The survival of juvenile marine fishes, which support commercial fisheries and provide a prey resource, is often dependent on conditions in protective and nearshore habitats. We examined the trophic interactions of several juvenile fishes in the nearshore Gulf of Alaska (GOA) including Pacific cod (Gadus microcephalus), saffron cod (Eleginus gracillis), walleye pollock (Gadus chalcogrammus), Pacific sand lance (Ammodytes hexapterus), Pacific herring (Clupea pallasii), rockfish (Sebastes spp.) and greenlings (Hexagrammos spp.). We used fatty acid (FA) and stable isotope (SI) markers to evaluate foraging ecology and the potential for competition among age-0 fish species in broad east (134°W – 136°W) and west (149°W – 153°W) regions of the GOA. Sampling efforts were greater in the west GOA, so many of our findings were focused in that region. In the west GOA, FA and SI markers indicated that Pacific cod and saffron cod usually shared similar diets, potentially leading to competition for resources. Also in the west GOA, we found evidence that Pacific cod and walleye pollock both relied to similar extents on calanoid copepods during summer. Juvenile sand lance and herring were much smaller than the other species and had diets that contrasted with all other species. In both the east and west GOA, rockfish were present in two distinct size classes with the smaller size feeding at a lower trophic level than all other fish species in the study. The smaller rockfish likely consumed mainly calanoid copepods. Throughout the east and west GOA, greenling and rockfish typically consumed prey with a very different lipid source than the other juvenile fish. In addition, we noted few consistencies in FA and SI markers between the east and west, except in rockfish diets. Overall, we found a complex relationship within the nearshore fish communities in the east and west GOA that showed substantial variation across bays, seasons and subareas.

Pacific capelin Mallotus catervarius are planktivorous small pelagic fish that serve an intermediate trophic role in marine food webs. Due to the lack of a directed fishery or monitoring of capelin in the Northeast Pacific, limited information is available on their distribution and abundance, and how spatio-temporal fluctuations in capelin density affect their availability as prey. To provide information on life history, spatial patterns, and population dynamics of capelin in the Gulf of Alaska (GOA), we modeled distributions of spawning habitat and larval dispersal, and synthesized spatially indexed data from multiple independent sources from 1996 to 2016. Potential capelin spawning areas were broadly distributed across the GOA. Models of larval drift show the GOA's advective circulation patterns disperse capelin larvae over the continental shelf and upper slope, indicating potential connections between spawning areas and observed offshore distributions that are influenced by the location and timing of spawning. Spatial overlap in composite distributions of larval and age-1+ fish was used to identify core areas where capelin consistently occur and concentrate. Capelin primarily occupy shelf waters near the Kodiak Archipelago, and are patchily distributed across the GOA shelf and inshore waters. Interannual variations in abundance along with spatio-temporal differences in density indicate that the availability of capelin to predators and monitoring surveys is highly variable in the GOA. We demonstrate that the limitations of individual data series can be compensated for by integrating multiple data sources to monitor fluctuations in distributions and abundance trends of an ecologically important species across a large marine ecosystem.

We verified the accuracy of interpolated bathymetric surfaces created from historic (1924-2003) National Ocean Service smooth sheet bathymetric soundings and shorelines with single-beam echosounder measurements of seafloor depth obtained in the spring and summer of 2013. Independent comparisons were made at ten inshore locations in the central and eastern Gulf of Alaska as an effort to groundtruth the fish habitat layers provided for NPRB's (North Pacific Research Board) sponsored Gulf of Alaska - Integrated Ecosystem Research Program (GOA-IERP). Ordinary least squares linear regressions determined that the GOA-IERP soundings could successfully predict interpolated smooth sheet bathymetry (gridded or raster surface) at all sites (best R-2 = 1.0), although the oldest smooth sheets from 1924 (R-2 = similar to 0.90) and 1925 (R-2 = similar to 0.80) had the poorest fits. Standardized residuals were geographically clustered at all sites, with larger residuals often observed in areas of rapid depth transition, but >= 93% of residuals at all sites were within two standard deviations. Residual analysis indicates that the standardized residuals increase with depth, slope, distance to nearest smooth sheet sounding, and distance to nearest smooth sheet navigation station. This indicates that errors in navigation were greater farther offshore, interpolations were worse in areas of sparse soundings, and the consequences were more significant in steeper and deeper areas. Overall, we conclude that the smooth sheet bathymetry was successfully ground truthed and useful for fish habitat descriptions.

