High diversity of coastal fishes is found in Western Pacific, East Asian, Australasian, Southern African and Caribbean waters, while the greatest diversity of tunas and bill-fishes is found in Tasm...

Citation: Testor P, Young Bd, Rudnick DL, Glenn S, Hayes D, Lee CM, Pattiaratchi C, Hill K, Heslop E, Turpin V, Alenius P, Barrera C, Barth JA, Beaird N, Bécu G, Bosse A, Bourrin F, Brearley JA, Chao Y, Chen S, Chiggiato J, Coppola L, Crout R, Cummings J, Curry B, Curry R, Davis R, Desai K, DiMarco S, Edwards C, Fielding S, Fer I, Frajka-Williams E, Gildor H, Goni G, Gutierrez D, Haugan P, Hebert D, Heiderich J, Henson S, Heywood K, Hogan P, Houpert L, Huh S, Inall ME, Ishii M, Ito S-i, Itoh S, Jan S, Kaiser J, Karstensen J, Kirkpatrick B, Klymak J, Kohut J, Krahmann G, Krug M, McClatchie S, Marin F, Mauri E, Mehra A, Meredith MP, Meunier T, Miles T, Morell JM, Mortier L, Nicholson S, O’Callaghan J, O’Conchubhair D, Oke P, Pallàs-Sanz E, Palmer M, Park J, Perivoliotis L, Poulain P-M, Perry R, Queste B, Rainville L, Rehm E, Roughan M, Rome N, Ross T, Ruiz S, Saba G, Schaeffer A, Schönau M, Schroeder K, Shimizu Y, Sloyan BM, Smeed D, Snowden D, Song Y, Swart S, Tenreiro M, Thompson A, Tintore J, Todd RE, Toro C, Venables H, Wagawa T, Waterman S, Watlington RA and Wilson D (2021) Corrigendum: OceanGliders: A Component of the Integrated GOOS. Front. Mar. Sci. 8:696100. doi: 10.3389/fmars.2021.696100 Corrigendum: OceanGliders: A Component of the Integrated GOOS

Chapter 19 ENSO Impact on Marine Fisheries and Ecosystems Patrick Lehodey, Patrick Lehodey Collecte Localisation Satellite, Ramonville St Agne, FranceSearch for more papers by this authorArnaud Bertrand, Arnaud Bertrand Institut de Recherche pour le Développement (IRD), MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, FranceSearch for more papers by this authorAlistair J. Hobday, Alistair J. Hobday CSIRO Oceans and Atmosphere, Hobart, TAS, AustraliaSearch for more papers by this authorHidetada Kiyofuji, Hidetada Kiyofuji National Research Institute of Far Seas Fisheries, Japan Fisheries Research and Education Agency, Shimizu, Shizuoka, JapanSearch for more papers by this authorSam McClatchie, Sam McClatchie 38 Upland Rd, Huia, Auckland, 0604 New ZealandSearch for more papers by this authorChristophe E. Menkès, Christophe E. Menkès Institut de Recherche pour le Développement (IRD), ENTROPIE (IRD/CNRS/Univ. La Réunion), Nouméa, New CaledoniaSearch for more papers by this authorGraham Pilling, Graham Pilling The Pacific Community (SPC), Noumea, New CaledoniaSearch for more papers by this authorJeffrey Polovina, Jeffrey Polovina 196 Pauahilani Pl., Kailua, HI, USASearch for more papers by this authorDesiree Tommasi, Desiree Tommasi Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, CA, USA NOAA Southwest Fisheries Science Center, La Jolla, CA, USASearch for more papers by this author Patrick Lehodey, Patrick Lehodey Collecte Localisation Satellite, Ramonville St Agne, FranceSearch for more papers by this authorArnaud Bertrand, Arnaud Bertrand Institut de Recherche pour le Développement (IRD), MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, FranceSearch for more papers by this authorAlistair J. Hobday, Alistair J. Hobday CSIRO Oceans and Atmosphere, Hobart, TAS, AustraliaSearch for more papers by this authorHidetada Kiyofuji, Hidetada Kiyofuji National Research Institute of Far Seas Fisheries, Japan Fisheries Research and Education Agency, Shimizu, Shizuoka, JapanSearch for more papers by this authorSam McClatchie, Sam McClatchie 38 Upland Rd, Huia, Auckland, 0604 New ZealandSearch for more papers by this authorChristophe E. Menkès, Christophe E. Menkès Institut de Recherche pour le Développement (IRD), ENTROPIE (IRD/CNRS/Univ. La Réunion), Nouméa, New CaledoniaSearch for more papers by this authorGraham Pilling, Graham Pilling The Pacific Community (SPC), Noumea, New CaledoniaSearch for more papers by this authorJeffrey Polovina, Jeffrey Polovina 196 Pauahilani Pl., Kailua, HI, USASearch for more papers by this authorDesiree Tommasi, Desiree Tommasi Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, CA, USA NOAA Southwest Fisheries Science Center, La Jolla, CA, USASearch for more papers by this author Book Editor(s):Michael J. McPhaden, Michael J. McPhadenSearch for more papers by this authorAgus Santoso, Agus SantosoSearch for more papers by this authorWenju Cai, Wenju CaiSearch for more papers