Non‐stationary effects of multiple drivers on the dynamics of Japanese sardine (Sardinops melanostictus, Clupeidae)
Fish and Fisheries
Non‐stationary driver‐response relationships are increasingly being recognized by scientists, und... more Non‐stationary driver‐response relationships are increasingly being recognized by scientists, underlining that a paradigm shift out of conventional stationary relationships is crucial. Japanese sardine (Sardinops melanostictus, Clupeidae) is a typical small pelagic fish in the northwestern Pacific with considerable fluctuations in productivity, bringing about great economic and ecological concerns. Numerous studies suggest that the population dynamics of Japanese sardine is an integrated process affected by multiple density‐dependent, fishing and climatic drivers. However, little has hitherto been done to incorporate the non‐stationary effects of multiple drivers, impeding progresses in understanding the population dynamics and in developing management strategies. In this study, we adopted variable coefficients generalized additive models to reveal the non‐stationary effects of density dependence, fishing pressure and climatic conditions on the population dynamics of Japanese sardin...
Due to persistent fishing expansion in the China Seas over the past six decades, fisheries resour... more Due to persistent fishing expansion in the China Seas over the past six decades, fisheries resources have been over-exploited; as a result, exploited fish have become smaller in size and younger in age. Marine piscivorous fish constituted a large portion of Chinese fisheries catch, long-term variability of which has rarely been investigated despite intense fishing pressure and climate change. In this study, we attempt to identify their responses to climate change and fishing activities and to provide scientific basis for sustainable exploitation of these resources. Seven taxa from pelagic to demersal species inhabiting either cold-water or warm-water were selected to represent the piscivorous fish assemblage in the China Seas. Total catch of these piscivorous fish in the China Seas increased during the early 1990s, stabilizing around 1.2 million tons after 1997. Principal component analysis (PCA) showed evident interannual-decadal variabilities in the catch of these fish with step c...
Climate‐induced nonlinearity in pelagic communities and non‐stationary relationships with physical drivers in the Kuroshio ecosystem
Fish and Fisheries, 2020
Climate‐induced nonlinearity in biological variability and non‐stationary relationships with phys... more Climate‐induced nonlinearity in biological variability and non‐stationary relationships with physical drivers are crucial to understand responses of marine organisms to climate variability. These phenomena have raised concerns in the northeastern North Pacific, but are out of the spotlight in the northwestern North Pacific in spite of potential implications for this productive system under increased climate variability. Pelagic communities in the Kuroshio ecosystem have both ecological and economic importance. However, patterns of climate‐induced nonlinearity in pelagic communities are not well understood, and existence of non‐stationarity in their relationships with physical drivers remains obscure. Here, we compile large numbers of climatic, oceanic and biological long‐term time‐series data and employ diverse statistical techniques to reveal such climate‐induced nonlinearity and non‐stationarity. Results show that pelagic communities in the Tsushima and Pacific areas (major areas ...
The lack o f basic knowledge on stock dynamics o f northern shrimp Pandalus borealis, a protandri... more The lack o f basic knowledge on stock dynamics o f northern shrimp Pandalus borealis, a protandric hermaphrodite, has caused difficulty in regulating fishing effort on a scientific basis and in understanding potential causes behind population fluctuations and collapses. Previous length-based population models (LBMs), developed for other species, are undesirable primarily for two reasons: (1) individual cohort dynamics are masked; (2) variations in annual natural mortality (M) are ignored. This research was primarily aimed at developing a more advanced LBM that provides estimates o f parameters such as recruitment (R), fishing mortality (F) and especially annual M. Simulation-estimation experiments were conducted to evaluate model performance. Despite model complexity, annual M ean be well estimated provided measurement errors in survey biomass estimates are low. The common assumption o f constant M created biased parameter estimates. Estimated M o f P. borealis in Kachemak Bay, Alas...
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Ecosystem indicatorsfor variability in species’trophic levels Jodie Reed, Lynne Shannon, Laure Velez, Ekin Akoglu, Alida Bundy, Marta Coll, Caihong Fu, Elizabeth A. Fulton, Arnaud Grüss, Ghassen Halouani, et al.
Please note that this is an author-produced PDF of an article accepted for publication following ... more Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.
