was reduced by 12.9%, while pollock still comprised 95.4% by weight new type of salmon excluder. of the groundfish capture, with flatfish and cod being the primary bycatch. Active industry interest has motivated continued work to improve and apply these excluders. Steve Barbeaux Steve 34 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Bycatch Reduction Exploring Temperature and Bycatch Rates Project 731

To further prevent salmon bycatch in the Scientists participating in this study are deploying up to 20 pollock fishery,P roject 731 is investigating the relationship temperature-depth recorders on the trawl nets of Bering between water column structure and temperature, and Sea fishing vessels to collect the necessary physical data to the spatial patterns in the catch of pollock, salmon, and relate to the catch information. If a significant relationship other species. Researchers think temperature is one of the between temperature and catch rates for pollock, salmon, strongest factors controlling where pollock live. We know and other incidental species is found, this could be a quick less about the specific temperature preferences for adult and useful tool for fishermen to predict bycatch rates of and young salmon in the Bering Sea, which Project 204 salmon and other species, resulting in more selective “tem- revealed to have substantial variation. perature-directed fishing.”

FISH & INVERTS :: Bycatch Reduction Electronic Bycatch Monitoring Project 325

To account for bycatch when assessing fish stocks and setting fishing quotas, resource managers need to know the amounts. Independently collected at-sea data is essential for science, management, and compliance monitoring objectives. Over the past two decades, the traditional method of at-sea monitoring of commercial fisheries by human observers has grown.

With growing monitoring needs, increasing costs and space limits on smaller vessels hampering human observing programs, technology-based at-sea monitoring has emerged. In partnership with industry, Project 325 experimented with hardware and software to develop a verifiable and efficient method of remotely counting bycatch aboard certain trawl vessels that would allow a trained human observer on land to evaluate and process catch data collected remotely at sea.

Once the tool was designed, 2.5 terabytes of shipboard video data were collected, which a professional fisheries observer viewed to identify at-sea discards by event and, if possible, by species. The reviewer watched videos covering a total of 780 hours of at-sea activities, and determined whether there were any bycatch and discards on each haul. It took only 68 hours to physically review and produce reports on those videos, compressing time by a ratio of 11.5:1. The project successfully demonstrated that electronic bycatch monitoring is feasible and could be con-

sidered by management agencies as an additional tool to Mark Buckley on-board human observers. Technicians secure a downward-looking canera to trawler stern gantry. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 35

FISH & INVERTS :: Bycatch Reduction Comparing Electronic and Human Observers in the Halibut Longline Fishery Project 712

The majority of vessels operating in the Pacific halibut fishery are not required to have observers, Carwyn Hammond and their bycatch rates are not well estimated. Previous research documented successful electronic monitoring FISH & INVERTS :: Bycatch Reduction efforts of Pacific halibut longline fishing on chartered research vessels, yet the technique was not tested in the Bycatch Crab Survival commercial halibut fishery, where a much broader range Project 711 of environmental and physical factors affects the vessel operations. Project 711 addresses the issue of unobserved Bering Sea crab injury and mortality after seafloor trawl Project 712 is evaluating and comparing electronic video encounters. Bycatch that comes aboard can be enumerated monitoring and human observers of bycatch in a commer- and included in assessment calculations, but some species cial halibut longline fishery by conducting a cooperative suffer injury or mortality without ever being observed and study with the commercial fishing industry with various ves- counted. To tackle this problem, researchers are designing sel configurations. The resulting information will be key in a recapture net as well as developing handling and holding determining the most cost-effective, efficient, and precise procedures onboard commercial vessels. They will stan- bycatch monitoring methods for this fishery. dardize reflex impairment observations (a method to tell how well a crab is doing) in the lab, then combine these developments to assess the mortality probabilities of crab that have passed the sweeps, wings, and central footrope of a commercial groundfish trawl.

Causes of Major Species Decline

Understanding why some major species populations have declined are among the highest priority ecosystem research needs. Some species, like crab, shrimp and pollock, are particularly important owing to their high economic value while others, like western Alaska salmon, have cultural significance and local value.

Still others, including sharks and arrowtooth flounder, Crab research projects focused on diseases affecting snow play important roles in restructuring the ecosystem. and tanner crab, as well as on the mysterious disappear- Understanding the role of natural and human causes ance of the populations of red king crab near Kodiak that on declines of crab, shrimp, western Alaska salmon, once supported the largest king crab fishery in the world. Greenland turbot, walleye pollock, and halibut and Salmon projects looked at the dramatic decline of Kvichak increases in arrowtooth flounder, other flatfish, sharks, sockeye salmon runs, the distribution of sockeye and chum and skates is important to developing management strat- salmon in the Bering Sea, and life histories of Copper River egies that reflect their causes. From 2002-2008, the Board salmon. funded six projects in this category focused on crab and salmon for just under $1.4 million. 36 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

CRAB

Much research has focused on climate variability impacts on recruitment and growth for groundfish and salmon, but relatively little work has been done in this respect with crab stocks. Yet their high commercial value makes it important to better understand the effects of fishery management and environmental processes on crab abundance.