by this author First published: 23 October 2020 https://doi.org/10.1002/9781119548164.ch19Citations: 2Book Series:Geophysical Monograph Series AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary El Niño events were first perceived several centuries ago as a dramatic change in the marine resources along the Peruvian coast. It is now recognized as part of the world's largest natural climate fluctuation: the El Niño Southern Oscillation (ENSO). There is a rapidly growing body of scientific literature showing that ENSO has physical and ecological impacts throughout the Pacific Ocean and more broadly across the other oceanic basins through atmospheric teleconnections. This review details a range of these examples in all major ecosystems impacted by ENSO in the Pacific Ocean. Teleconnections with other basins are also discussed, as are the diversity of changes associated with ENSO phases and their consequences on fisheries sustained by these ecosystems. Information is provided on the emerging complexity of the connection between ENSO and the ocean ecosystems, and particularly the diversity of El Niño types, characterized by eastern and central spatial patterns and differences in intensity. As these mechanisms become better understood, useful predictive capacity for ecosystem and fisheries management will result. However, growing evidences suggest that climate change may have already started interacting with ENSO dynamics and effects, complicating mechanistic understanding. Citing Literature El Niño Southern Oscillation in a Changing Climate RelatedInformation

Multidisciplinary, integrated ocean observing programs provide critical data for monitoring the effects of climate change on marine ecosystems. California Cooperative Oceanic Fisheries Investigations (CalCOFI) samples along the US West Coast and is one of the world’s longest-running and most comprehensive time series, with hydrographic and biological data collected since 1949. The pairing of ecological and physical measurements across this long time series informs our understanding of how the California Current marine ecosystem responds to climate variability. By providing a baseline to monitor change, the CalCOFI time series serves as a Keeling Curve for the California Current. However, challenges remain in connecting the data collected from long-term monitoring programs with the needs of stakeholders concerned with climate change adaptation (i.e., resource managers, policy makers, and the public), including for the fisheries and aquaculture sectors. We use the CalCOFI program as a case study to ask: how can long-term ocean observing programs inform ecosystem based management efforts and create data flows that meet the needs of stakeholders working on climate change adaptation? Addressing this question and identifying solutions requires working across sectors and recognizing stakeholder needs. Lessons learned from CalCOFI can inform other regional monitoring programs around the world, including those done at a smaller scale in developing countries.

The OceanGliders program started in 2016 to support active coordination and enhancement of global glider activity. OceanGliders contributes to the international efforts of the Global Ocean Observation System (GOOS) for Climate, Ocean Health, and Operational Services. It brings together marine scientists and engineers operating gliders around the world: (1) to observe the long-term physical, biogeochemical, and biological ocean processes and phenomena that are relevant for societal applications; and, (2) to contribute to the GOOS through real-time and delayed mode data dissemination. The OceanGliders program is distributed across national and regional observing systems and significantly contributes to integrated, multi-scale and multi-platform sampling strategies. OceanGliders shares best practices, requirements, and scientific knowledge needed for glider operations, data collection and analysis. It also monitors global glider activity and supports the dissemination of glider data through regional and global databases, in real-time and delayed modes, facilitating data access to the wider community. OceanGliders currently supports national, regional and global initiatives to maintain and expand the capabilities and application of gliders to meet key global challenges such as improved measurement of ocean boundary currents, water transformation and storm forecast.