Shallow coastal waters of the Gulf of Alaska (GOA) serve as nursery habitats for young-of-year Pacific cod (Gadus macrocephalus). However, little is known regarding the relative contribution of these areas to the adult offshore stock. Trace elements incorporated into the otolith matrix can reflect the environmental conditions to which a fish has been exposed during its lifetime. When analyzed together, a suite of elements can serve as a natural marker, characteristic of a particular environment. We evaluated the potential of otolith elemental signatures to identify nursery habitats of age-0 Pacific cod, focusing on spatial patterns within and across the eastern and western GOA. Fish were collected from shallow nearshore areas within five large embayments in summer and fall, and element:calcium ratios were measured from two different time stanzas within the otolith. Elemental ratios were found to change over short (2 month) time periods and were related to seasonal changes in temperature and salinity. Fish were classified to nursery habitats using quadratic discriminant analysis based on their otolith elemental signatures; classification accuracy to individual bays ranged from 30% to 95%, with an overall success rate of 59%. Classification accuracy improved to 78% at greater spatial scales (eastern versus western GOA). Our results point out the limitations of this application to Gulf of Alaska Pacific cod and other widely distributed species residing in coastal embayments. While some nursery habitats impart unique chemical signatures to otoliths, it may not be possible to distinguish among specific areas without considering additional factors. However, our work demonstrates that otolith microchemistry may be a useful tool for understanding source contributions to the Pacific cod population at larger regional scales within the GOA.

Overview The implementation of new National Standard guidelines published by NOAA Fisheries in 2009 requires the classification of fish stocks in a fishery management plan (FMP). Target stocks, as well as non-target stocks that are caught incidentally in large numbers, are considered to be “in the fishery”. Annual catch limits (ACLs) are required for these stocks. Fishery management councils have the option of designating a second category of less-impacted stocks, “Ecosystem Components” (EC), for which ACLs are not required. However, these stocks are monitored and councils may adopt management measures designed to limit incidental catches of EC stocks. To aid in the classification of stocks, as well as to provide advice on the formation of stock complexes and other management actions, NOAA Fisheries convened a Vulnerability Evaluation Working Group (VEWG) in 2008. This group was tasked with developing an analytical tool for assessing the vulnerability of stocks in an FMP (the word “vulnerability” appears frequently in the National Standard guidelines). The work of the VEWG is complete and will be published soon as a NOAA Technical Memorandum and in a peer-reviewed journal. A preliminary report and other supporting materials that explain the group’s work in detail can be found at www.nmfs.noaa.gov/msa2007/vulnerability.htm. Here, a brief review of the analysis is provided to aid interpretation of the results for Alaska groundfish. The analysis developed by the VEWG is based on previous work in Australia and elsewhere. It compares two main features of a fish stock that together influence its vulnerability to fishing: productivity, which determines a population’s natural capacity for growth and its resilience to fishery impacts; and susceptibility, which indicates how severe those fishery impacts are likely to be for the population. Productivity and susceptibility are evaluated by scoring a number of related attributes. For productivity, these are mainly life-history traits such as natural mortality rate and age at maturity; susceptibility attributes include spatial overlap between the stock and the fishery, stock status, etc. The table below lists all attributes evaluated in the productivity-susceptibility analysis (PSA):

A series of daytime replicate (spring/summer/fall) acoustic surveys were conducted at 11 inshore sites along the Kodiak Island/Kenai Peninsula area and the outer coast of Southeast Alaska as part of the Gulf of Alaska Integrated Ecosystem Research Program in 2010, 2011, and 2013. A two-frequency technique was used to classify backscatter as 'fish' or'macrozooplankton' based on the observed relative frequency response, which are used as proxies for the abundance of fish with swimbladders and large-bodied zooplankton. There was a strong 'site effect'; that is, consistent differences among sites. However, acoustic backscatter classified as fish and macrozooplankton was highly variable among repeat visits. The effects of site (i.e. sampling location) were larger than those of season or year. There were no consistent differences in backscatter between sites in the Kodiak Island/Kenai Peninsula area and Southeast Alaska. The acoustic proxies for the abundance of fish and large-bodied zooplankton increased substantially with increasing bottom depth over a depth range of 5-250 m, both within and across inshore sites. Backscatter from both fish and macrozooplankton was low at water depths < 80 m. In the inshore Gulf of Alaska, water depth appears to be a key characteristic structuring pelagic communities during daytime with sound-scattering fishes and large-bodied zooplankton being scarce in relatively shallow inshore habitats compared to adjacent deeper habitats.