FISH & INVERTS :: Causes of Decline of Major Species :: Crab Bitter Crab Syndrome in Snow and Tanner Crab Projects 306, 623

Snow and Tanner crab were discussed previ- are unable to get parasite samples from the environment, ously under projects 508 and 814. Project 306 studied even though they targeted areas of known high infestation the causative agent of bitter crab syndrome in these two prevalence. Whether free-living life history stages exist or species as a possible key player in increased natural mor- at what densities, and which environmental parameters are tality and poor recruitment. A parasitic dinoflagellate influencing their abundance, remain to be studied. (Hematodinium spp.) causes bitter crab syndrome, which is fatal in snow and Tanner crabs. Infections occur in crus- Project 623 followed up on these problems and is develop- taceans of all sizes and ages, but juveniles are particularly ing an even more precise, quantitative molecular monitoring susceptible. Although the parasite causes death, research- tool (quantitative real-time polymerase chain reaction) for ers know little about its life history, or how crabs become Hematodinium. Researchers hope this improved technique infected, yet our understanding is critical for commercially will not only detect the presence, but let us monitor the important crabs in the Bering Sea. effects on Tanner crab size frequencies and general population trends, as well as identify potential infection vectors Using a series of molecular techniques, researchers identi- or reservoirs of the parasite, thereby providing key life his- fied two species of this parasite: one infects the blue king tory parameters that have eluded us so far. Assessing these crab, and one that appears to infect all other decapod disease dynamics would greatly aid managers in develop- hosts studied. Investigators identified an assay to better ing alternative harvest strategies to minimize losses due to detect the presence of Hematodinium, which is the current Hematodinium infections. focus of bitter crab syndrome monitoring efforts. Scientists

Chionoecetes opilio Chionoecetes baidi

Prevalence of BCS in eastern Bering Sea snow and Tanner crabs, 1988-1998. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 37

FISH & INVERTS :: Causes of Decline of Major Species :: Crab Red King Crab Mystery Project 509

Kodiak once supported the largest red king To create prospects of recovery and to learn about future crab fishery in the world, with peak landings at 94.4 million sustainability, researchers constructed a population dynamics pounds (43,000 metric tons) in 1965, worth $12.2 million model using historical fishery and survey data to estimate at the time. After 15 years of declines, the fishery closed in abundance, recruitment, and fishing and natural mortality 1983, but despite the closure, the red king crab population over the years 1960 to 2004. They also used geographical never recovered. The reasons for the collapse and failure to analyses to explore potential fishery and ecological factors recover remain a mystery that Project 509 set out to solve. in the crab decline.

The study found that during a critical time of fishery development in the late 1960s, a period of strong recruitment promoted fishery overcapitalization, resulting in unsus- tainable harvest rates, particularly from 1981 to 1982. Recruitment failed, resulting in extremely high fishing mortality rates on a declining population of mature males, and producing sex ratios skewed toward females. Adverse environmental and ecological changes likely magnified these problems.

The stock has remained low, at less than one million males and has been stable since 1985, suggesting that predation may be preventing stock recovery. This new analysis will contribute to setting appropriate harvest strategies, and also help evaluate proposed stock enhancement activities. Annual harvests (metric tons) of red king crab from the Kodiak Management Area Scientists will next look in more detail at the effects of eco- during 1950-1982. logical and environmental factors on recruitment for this species.

salmon

Salmon are another species of special interest, particularly concerning some of their regional declines and their implication on commercial and subsistence use, but also concerning their ocean migrations and intermingling of stocks on the high seas, effects of fisheries and environmental conditions on ocean survival, and the issue of overall ocean rearing capacity which is being stressed by increasing releases of young salmon from hatcheries around the Pacific Rim. Greg Ruggerone Greg Sockeye salmon.

