California Sea Grant College Program

Located at the land-sea interface, the highly dynamic sandy beach and surf zone ecosystem is one of the coastal zones used most intensely by humans (e.g., recreation, fishing, tourism). Surf zones are also important as fish habitat; however, the factors structuring fish assemblages in the surf zone are relatively understudied due to challenges associated with sampling this dynamic environment. To investigate temporal influences on surf zone fish communities, we evaluated seasonal trends in the fish assemblage and associations with environmental conditions using baited remote underwater video stations (BRUVS) at four beaches on the Northeast Pacific coast (California, USA) from July 2020 to June 2021. Our study region is characterized by strong seasonality in productivity (due to spring upwelling) and the wave climate (in response to winter storms), making it an ideal location for evaluating seasonal change in surf zone fish. We found that surf zone fish assemblages exhibited marked seasonality and site-to-site variability. Two species of surfperch (Amphistichus argenteus and A. koelzi) and leopard sharks (Triakis semifasciata) were more common in the winter and spring, corresponding with surfperch spawning, while flatfishes were more abundant in the summer. Fish species composition was most affected by distance from shore (as a proxy for surf zone width), visibility, water temperature, percent cover of combined macroalgae and surfgrass, and breaker wave height, with significant effects detected for distance from shore and breaker height. Fish species that exhibited higher abundance in the winter, including A. argenteus, A. koelzi, and T. semifasciata, were associated with larger waves and wider surf zones. Our results highlight the influence of seasonal variation in environmental conditions on fish communities in the dynamic, coastal surf zone ecosystem, with potential management implications for several highly abundant species targeted by recreational fisheries.

The ocean is rapidly changing through warming, sea-level rise, ocean acidification, declining oxygen concentrations, and altered circulation patterns, which are reshaping marine ecosystems worldwide. These changes necessitate a complete and holistic view of affected marine ecosystems. Long-term ocean monitoring programs are crucial for understanding these changes and guiding sustainable management. The California Cooperative Oceanic Fisheries Investigations (CalCOFI)*1, initiated in 1949, is one of the world's longest-running and most comprehensive marine ecosystem observing programs. CalCOFI collects extensive ocean data across all Essential Ocean Variables in the Southern California Current four times a year (Gallo et al. 2022). This encompasses over 36 physical and chemical parameters, 2,500 biological parameters, and 50,000 environmental DNA sequences, measured simultaneously (Satterthwaite et al. 2025). These data have illuminated long-term ecosystem patterns, supported marine management, and enhanced our understanding of how climate variability and change impact the California Current. Given its long history and collaborative nature, CalCOFI's data are fragmented across more than 30 disparate datasets, managed by different entities, served in various locations, with inconsistent naming and limited integration (Fig. 1), which hinders a holistic ecosystem understanding. Thus, CalCOFI exemplifies similar challenges and opportunities of mobilizing and integrating ocean data on a global scale.

A holistic understanding of social-ecological systems is essential to foster resilient, adaptive, and sustainable marine ecosystems and human communities. Yet, the integration of social and ecological dimensions is still developing within natural resource management, as are the indicators necessary to monitor them. In this study, we assess the integration of social and ecological indicators in marine management through a case study exploring the use of and degree of linkage between social and ecological indicators in US federal environmental and ocean resource agencies. Using a survey, we collected indicator sets or reports developed by these US federal agencies and found that 7 out of 11 total reports contained both social and ecological indicators. Within those reports, there were 333 social indicators. Only 35% (116) of the social indicators could be directly linked to commonly monitored ecological indicators. Social-ecological connections were focused on many themes, including tourism and recreation, fishing and marine resource use, resilience of coastal communities, well-being, cultural/spiritual value, economic impact, environmental and resource management education, and participation in resource management. These results suggest that some integration of social and ecological indicators within the ocean and environmental-focused federal agencies in the US is occurring, but it is not widespread. Exploring and applying methods that facilitate the integration of social and ecological indicators is the next frontier in achieving management of the environment as a combined social-ecological system.

