scholarly journals Trade-offs between invertebrate fisheries catches and ecosystem impacts in coastal New Zealand

2015 ◽  
Vol 72 (5) ◽  
pp. 1380-1388 ◽  
Author(s):  
Tyler D. Eddy ◽  
Marta Coll ◽  
Elizabeth A. Fulton ◽  
Heike K. Lotze
Keyword(s):  
New Zealand ◽  
Maximum Sustainable Yield ◽  
Trophic Levels ◽  
Management Approach ◽  
Ecosystem Structure ◽  
Catch Per Unit Effort ◽  
Ecosystem Impacts ◽  
Ecosystem Effects ◽  
Trade Offs ◽  
Exploitation Rate

Abstract Invertebrate catches are increasing globally following the depletion of many finfish stocks, yet stock assessments and management plans for invertebrates are limited, as is an understanding of the ecosystem effects of these fisheries. Using an ecosystem modelling approach, we explored the trade-offs between invertebrate catches and their impacts on the associated ecosystem on the south coast of Wellington, New Zealand. We simulated exploitation of lobster (Jasus edwardsii), abalone (Haliotis australis, H. iris), and sea urchin (Evechinus chloroticus) over a range of depletion levels—from no depletion to local extinction—to estimate changes in target catches and associated effects on other species groups, trophic levels, and benthic and pelagic components. Exploitation of lobster showed the strongest ecosystem effects, followed by abalone and urchin. In all three fisheries, the current exploitation rate exceeds that which produces maximum sustainable yield, with considerable ecosystem effects. Interestingly, a reduced exploitation rate is predicted to increase target catches (and catch-per-unit-effort), thereby strongly reducing ecosystem effects, a win–win situation. Our results suggest that invertebrate exploitation clearly influences ecosystem structure and function, yet the direction and magnitude of responses depend on the target group and exploitation rate. An ecosystem-based fisheries management approach that includes the role of invertebrates would improve the conservation and management of invertebrate resources and marine ecosystems on broader scales.

Effectiveness of lobster fisheries management in New Zealand and Nova Scotia from multi-species and ecosystem perspectives

2016 ◽  
Vol 74 (1) ◽  
pp. 146-157 ◽  
Author(s):  
Tyler D. Eddy ◽  
Julio N. Araújo ◽  
Alida Bundy ◽  
Elizabeth A. Fulton ◽  
Heike K. Lotze
Keyword(s):  
New Zealand ◽  
Nova Scotia ◽  
Fisheries Management ◽  
Single Species ◽  
Homarus Americanus ◽  
Maximum Sustainable Yield ◽  
Ecosystem Impacts ◽  
Ecosystem Effects ◽  
Trade Offs ◽  
Large Predators

In New Zealand and Nova Scotia, lobster (Jasus edwardsii and Homarus americanus, respectively) is the most valuable export fishery. Although stock assessments and indicators assist in evaluating lobster fisheries, ecosystem effects are largely unknown, hindering ecosystem-based fisheries management (EBFM). We employed ecosystem models for the Cook Strait, New Zealand and western Scotian Shelf, Nova Scotia, Canada, to evaluate trade-offs between catches and ecosystem impacts in lobster fisheries from single- and multi-species perspectives. We ran simulations to independently determine exploitation rates that produced maximum sustainable yield (MSY) for lobster, and for all fished groups. We then ran simulations using these MSY exploitation rates simultaneously, and simulations to maximize multi-species MSY (MMSY). Our results indicate that current lobster exploitation rates in both regions are greater than those producing MSY, and have significant ecosystem impacts. Simulating multi-species fisheries, in both systems the sum of single-species MSY for all fished groups was less than the sum of catches where exploitation rates were run simultaneously. Runs maximizing MMSY across the entire ecosystem increased exploitation rates on many fished groups, and produced even greater total catch—yet with much greater ecological costs—and in Nova Scotia, collapses of sharks, large predators, and lobster themselves. As fisheries management moves towards multi-species and ecosystem-based approaches, we suggest that MMSY targets should be treated similarly to MSY—not as a target, but a limit. Even then, careful evaluation is required before implementation to ensure that there are no undesirable economic or ecological consequences.

