CAFA Publications

Author(s): E.L. Hazen, K.L. Scales, S.M. Maxwell, D. Briscoe, H. Welch, S.J. Bograd, H. Bailey, S.R. Benson, T. Eguchi, H. Dewar, S. Kohin, D.P. Costa, L.B. Crowder, R.L. Lewison

Project PI: Jacox
DOI: 10.1126/sciadv.aar3001

Seafood is an essential source of protein for more than 3 billion people worldwide, yet bycatch of threatened species in capture fisheries remains a major impediment to fisheries sustainability. Management measures designed to reduce bycatch often result in significant economic losses and even fisheries closures. Static spatial management approaches can also be rendered ineffective by environmental variability and climate change, as productive habitats shift and introduce new interactions between human activities and protected species. We introduce a new multispecies and dynamic approach that uses daily satellite data to track ocean features and aligns scales of management, species movement, and fisheries. To accomplish this, we create species distribution models for one target species and three bycatch-sensitive species using both satellite telemetry and fisheries observer data. We then integrate species-specific probabilities of occurrence into a single predictive surface, weighing the contribution of each species by management concern. We find that dynamic closures could be 2 to 10 times smaller than existing static closures while still providing adequate protection of endangered nontarget species. Our results highlight the opportunity to implement near real-time management strategies that would both support economically viable fisheries and meet mandated conservation objectives in the face of changing ocean conditions. With recent advances in eco-informatics, dynamic management provides a new climate-ready approach to support sustainable fisheries.

Author(s): D. Politikos, E.N. Curchitser, K.A. Rose, D.M. Checkley, J. Fiechter

Project PI: Jacox
DOI: https://doi.org/10.1111/fog.12381

Recruitment varies substantially in small pelagic fish populations. Understanding of the mechanisms linking environment to recruitment is essential for the effective management of fisheries resources. In this study, we used a fully coupled end-to-end ecosystem model to study the effect of climate variability on sardine recruitment in the California Current System during 1965–2006. Ocean variability was represented by ROMS hydrodynamic and NEMURO biogeochemical models, and sardine population dynamics was simulated through a full life cycle individual-based model. Model analysis was designed to elucidate how changes in abiotic and biotic conditions may impact the spawning habitats, early life stage survival, and ultimately recruitment of sardine. Our findings revealed the importance of spatial processes to shape early life stages dynamics. Shifts in spawning habitats were dictated by the spatial variations in temperature and the behavioral movement of adults. Additionally, the spatial match of eggs with warmer temperatures and larvae with their prey influenced their survival. The northward shifts in spawning locations and the accomplishment of good recruitment in warmer years agreed with existing knowledge. Egg production and survival during egg and yolk-sac larval stages were key factors to drive the long-term variations in recruitment. Finally, our analysis provided a quantitative assessment of climate impact on year-to-year variation in sardine recruitment by integrating multiple hypotheses.

Author(s): Muhling, Barbara, et al.

Project PI: Jacox
DOI: https://calcofi.org/publications/calcofireports/v60/Vol60-Muhling.pdf

Juvenile north Pacific albacore (Thunnus alalunga) forage in the California Current System (CCS), supporting fisheries between Baja California and British Columbia. Within the CCS, their distribution, abundance, and foraging behaviors are strongly variable interannually. Here, we use catch logbook data and trawl survey records to investigate how juvenile albacore in the CCS use their oceanographic environment, and how their distributions overlap with the habitats of four key forage species. We show that northern anchovy (Engraulis mordax) and hake (Merluccius productus) habitat is associated with productive coastal waters found more inshore of core juvenile albacore habitat, whereas Pacific sardine (Sardinops sagax) and boreal clubhook squid (Onychoteuthis borealijaponica) habitat overlaps more consistently with that of albacore. Our results can improve understanding of how albacore movements relate to foraging strategies, and why preyswitching behavior occurs. This has relevance for the development of ecosystem models for the CCS, and for the eventual implementation of ecosystem-based fishery management.

Author(s): Smith, J. A., Muhling, B., Sweeney, J., Tommasi, D., Pozo Buil, M., Fiechter, J., & Jacox, M. G.

