A comparison of the Bering Sea, Gulf of Alaska, and Aleutian Islands large marine ecosystems through food web modeling / by K. Aydin ... [et al.]

Detailed mass balance food web models were constructed to compare ecosystem characteristics for three Alaska regions: the eastern Bering Sea (EBS), the Gulf of Alaska (GOA), and the Aleutian Islands (AI). This paper documents the methods and data used to construct the models and compares ecosystem structure and indicators across models. The common modeling framework, including biomass pool and fishery definitions, resulted in comparable food webs for the three ecosystems which showed that they all have the same apex predator—the Pacific halibut longline fishery. However, despite the similar methods used to construct the models, the data from each system included in the analysis clearly define differences in food web structure which may be important considerations for fishery management in Alaska ecosystems. The results showed that the EBS ecosystem has a much larger benthic influence in its food web than either the GOA or the AI. Conversely, the AI ecosystem has the strongest pelagic influence in its food web relative to the other two systems. The GOA ecosystem appears balanced between benthic and pelagic pathways, but is notable in having a smaller fisheries catch relative to the other two systems, and a high biomass of fish predators above trophic level (TL) 4, arrowtooth flounder and halibut. The patterns visible in aggregated food webs were confirmed in additional more detailed analyses of biomass and consumption in each ecosystem, using both the single species and whole ecosystem indicators developed here

Government-Industry Cooperative Fisheries Research in the North Pacific under the MSFCMA

The National Marine Fisheries Service’s Alaska Fisheries Science Center (AFSC) has a long and successful history of conducting research in cooperation with the fishing industry. Many of the AFSC’s annual resource assessment surveys are carried out aboard chartered commercial vessels and the skill and experience of captains and crew are integral to the success of this work. Fishing companies have been contracted to provide vessels and expertise for many different types of research, including testing and evaluation of survey and commercial fishing gear and development of improved methods for estimating commercial catch quantity and composition. AFSC scientists have also participated in a number of industry-initiated research projects including development of selective fishing gears for bycatch reduction and evaluating and improving observer catch composition sampling. In this paper, we describe the legal and regulatory provisions for these types of cooperative work and present examples to illustrate the process and identify the requirements for successful cooperative research

A cross-ecosystem comparison of temporal variability in recruitment of functionally analogous fish stocks

As part of the international MENU collaboration, variability in temporal patterns of recruitment and spawning stock were compared among functionally analogous species from four marine ecosystems including the Gulf of Maine/Georges Bank, the Norwegian/Barents Seas, the eastern Bering Sea and the Gulf of Alaska. Variability was characterized by calculating coefficients of variation for each time series and by representing the time series as anomalies. Patterns of synchrony and asynchrony in recruitment and spawning stock indices were examined among and between ecosystems and related to observed patterns in biophysical properties (e.g. local trophodynamics, local hydrography and large scale climate indices) using a wide range of time series analyses, autocorrelation corrections, autoregressive processes, and multivariate cross-correlation analyses. Of all the commonalities, the relatively similar cross-ecosystem and within-species magnitude of variation was most notable. Of all the differences, the timing of high or low recruitment years across both species and ecosystems was most notable. However, many of the peaks in these indices of recruitment were synchronous across ecosystems for functionally analogous species. Yet the relationships (or lack thereof) between recruitment anomalies and key biophysical properties demonstrated that no one factor consistently caused large recruitment events. Our observations also suggested that there was no routine and common set of factors that influences recruitment; often multiple factors were of similar relative prominence. This work demonstrates that commonalities and synchronies in recruitment fluctuations can be found across geographically very distant ecosystems, but biophysical causes of the fluctuations are difficult to partition. Keywords: Ecosystem, recruitment, trophodynamics, variation

A comparison of community and trophic structure in five marine ecosystems based on energy budgets and system metrics

As part of the international MENU collaboration, energy budget models for five marine ecosystems were compared to identify differences and similarities in trophic and community characteristics across ecosystems. We examined the Gulf of Maine and Georges Bank in the Northwest Atlantic Ocean, the combined Norwegian/Barents Seas in the Northeast Atlantic Ocean, and the eastern Bering Sea and the Gulf of Alaska in the Northeast Pacific Ocean. Comparable energy budgets were constructed for each ecosystem by aggregating information for similar species groups into consistent functional groups across all five ecosystems. Several ecosystem metrics (including functional group production, consumption, and biomass ratios, ABC curves, cumulative biomass, food web macrodescriptors, and network metrics) were examined across the ecosystems. The comparative approach clearly identified data gaps for each ecosystem, an important outcome of this work. Commonalities across the ecosystems included overall high primary production and energy flow at low trophic levels, high production and consumption by carnivorous zooplankton, and similar proportions of apex predator to lower trophic level biomass. Major differences included distinct biomass ratios of pelagic to demersal fish, ranging from highest in the Norwegian/Barents ecosystem to lowest in the Alaskan systems, and notable gradients in primary production per unit area, highest in the Alaskan and Georges Bank/Gulf of Maine ecosystems, and lowest in the Norwegian ecosystems. While comparing a disparate group of organisms across a wide range of marine ecosystems is challenging, this work demonstrates that standardized metrics both elucidate properties common to marine ecosystems and identify key distinctions for fishery management