FISH & INVERTS :: Causes of Decline of Major Species :: Salmon Kvichak Salmon Declines Project 321

Kvichak sockeye salmon, once the largest were associated with the ocean age structure of the popu- sockeye stock in the world with up to 50% of the world’s lations, with age-2 salmon experiencing greater declines as sockeye production, declined by 73% between 1991-1999 compared to age-3s, likely due to their smaller size. from 1990 stock levels. To find out what caused this dramatic decline, Project 321 examined external human and The authors of the study hypothesize that Kvichak salmon environmental factors, as well as possible changes in bio- may have declined because of reduced at-sea growth logical characteristics of this species. during late marine stages, which produces the highest percentage of ocean age-2 sockeye in Bristol Bay. In addition Researchers found no evidence to support the previously to the impacts of these environmental conditions, the study postulated idea that the decline was due to a regula- also examined the possible role of beluga whale predation tory change in the mid-1980s that led to more stable on smolts migrating out to sea. The analysis estimated that escapement levels. Indeed, specific cyclical spawning approximately two million smolts are consumed by belu- escapements do not seem necessary to achieve high pro- gas in the Kvichak each year, thus reducing the run by less ductivity of Kvichak salmon. A detailed look at patterns than 2% per year. The absolute effect of these predation in smolt abundance and survival at sea indicates that the rates on smolts on the subsequent return of adult sock- decline was driven by factors influencing marine survival eye salmon was estimated to be an average of 180,000 and ocean conditions influencing subsequent processes fish, or about 2%. Given these results, it is unlikely beluga in freshwater. Several other Bristol Bay stocks also declined whales could have played an important role in the decline during these years, although not as deeply. Those declines of salmon returning to the Kvichak River. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 39

FISH & INVERTS :: Causes of Decline of Major Species :: Salmon Distribution of Sockeye and Chum Salmon in the Bering Sea Project 303

Project 303 extensively analyzed the interplay including fall chum salmon from the Yukon River, were dis- between ecological and oceanographic factors influenc- tributed mainly in the eastern North Pacific Ocean. ing the distribution and abundance of Asian and North American sockeye and chum salmon in the Bering Sea. Researchers hypothesize that fish migrate from hatcher- Researchers looked at stock composition at different sta- ies through the Sea of Okhotsk, seasonally through the tions as well as seasonal migration routes and timing. Bering Sea and northwestern Gulf of Alaska, then back to Japan. For sockeye salmon, U.S. investigators identified a The study was carried out under the auspices of the Bering- broader distribution of North American stocks than sug- Aleutian Salmon International Survey (BASIS) developed by gested by historical tagging studies. Bristol Bay salmon the North Pacific Anadromous Fish Commission (NPAFC), were the most widely-distributed, accounting for more and included researchers from the U.S., Japan, and Russia, than half the mixtures in all areas except the southwest- who shared access to a common, comprehensive database ern Bering Sea. Russian salmon were primarily detected on salmon distribution and environmental conditions in the in the western Bering Sea, and differences were detected Bering Sea. in the distributions between the eastern- and the western- Kamchatka Peninsula populations. Salmon from the Gulf Because of the large number of collaborators from the of Alaska were also widely distributed throughout much of three different nations, the coordination and exchange of the Bering Sea, although at low proportions relative to the ecological data proceeded slowly, and while substantial Pacific Ocean production estimates. progress was made, this project was not able to fully investigate the factors affecting the oceanic distribution and Data from this project have provided the founda- abundance of each regional stock. Through the genetic tion for continuing studies by NPAFC scientists, Pacific analysis of juvenile salmon captured at stations through- Salmon Commission studies by the National Ocean and out the Bering Sea, however, researchers did determine Atmospheric Administration and Alaska Department of that Asian and North American chum stocks were not ran- Fish and Game, and are being used by Fish and Game to domly distributed. Japanese salmon roamed the central improve harvest management in Southeast Alaska, Cook Bering Sea, similar to Russian salmon which also spread Inlet, and Bristol Bay. into the North PacificO cean. Northwestern Alaska salmon,

Greg Ruggerone 40 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Causes of Decline of Major Species :: Salmon Copper River Salmon Project 310

Salmon are an integral component of the socioeconomic and ecological landscape of the North Pacific. Most species live part of their lives in fresh water, in estuaries and in the open sea. The amount of time that they spend in these habitats varies greatly in the early life histories and migratory behaviors of coho and sockeye salmon, both on local and regional scales.