Journal of Northwest Atlantic Fishery Science, 2000
In general, dynamics of a population are governed by natural mortality (M) and a spawner-recruit ... more In general, dynamics of a population are governed by natural mortality (M) and a spawner-recruit relationship (S-R). Two models of M (constant and increasing M both with lognormal error of CV of 20%) and recruitment (R) (constant and Beverton-Holt (B-H) R both with lognormal error of CV of 50%) were examined for a simulated population with population parameters identical to those estimated for the pink shrimp population in Kachemak Bay. Fishing was simulated with 6 levels of constant harvest rates (0.0 to 0.9) and 3 levels of threshold (0 to 40% of virgin spawning stock biomass (SSB 0)). With constant M ≤ 0.4, no threshold management was necessary under optimal harvesting. For a population of constant R, threshold management only resulted in lower yield, but had little effect on population sustainability. But threshold management was essential to prevent a population with B-H R from crashing. In light of the importance of the M and S-R relationships, pre-season management was conducted with M and R higher than, lower than, or equal to their true levels. Survey sampling was assumed to occur once every 1 to 3 years. A too low specification of M resulted in higher cumulative yield and risk regardless of sampling frequency. But more frequent sampling helped reduce the risk. On the other hand, mis-specification of R had very little effect on forecasting population abundance if the population was sampled annually. Less frequent sampling induced higher risk if R was specified too high, but it had little effect if R was specified too low. In conclusion, frequent sampling and good understanding of M are most important for sound management of the shrimp fishery.
Fish community structure (FCS) of the Yellow Sea (YS) is affected by multiple pressures. Quantify... more Fish community structure (FCS) of the Yellow Sea (YS) is affected by multiple pressures. Quantifying the responses of indicators of FCS (IFCSs) to pressures is a key aspect of ecosystem-based fisheries management. Quantitative methodology has hitherto been rarely applied to evaluate the performance of ecological indicators in response to physical and anthropogenic pressures and management actions. In this study, we adopted a quantitative and flexible framework to quantify the performance of IFCSs in the YS as well as to identify a suite of operational IFCSs to evaluate the status of the FCS via two state-space approaches. A total of 22 IFCSs were tested for their responses to three types of pressures including anthropogenic activities (fishing), large-scale climate change, and regional environmental variables. Our results indicate that the majority of IFCSs have good performance in terms of sensitivity in their responses to pressures, but weak performance in terms of robustness. The...
In the context of ecosystem-based fisheries management, which should consider changing and uncert... more In the context of ecosystem-based fisheries management, which should consider changing and uncertain environmental conditions, the development of ecosystem-based biological reference points (EBRPs) to account for important multi-species (MS) interactions, fishery operations, and climate change, is of paramount importance for sustainable fisheries management. However, EBRPs under varying plankton productivity states and fisheries management strategies are seldom developed, and the ecosystem effects of these changes are still largely unknown. In this study, ecosystem-based FMSY (fishing mortality rate at MSY) values were estimated within an end-to-end ecosystem model (OSMOSE) for three focused fish species (Pacific Herring, Clupea pallasii; Pacific Cod, Gadus macrocephalus; Lingcod, Ophiodon elongatus) under three plankton productivity states of differing plankton biomass at high, current, and low levels. In addition, ecosystem effects were compared across different plankton productiv...
Understanding what drives the population-and community-scale consequences of predator-prey intera... more Understanding what drives the population-and community-scale consequences of predator-prey interactions is a key question in ecology. The strength of predator control and trophic cascades is remarkably variable among systems, even within a system type (Pace, Cole,
to categorizing and exploring cumulative risk can be applied to evaluate other community properti... more to categorizing and exploring cumulative risk can be applied to evaluate other community properties and indicators and our findings could provide guidance in fisheries management.
Ecosystem models are valuable tools for informing fisheries management due to their ability to si... more Ecosystem models are valuable tools for informing fisheries management due to their ability to simulate the spatial dynamics of modelled species, their trophic interactions, and their responses to fishing in an ecosystem context. In this study, we developed an OSMOSE (Object-oriented Simulator of Marine Ecosystems Exploitation) model for the Pacific North Coast Integrated Management Area (PNCIMA) ecosystem off western Canada, which simulated the entire life cycle of six key species and for the first time integrated spatial population structure and “background” taxa. Background taxa are of secondary importance for the study at hand but have the potential to be important prey or predators of the key species. The primary aim of the study was to explore how the population dynamics of the key species differed over time and different management areas, with results focusing on Pacific Herring (Clupea pallasii) and Pacific Cod (Gadus macrocephalus) that have been assessed on a single-specie...