Small pelagic fishes (i.e. sardines [Sardinops spp.] and anchovies [Engraulis spp.]; hereafter ‘forage fish’) support very large fisheries globally, but in recent years, the catches of sardine and anchovy off California have been very low. Sardine catches were two orders of magnitude lower, and anchovy catches are an order of magnitude lower than the historical maximum catch rates in this region (NMFS, 2009; Hill, Crone & Zwolinski, 2017). Declines in small pelagic fish biomass have occurred in spite of precautionary management including: very low exploitation rates, an environmentally informed harvest control rule for sardine and generous reserve thresholds to provide a buffer for forage and stock recovery (NMFS, 2009; Hill et al., 2017). Clearly something is missing. In addition to commercial harvest, the non-commercial value of forage fishes in the California Current System is a fundamentally important resource base for fish, mammal and seabird predators (Szoboszlai et al., 2015). In recent years, the largest removals of forage fish in the California Current System are by demersal fish, marine mammals, seabirds (Thayer, Szoboszlai & Sydeman, 2017) and then by fisheries, arranged in order of magnitude. Forage fish removals by commercial fisheries off California are currently <15% of consumption by marine mammals. While there is considerable uncertainty in this estimate, it is likely to be approximately correct. For example, California sea lion [Zalophus californianus], once a highly depleted marine mammal species, is now above 250 000 individuals (Laake et al., 2018). Using a conservative, non-pup provisioning ration of 5 kg/individual/day (Costa, Antonelis & DeLong, 1991; Williams et al., 2007), the forage fish harvest would be 446 000 mt (metric tons) /year. If even a tenth is anchovy, this is greater than human harvest, without considering other marine mammals, marine birds or higher trophic-level fishes. The sardine fishery off California has been closed since 2015 following a stock assessment (Hill et al., 2015) estimating biomass less than the reserve threshold of 150 000 mt; a limit set to protect the sardine stock. Anchovy have been fished in the last decade (2006–2016) in the absence of a catch limit, although there is a trigger threshold, and catches have been very low (1020–17 284 mt; Lowther & Liddel, 2016). In 2016, a catch limit for anchovy was set at 25 000 mt, but actual catches (8366 mt) remained well below the catch limit. Despite this, the catch limit was challenged by environmental NGOs seeking to close the fishery, and the District Court ruled against the National Marine Fisheries Service (NMFS) for failing to apply ‘best available science’ (MacCall et al., 2016) when setting the catch limit. The court ruling, which at the time of writing may still be appealed, required NMFS to revise the catch limit. NMFS relied on historical data to establish the initial catch limit, rather than the analysis by MacCall et al. (2016), which had some problems – first, the spatial coverage was inadequate for an accurate biomass estimate (FRD, 2016), and second, the anchovy biomass estimate by MacCall et al. (2016) was less than the estimated consumption by marine mammals alone, which should not be the case unless the turnover of anchovy was phenomenally high. The timing of the lawsuit was unfortunate, in that NMFS acoustic-trawl survey data available shortly after the court case estimated the anchovy biomass at 150 000 mt (Zwolinski et al., 2017). At a biomass of more than 150 000 mt, a catch of <25 000 mt would still be precautionary for these fast growing fish. The focus on commercial fishery catches ignores an important source of sardine and anchovy mortality. Recovery of marine mammal populations implies large changes in natural mortality of forage fish. Following the introduction of the Marine Mammal Protection act in 1972, NMFS has monitored mammal populations in the California Current System and developed criteria to evaluate population recovery. It is now apparent that some of these populations, such as the California sea lion have recovered and are approaching carrying capacity (Laake et al., 2018). When food limitation contributes to mortality, populations can be expected to exhibit density-dependent mortality, or difficulty in adequately feeding their young (McClatchie et al., 2016; Wells et al., 2017), and may exert significant pressure on forage resources in their feeding range. The impact of mammalian predators on forage is far larger than the impact of current fishing levels off southern California, and the mammals are only one component of the predator complex exploiting forage fishes (Szoboszlai et al., 2015; Thayer et al., 2017). Given that natural predation is the largest removal of forage fish in the California Current System, we believe that the January 2017 court order was misguided because it failed to address wider issues than the anchovy catch limit. First, does the commercial forage fishery have a right to exist? Second, what kind of natural ecosystem is desirable in the modern day context? And last, is restoration of forage fish to some stable pre-fishery level desirable or even possible? In the context of multiple use of natural resources, small fisheries, managed in a precautionary way, should be compatible with recovered predator populations. For example, in the last 40 years, marine mammal assessments (see [http://www.nmfs.noaa.gov/pr/sars/species.htm]) show that California sea lions have recovered at near maximal rates while small pelagic fisheries, managed in a precautionary manner, continued to exist (see catches on the Pelagic Fisheries Information System [http://pacfin.psmfc.org/]). Sardine and anchovy fisheries, comparable to the historical fisheries off California, are far different from the smaller fisheries of the last decade. In our opinion, such small fisheries have a right to exist. The question is, how large should the fisheries be allowed to become? This bears directly on the second question of what kind of ecosystem is desirable off modern southern California? Do we want the natural predator populations to grow sufficiently to consume all of the forage resources available to them, at which point they will show density dependence? Or are we willing to accept a somewhat lower forage fish population threshold at which density dependent stresses become evident in the natural predators, and permit the commercial sector to harvest a fraction of the forage resource? Finally, while it is recognized that fishing pressure on pelagic forage fish can increase the probability, and even the rate, of stock collapse (Essington et al., 2015), it is well documented that forage fish populations collapse repeatedly and these collapses are a common feature of sardine and anchovy population dynamics, even in the absence of commercial fishing (Baumgartner, Soutar & Ferreira-Bartrina, 1992; Field et al., 2009; McClatchie et al., 2017). The inescapable conclusion, from long time series palaeoceanographic studies, is that sardine and anchovy populations are not stable, and so it is not possible to restore them to some stable pre-fishery level, because it does not exist. The repeated collapse and recovery of these forage fishes occurred during periods when marine mammals and other predators were at very low exploitation levels, which also supports the case that there were times when forage was low and the predator populations would have experienced density-dependent stresses. It is tempting to assume that ecosystem-based fishery management approaches are the answer, but no one knows how the California Current System functioned in the absence of humans. A key question is whether the system is characterized by high forage fish standing stock (units of mass/ volume), or by high productivity (mass/ volume/ time) but low standing stock. Palaeoceanographic studies of forage fish scales in sediment cores clearly indicate that upwelling, primary production and the biomass of forage fishes have varied over orders of magnitude at different temporal scales (Skrivanek & Hendy, 2015). But do sediment fish scale records reflect high standing stock of forage fishes? Or do fish scale records indicate biomass that was rapidly consumed and flowed through higher trophic levels before being deposited to the sediment as fish scales? If the California Current System functions as a tightly coupled system, with long-lived predators, then standing stocks of forage fishes should be low when predators are abundant. If the California Current System is loosely coupled, then standing stocks of forage fishes may accumulate when production exceeds the capacity for higher trophic levels to consume it. This surplus standing stock would arguably be available to the fishery. The true nature of the California Current System may never be known, but it is clear that following the recovery of marine mammal and seabird predators, and the recovery of over-harvested fish stocks, there is, and will continue to be, an increase in competition between protected resources, higher trophic-level fisheries and direct harvest of forage fishes. Large standing stocks of forage fishes are unlikely to be a common feature of the restored California Current System. It seems unrealistic to assume that closing the tiny anchovy fishery will have the desired biological effect of creating a larger anchovy standing stock when predator populations have recovered. More attention to the role of predation and competition in determining small pelagic fish biomass is likely to be a more useful approach to managing expectations regarding forage fish biomass. Future research should include estimating abundance of pre-recruit forage fishes since the relationships between adults and environmental variables are weak (McClatchie, 2013), possibly due to the variable effects of predator mortality. While pre-recruits are also preyed upon, we expect them to show a clearer relationship with environmental variability, and to be less variable than ichthyoplankton abundances, due to lower rates of mortality. More effort should also be expended to estimate forage fish abundance in the foraging range of predators near their breeding colonies. Forage fishes are highly mobile and their full range is not available to breeding predators. It would be possible to determine times and locations where forage fishes should be managed to facilitate successful breeding by predators, and to develop a mechanism facilitating coexistence of both predators and small forage fisheries. Finally, anchovy, sardine, mackerels (Scomber japonicus and Trachurus symmetricus) and market squid (Doryteuthis opalescens) form a community of forage species. Since marine mammals and other top predators are highly adept at prey switching, it is not reasonable to consider natural mortality on one species without considering the standing stocks of the other forage species. We suggest a portfolio approach to the management of small pelagic fisheries (Link, 2017). We appreciate pre-submission reviews by Kevin Hill, Joshua Lindsay, Edward Weber, William Watson, Dale Sweetnam, Gerard DiNardo, and Kristen Koch, and the helpful comments of the journal editors. The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the authors and do not necessarily reflect the views of NOAA or the Department of Commerce.