For sea-going sockeye salmon, time growing up in estuaries may be critical for survival. Project 310 aimed to quantify the spatial and temporal variability in the age that Mary Bishop they migrate to sea and the relative contribution of dif- Otoliths lay down daily growth rings that take into account the chemical concentra- ferent freshwater and marine residence strategies to the tions of ambient water chemistry. surviving spawners in the Copper River watershed. Both species spent only a relatively brief period in estua- Scientists estimated the time coho and sockeye salmon rine waters, an average of 30 days, but during that time spent in estuaries using traditional fisheries sampling ingested substantial quantities of food, clearly pointing to techniques—mid-water trawls, fyke nets, and seine sam- the critical role of these estuarine habitats to ensure subse- ples. They also used micro-chemical analysis of strontium quent marine survival. The authors point out that natural or concentration in otoliths of juvenile and adults within the human-caused alterations to these vital habitats may have Copper River Delta. serious consequences for sustainable harvest of salmonids. Deborah MercyDeborah Researchers sample for coho and sockeye salmon in the Copper River Delta. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 41

Implications of Ecosystem Change on Fishery Management

Harvest rates may be sustainable for single species, yet may have significant impacts on the overall biodiversity of the oceans at the complex, species, stock, and genetic levels. Fish are not removed evenly within the population and the potential exists for competition between fisheries and other species for resources.

Changes in the ecosystem may at first only affect species a particular species based on an optimal harvest of a mix of and habitats not managed or harvested, yet eventually species, rather than solely by the species biomass. reverberate through the food web and have unexpected consequences for fishery management. To provide critical information for such implementation, the Board has funded ten projects for just over $1.5 million, Ideally, new multispecies fishery management strategies focused on the role of climate and forage species in fishery should consider the full range of ecosystem change impli- management, as well as on the development of ecosystem cations to determine acceptable biological catch levels for indicators.

Environmental Change

Most assessments of the potential role of climate and environmental conditions on fish and fisheries consider statistical relationships between various climate indices, such as the PacificD ecadal Oscillation, the Aleutian Low Pressure Index, and time-series of fish catches and recruitment. Although researchers speculate about cause and effect, explicit links between environmental conditions and species composition, fish survival and growth remain largely uncertain.

Ray Morse 42 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Implications of Ecosystem Change on Fishery Management :: Environmental Change Environmental Factors in Herring Predictions for Bristol Bay Project 208 Mike Miller Mike

Project 208 investigated links between environ- The study found recruitment variability depends, in part, on mental factors and a variety of population parameters for the match between where and when herring larvae emerge Pacific herring in Bristol Bay. By analyzing historical catch with bio-physical conditions, such as the spring plank- data, the study surmised that after spawning, Togiak her- ton bloom during March and April. Conditions along the ring migrate clockwise around Bristol Bay and are harvested herring migration corridor and in coastal spawning areas in a small food-and-bait fishery off ofD utch Harbor in July. also affected the timing of both the arrival and spawning of herring in northern Bristol Bay. Researchers concluded Herring then migrate northwest along the continental shelf that ocean temperature changes near the ice edge, which break to the Pribilof Islands where they spend fall and win- are controlled by atmospheric pressure gradients over the ter. In completing their migration, herring may migrate North Pacific Ocean, explain most of the interannual vari- over 1,000 miles annually, providing an important eco- ability of herring spawning, and that placing new moorings logical link between primary production and upper-level in these areas to provide more accurate local information predators, as well as between nearshore and offshore food would likely further improve herring spawning predictions. webs in the Bering Sea.

FISH & INVERTS :: Implications of Ecosystem Change on Fishery Management :: Environmental Change Climate Change and Pacific Cod Productivity Project 605

Throughout the 1990s and early 2000s, reduced Project 605 is investigating the responses of larval/juve- sea ice cover corresponded with a northward spread of nile stages exposed to varying temperature and food commercially important species in the Bering Sea, includ- regimes. Investigators are designing models to make spa- ing Pacific cod. Pacific cod have undergone significant tially explicit maps of survival probabilities at monthly and shifts in their diet and in their abundance. Like other spe- annual scales. They are using data taken from lab studies cies in this family, Pacific cod are very productive, laying up and coupling these with field data on larval and juvenile to 5,000,000 semi-demersal eggs in one batch during the distributions, temperature and primary productivity to give spring spawning season. This makes them particularly vul- insight into the link between climate change and Pacific nerable to changing environmental conditions during this cod productivity. critical period. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 43

F ea t u re P R O J E C T

FISH & INVERTS :: Implications of Ecosystem Change on Fishery Management :: Environmental Change Jellyfish Fluctuations Project 606

A link between climate change and productivity is sought in Project 606 for jellyfish, which have undergone dramatic fluctuations in biomass in the Bering Sea. Jellyfish can adversely affect commercial fisheries by clogging nets, by feeding on young fish, and by competing with fish for zooplankton prey.