Major estuaries globally are experiencing fast-paced changes in hydrology and ecosystem dynamics. However, connecting alteration of river flow regimes to estuarine fish population dynamics remains a challenge, partly due to the untested assumption that flow regimes, fish dynamics, and the resulting flow–ecology relationships are stationary (i.e., have no systematic changes in mean or variance over time). Here, we studied the endangered population segment of Longfin Smelt (Spirinchus thaleichthys) in the San Francisco Estuary, which depends on seasonal river flows to reproduce. We used extensive biomonitoring data (1980–2020) and two time-series modeling techniques, namely multivariate autoregressive state-space (MARSS) models and dynamic linear models (DLMs), to understand how population dynamics respond to interannual flow variation, and whether flow–ecology relationships have changed over time. MARSS outputs showed that population trajectories are best explained by a combination of lateral and vertical dimensions of habitat structure, that is, whether individuals were collected in channels versus shoals, and in pelagic versus benthic environments. In turn, DLMs revealed time-varying, but often positive effects of flow on young-of-the-year abundance in shallow channel and shoal habitats, but no consistent relationships for older individuals (age-1+), likely due to other drivers influencing survival from age-0 and age-1+. Finally, we found that the two modeling approaches showed agreement only in about 30% of the cases. Divergence in the sign and/or magnitude of flow effects suggests that time-averaged approaches may sometimes oversimplify non-stationary relationships between the environment and fish population dynamics. From a conservation standpoint, the gradually weakening but positive flow–ecology relationship (as opposed to a step change in the relationship) suggests that it may still be possible to reverse the steep population declines of Longfin Smelt through a combination of flow and habitat restoration actions. While we focused on a particular endangered population, our quantitative approach is transferable to other taxa and geographies, and could help inform management of flow-dependent resources in systems strongly affected by non-stationarity. We contend that time-varying flow–ecology relationships are needed to better capture ecological realism, and could help design more effective conservation strategies in fast-changing environments.

In California’s Russian River watershed, home to imperiled salmon and steelhead populations, an intensive long-term monitoring program plays an integral role in supporting species recovery. The program conducts life cycle and basinwide monitoring of natural- and hatchery-origin coho salmon using PIT antenna arrays, downstream migrant traps, snorkel counts, electrofishing, and spawner surveys paired with environmental monitoring. The program has also served as a foundation for targeted research by providing baseline data and monitoring infrastructure. Long-term and consistent tracking of population metrics has indicated modest but meaningful positive trends in abundance, but has also revealed unanticipated bottlenecks to population recovery, many of which are related to low streamflow. Monitoring has also revealed complex movement patterns of juveniles and adults throughout the watershed that have broadened our understanding of salmon life history diversity and the importance of managing for diversity as a key strategy for recovering salmon. Minor adaptations to the monitoring program have enabled evaluation of specific recovery actions, including genetic intervention, flow augmentation from off-channel storage, fish passage remediation, and physical habitat restoration projects. Critical to the effectiveness of the Russian River’s monitoring program has been the ability to manage and share data through a centralized database. This has facilitated development of data dashboards that are used for management decision-making and long-term recovery planning and prioritization. We reflect on the evolution of the Russian River monitoring program, including benefits and challenges of long-term and spatially-distributed monitoring in a hatchery-supplemented population and lessons learned that have relevance for salmon recovery efforts across their range.

Objective Variability in somatic growth of marine fish can affect their reproductive potential and survival and, therefore, the productivity of a population. Understanding how growth might vary among species can improve predictions of population status and responses to environmental change. Our objective was to characterize the variability in growth and body condition of groundfish species along the U.S. West Coast to support their monitoring and assessment. Methods We used geostatistical models to estimate growth rate and body condition, two interrelated traits associated with somatic growth, across space and time for nine commercially important U.S. West Coast groundfish species. We fit generalized linear mixed models with Gaussian Markov random fields to biological data collected from annual bottom trawl surveys to estimate variability at a 4- × 4-km spatial resolution. Results Our models uncover spatiotemporal variability in growth rate and body condition in all nine groundfish species with limited trends shared among species with similar traits, suggesting a greater influence from niche partitioning acting on local scales. Such interspecific differences in growth rate and body condition also occurred at regional scales, with some species exhibiting positive responses while others declined. Conclusions These findings reveal the dynamic nature of somatic growth among groundfish species and provide insight into potential mechanisms of its variability that could be considered within climate-enhanced assessments of population status for marine fish.