We used univariate and multivariate spatiotemporal delta models to quantify changes in the distribution of ichthyoplankton in the southern California Current System from 1951 to 2016. We focus on mesopelagic species, because they are most abundant, and on northern anchovy (Engraulis mordax), Pacific sardine (Sardinops sagax), and Pacific hake (Merluccius productus), because they are important commercial and forage fish species. Univariate models indicated that changes in the relative abundance, area occupied, center of gravity, and spatiotemporal variability of numerically dominant warm-water and cool-water-associated mesopelagic ichthyoplankton show strong species-specific differences. Multivariate models revealed that the warm-water-associated mesopelagic assemblage exhibits an increasing, nonmonotonic, secular trend of increasing relative abundance underlying interannual variability, suggesting a tropicalization of the southern California Current System. In contrast, the cool-water-associated mesopelagic assemblage shows mainly interannual variability, with little secular trend over the 65-year period. Correlation matrices of the modeled ichthyoplankton densities showed that the spatial distributions of northern anchovy and Pacific hake are highly correlated with cool-water mesopelagic ichthyoplankton, but Pacific sardine is spatially correlated with both warm- and cool-water-associated mesopelagic species. Declines of adult sardine, anchovy, and hake are occurring concurrently with tropicalization of the southern California Current System. The most parsimonious explanation for tropicalization of the ichthyoplankton is increased presence of Pacific Equatorial-influenced Water in the inshore southern California region. We modeled the distribution of ichthyoplankton in the southern California Current System from 1951 to 2016. We focus on abundant mesopelagic species and on northern anchovy (Engraulis mordax), Pacific sardine (Sardinops sagax), and Pacific hake (Merluccius productus), because they are important commercial and forage fish species. Single species models indicated that changes in abundance, area, distribution center, and variability of the most abundant mesopelagic ichthyoplankton associated with warm and cool water show strong differences between the species. Models of species groups revealed that the warm-water mesopelagic larval fishes exhibit a long-term trend of increasing relative abundance underlying year-to-year variability, suggesting tropicalization of the southern California Current System. In contrast, the cool-water mesopelagic larvae show mainly year-to-year variability, with little long-term trend. Correlations between the modeled species showed that the spatial distributions of northern anchovy and Pacific hake are highly correlated with cool-water mesopelagic larvae, but Pacific sardine is correlated with both warm- and cool-water-associated mesopelagic species. The spatial variability of hake over time is highly positively correlated with cool-water mesopelagics and with northern anchovy, but sardine fluctuate independently of the mesopelagics and both anchovy and hake. Declines of adult sardine, anchovy, and hake are occurring concurrently with tropicalization of the southern California Current System. The simplest explanation for more tropical ichthyoplankton is increased presence of Pacific Equatorial-influenced Water in the inshore southern California region.

