George M. Watters's research while affiliated with National Oceanic and Atmospheric Administration and other places
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Publications (92)
Autonomous underwater gliders may be viable adjuncts to or in some cases replacements for ship-based oceanographic sampling. Gliders and ships acoustically sample the water column differently, with ships sampling all depths simultaneously in a single vertical pulse and gliders sampling shorter vertical segments of the water column in an up and down...
This study was performed to aid the management of the fishery for Antarctic krill Euphausia superba. Krill are an important component of the Antarctic marine ecosystem, providing a key food source for many marine predators. Additionally, krill are the target of the largest commercial fishery in the Southern Ocean, for which annual catches have been...
During austral summer 2018/2019, we deployed an array of six submerged moorings equipped with Nortek Signature100 integrated wideband echosounder and acoustic Doppler current profilers (ADCPs) on the continental shelf of the northern Antarctic Peninsula. Acoustic data from these instruments were used to classify targets, estimate water flow and the...
Antarctic fur seals (AFS) are an ecologically important predator and a focal indicator species for ecosystem-based Antarctic fisheries management. This species suffered intensive anthropogenic exploitation until the early 1900s, but recolonized most of its former distribution, including the southern-most colony at Cape Shirreff, South Shetland Isla...
Estimates of the distribution and density of Antarctic krill (Euphausia superba Dana, 1850) were
derived from a large-scale survey conducted during the austral summer in the Southwest
Atlantic sector of the Southern Ocean and across the Scotia Sea in 2018–19, the ‘2018–19
Area 48 Survey’. Survey vessels were provided by Norway, the Association of R...
As the first large-scale (>150,000 km 2) marine protected area (MPA) on the high seas, the Ross Sea region MPA sets a precedent for other MPAs in areas beyond national jurisdiction. In the myriad of MPA guides and rankings (including the new "MPA Guide"), categorization and evaluation of the Ross Sea region MPA also sets precedent for categorizing...
We compare estimates of krill density derived from gliders to those from contemporaneous and previous ship-based surveys. Our comparisons cover several temporal and spatial scales within two strata around the northern Antarctic Peninsula (off Cape Shirreff on the north side of Livingston Island and in the Bransfield Strait). Our objective is to exp...
Southern Ocean ecosystems are rapidly changing due to climate variability. An apparent beneficiary of such change in the western Antarctic Peninsula (WAP) is the gentoo penguin Pygoscelis papua, which has increased its population size and expanded its range southward in the last 20 years. To better understand how this species has responded to large...
Estimating when and where survival bottlenecks occur in free-ranging marine predators is critical for effective demographic monitoring and spatial planning. This is particularly relevant to juvenile stages of long-lived species for which direct observations of death are typically not possible. We used satellite telemetry data from fledgling Adélie,...
Marine protected areas, especially when they are or include no-take zones, can support conservation objectives by creating an area where marine organisms are protected from human disturbances, particularly fishing. The coast of the Antarctic continent is the only habitat of the iconic Adélie penguin, whose main diet is Antarctic krill. Current thre...
To implement ecosystem-based approaches to fisheries management, decision makers need insight on the potential costs and benefits of the policy options available to them. In the Southern Ocean, two such options for addressing trade-offs between krill-dependent predators and the krill fishery include "feedback management" (FBM) strategies and marine...
Overwinter environmental conditions are a major driver of larval survival, recruitment, and reproductive pre-conditioning in Antarctic krill (Euphausia superba). Few winter studies exist from which to infer impacts of changing environmental conditions on the biology of krill. Here demographic and maturity patterns of krill during five winters are e...
Efforts are underway to forward a marine protected area (MPA) in the Western Antarctic Peninsula, guided by an internationally agreed framework of protected area objectives. Preliminary MPA boundaries were evaluated against some of these objectives using a static, map-based process, yet further assessment and additional objectives could be addresse...
Both costs and benefits must be considered when implementing marine protected areas (MPAs), particularly those associated with fishing effort displaced by potential closures. The Southern Ocean offers a case study in understanding such tradeoffs, where MPAs are actively being discussed to achieve a range of protection and sustainable use objectives...
Winter sea-ice conditions are considered important for Antarctic krill Euphausia superba survival and recruitment, yet few broad-scale longitudinal studies have examined the underlying relationships between winter conditions and krill recruitment. We used data from a 4 yr winter study of krill condition (lipid content), diet (stable isotopes and fa...
Low catch limits for forage species are often considered to be precautionary measures that can help conserve marine predators. Difficulties measuring the impacts of fisheries removals on dependent predators maintain this perspective, but consideration of the spatio-temporal scales over which forage species, their predators, and fisheries interact c...