Federal fishery management rules in the United States have recently changed, necessitating an examination of which fish stocks require annual catch limits and how appropriate stock complexes are formed. We used an analytical approach termed productivity–susceptibility analysis (PSA) to analyze the vulnerability of federally managed Alaska groundfish stocks to overfishing. The focus of the effort was non-target stocks that have limited data available for determining stock status and vulnerability. The PSA approach was originally created to assess risks to bycatch in Australian trawl fisheries and compares productivity attributes (e.g. life-history traits) to factors that determine a stock's susceptibility to fishing impacts, producing a combined score indicative of a stock's relative vulnerability to overfishing. We used a form of the PSA developed by a working group from the U.S. National Marine Fisheries Service specifically for use in assessing vulnerability in federally managed fisheries. Alaska groundfish displayed a wide range of vulnerability scores, and this result was mainly due to variability in productivity scores. Susceptibility scores varied less than productivity scores and were centered on an intermediate value. The inclusion of target stocks in the PSA was valuable for assessing the relative vulnerability of the non-target stocks. Sensitivity analyses indicated that PSAs respond differently to changes in attribute scores depending on their initial conditions, and managers should be careful in interpreting changes in PSA results when stocks are re-evaluated.

P>The 2006 reauthorisation of the Magnuson-Stevens Fishery Conservation and Management Act requires annual catch limits for all target and non-target species within federally managed fisheries in the United States. In Alaska, both target and non-target species in the Alaska groundfish fisheries have been managed using catch limits since the early 1990s. Non-target species that are caught incidentally in a fishery require monitoring to ensure that the population is not negatively impacted by commercial fishing. Resource assessment scientists have been challenged with obtaining sufficient data to recommend an acceptable catch level for management of these species. This paper reviews three case studies where a catch limit is determined for non-target species when certain data are limited: (1) varying levels of biomass and catch data for all species within a species group or complex; (2) adequate catch data but no biomass data; (3) emerging target fishery of data-poor species, plus an example of how a complex of ecosystem component species is managed.

In total, 41 fish stocks in US ocean waters continue to be fished at unsustainable levels, and 46 fish stocks are overfished. In 2006, the US Congress required the implementation of annual catch limits (ACLs) and accountability measures by 2010 to prevent overfishing, and by 2011 to recover overfished stocks. These requirements were modelled on the existing management system for Northeast Pacific groundfish, where more than 20 fish stocks and assemblages have been managed sustainably for 30 years. Science-based overfishing levels and acceptable biological catches (ABCs) have been implemented for each stock or assemblage, with buffers between the two to avoid overfishing. Total allowable catches are set at or below the acceptable biological catch. Suballocations of quotas by season, area, and gear type, along with in-season fishery closures based on extensive observer coverage and vessel monitoring, ensure that quotas are not exceeded. To comply with ACL requirements, the North Pacific Fishery Management Council has defined ABC as an ACL. We demonstrate the effectiveness of ACLs for successful management of Northeast Pacific groundfish, suggesting that their use in other US fisheries might reduce the risk of overfishing and enhance the recovery of overfished stocks.