Project PI: Jacox
DOI: https://doi.org/10.1111/fog.12529

Many fish species are shifting spatial distributions in response to climate change, but projecting these shifts and measuring their impact at fine scales are challenging. We present a simulation that projects change in fishery landings due to spatial distribution shifts, by combining regional ocean and biogeochemical models (forced by three earth system models, ESMs: GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-MR), correlative models for species distribution and port-level landings, and a simulation framework which provides realistic values for species abundance and fishery conditions using an historical “reference period”. We demonstrate this approach for the northern subpopulation of Pacific sardine, an iconic commercial species for the U.S. West Coast. We found a northward shift in sardine landings (based on the northern subpopulation's habitat suitability), with projected declines at southern ports (20%–50% decline by 2080) and an increase (up to 50%) or no change at northern ports, and this was consistent across the three ESMs. Total sardine landings were more uncertain, with HadGEM2 indicating a 20% decline from 2000 to 15 levels by 2070 (a rate of 170 mt/y), IPSL a 10% increase (115 mt/y), and GFDL an 15% increase by the year ~2050 followed by a sharp decrease. The ESMs also differed in their projected change to the timing of the fishing season and frequency of fishery closures. Our simulation also identified key constraints on future landings that can be targeted by more tactical assessment; these included the seasonality of quota allocation and the abundance of other species in the catch portfolio.

Author(s): Alexander, M. A., S. Shin, J. D. Scott, E. Curchitser, C. Stock

Project PI: Jacox
DOI: https://doi.org/10.1175/JCLI-D-19-0117.1

ROMS, a high-resolution regional ocean model, was used to study how climate change may affect the northwestern Atlantic Ocean. A control (CTRL) simulation was conducted for the recent past (1976–2005), and simulations with additional forcing at the surface and lateral boundaries, obtained from three different global climate models (GCMs) using the RCP8.5 scenario, were conducted to represent the future (2070–99). The climate change response was obtained from the difference between the CTRL and each of the three future simulations. All three ROMS simulations indicated large increases in sea surface temperatures (SSTs) over most of the domain except off the eastern U.S. seaboard resulting from weakening of the Gulf Stream. There are also substantial intermodel differences in the response, including a southward shift of the Gulf Stream in one simulation and a slight northward shift in the other two, with corresponding changes in eddy activity. The depth of maximum warming varied among the three simulations, resulting in differences in the bottom temperature response in coastal regions, including the Gulf of Maine and the West Florida Shelf. The surface salinity decreased in the northern part of the domain and increased in the south in all three experiments, although the freshening extended much farther south in one ROMS simulation relative to the other two, and also relative to the GCM that provided the large-scale forcing. Thus, while high resolution allows for a better representation of currents and bathymetry, the response to climate change can vary considerably depending on the large-scale forcing.

Author(s): Slesinger, E., Saba, G., Young, R., Andres, A., Saba, V., Phelan, B., Rosendale, J., Wieczorek, D., Seibel, B.

Project PI: Saba
DOI: https://doi.org/10.1371/journal.pone.0244002

Over the last decade, ocean temperature on the U.S. Northeast Continental Shelf (U.S. NES) has warmed faster than the global average and is associated with observed distribution changes of the northern stock of black sea bass (Centropristis striata). Mechanistic models based on physiological responses to environmental conditions can improve future habitat suitability projections. We measured maximum, standard metabolic rate, and hypoxia tolerance (Scrit) of the northern adult black sea bass stock to assess performance across the known temperature range of the species. Two methods, chase and swim-flume, were employed to obtain maximum metabolic rate to examine whether the methods varied, and if so, the impact on absolute aerobic scope. A subset of individuals was held at 30˚C for one month (30chronic˚C) prior to experiments to test acclimation potential. Absolute aerobic scope (maximum–standard metabolic rate) reached a maximum of 367.21 mgO2 kg-1 hr-1 at 24.4˚C while Scrit continued to increase in proportion to standard metabolic rate up to 30˚C. The 30chronic˚C group exhibited a significantly lower maximum metabolic rate and absolute aerobic scope in relation to the short-term acclimated group, but standard metabolic rate or Scrit were not affected. This suggests a decline in performance of oxygen demand processes (e.g. muscle contraction) beyond 24˚C despite maintenance of oxygen supply. The Metabolic Index, calculated from Scrit as an estimate of potential aerobic scope, closely matched the measured factorial aerobic scope (maximum / standard metabolic rate) and declined with increasing temperature to a minimum below 3. This may represent a critical threshold value for the species. With temperatures on the U.S. NES projected to increase above 24˚C in the next 80-years in the southern portion of the northern stock’s range, it is likely black sea bass range will continue to shift poleward as the ocean continues to warm.