Evaluation of a management decision rule for a New Zealand rock lobster substock

1997 ◽  
Vol 48 (8) ◽  
pp. 1093 ◽  
Author(s):  
Paul J. Starr ◽  
Paul A. Breen ◽  
Ray H. Hilborn ◽  
Terese H. Kendrick
Keyword(s):  
New Zealand ◽  
Decision Rule ◽  
Maximum Sustainable Yield ◽  
Assessment Model ◽  
Management Decision ◽  
Catch Per Unit Effort ◽  
Rock Lobster ◽  
Management Actions ◽  
Age Structured ◽  
The Impact

The performance of a proposed management ‘decision rule’–an algorithm that specifies management actions when specified criteria are met–was evaluated by exploring the impact of different choices for three decision-rule parameters on the ability of the rule to achieve management objectives. To do this, forward simulations from an age-structured assessment model for the substock of red rock lobster (Jasus edwardsii) off southern New Zealand were used. The size of this substock is currently estimated to be about one-third of BMSY (the level of vulnerable biomass that would produce maximum sustainable yield), and the management goal is to rebuild it to BMSY. A target rebuilding trajectory to BMSY was generated by allowing the model population to rebuild under the current catch regime with constant recruitment. The decision rule is based on comparison of observed catch per unit effort (CPUE) to predicted CPUE. Process and observation errors, each with a coefficient of variation of 20%, were introduced, and five values were used for each of the three parameters of the rule. The decision rule was effective in removing all instances of failure to rebuild and all excessively slow rebuilding trajectories. The decision rule was also applied to an arbitrarily depressed starting substock size, and the conclusions were the same.

scholarly journals Achieving maximum sustainable yield in mixed fisheries: a management approach for the North Sea demersal fisheries

2016 ◽  
Vol 74 (2) ◽  
pp. 566-575 ◽  
Author(s):  
Clara Ulrich ◽  
Youen Vermard ◽  
Paul J. Dolder ◽  
Thomas Brunel ◽  
Ernesto Jardim ◽  
...  
Keyword(s):  
North Sea ◽  
Regional Scale ◽  
Single Species ◽  
Maximum Sustainable Yield ◽  
Management Approach ◽  
Sustainable Yield ◽  
Total Allowable Catch ◽  
The North ◽  
Trade Offs ◽  
The North Sea

Achieving single species maximum sustainable yield (MSY) in complex and dynamic fisheries targeting multiple species (mixed fisheries) is challenging because achieving the objective for one species may mean missing the objective for another. The North Sea mixed fisheries are a representative example of an issue that is generic across most demersal fisheries worldwide, with the diversity of species and fisheries inducing numerous biological and technical interactions. Building on a rich knowledge base for the understanding and quantification of these interactions, new approaches have emerged. Recent paths towards operationalizing MSY at the regional scale have suggested the expansion of the concept into a desirable area of “pretty good yield”, implemented through a range around FMSY that would allow for more flexibility in management targets. This article investigates the potential of FMSY ranges to combine long-term single-stock targets with flexible, short-term, mixed-fisheries management requirements applied to the main North Sea demersal stocks. It is shown that sustained fishing at the upper bound of the range may lead to unacceptable risks when technical interactions occur. An objective method is suggested that provides an optimal set of fishing mortality within the range, minimizing the risk of total allowable catch mismatches among stocks captured within mixed fisheries, and addressing explicitly the trade-offs between the most and least productive stocks.

scholarly journals Possible ecosystem impacts of applying MSY policies from single-species assessment

2005 ◽  
Vol 62 (3) ◽  
pp. 558-568 ◽  
Author(s):  
Carl J. Walters ◽  
Villy Christensen ◽  
Steven J. Martell ◽  
James F. Kitchell
Keyword(s):  
Time Series Data ◽  
Single Species ◽  
Maximum Sustainable Yield ◽  
Series Data ◽  
Ecosystem Structure ◽  
Widespread Application ◽  
Predator Species ◽  
Ecosystem Impacts ◽  
Term Data