A goal of tracking migratory animals is to characterize the habitats they use and to interpret population processes with respect to conditions experienced en route to, and within, overwintering areas. For migratory seabirds with broad breeding ranges, inferring population-level effects of environmental conditions that are experienced during migrato...
Mixed trophic impact analysis.
Black indicates a negative impact, white indicates a positive impact; size of the circle indicates strength of the impact.
(TIF)
The pelagic ecosystems of the Western Antarctic Peninsula are dynamic and changing rapidly in the face of sustained warming. There is already evidence that warming may be impacting the food web. Antarctic krill, Euphausia superba, is an ice-associated species that is both an important prey item and the target of the only commercial fishery operatin...
Assimilation and production efficiency values.
(PDF)
Calibrated model results for groups without time series data.
(PDF)
Three alternative forms of the spawner-recruit relationship – the Beverton-Holt and two expressions of the Ricker function - and a fourth form representing annual recruitment deviations without an explicit relationship to spawning biomass, were applied in an integrated assessment model for Antarctic krill. Model data were from the international kri...
An integrated model assessing the status and productivity of Antarctic krill (Euphausia superba, hereafter krill) was configured to estimate different subsets of 118 potentially estimable parameters in alternative configurations. We fixed the parameters that were not estimated in any given configuration at pre-specified values. The model was fitted...
Cross-test using cfg I as the operating model and cfg XVI as the estimating model.
A) Summer IKMT pseudo-data for length compositions from 1991 to 2002 (vertical bars) and fits (lines). B) Recruitment and spawning biomass in the operating model (solid lines) and estimating model (dashed). C) Fits (lines) to fishery catches (points).
(DOCX)
Cfg XVI self-test with simulated data.
A) Summer IKMT pseudo-data for length compositions from 1991 to 2002 (vertical bars) and fits (lines). B) Recruitment and spawning biomass in the operating model (solid lines) and estimating model (dashed). C) Fits (lines) to fishery catches (points).
(DOCX)
Likelihood components for simulated data summed over catches, survey indices, compositions from surveys and the fishery, and penalties on F and recruitment for cfg I and XVI.
The first Roman numeral in the row names is the operating model and the second is the estimating model (i.e. "cfg_I_XVI" was operating model I and estimating model XVI).
(DOCX...
Estimating operating model values from cfg XVI of the product of fishery catchability and fishery mortality ln(qf)Fy fitted to pseudo-data.
(A) self-test (B) self-test with the fishing mortality penalties (Λ5,Λ6 in S1 "Model equations") removed, and (C) cross-tests with other configurations that estimated fishing mortality.
(DOCX)
Cfg I self-test with simulated data.
A) Summer IKMT pseudo-data for length compositions from 1991 to 2002 (vertical bars) and fits (lines). B) Recruitment and spawning biomass in the operating model (solid lines) and estimating model (dashed). C) Fits (lines) to fishery catches (points).
(DOCX)
Likelihood components for the original cfg I and cfg XVI fits to real data.
Components are summed over catches, surey indices, compositions from surveys and the fishery, and penalties on F and recruitment.
(DOCX)
Cross-tests for recruitment and spawning biomass using simulated data.
Cfg XI was the operating model and cfgs I, V, X, XI and XVI were estimating models.
(DOCX)
Cross-test using cfg XVI as the operating model and cfg I as the estimating model.
A) Summer IKMT pseudo-data for length compositions from 1991 to 2002 (vertical bars) and fits (lines). B) Recruitment and spawning biomass in the operating model (solid lines) and estimating model (dashed). C) Fits (lines) to fishery catches (points).
(DOCX)
Collecting spatially extensive data on phenology and reproductive success is important for seabird conservation and management, but can be logistically challenging in remote regions. Autonomous time‐lapse camera systems offer an opportunity to provide such coverage.
We describe a method to estimate nest‐level breeding phenology and reproductive suc...
Outcomes of ocean warming impacts on krill growth for whales and fish under RCP 8.5 by small-scale management unit.
Marginal impacts on whale (A) and fish (B) abundance owing to the effects of ocean warming on krill growth from RCP 8.5 by the end of the 21st century. Areas without color indicate species group are not modeled as recruiting there.
(T...
Changes in depletion due to fishing for whales and fish.
Changes in modeled SSMU-specific risk of falling below the 75% depletion threshold (i.e. depletion risk) over the 21st century for whale (A, grey) and fish (B, blue) abundance owing to scenarios with and without fishing for the RCP 2.6 (large, light circles) and RCP 8.5 (small, dark circles)...