Jellyfish populations respond promptly to changes in physical and biological conditions, both by changes in the rates of production of young jellyfish, and by increased feeding and growth in good conditions. To explore the effects of climate change on jellyfish populations in the Bering Sea, this study is using a 27-year time series of jellyfish catches, which extends through two major regime shifts.R esearchers are exploring links between current flow and jellyfish distribution and abundance, and determining the effects of variations in physical (sea ice, temperature, atmospheric Trend in jellyfish biomass from standardized trawl surveys in the variables, currents) and biological conditions (zooplankton, forage fish) on where Bering Sea since 1975. Shown are the total biomass (black line) and jellyfish occur. Our increased understanding of how environmental changes influ- subsets for the SE (red) and NW (blue) Middle Shelf Domains. The ence jellyfish abundance and distribution will help us understand and predict their inset shows the sampling areas on the Bering Sea shelf. potential impacts on fish populations in the Bering Sea.

Understanding jellyfish abundance and distribution helps us predict their impact on fish populations in the Bering Sea. Russell Hopcroft Russell 44 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Implications of Ecosystem Change FISH & INVERTS :: Implications of Ecosystem Change on Fishery Management :: Environmental Change on Fishery Management :: Environmental Change Growth Rates of Snow Crab Genetic Differences in Project 713 Walleye Pollock Project 610 Snow crab distribution in the Bering Sea has shifted north from Bristol Bay to northwest of St. Matthew Scientists know or infer relationships between Island, with evidence of decreasing body size from south to environmental factors like temperature, currents, or primary north. The commercial importance of snow crab, and inves- productivity and fish year-class strength for many species. tigations into their stock dynamics in the Bering Sea was Yet they are uncertain whether larval and juvenile mortal- previously described under projects 508, 624, 812, and 813. ity is random as a consequence of varying environmental parameters, or whether specific genotypes are favored Project 713 expands on some of this work and links to under certain conditions. Project 624, but specifically aims at understanding the relationship between temperature and the growth rate and Project 610 is using population genomics to estimate diets of settled juveniles and adults around St. Lawrence genetic differences in space and time for walleye pollock Island. The study will provide a critical piece of informa- in the Bering Sea for two years with contrasting environ- tion in the life cycle of this species by predicting when mental conditions, in particular, temperature. Scientists are and where snow crabs may reach marketable size in more also identifying molecular markers that undergo selective northern areas as the climate warms. evolutionary pressure and assessing the scope for adaptation to changing climate conditions.

FISH & INVERTS :: Implications of Ecosystem Change on Fishery Management :: Environmental Change Impacts of Grazers on Kelp Project 407

Kelp beds are highly productive systems that play an important role in nearshore carbon fixation. Many different kinds of invertebrates live in kelp beds, and are prey for other species. Greenlings, ronquils, pricklebacks, and sculpins all use kelp beds as feeding grounds, nurser- ies, refuges and spawning grounds. Several commercially important fish species, including herring and halibut, depend on nearshore kelp beds during different parts of Heloise Chenelot, their life cycle. Finally, marine mammals, especially sea otters, forage in kelp for sea urchins, clams and other inver- variability of canopy kelp beds in Kachemak Bay, especially tebrates, and wrap themselves in large blades of bull kelp of the dominant, canopy-forming species N. luetkeana, during resting periods. Such biological diversity and cas- which has very limited defense mechanisms against this cading trophic systems depend on the abundance, health, grazer. and stability of the kelp beds. The persistence and abundance of these living habitats are at the mercy of changing Considering the multitude of factors and their variability environmental conditions and grazing pressure. from year to year that likely control kelp recruitment and growth as well as grazer recruitment in Kachemak Bay, it To better understand the environmental and biological is extremely difficult to predict where and when L. vincta dynamics controlling the health of kelp beds and impli- will decimate kelp beds. While at present the researchers cations on fisheries, Project 407 specifically investigated found that kelp beds are reasonably resilient and can re- the grazer-kelp relationship between the gastropod, establish a few years after decimation, it is unclear how this Lacuna vincta, and four common kelp species (Nereocystis resilience may change with changing environmental condi- luetkeana, Agarum clathratum, Saccharina latissima, S. sub- tions. A small but abundant species like L. vincta is difficult simplex) in Kachemak Bay, Alaska. The study showed that to monitor and manage. Learning from terrestrial examples L. vincta, which is only a few millimeters long, is seasonally of ecological pest control, the authors concluded that a abundant in the shallow subtidal zone and reaches den- next step would be to identify natural predators of L. vincta sities of 70 snails per square meter in summer. This snail within the system to better understand the level of natural appears to be a driving force in the spatial and temporal control of the grazer within the system. NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 45

The Role of Forage Species

While capelin, eulachon, sand lance, myctophids, and other forage fish are an important component of the North Pacific ecosystem, many aspects of their ecology and population dynamics remain unknown. We understand some of the effects of changes in local availability of forage fish to some seabird colonies, and have estimates of their importance as prey for several commercially important fish species. Yet ecosystem-wide implications of forage fish changes on other ecosystem components remain speculative.