Assessing the vulnerability of stocks to fishing practices in U.S. federal waters was recently highlighted by the National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration, as an important factor to consider when 1) identifying stocks that should be managed and protected under a fishery management plan; 2) grouping data-poor stocks into relevant management complexes; and 3) developing precautionary harvest control rules. To assist the regional fishery management councils in determining vulnerability, NMFS elected to use a modified version of a productivity and susceptibility analysis (PSA) because it can be based on qualitative data, has a history of use in other fisheries, and is recommended by several organizations as a reasonable approach for evaluating risk. A number of productivity and susceptibility attributes for a stock are used in a PSA and from these attributes, index scores and measures of uncertainty are computed and graphically displayed. To demonstrate the utility of the resulting vulnerability evaluation, we evaluated six U.S. fisheries targeting 162 stocks that exhibited varying degrees of productivity and susceptibility, and for which data quality varied. Overall, the PSA was capable of differentiating the vulnerability of stocks along the gradient of susceptibility and productivity indices, although fixed thresholds separating low-, moderate-, and highly vulnerable species were not observed. The PSA can be used as a flexible tool that can incorporate regional-specific information on fishery and management activity.

Changes in assessment methodology: Assessment of squids is challenging due to a lack of reliable data and their unusual life history. In this document we suggest several alternatives for calculating ABC and OFL using the NPFMC’s tier system. Tier 5 requires reliable estimates of biomass and natural mortality rate (M). Under Tier 5, OFL is calculated as M * biomass, while ABC = 0.75 * M * biomass. For squids, we suggest two alternatives for modifying Tier 5 to accommodate the high turnover rate in squid populations. Option 1 uses a modified value of M based on experience with squid fisheries elsewhere in the Pacific and Atlantic Oceans. Option 2 uses a decay function to account for squid mortality throughout the fishing season.

Life-history strategies of four Pacific cod (Gadus macrocephalus) stocks in the eastern North Pacific Ocean are outlined. Southern stocks grew and matured quicker, but reached smaller maximum size and had shorter lifespans than northern stocks. The tradeoffs resulted in similar lifetime reproductive success among all stocks. Growth was highly dependent on latitude, but not on temperature, possibly because of differences in the duration of the growing season. Comparisons with Atlantic cod (Gadus morhua) revealed similar latitude/growth relationships among Atlantic cod stocks grouped by geographic region. In Pacific cod, greater size and longevity in the north appeared to be adaptations to overcome environmental constraints on growth and to maintain fitness. An egg production-per-recruit model suggested that the life-history strategy of northern Pacific cod stocks made them less resilient to fishing activity and age truncation than southern stocks.

Executive summary The NPFMC is considering action that would treat the eastern Bering Sea and Aleutian Islands separately for the purposes of Pacific cod management. This report is intended to summarize existing biological information on Pacific cod that may be useful in evaluating this action. The following conclusions may be useful and are described in greater detail in the report: 1) There is highly significant genetic isolation by distance in the Pacific cod stocks of North America (i.e. genetic differences among individuals increase with geographic distance; Fig. 1-2).This result, as well as several different genetic comparisons among regional groupings, suggest that Pacific cod stocks in the Aleutian Islands archipelago are distinct from those along the contiguous Alaska Peninsula. 2) In 2005, length at age was significantly higher in the AI than in the EBS for both female and male cod (Table 2-1, Figs. 2-2 & 2-3). This difference is present at all ages. 3) Commercial trawls in the AI catch bigger female and male cod than do trawls in the EBS (Figs. 3-1, 3-2 & 3-3). From 2004 to 2006, the mode for cod in the EBS occurred at 65-70 cm, while the mode for females in the AI occurred at 80-85 cm. Fish smaller than 50 cm were evident in EBS trawls, but were rare in the AI. 4) Estimates of age composition suggest that commercial trawls in the AI also catch older fish (Fig. 4-1). In particular, cod older than age 8 are largely absent from EBS trawls, while 8-11 year old fish were common in AI trawls. Age estimates were obtained by applying the growth models used in (2) above to the size composition in (3) above. 5) Length-weight relationships did not differ between the AI and EBS in 2005 (Figs. 5-1 & 5-2). 6) Length-specific gonad weight, a proxy for reproductive potential, was equal between the EBS and AI in 2005 (Fig. 6-1A). Length-specific fecundity (Fig. 6-1B) and egg size were significantly different between the EBS and AI in 2005, but the differences were small and may not be biologically relevant. 7) The fatty acid composition of egg polar lipids differed between the EBS and AI (Figs. 7-1 &7-2). Similar differences in other fish species have been used as an indicator of genetic differentiation and stock structure. 8) Cod appear to spawn in several locations in the AI and throughout the EBS (Fig. 8-1). 9) Tagged …