Proportional distributions of krill catch by SSMU.
Proportions used in earlier versions of the model are under “Previous Model” (Table 2 in [13]). The updates used here, “Current Model”, are derived from catches taken during the 2009–2015 fishing seasons and under limits at finer spatial scales specified by current management [16]. Both include the...
Projected annual marginal impacts to assess lasting impacts of fishing on predator groups.
The annual marginal impacts plotted each year (x-axis) across model scenarios when fishing is stopped immediately (green), after 20 years (orange), after 45 years (gray), after 70 years (yellow), or never, for penguins (A), seals (B), whales (C), and fish (D)...
Climate change is a threat to marine ecosystems and the services they provide, and reducing fishing pressure is one option for mitigating the overall consequences for marine biota. We used a minimally realistic ecosystem model to examine how projected effects of ocean warming on the growth of Antarctic krill, Euphausia superba, might affect populat...
Outcomes of ocean warming for krill and their predators under RCP 2.6 by small-scale management unit.
Marginal impacts on krill biomass (A) and penguin (B), seal (C), whale (D), and fish (E) abundance owing to the effects of ocean warming on krill growth from RCP 2.6 by the end of the 21st century. Areas without color indicate species groups are no...
The goal of the work is establishing of CEMP camera and penguin ARGOS tags
network in Subarea 48.1 at penguin colonies at Argentine Island Archipelago as a part
of the CCAMLR/CEMP Projects, initiated by scientists from USA, Argentina, Poland and
Ukraine and suported by the CEMP Fund in 2014/15. The results of the project
fullfilment will allow anal...
Climate change will affect Antarctic krill Euphausia superba, krill-dependent predators, and fisheries in the Southern Ocean as areas typically covered by sea ice become ice-free in some winters. Research cruises conducted around the South Shet-land Islands of the Antarctic Peninsula during winters with contrasting ice conditions provide the first...
Animation of the seasonal movements of Antarctic fur seals and Adélie, chinstrap, and gentoo penguins, and the krill fishery in Subareas 48.1 and 48.2, 2009–2014.
The small-scale management unit boundaries are drawn for reference.
(MP4)
Zipped file of telemetry data, acoustic survey data for krill, and penguin and fur seal abundance data used in this analysis.
(ZIP)
Mitigating direct and indirect interactions between marine predators and fisheries is a motivating factor for ecosystem-based fisheries management (EBFM), especially where predators and fisheries compete for a shared resource. One difficulty in advancing EBFM is parameterizing clear functional responses of predators to indices of prey availability....
Animation of the seasonal movements throughout the Southern Ocean of Antarctic fur seals and Adélie, chinstrap, and gentoo penguins, 2009–2014.
(MP4)
Predator-specific maps of overlap with the krill fishery.
(DOCX)
An integrated, age-structured model was fitted to different combinations of survey data using two forms of selectivity (logistic or double-logistic) with time-constant or annually varying selectivity to investigate the population dynamics of Antarctic krill (Euphausia superba) near the Antarctic Peninsula. The data were from surveys conducted by th...
Closely related species with similar ecological requirements should exhibit segregation along spatial, temporal, or trophic niche axes to limit the degree of competitive overlap. For migratory marine organisms like seabirds, assessing such overlap during the non-breeding period is difficult because of long-distance dispersal to potentially diffuse...
Antarctic krill Euphausia superba are a key part of the marine food web and are the target of the largest fishery in the Southern Ocean. Although ecosystem and management models typically assume that krill are passive drifters, their relatively large size and strong swimming ability suggest that the active movement of krill may play an important ro...
‘Wasp-waist’ control of marine ecosystems is driven by a combination of top-down and bottom-up forcing by a few abundant short-lived species occupying intermediate trophic levels that form a narrow ‘waist’ through which energy flow from low to high trophic levels is controlled. It has been assumed that wasp-waist control occurs primarily in highly...
Decision-makers charged with implementing ecosystem-based management (EBM) rely on scientists to predict the consequences of decisions relating to multiple, potentially conflicting, objectives. Such predictions are inherently uncertain, and this can be a barrier to decision-making. The Convention on the Conservation of Antarctic Marine Living Resou...
Understanding the temporal variability in vital rates (e. g. growth and survivorship) of wild populations is practically and statistically difficult but crucial for connecting such variation to mechanistic drivers and their population consequences. For somatic growth, empirical estimates of variation are rare because they often require expensive lo...