Little is also known about the effects of large fluctuations of crab, shrimp, flatfish, and sharks on other ecosystem components through competition and predation. As intermediaries in the food web, all of these species are important conveyors of trophic energy through the food web and variation in their productivity impacts many other predators, such as fish, seabirds, and marine mammals. John Piatt

FISH & INVERTS :: Implications of Ecosystem Change on Fishery Management :: The Role of Forage Species Forage Fish Productivity Nearshore in the Gulf of Alaska Project 308

In late summer, large numbers of small, silver- colored smelts (capelin and eulachon) and brass-colored young-of-the-year walleye pollock, search the coastal waters of the Gulf of Alaska for zooplankton. Project 308 examined the effects of coastal hydrography and sea- sonality on forage fish productivity as mediated through bottom-up processes in the western Gulf of Alaska.

Researchers found that the offshore flow near the Shelikof sea valley had high concentrations of krill and large copepods. Fish in regions of high krill and large copepod densities ate more of these prey, were larger and in better condition, had more growth potential, and/or more fish per volume than areas with lower concentrations of prey. Climate-related forcing on hydrographic dynamics in the Gulf of Alaska most affected forage fish growth potentials by altering how much food is available. Also, nursery areas, especially for pollock, near Kodiak Island appeared to provide environmental conditions that tempered wintertime adversity, implying that regional differences in wintertime nursery habitat for this species could be relevant for juvenile walleye pollock survival and subsequent recruitment of individuals to spawning populations. 46 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

FISH & INVERTS :: Implications of Ecosystem Change on Fishery Management :: The Role of Forage Species Characterizing Forage Resources of the Aleutian Islands Project 630

Location of study area and major predator core areas routinely visited by the Tiglax. Map of fishing effort by method during summer 2006.

Our lack of knowledge about forage fish Midwater trawls sampled pelagic forage species and beach biology or links to predator distribution and abundance seines captured nearshore forage species. Twenty-four spe- extends to the Aleutian Islands. Relatively few studies have cies of pelagic fishes and 30 species of nearshore fishes described the regional distribution and abundance of non- were documented throughout the study area. Walleye pol- commercial nearshore and offshore forage resources in the lock, Pacific sand lance and spawning capelin dominated the Aleutian archipelago, in part, because surveying such a pelagic catch, and young-of-the-year gadids, Pacific sand large area is expensive and difficult, and abundance esti- lance and pink salmon dominated the nearshore catch. mates are difficult due to the patchiness of schooling fish and invertebrates. A longitudinal gradient of physical oceanography suggested cooler, more saline, and nutrient rich conditions in Nevertheless, Project 630 opportunistically used estab- the west (central Aleutians) compared to the east (Alaska lished research platforms to sample prey and quantify Peninsula). Researchers found that automated data collec- ocean climate conditions to gain a better understanding tion using equipment permanently installed on the vessel of the ecological relationships between marine predators, is an efficient and cost-effective way to sample the marine prey resources, and marine habitat. Using the U.S. Fish and environment during travel of the Tiglax. Opportunistic Wildlife Service M/V Tiglax, a vessel that routinely travels sampling of station data—CTD, plankton tows, beach throughout the Alaska Maritime National Wildlife Refuge seines—was moderately efficient, while trawling was least along the Alaska Peninsula and Aleutian archipelago, efficient of all sampling procedures. However, during nor- researchers recorded acoustic backscatter and measured mal operations the refuge bore the cost of transit time, sea surface temperature and salinity using haul-mounted leading to great efficiency in spatial sampling. This research equipment. platform has enormous potential for monitoring key ecosystem components in the Gulf of Alaska and Aleutian archipelago on seasonal, annual, and decadal time-scales.

Carrie Eischens NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 47

Ecosystem Indicators

As we move toward ecosystem-based fishery management, discussions focus on identifying ecosystem indicators that will monitor trends in the ecosystem and help evaluate whether current management measures are achieving their objectives. On a smaller level, fish quality expressed as energy density could be an index for the health of individual fish.P roject 210 supported the purchase of the equipment necessary to carry out such analyses. Many other species-specific and region-wide environmental parameters have been suggested as indicators of ecosystem status. But even though such indicators are reported, and fisheries in the Gulf of Alaska, Bering Sea, and Aleutian Islands are managed very progressively under a suite of ecosystem considerations, we still need to develop a more integrated, formalized approach.