Abstract Ecosim models have been fitted to time-series data for a wide variety of ecosystems for which there are long-term data that confirm the models' ability to reproduce past responses of many species to harvesting. We subject these model ecosystems to a variety of harvest policies, including options based on harvesting each species at its maximum sustainable yield (MSY) fishing rate. We show that widespread application of single-species MSY policies would in general cause severe deterioration in ecosystem structure, in particular the loss of top predator species. This supports the long-established practice in fisheries management of protecting at least some smaller “forage” species specifically for their value in supporting larger piscivores.

scholarly journals Ecosystem approach to harvesting in the Arctic: Walking the tightrope between exploitation and conservation in the Barents Sea

AMBIO ◽  
2021 ◽  
Author(s):  
Michael R. Heath ◽  
Déborah Benkort ◽  
Andrew S. Brierley ◽  
Ute Daewel ◽  
Jack H. Laverick ◽  
...  
Keyword(s):  
Food Web ◽  
Barents Sea ◽  
Demersal Fish ◽  
Reference Points ◽  
Trophic Levels ◽  
Planktivorous Fish ◽  
The Arctic ◽  
Ecosystem Structure ◽  
The Barents Sea ◽  
Trade Offs

AbstractProjecting the consequences of warming and sea-ice loss for Arctic marine food web and fisheries is challenging due to the intricate relationships between biology and ice. We used StrathE2EPolar, an end-to-end (microbes-to-megafauna) food web model incorporating ice-dependencies to simulate climate-fisheries interactions in the Barents Sea. The model was driven by output from the NEMO-MEDUSA earth system model, assuming RCP 8.5 atmospheric forcing. The Barents Sea was projected to be > 95% ice-free all year-round by the 2040s compared to > 50% in the 2010s, and approximately 2 °C warmer. Fisheries management reference points (FMSY and BMSY) for demersal fish (cod, haddock) were projected to increase by around 6%, indicating higher productivity. However, planktivorous fish (capelin, herring) reference points were projected to decrease by 15%, and upper trophic levels (birds, mammals) were strongly sensitive to planktivorous fish harvesting. The results indicate difficult trade-offs ahead, between harvesting and conservation of ecosystem structure and function.

White clover sensitivity to UV-B radiation - biochemical relationships and interaction with drought

2003 ◽  
pp. 273-277
Author(s):  
R.W. Hofmann ◽  
B.D. Campbell ◽  
E.E. Swinny ◽  
S.J. Bloor ◽  
K.R. Markham ◽  
...  
Keyword(s):  
New Zealand ◽  
White Clover ◽  
Ultraviolet B ◽  
Summer Drought ◽  
Stress Protection ◽  
Trade Offs ◽  
Population Comparisons ◽  
Potential Benefits ◽  
Quercetin Glycosides ◽  
Balance Trade

During summertime in New Zealand, white clover experiences high levels of ultraviolet-B (UV-B) radiation. This frequently coincides with periods of summer drought. We investigated responses to UV-B and to the combination of UV-B and drought in various white clover populations, including New Zealand cultivars and ecotypes as well as overseas germplasm. The results were obtained under controlled environmental conditions in three independent trials. Overall, white clover growth was reduced by UV-B. The population comparisons indicated that low growth rate and adaptation to other forms of stress may be related to UV-B tolerance under well-watered conditions, but not during extended periods of drought. Flavonoid pigments that are involved in stress protection were strongly increased under UV-B and were further enhanced in the combination of UV-B and drought. The responses among these flavonoids were highly specific, with more pronounced UV-B-induced increases in quercetin glycosides, compared to their closely related kaempferol counterparts. UV-B toler ance of the less productive white clover populations was linked to the accumulation of quercetin compounds. In conclusion, these studies suggest (i) that slow-growing white clover ecotypes adapted to other stresses have higher capacity for biochemical acclimation to UV-B under well-watered conditions and (ii) that these biochemical attributes may also contribute to decreased UV-B sensitivity across white clover populations under drought. The findings alert plant breeders to potential benefits of selecting productive germplasm for high levels of specific flavonoids to balance trade-offs between plant productivity and stress tolerance. Keywords: Drought, flavonoids, genetic variation, HPLC, kaempferol, quercetin, str ess, Trifolium repens L., ultraviolet-B, white clover

scholarly journals Integrating Ecosystem Services and Human Demand for a New Ecosystem Management Approach: A Case Study from the Giant Panda World Heritage Site