Following the marine heat wave of 2014-16, the California Current System (CCS) trended towards more typical conditions north of Point Conception, California, from mid-2017 to mid-2018, but became highly abnormal in the south by mid-2018.Two basinscale indices (Pacific Decadal Oscillation and Oceanic Nino Index) were close to neutral, but the North Pacific Gyre Oscillation was extremely low at the end of 2017 and beginning of 2018. Regional analyses demonstrated that upwelling was close to normal throughout most of the CCS with the exception of high upwelling from northern California to Washington in summer and fall of 2017. Sea surface temperature was close to normal throughout most of the CCS but warmed to record levels in summer 2018 in southern California and northern Baja California. In spring 2018, surface chlorophyll a was negatively anomalous throughout most of the US West Coast with localized hot spots around the Columbia River, in the Gulf of Farallones, and Monterey Bay. Lipid-rich copepod densities and sizes returned to normal levels in the northern CCS, and euphausiid abundances were above average in central California but below average in southern California in spring 2018. Abundances of 7 zooplankton taxa were slightly to well above average off of northern Baja California in late 2017. Pyrosomes, which are associated with warm water, were found throughout the CCS. The fish assemblage off Oregon and Washington was comprised of both northern and southern/offshore species. In the central region (near Monterey Bay) most fishes were close to long-term mean abundances; however, adult northern anchovy (Engraulis mordax) abundance was the highest on record. The ichthyoplankton assemblage off southern California had a tropical signal similar to 2014-15 as warm-water associated mesopelagic abundances were close to record highs and cold water mesopelagics abundances were very low.Anchovy larvae abundances in southern California were the highest since the 1960s. Indicators that can affect salmon survival were mixed in 2018. On the one hand, several indices forecast high salmon return (moderate-high salmon yearling abundance, high larval fish (salmon prey) abundance, normal lipid-rich copepod abundances). On the other hand, low survival was predicted by high fall PDO, high abundances of offshore larval fishes, and above average abundance of lipid-poor copepods.This unusual mix of indicators makes it difficult to forecast salmon returns in upcoming years. Common murre (Urfa aalge) reproduction was historically low in the northern CCS in 2017 as colonies experienced complete reproductive failure both at Yaquina Head, Oregon, and Castle Rock, California. In both cases, forage was scarce, birds conducted long foraging excursions which left eggs unattended for extended periods, and many eggs were consumed by avian predators. Brandt's (Phalacrocorax peniscillatus) and pelagic (P. pelagicus) cormorants had above average reproductive success in 2017 at Yaquina Head, but Brandt's cormorant also had total reproductive failure in 2017 at Castle Rock. At Southeast Farallon Island murre, Brandt's cormorant, and pelagic cormorant productivity was close to average in 2017, and Brandt's cormorant and murre were slightly above average in 2018. Preliminary 2018 results fromYaquina Head also indicated that murre successfully produced chicks for the first time since 2014. At-sea bird surveys in the north demonstrated that sooty shearwater and common murre abundances were historically low in 2017, but increased to some of the highest values on record in 2018. By contrast, the at-sea surveys off central California found that murre densities were anomalously high in 2017 but fell to an average level in 2018. Improving California sea lion (Zalophus californianus) pup condition continued from 2016 into 2017 as live pup counts, pup weight, and rate of growth were above average. Augmented pup conditions in 2016-17 was likely driven by increased availability of anchovy, as anchovy remains were found in nearly 100% of sea lion scat. There were record high encounters with Humpback whales (Megaptera novaeangliae) off central California in 2018. Overall, much of the CCS was in more of a normal state through mid-2018 relative to the past 5 years. However, remnants of the 2014-16 marine heat wave were still resonating in the north, and another highly anomalously warm water event affected the southern part of the CCS in summer 2018. Thus, while the CCS was returning to typical conditions in the north, it was anything but normal in the south in 2018.