FISH & INVERTS :: Implications of Ecosystem Change on Fishery Management :: Ecosystem Indicators Using Ecosystem Indicators in Resource Management Project 502

The Board funded project 502 to help define Although this project was ambitious and no specific indica- a framework within which to choose and implement the tors were chosen, substantial progress was made, and a use of ecosystem indicators for management. Ecosystem series of recommendations was brought forward. indicators are part of a larger process that considers policy- level goals for an ecosystem, and so should be linked to Participants noted that ecosystem-level and community- operational objectives and performance criteria. Although level conservation thresholds are relatively new ideas the project focused on the Bering Sea, the intent was to in marine conservation, and they need further research. provide insights, findings, and recommendations more Existing indicators need to be synthesized into a usable broadly applicable to the North Pacific and adjacent seas. set of parameters, linked to operational objectives, and evaluated using a formal evaluation and selection process Using a workshop approach, the lead investigators involved available from other disciplines. the Bering Sea and international community to discuss a variety of topics, including: While the workshop did not address socio-economic oper- • development of operational objectives for the south- ational objectives for the Bering Sea and North Pacific, eastern Bering Sea ecosystem investigators noted that links between the well-being of • evaluation of the Ecosystem Consideration chapter of people and healthy marine ecosystems require a level the SAFE report and the PICES Marine Ecosystems of of attention comparable to those for ecosystem conser- the North Pacific publication vation objectives. They concluded that the North Pacific • investigation of methodologies to monitor system- Fishery Management Council should play a central role in wide structural changes within the marine ecosystem shepherding the development of these socio-economic • identification of steps to validate indicator perfor- objectives and indicators for the southeastern Bering Sea mance, improve the monitoring network, and integrate and Gulf of Alaska ecosystems. indicators into predictive models

Schematic that matches indicators to objectives using a Driver-Pressure-State- Illustration of an indicator, reference points, and performance measures relative to Impact-Response approach. an ecosystem operational objective. Modified after AOF (2003). 48 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

Management Tools

One of the key roles the North Pacific Research Board can play in Alaska’s seas is to foster collaboration, data synthesis, and coordination.

Workshops help bring together regional, national, and international experts to discuss pertinent ecosystem and management questions and develop recommendations to move forward, or to fund the establishment of statewide databases that can be used by researchers and managers to plan and evaluate research needs in a broader context.

Recognizing the importance of this role, the Board has funded a variety of activities related to the different ecosystem components discussed in this report, and from 2002-2008 specifically, six projects related predominately to fish and invertebrates for almost $700,000.

Workshops

The Arctic is changing. Temperatures are rising, and summer sea ice extent is decreasing. Rivers are discharging more water, sea levels are rising, permafrost is thawing and coasts are eroding. Resident species may shift their ranges and when they reproduce. Ice-dependent species may lose habitat. Hunting cultures may disappear, and access to traditional foods may change. Marine shipping access to natural resources and fisheries may increase.

Despite these potential changes, relatively little is known about the Arctic Ocean and northern Bering Sea ecosystems. We urgently need to synthesize knowledge about the biology and oceanography of this region to have a baseline from which to observe and understand ongoing changes. Elizabeth Eubanks NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 49

F ea t u re P R O J E C T

FISH & INVERTS :: Management Tools :: Workshops Arctic Synthesis Workshop Project 503

Project 503 brought together 30 experts as part of an international workshop focused on the Chukchi and Beaufort seas. Participants discussed the state of knowledge, information gaps and research needs in physical and chemical oceanography, sea ice, phytoplankton, microbes, zooplankton, benthos sea floor, fish, seabirds, and marine mammals. They noted possible future efforts that might be undertaken by NPRB. In the western Arctic, climate change may affect the environment in two general ways. External changes will be forced through changes in sea ice processes and shifts in the transport rates and properties of Pacific waters through the Bering Strait. Internally forced changes involve the responses of resident biological populations to altered temperatures and the timing of events in their annual life cycles.

Because each mechanism is system-wide, researchers concluded that these changes will ultimately affect all trophic levels. This will lead to further changes in Sea ice as seen from below can support high the pathways and amount of energy transferred to fish, seabird, and marine mam- densities of amphipods (dark blotches above, mal populations, and consequently impact their abundance and distribution. with close-up shown in inset). Some species are only found associated with sea ice and may be at risk as summer sea ice declines. Based on these two mechanisms, the workshop made several recommendations on how to proceed with future research, including the need for: • data consolidation and analysis • interdisciplinary research approaches Researchers concluded • continuation and/or establishment of long-term time-series that climate change • collaboration and cooperation between agencies and programs • year-round observations will ultimately affect • establishment of research support infrastructure • biogeochemical and ecological modeling all trophic levels. • training of taxonomic expertise Jennifer Nomura 50 NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES

databases

Scientists have been collecting information about the oceans for over a hundred years, yet in many instances these data are scattered throughout published and unpublished reports all over the world, many in paper format, unavailable to the general public and much of the scientific community. As a result, many questions that we might resolve with previously collected data remain unanswered. New studies are being funded that are potentially redundant to previous or ongoing efforts elsewhere in the world. Given a financial climate of limited funding for ocean research, and an ocean climate that is undergoing dramatic changes that affect us all, it has become more important than ever to bring existing information together in a format usable for management, research, and research planning by all.