ICES Journal of Marine Science: Journal du Conseil, 2016
Trophic level (TL)-based indicators are commonly used to track the ecosystem effects of fishing a... more Trophic level (TL)-based indicators are commonly used to track the ecosystem effects of fishing as the selective removal of organisms from the food web may result in changes to the trophic structure of marine ecosystems. The use of a fixed TL per species in the calculation of TL-based indicators has been questioned, given that species’ TLs vary with ontogeny, as well as over time and space. We conducted a model-based assessment of the performance of fixed TL-based indicators vs. variable TL-based indicators for tracking the effects of fishing pressure. This assessment considered three TL-based indicators (the trophic level of the landed catch (TLc), the marine trophic index (MTI) and the trophic level of the surveyed community (TLsc)), three fishing scenarios that targeted specific model groups (the low TL scenario (LTL), the high TL scenario (HTL) and a scenario encompassing broad-scale exploitation (ALL)) and ten contrasting marine ecosystems with four types of ecosystem modelling...
To improve the ability of managers to make appropriate decisions, we analyzed chum salmon Oncorhy... more To improve the ability of managers to make appropriate decisions, we analyzed chum salmon Oncorhynchus keta data from central British Columbia and evaluated alternative escapement goals and the potential impacts of environmental change on fishery performance.Fishery performance was expressed in terms of mean catch and the probability of annualcatches exceeding 100,000 fish. We investigated Ricker and Beverton–Holt stock–recruitmentrelationships and tested if environmental variation as reflected by sea surface temperature anomalies (SSTA) improved these relationships. Uncertainties associated with stock–recruitment model parameters were evaluated using a Bayesian approach. Posterior distributions of the parameters were generated using Monte Carlo Markov Chain procedures. Our data set was relatively informative as reflected by the well defined probability distributions of the stock– recruitment parameters. Fishery performance was assessed through stochastic projections over three gene...
Non‐stationary effects of multiple drivers on the dynamics of Japanese sardine (Sardinops melanostictus, Clupeidae)
Fish and Fisheries
Non‐stationary driver‐response relationships are increasingly being recognized by scientists, und... more Non‐stationary driver‐response relationships are increasingly being recognized by scientists, underlining that a paradigm shift out of conventional stationary relationships is crucial. Japanese sardine (Sardinops melanostictus, Clupeidae) is a typical small pelagic fish in the northwestern Pacific with considerable fluctuations in productivity, bringing about great economic and ecological concerns. Numerous studies suggest that the population dynamics of Japanese sardine is an integrated process affected by multiple density‐dependent, fishing and climatic drivers. However, little has hitherto been done to incorporate the non‐stationary effects of multiple drivers, impeding progresses in understanding the population dynamics and in developing management strategies. In this study, we adopted variable coefficients generalized additive models to reveal the non‐stationary effects of density dependence, fishing pressure and climatic conditions on the population dynamics of Japanese sardin...
Due to persistent fishing expansion in the China Seas over the past six decades, fisheries resour... more Due to persistent fishing expansion in the China Seas over the past six decades, fisheries resources have been over-exploited; as a result, exploited fish have become smaller in size and younger in age. Marine piscivorous fish constituted a large portion of Chinese fisheries catch, long-term variability of which has rarely been investigated despite intense fishing pressure and climate change. In this study, we attempt to identify their responses to climate change and fishing activities and to provide scientific basis for sustainable exploitation of these resources. Seven taxa from pelagic to demersal species inhabiting either cold-water or warm-water were selected to represent the piscivorous fish assemblage in the China Seas. Total catch of these piscivorous fish in the China Seas increased during the early 1990s, stabilizing around 1.2 million tons after 1997. Principal component analysis (PCA) showed evident interannual-decadal variabilities in the catch of these fish with step c...