To correctly interpret trends in species’ abundance in long time series it is essential to account and correct for biases that may arise in association with changes in sampling methodology. We assess how gear changes for oblique plankton net tows (from 1 m diameter ring to 0.71 m diameter bongo net in 1977) affected ichthyoplankton abundance estimates from the California Cooperative Oceanic Fisheries Investigations (CalCOFI) program. Paired ring and bongo net samples were analyzed from 133 stations sampled in 1977–78. To quantitatively correct for net-associated bias, we first modeled abundance in bongo nets as a function of abundance in ring nets for larvae and eggs summed across all taxa during day and night with generalized linear models (GLM; identity link with gamma error structure). Models suggest that greater visual avoidance for ring than bongo nets induces bias in abundance estimates as slope estimates were greater than 1 for combined larvae during the day but did not differ significantly from 1 for combined larvae at night, or eggs during day or night. Ratios of summed abundances between bongo and ring nets for the 15 most common taxa indicated that there were significantly higher abundances for 4 taxa in the bongo than the ring net during the day but values did not differ at night between net types. To make data collected in ring nets before 1978 more comparable to data from bongo nets our results suggest it is necessary to adjust abundance estimates during the day from ring nets by a factor of 2 for Cyclothone spp., 2.17 for Diogenichthys spp., 2.06 for Engraulis mordax, and 1.53 for Vinciguerria spp. It may also be necessary to reevaluate results from past studies that utilize the CalCOFI larval time series that did not correct for net bias. More data are needed to ascertain the effect of net change on species such as Sardinops sagax or Tarletonbeania crenularis that were uncommon in the late 1970s but have been encountered frequently in recent years. INTRODUCTION Long time series are essential for truly understanding the mechanisms governing variability in the dynamics of populations and communities in all ecosystems (Krebs et al. 2001; McClatchie 2014). Short-term fluctuations are often nested within long-period dynamics and attempts to discern the causes of species variability over short time periods may produce erroneous conclusions (McClatchie et al. 2017). This is particularly true in an era of rapid climate change as the effect of changes in environmental conditions on ecosystems can be conceptualized only when placed in the context of a long time series. Therefore, it is extremely important for species management and conservation programs to maintain and build upon long time series over upcoming years and decades. Equally important as maintaining long time series is ensuring that samples collected over time are comparable to one another. Bias can arise if systematic differences in collection methods that affect the probability of capturing an organism are imposed upon the time series (MacKenzie et al. 2002). For example, trends from fisherydependent data may not reflect true population dynamics of a fished species if the fleet introduced more effective gear for catching the targeted species at some point in the time series. Accounting for methodological differences in data collection is imperative to properly interpret potential changes in species abundances for time series analysis (MacKenzie et al. 2005). The California Cooperative Oceanic Fisheries Investigations (CalCOFI) program provides some of the most complete marine ecosystem monitoring data in the world. CalCOFI has continuously sampled biological (plankton tows) and oceanographic conditions (CTD and water collections) from the same 66 core stations off southern California since 1951 (McClatchie 2014). From a biological perspective, the resultant data give information on variability in the distribution and abundance of zooplankton (McGowan and Walker 1985; McGowan et al. 1998; Lavaniegos and Ohman 2007) and ichthyoplankton (Hsieh et al. 2005; Hsieh et al. 2006; Hsieh et al. 2009; Lindegren et al. 2016) over more than six decades. At several points in the time series CalCOFI plankton sampling was changed to introduce methodological improvements. In all years, samples were obtained by lowering a net to a set depth and towing it obliquely (at a 45 ̊ angle) to the surface at a constant speed. However, THOMPSON ET AL.: CORRECTING FOR BIAS IN CALCOFI ICHTHYOPLANKTON ABUNDANCE ESTIMATES CalCOFI Rep., Vol. 58, 2017 114 lected using both nets at the same 160 stations during seven CalCOFI cruises between winter 1977 and summer 1978. At present, net effects on sampling efficiency have been thoroughly vetted for zooplankton (Smith 1974; Brinton and Townsend 1981; Ohman and Smith 1995; Rebstock 2001; Ohman and Lavaniegos 2002). However, with the exception of an investigation on northern anchovy, Engraulis mordax (Hewitt 1980), comparable analyses have not been published for ichthyoplankton. Here we evaluate if larval abundance estimates are biased by gear type and test the hypothesis that bias will be greater during the day when larvae would be able to better see and avoid the ring than the bongo net.