FISH & INVERTS :: Management Tools :: Databases Electronic Warehouse for Salmon Data Project 311

Throughout Alaska, hundreds of thousands warehouse through which historical salmon sampling and of salmon are examined annually for sex and size informa- scale pattern data can be maintained and updated annu- tion, and scales are collected for age data. This enormous ally from collections throughout the state. sampling effort over 40-plus years has resulted in millions of data records and scale samples. Designed to inventory all collections, the project established a steering committee composed of state, federal, Although useful for local management needs, there has and research interests and developed a standardized web- been no common process or protocol for managing and accessible database where the sampling information is preserving the historical data and scale samples. Project now accessible, preserved, and facilitates future research 311 initiated a process for establishing an electronic data and management (see http://www.taglab.org/).

FISH & INVERTS :: Management Tools :: Databases Salmon Research and Monitoring Metadata Project 504

The commercial and cultural importance of Alaska, and can summarize the information by species, life salmon in Alaska is reflected in the number of projects and history stage, bioregion, disciplinary topic, research issue, amount of money that has been invested into better under- and management information needs. standing their biology and forecasting their productivity. Salmon research problems are ecologically complex, cover Although much effort was spent to collaborate and coor- large expanses of marine, estuarine and freshwater habi- dinate with all of the relevant organizations involved in tats, and are being studied by many different organizations salmon research, many researchers did not respond to the and programs. request to share their project information. Also, the Alaska Department of Fish and Game, which contributes the larg- Concerns have been raised about the efficacy of the millions est number of salmon research studies in Alaska, asked to of dollars annually dedicated to this topic, and whether the be withdrawn from the survey. most important management-oriented questions are being addressed. Project 504 gathered the necessary metadata Although the project reported an annual funding level of on salmon research and monitoring, and designed an over $11 million for salmon, it is likely only a portion of what online database that is easily searchable so that decision- is actually spent. Future efforts to create a living compen- makers could determine whether additional funding is dium of research projects on this or other topics will clearly warranted for salmon research and for what research topics. need established agreements between organizations and a The database contains 457 recent salmon research stud- commitment by all involved before going forward. ies, and 13,533 records of salmon monitoring programs in NORTH PACIFIC RESEARCH BOARD :: SCIENCE PROGRAM :: FISH & INVERTEBRATES 51

FISH & INVERTS :: Management Tools :: Databases Herring Database Project 728

Pacific herring is a bellwether species for North Pacific marine ecosystems. Herring roe fisheries are among the most lucrative, competitive, and controversial in the region, often pitting commercial and subsistence users against one another. Productive spawning areas and times are limited, and the historical population dynamics and technology of herring are not well understood. Many communities with local and traditional knowledge of herring fisheries claim that historical stocks were larger and spawning areas more numerous, but that they have dwindled due to over-harvesting, predation, disease, development, and climate change.

While shifts in stocks and spawning areas have been reasonably well documented since 1980, no one has synthesized the deeper archaeological, historical, and ethno-ecological records on herring spawning areas and their relation to local ecosystems. Project 728 will synthesize this information for Southeast Alaska from Dixon Entrance to Yakutat Bay, where herring and herring roe were traditionally harvested. Using published and unpublished archaeological, ethnological, historical and biological records as well as community focus groups in each historical herring stock region, the project will compile historical and spatial information into a database. This will allow researchers to investigate the extent of historic and prehistoric herring spawning and massing areas, link changes in herring spawn extent and intensity to environmental and human factors in the socio-ecological system, and identify sensitive areas for protection and potential restoration of herring spawning.

Herring Stock Assessments from Dressel, et al (2005). FISH & INVERTEBRATES Alaska’s Ocean Bounty 2002-2008 research summary

North Pacific Research Board

Mission NPRB supports research to build a clear understanding of the North Pacific, Bering Sea, and Arctic Ocean ecosystems that enables effective management and sustainable use of marine resources.

Fish & Invertebrates is one in a series of publications produced by the North Pacific Research Board in support the 2005 Science Plan developed with guidance from the National Research Council of the U.S. National Academies of Sciences.

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