Author(s): McClenachan L, SB Scyphers, JH Grabowski

Project PI: Scyphers
DOI: https://doi.org/10.1007/s13280-019-01156-3

The ability of resource-dependent communities to adapt to climate change depends in part on their perceptions and prioritization of specific climate-related threats. In the Maine lobster fishery, which is highly vulnerable to warming water associated with climate change, we found a strong majority (84%) of fishers viewed warming water as a threat, but rank its impacts lower than other drivers of change (e.g., pollution). Two-thirds believed they will be personally affected by warming waters, but only half had plans to adapt. Those with adaptation plans demonstrated fundamentally different views of human agency in this system, observing greater anthropogenic threats, but also a greater ability to control the fishery through their own actions on the water and fisheries management processes. Lack of adaptation planning was linked to the view that warming waters result from natural cycles, and the expectation that technological advancements will help buffer the industry from warming waters.

Author(s): McClenachan L, M Marra, N Record, J Grabowski, B Neal, SB Scyphers.

Project PI: Scyphers
DOI: https://doi.org/10.1111/faf.12400

Climate-driven warming has both social and ecological effects on marine fisheries. While recent changes due to anthropogenic global warming have been documented, similar basin-wide changes have occurred in the past due to natural temperature fluctuations. Here, we document the effects of rapidly changing water temperatures along the United States’ east coast using observations from fisheries newspapers during a warming phase (1945–1951) and subsequent cooling phase (1952–1960) of the Atlantic Multidecadal Oscillation, which we compared to similar recent observations of warming waters (1998–2017). Historical warming and cooling events affected the abundance of species targeted by fishing, the prevalence of novel and invasive species, and physical access to targeted species. Fishing communities viewed historical cooling waters twice as negatively as they did warming waters (72% vs. 35% of observations). Colder waters were associated with a decrease in fishing opportunity due to storminess, while warming waters were associated with the potential for new fisheries. In contrast, recent warming waters were viewed as strongly negative by fishing communities (72% of observations), associated with disease, reductions in abundances of target species, and shifts in distributions across jurisdictional lines. This increasing perception that warming negatively affects local fisheries may be due to an overall reduction of opportunity in fisheries over the past half century, an awareness of the relative severity of warming today, larger changes in American culture, or a combination of these factors. Negative perceptions of recent warming waters’ effects on fisheries suggest that fishing communities are currently finding the prospect of climate adaptation difficult.

Author(s): Gray SA, SB Scyphers

Project PI: Scyphers
DOI: https://doi.org/10.1016/B978-0-12-805375-1.00022-2

Including stakeholders in environmental monitoring and research has been an increasingly recognized necessity for understanding the complex nature of marine social–ecological systems (SES). Stakeholder engagement and participation is often an essential ingredient for successful conservation and management. As a result, new inclusive approaches to scientific research have emerged under a broad umbrella often referred to as “citizen science.” These are collaborative research efforts that include stakeholders in the scientific process and strive to in various ways (1) decrease uncertainty of the dynamics of marine SES through collaborative data collection; (2) harness the expertise and knowledge of stakeholders that rely on marine resources to better understand these systems; and (3) provide a venue for more inclusive forms of resource and ecosystem management decision-making. Although the literature on citizen science shows that it is a popular way to collaboratively understand and collaboratively make decisions about natural resources, to date there is little information about how citizen science can specifically support social–ecological research and participatory decision-making in marine systems. In this chapter, we provide an overview of how participatory approaches to citizen science have been applied in marine research. Further, we theorize about the role that emerging online technologies may play in the future for collaborative science, decision-making, and marine policy.

Author(s): Tableau, A., J.S. Collie, R. Bell, and C. Minto

Project PI: Collie
DOI: https://doi.org/10.1139/cjfas-2018-0255

The Northwest Atlantic continental shelf is a large ecosystem undergoing rapid environmental changes, which are expected to modify the productivity of natural marine resources. Current management of most fished species assumes stationary production relationships or time-invariant recruitment rates. With linear state-space models, we examined the evidence of dynamic productivity for 25 stocks of the Northeast US shelf. We expanded the suite of options available within the state-space approach to produce robust estimates. Fifteen of the stocks exhibited time-varying productivity or changes in their maximum reproductive rate. Few productivity time series are related across the whole region, though adjacent stocks of the same species exhibited similar trends. Some links to region-wide environmental variables were observed. We demonstrate that fish recruitment can often be better predicted over a short-term horizon by accounting for dynamic productivity, which could be valuable for fisheries management. Improving predictions by incorporating environmental covariates or covariance among the stocks must be considered case by case and with caution, as their relationships may change over time.