Motorcycle Helmet Effectiveness in Reducing Head, Face and Brain Injuries by State and Helmet Law

Background: Despite evidence that motorcycle helmets reduce morbidity and mortality, helmet laws and rates of helmet use vary by state in the U.S. Methods: We pooled data from eleven states: five with universal laws requiring all motorcyclists to wear a helmet, and six with partial laws requiring only a subset of motorcyclists to wear a helmet. Data were combined in the Crash Outcome Data Evaluation System\u27s General Use Model and included motorcycle crash records probabilistically linked to emergency department and inpatient discharges for years 2005-2008. Medical outcomes were compared between partial and universal helmet law settings. We estimated adjusted relative risks (RR) and 95 % confidence intervals (CIs) for head, facial, traumatic brain, and moderate to severe head/facial injuries associated with helmet use within each helmet law setting using generalized log-binomial regression. Results: Reported helmet use was higher in universal law states (88 % vs. 42 %). Median charges, adjusted for inflation and differences in state-incomes, were higher in partial law states (emergency department $1987 vs.$1443; inpatient $31,506 vs.$25,949). Injuries to the head and face, including traumatic brain injuries, were more common in partial law states. Effectiveness estimates of helmet use were higher in partial law states (adjusted-RR (CI) of head injury: 2.1 (1.9-2.2) partial law single vehicle; 1.4 (1.2, 1.6) universal law single vehicle; 1.8 (1.6-2.0) partial law multi-vehicle; 1.2 (1.1-1.4) universal law multi-vehicle). Conclusions: Medical charges and rates of head, facial, and brain injuries among motorcyclists were lower in universal law states. Helmets were effective in reducing injury in both helmet law settings; lower effectiveness estimates were observed in universal law states

Trophic level determinants of biomass accumulation in marine ecosystems

Metrics representative of key ecosystem processes are required for monitoring and understanding system dynamics, as a function of ecosystem-based fisheries management (EBFM). Useful properties of such indicators should include the ability to capture the range of variation in ecosystem responses to a range of pressures, including anthropogenic (e.g. exploitation pressures) and environmental (e.g. climate pressures), as well as indirect effects (e.g. those related to food web processes). Examining modifications in ecological processes induced by structural changes, however, requires caution because of the inherent uncertainty, long feedback times, and highly nonlinear ecosystem responses to external perturbations. Yet trophodynamic indicators are able to capture important changes in marine ecosystem function as community structures have been altered. One promising family of such metrics explores the changing biomass accumulation in the middle trophic levels (TLs) of marine ecosystems. Here we compared cumulative biomass curves across TLs for a range of northern hemisphere temperate and boreal ecosystems. Our results confirm that sigmoidal patterns are consistent across different ecosystems and, on a broad scale, can be used to detect factors that most influence shifts in the cumulative biomass−TL curves. We conclude that the sigmoidal relationship of biomass accumulation curves over TLs could be another possible indicator useful for the implementation of EBFM

Implementing Ecosystem Approaches to Fishery Management: Risk Assessment in the US Mid-Atlantic

Fishery managers worldwide are evaluating methods for incorporating climate, habitat, ecological, social, and economic factors into current operations in order to implement Ecosystem Approaches to Fishery Management (EAFM). While this can seem overwhelming, it is possible to take practical steps toward EAFM implementation that make use of existing information and provide managers with valuable strategic advice. Here, we describe the process used by the U.S. Mid-Atlantic Fishery Management Council (Council) to develop an ecosystem-level risk assessment, the initial step proposed in their recently adopted EAFM guidance document. The Council first defined five types of Risk Elements (ecological, economic, social, food production, management) and identified which management objectives aligned with each element. Based on an existing ecosystem status report for the region and other existing sources (including expert opinion), potential ecological, social, economic, and management indicators were identified for each risk element. Finally, low, low-moderate, moderate-high, and high risk criteria were defined for each indicator, and the indicator data were used to score each risk element using the criteria. The ultimate outcome is a ranked risk assessment in order to focus on the highest risk issues for further evaluation and mitigation. The risk assessment highlights certain species and certain management issues as posing higher cumulative risks to meeting Council management objectives when considering a broad range of ecological, social, and economic factors. Tabular color coded summaries of risk assessment results will be used by the Council to prioritize further EAFM analyses as well as research plans over the coming 5 years. As ecosystem reporting and operational EAFM continue to evolve in future years, the Council foresees integrating these efforts so that ecosystem indicators are refined to meet the needs of fishery managers in identifying and managing risks to achieving ecological, social, and economic fishery objectives. Overall, ecosystem indicator-based risk assessment is a method that can be adapted to a wide range of resource management systems and available information, and therefore represents a promising way forward in the implementation of EAFM