The canopy-forming feather boa kelp Egregia menziesii exhibits remarkable morphological variability across its geographic range. Regional morphotypes of Egregia were once considered separate species, but they were not determined to be genetically distinct; instead, their morphology was thought to reflect local physical or environmental conditions. Although morphological variation in Egregia has long been observed and was previously characterized through field surveys in the early 2000s, we revisited this topic using digital morphometrics (i.e., image analysis) of 1624 macroalgal herbarium specimens from California dating back to the 19th century. We observed that the morphology of Egregia (rachis texture, lateral blade shape, and blade or pneumatocyst density) varied along a latitudinal gradient and could be predicted by seawater temperature and wave height. We also identified some region-specific morphological changes in recent decades. Further, the monthly presence or absence of sporophylls in southern-region specimens provided preliminary evidence into the reproductive phenology of Egregia. Herbarium collections are invaluable for studying patterns in morphology because they showcase inter- and intraspecific variability and establish a baseline for comparison through time. Integrating natural historical and contemporary data will be critical for understanding and predicting future trends in the context of ocean warming.

Historically, California brown pelicans experienced reproductive failure and population decline induced by the pesticide dichlorodiphenyltrichloroethane (DDT). Although the population recovered after the 1972 DDT ban, nontargeted analytical methods have identified over 45 DDT-related compounds (DDT+) and other typically unmonitored halogenated organic compounds (HOCs) in regional upper trophic level wildlife species, presumably originating from the persistent and chemically-complex DDT manufacturing waste deposited in the Southern California Bight (SCB). However, there is limited data on DDT+ in previously endangered bird populations, including the brown pelican. We identified 183 HOCs in seven brown pelican liver samples (131 ± 48, mean ± SD) via nontargeted analysis. Seventeen DDT+ compounds were identified, including four tris(4-chlorophenyl)methane (TCPM)-related compounds, and 17 polychlorinated terphenyls (PCTs), all of which were not assessed in prior pelican research. Quantitative targeted analysis was conducted for three classes: DDT+, polychlorinated biphenyls (PCB), and polybrominated diphenyl ethers (PBDE). Among these three classes, DDT+ was the dominant chemical class (∑13DDT+, 0.56–197 μg/g lw), followed by (∑14PCB, 0.24–96 μg/g lw), and (∑6PBDE, 0.01–5.61 μg/g lw). ∑13 DDT+ primarily consisted of p,p’-DDE (77 % ± 15 %), 4,4′,4″-TCPM (12 % ± 10 %), p,p’-DDMU (6 % ± 3 %), and 4,4′,4″-TCPMOH (5 % ± 6 %). These results demonstrate the continuous exposure of known historical HOCs and a chemically diverse set of under-monitored HOCs, including DDT+. Additionally, levels of detection are consistent with recent wildlife studies in the region, suggesting pervasive contamination of a unique profile of HOCs throughout the SCB food web.

Objective: Investment in salmon habitat restoration often focuses on natal streams, with a goal of improving access for spawning fish and increasing early life survival of juveniles. This work is justified by a large body of research; however, return on investment in natal streams (at least in terms of increased adult abundance) has, so far, been marginally successful at best. The factors that constrain salmon populations may shift in space and time, and accurately tracking these constraints requires monitoring the full spatial and temporal scope of the salmon life cycle. In particular, juvenile salmon emigration through main-stem rivers to the ocean is not well studied and is poorly understood. Low emigration survival can prevent successful upstream habitat restoration from being realized as increased adult recruitment. Methods: We present acoustic telemetry studies from two coastal California rivers to estimate seaward emigration survival of Coho Salmon Oncorhynchus kisutch from their natal streams. We contrast emigration survival with other life stages and with relative restoration investment in main-stem rivers. Results: In both watersheds, survival was low and highly variable across years. Main-stem river segments had the lowest survival, and survival was lower for migrants that traveled greater lengths in risky main stems. Main-stem emigration occurred over a very short time span, yet survival was similar to or lower than that of other juvenile freshwater life stages (e.g., oversummer and overwinter survival), which occur over much longer time spans. We also found that later emigrants had lower survival than earlier emigrants in both rivers. A summary of restoration investment in both watersheds indicates that much less planning and restoration implementation is occurring in main-stem rivers than in small natal streams. Conclusions: Taken together, our results suggest that juvenile emigration success is likely an important constraint on salmon population recovery. Greater understanding of and greater investment in main-stem rivers are sorely needed.