Climate‐induced nonlinearity in pelagic communities and non‐stationary relationships with physical drivers in the Kuroshio ecosystem
Fish and Fisheries, 2020
Climate‐induced nonlinearity in biological variability and non‐stationary relationships with phys... more Climate‐induced nonlinearity in biological variability and non‐stationary relationships with physical drivers are crucial to understand responses of marine organisms to climate variability. These phenomena have raised concerns in the northeastern North Pacific, but are out of the spotlight in the northwestern North Pacific in spite of potential implications for this productive system under increased climate variability. Pelagic communities in the Kuroshio ecosystem have both ecological and economic importance. However, patterns of climate‐induced nonlinearity in pelagic communities are not well understood, and existence of non‐stationarity in their relationships with physical drivers remains obscure. Here, we compile large numbers of climatic, oceanic and biological long‐term time‐series data and employ diverse statistical techniques to reveal such climate‐induced nonlinearity and non‐stationarity. Results show that pelagic communities in the Tsushima and Pacific areas (major areas ...
The lack o f basic knowledge on stock dynamics o f northern shrimp Pandalus borealis, a protandri... more The lack o f basic knowledge on stock dynamics o f northern shrimp Pandalus borealis, a protandric hermaphrodite, has caused difficulty in regulating fishing effort on a scientific basis and in understanding potential causes behind population fluctuations and collapses. Previous length-based population models (LBMs), developed for other species, are undesirable primarily for two reasons: (1) individual cohort dynamics are masked; (2) variations in annual natural mortality (M) are ignored. This research was primarily aimed at developing a more advanced LBM that provides estimates o f parameters such as recruitment (R), fishing mortality (F) and especially annual M. Simulation-estimation experiments were conducted to evaluate model performance. Despite model complexity, annual M ean be well estimated provided measurement errors in survey biomass estimates are low. The common assumption o f constant M created biased parameter estimates. Estimated M o f P. borealis in Kachemak Bay, Alas...
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Ecosystem indicatorsfor variability in species’trophic levels Jodie Reed, Lynne Shannon, Laure Velez, Ekin Akoglu, Alida Bundy, Marta Coll, Caihong Fu, Elizabeth A. Fulton, Arnaud Grüss, Ghassen Halouani, et al.
Please note that this is an author-produced PDF of an article accepted for publication following ... more Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.
Journal of Northwest Atlantic Fishery Science, 2000
In general, dynamics of a population are governed by natural mortality (M) and a spawner-recruit ... more In general, dynamics of a population are governed by natural mortality (M) and a spawner-recruit relationship (S-R). Two models of M (constant and increasing M both with lognormal error of CV of 20%) and recruitment (R) (constant and Beverton-Holt (B-H) R both with lognormal error of CV of 50%) were examined for a simulated population with population parameters identical to those estimated for the pink shrimp population in Kachemak Bay. Fishing was simulated with 6 levels of constant harvest rates (0.0 to 0.9) and 3 levels of threshold (0 to 40% of virgin spawning stock biomass (SSB 0)). With constant M ≤ 0.4, no threshold management was necessary under optimal harvesting. For a population of constant R, threshold management only resulted in lower yield, but had little effect on population sustainability. But threshold management was essential to prevent a population with B-H R from crashing. In light of the importance of the M and S-R relationships, pre-season management was conducted with M and R higher than, lower than, or equal to their true levels. Survey sampling was assumed to occur once every 1 to 3 years. A too low specification of M resulted in higher cumulative yield and risk regardless of sampling frequency. But more frequent sampling helped reduce the risk. On the other hand, mis-specification of R had very little effect on forecasting population abundance if the population was sampled annually. Less frequent sampling induced higher risk if R was specified too high, but it had little effect if R was specified too low. In conclusion, frequent sampling and good understanding of M are most important for sound management of the shrimp fishery.
Fish community structure (FCS) of the Yellow Sea (YS) is affected by multiple pressures. Quantify... more Fish community structure (FCS) of the Yellow Sea (YS) is affected by multiple pressures. Quantifying the responses of indicators of FCS (IFCSs) to pressures is a key aspect of ecosystem-based fisheries management. Quantitative methodology has hitherto been rarely applied to evaluate the performance of ecological indicators in response to physical and anthropogenic pressures and management actions. In this study, we adopted a quantitative and flexible framework to quantify the performance of IFCSs in the YS as well as to identify a suite of operational IFCSs to evaluate the status of the FCS via two state-space approaches. A total of 22 IFCSs were tested for their responses to three types of pressures including anthropogenic activities (fishing), large-scale climate change, and regional environmental variables. Our results indicate that the majority of IFCSs have good performance in terms of sensitivity in their responses to pressures, but weak performance in terms of robustness. The...