Environmental variability affects distributions of marine predators in time and space. With expected changes in the ocean climate, understanding the relationship between species distributions and the environment is essential for developing successful management regulations. Here we provide information on an ephemeral but important habitat for North Pacific loggerhead turtles (Caretta caretta) at the northeastern edge of their range. North Pacific loggerhead turtles nest on Japanese beaches and juveniles disperse throughout the North Pacific; some remain in the high seas of the central North Pacific whereas others transition to the eastern Pacific and forage near Baja California, Mexico. Loggerheads have also been reported along the United States west coast, with the majority of sightings off southern California. Here we describe their demography and distribution in the area, based on two aerial surveys (2011, 2015), at-sea sightings, and stranding records. Our aerial survey during fall 2015 determined density, abundance, and distribution of loggerheads in the area, when anomalous warming of the North Pacific and El Nino conditions co-occurred. Using line-transect analysis, we estimated ca. 15,000 loggerheads at the sea surface (CV = 21%) and more than 70,000 loggerheads when accounting for those that were submerged and not available for detection. Our survey during fall 2011 resulted in no loggerhead sightings, demonstrating a high variability of loggerhead density in the region. We encourage further research on loggerheads in the area to determine the mechanisms that promote their occurrence. These studies should include regular surveys throughout their foraging areas along the west coast of the North America as well as assessments of prey availability and local oceanographic conditions.

The Pacific sardine, Sardinops sagax, is a highly migratory coastal pelagic species that occurs from the tip of Baja California to the Gulf of Alaska and in the Gulf of California. We used fishery-independent egg surveys to characterize the relative amounts of sardine spawning habitat in the exclusive economic zones (EEZ5) of Mexico and the US during spring 2000-13. Most eggs were captured in the US EEZ from San Francisco to the Mexico-US border in all years sampled. A small fraction ranging from 0% to 10% of all eggs captured occurred in the Mexican EEZ, usually from Punta Eugenia north to the border. The abundance and distribution of eggs found in warmer waters between 15 degrees C to 18 degrees C off northern Baja California appear to be dependent on periods of more intense flow of the California Current, when sardine belonging to the northern subpopulation found in central and southern California extends southward into the nearshore area off Baja California. However, a small fraction of the southern subpopulation may also have spawned in coastal areas of the US-Mexican border during May in some years.

Author(s): OHMAN, Mark D; Mantua, Nate; Keister, Julie; Garcia-Reyes, Marisol; McClatchie, Sam | Abstract: El Nino-Southern Oscillation (ENSO) events activate long-distance teleconnections through the atmosphere and ocean that can dramatically impact marine ecosystems along the West Coast of North America, affecting diverse organisms ranging from plankton to exploitable and protected species. Such ENSO-related changes to marine ecosystems can ultimately affect humans in many ways, including via depressed plankton and fish production, dramatic range shifts for many protected and exploited species, inaccessibility of traditionally fished resources, more prevalent harmful algal blooms, altered oxygen and pH of waters used in mariculture, and proliferation of pathogens. The principal objective of the Forecasting ENSO Impacts on Marine Ecosystems of the US West Coast workshop was to develop a scientific framework for building an ENSO-related forecast system of ecosystem indicators along the West Coast of North America, including major biological and biogeochemical responses. Attendees realized that a quantitative, biologically-focused forecast system is a much more challenging objective than forecasting the physical system alone; it requires an understanding of the ocean-atmospheric physical system and of diverse organism-level, population-level, and geochemical responses that, in aggregate, lead to altered ecosystem states.

We use a new, well-calibrated 500 year paleorecord off southern California to determine collapse frequency, cross correlation, persistence, and return times of exploited forage fish populations. The paleorecord shows that "collapse" (defined as <10% of the mean peak biomass) is a normal state repeatedly experienced by northern anchovy, Pacific hake, and Pacific sardine which were collapsed 29-40% of the time, prior to commercial fishing exploitation. Mean (+/- SD) persistence of "fishable biomass" (defined as one third mean peak biomass from the paleorecord) was 19 +/- 18, 15 +/- 17, and 12 +/- 7 years for anchovy, hake, and sardine. Mean return times to the same biomass was 8 years for anchovy but 22 years for sardine and hake. Further, we find that sardine and anchovy are positively correlated over 400 years, consistent with coherent declines of both species off California. Persistence and return times combined with positive sardine-anchovy correlation indicate that on average 1-2 decades of fishable biomass will be followed by 1-2 decades of low forage. Forage populations are resilient on the 500 year time scale, but their collapse and recovery cycle (based on the paleorecord) are suited to alternating periods of high fishing mortality and periods of little or no fishing.