The generalised yield model (GYM) was used by CCAMLR to establish the precautionary
catch limit for the Antarctic krill (Euphausia superba) fishery. The current precautionary
catch limit was based on supplying the GYM with a natural mortality rate of 0.8 and
recruitment variability generated using a Beta distribution for proportional recruitment of...
An ecosystem approach to fisheries management is a widely recognized goal, but describing and measuring the effects of a fishery on an ecosystem is difficult. Ecological information on the entire catch (all animals removed, whether retained or discarded) of both species targeted by the fishery and nontarget species (i.e., bycatch) is required. We u...
The West Antarctic Peninsula (WAP) and adjacent Scotia Sea support abundant wildlife populations, many of which were nearly extirpated by humans. This region is also among the fastest-warming areas on the planet, with 5-6 °C increases in mean winter air temperatures and associated decreases in winter sea-ice cover. These biological and physical per...
Positive and negative relationships between pre- and post-smolt growth rates in salmonids have been observed, but the mechanisms underlying these relationships are not understood. We hypothesize that growth at sea is controlled by interactions between behavior and ocean conditions and that no one relationship is correct. We present a growth model w...
Established in 1982, the Convention for the Conservation of Antarctic Marine Living Resources is an international treaty between 25 nations to manage fisheries in the Southern Ocean. It is extremely difficult for individual countries to enforce policies in this vast and inhospitable region, making the data-sharing aspect of the partnership extremel...
Background/Question/Methods Most of the Eastern North Pacific population of gray whales migrates annually from feeding grounds in the Arctic to breeding and calving grounds off Baja California, MX. Estimates of calf production for this population are derived from shore based surveys that have been conducted for 16 consecutive years (1994-2009) duri...
Zeidberg and Robison (1) infer that the range expansion of Dosidicus gigas resulted from a top-down cascade caused by fishing for tunas and billfishes in the eastern equatorial Pacific (EEP). We offer an alternative perspective supported on three grounds. First, the thermal tolerance and plastic life history of D. gigas provide a parsimonious expla...
![FIGURE 2.—Posterior effects on the log-odds, log e [p/(1 À p)], of...](profile/Cindy-Bessey/publication/267021506/figure/fig1/AS:392104913195012@1470496504649/Posterior-effects-on-the-log-odds-log-e-p-1-A-p-of-early-maturation-in-male-coho_Q320.jpg)
We fitted hierarchical Bayesian models to coded wire tag data and studied the variation in the
probability that male coho salmon Oncorhynchus kisutch released at 72 locations in 41 basins and 8 regions
mature early. We used data from at least 10 cohorts at each location; therefore, our analysis was both spatially
and temporally more extensive than...
Fisheries scientists habitually consider uncertainty in parameter values, but often neglect uncertainty about model structure, an issue of increasing importance as ecosystem models are devised to support the move to an ecosystem approach to fisheries (EAF). This paper sets out pragmatic approaches with which to account for uncertainties in model st...
The responses of predators to environmental variability in the Antarctic Peninsula region have exhibited divergent patterns owing to variation in the geographic settings of colonies and predator life-history strategies. Five breeding colonies of Pygoscelis penguins from King George Island and Livingston Island, South Shetland Islands, Antarctica, w...
We assess the status of 2 dolphin stocks affected by purse-seine fishing in the eastern topical Pacific and evaluate hypotheses for their lack of re- covery. We use Bayesian methods and fit generalized models of logistic population growth to abundance estimates for northeastern offshore spotted dolphins Stenella attenuata attenuata and eastern spin...
Expansion of the krill fishery in the Scotia Sea-Antarctic Peninsula region beyond the current operational catch limit requires the development and assessment of methods for subdividing the precautionary catch limit amongst smaller spatial units. This paper compiles parameters for use in the ecosystem dynamic models that are needed to assess these...
Sexual maturation profoundly affects population dynamics, but the degrees to which genetic, top-down, and bottom-up controls affect age at maturity are unclear. Salmonid fishes have plastic age at maturity, and we consider genetic and environmental effects on this trait by developing fitness functions for coho salmon (Oncorhynchus kisutch). The fun...
We used temperature and depth data from 25 archival tags carried by Chinook salmon Oncorhynchus tshawytscha at sea to explore whether and how these fish alter their patterns of habi- tat use in response to variable oceanographic conditions off the coasts of Oregon and California. The Chinook salmon persistently used a narrow range of thermal habita...
Generalizations describing how top-down and bottom-up processes jointly influence the production of offspring (recruitment) and the number of reproducing adults are lacking. This is a deficiency because (1) it is widely recognized that both top-down and bottom-up processes are common in ecosystems; and (2) the relationship between the number of ind...