In the context of ecosystem-based fisheries management, which should consider changing and uncert... more In the context of ecosystem-based fisheries management, which should consider changing and uncertain environmental conditions, the development of ecosystem-based biological reference points (EBRPs) to account for important multi-species (MS) interactions, fishery operations, and climate change, is of paramount importance for sustainable fisheries management. However, EBRPs under varying plankton productivity states and fisheries management strategies are seldom developed, and the ecosystem effects of these changes are still largely unknown. In this study, ecosystem-based FMSY (fishing mortality rate at MSY) values were estimated within an end-to-end ecosystem model (OSMOSE) for three focused fish species (Pacific Herring, Clupea pallasii; Pacific Cod, Gadus macrocephalus; Lingcod, Ophiodon elongatus) under three plankton productivity states of differing plankton biomass at high, current, and low levels. In addition, ecosystem effects were compared across different plankton productiv...
Understanding what drives the population-and community-scale consequences of predator-prey intera... more Understanding what drives the population-and community-scale consequences of predator-prey interactions is a key question in ecology. The strength of predator control and trophic cascades is remarkably variable among systems, even within a system type (Pace, Cole,
to categorizing and exploring cumulative risk can be applied to evaluate other community properti... more to categorizing and exploring cumulative risk can be applied to evaluate other community properties and indicators and our findings could provide guidance in fisheries management.
Ecosystem models are valuable tools for informing fisheries management due to their ability to si... more Ecosystem models are valuable tools for informing fisheries management due to their ability to simulate the spatial dynamics of modelled species, their trophic interactions, and their responses to fishing in an ecosystem context. In this study, we developed an OSMOSE (Object-oriented Simulator of Marine Ecosystems Exploitation) model for the Pacific North Coast Integrated Management Area (PNCIMA) ecosystem off western Canada, which simulated the entire life cycle of six key species and for the first time integrated spatial population structure and “background” taxa. Background taxa are of secondary importance for the study at hand but have the potential to be important prey or predators of the key species. The primary aim of the study was to explore how the population dynamics of the key species differed over time and different management areas, with results focusing on Pacific Herring (Clupea pallasii) and Pacific Cod (Gadus macrocephalus) that have been assessed on a single-specie...
ICES Journal of Marine Science: Journal du Conseil, 2016
Trophic level (TL)-based indicators are commonly used to track the ecosystem effects of fishing a... more Trophic level (TL)-based indicators are commonly used to track the ecosystem effects of fishing as the selective removal of organisms from the food web may result in changes to the trophic structure of marine ecosystems. The use of a fixed TL per species in the calculation of TL-based indicators has been questioned, given that species’ TLs vary with ontogeny, as well as over time and space. We conducted a model-based assessment of the performance of fixed TL-based indicators vs. variable TL-based indicators for tracking the effects of fishing pressure. This assessment considered three TL-based indicators (the trophic level of the landed catch (TLc), the marine trophic index (MTI) and the trophic level of the surveyed community (TLsc)), three fishing scenarios that targeted specific model groups (the low TL scenario (LTL), the high TL scenario (HTL) and a scenario encompassing broad-scale exploitation (ALL)) and ten contrasting marine ecosystems with four types of ecosystem modelling...
To improve the ability of managers to make appropriate decisions, we analyzed chum salmon Oncorhy... more To improve the ability of managers to make appropriate decisions, we analyzed chum salmon Oncorhynchus keta data from central British Columbia and evaluated alternative escapement goals and the potential impacts of environmental change on fishery performance.Fishery performance was expressed in terms of mean catch and the probability of annualcatches exceeding 100,000 fish. We investigated Ricker and Beverton–Holt stock–recruitmentrelationships and tested if environmental variation as reflected by sea surface temperature anomalies (SSTA) improved these relationships. Uncertainties associated with stock–recruitment model parameters were evaluated using a Bayesian approach. Posterior distributions of the parameters were generated using Monte Carlo Markov Chain procedures. Our data set was relatively informative as reflected by the well defined probability distributions of the stock– recruitment parameters. Fishery performance was assessed through stochastic projections over three gene...
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