2019 ◽  
Vol 12 (1) ◽  
pp. 295 ◽  
Author(s):  
Bin Fu ◽  
Pei Xu ◽  
Yukuan Wang ◽  
Yingman Guo
Keyword(s):  
Ecosystem Services ◽  
Ecosystem Management ◽  
Giant Panda ◽  
Supply And Demand ◽  
World Heritage ◽  
World Heritage Site ◽  
Management Approach ◽  
Successful Implementation ◽  
Heritage Site ◽  
Trade Offs

Ecological management based on the ecosystem approach promotes ecological protection and the sustainable use of natural resources. We developed a quantitative approach to identify the ecological function zones at the country-scale, through integrating supply and demand of ecosystem services. We selected the biologically diverse hotspot of Baoxing County, which forms a part of the Sichuan Giant Panda World Heritage Site, to explore the integration of ecosystem services supply and demand for ecosystem management. Specifically, we assessed the various support, provision, regulating, and cultural services as classified by the Millennium Ecosystem Assessment. We applied the InVEST (Integrated Valuation of Ecosystem Services and Trade-offs) model to spatially map habitat quality, water retention, and carbon sinks, and used statistical data to evaluate food products, animal husbandry, and product supply services. We then quantified the demands for these services in terms of population, protected species, hydropower, water, and land use. The relationship between areas of supply and areas of demand was discussed for each township, and the spatial variability in the supply–demand relationship was also considered. As a result, we spatially divided the county into six ecological functional areas, and the linkages between each region were comprehensively discussed. This study thus provides a detailed methodology for the successful implementation of an ecosystem management framework on a county-scale based on the spatial partitioning of supply and demand.

Fish and invertebrate by-catch in the crab pot fishery in the Isle of Man, Irish Sea

2017 ◽  
Vol 98 (8) ◽  
pp. 2099-2111
Author(s):  
Fikret Öndes ◽  
Michel J. Kaiser ◽  
Lee G. Murray
Keyword(s):  
Irish Sea ◽  
Target Species ◽  
Catch Per Unit Effort ◽  
Isle Of Man ◽  
Ecosystem Effects ◽  
By Catch ◽  
Catch Rates ◽  
Taxonomic Groups ◽  
Catch Composition ◽  
Autumn And Winter

Baited trap or pot fisheries are considered to have relatively few wider ecosystem effects on the marine environment, particularly when compared with towed mobile fishing gear. However, this assumption is rarely tested in the field. This study aimed to determine the composition of non-target species that occur in crustacean pots and to assess spatial and temporal differences in catches in the waters around the Isle of Man, Irish Sea. The data were collected using fishery independent surveys and a questionnaire study. Based on fishery independent surveys, a total of five taxonomic groups and 43 species occurred as by-catch. The dominant by-catch species was velvet crab Necora puber. The by-catch per unit effort (BPUE) for all of the non-target species was low particularly in comparison to towed bottom gear fisheries around the Isle of Man. BPUE of species composition varied considerably between different locations around the Isle of Man. The results of both the fishery independent and questionnaire data suggested that the by-catch rates varied with season with peak BPUE occurring in spring which then declined into autumn and winter. By-catch composition did not decrease significantly with an increasing target species catch. Overall, by-catch was low relative to target species catch which may be partially attributable to the use of escape panels in pot fisheries in the Isle of Man.

Functional diversity alters the effects of a pulse perturbation on the dynamics of tritrophic food webs

2021 ◽  
Author(s):  
Ruben Ceulemans ◽  
Laurie Anne Myriam Wojcik ◽  
Ursula Gaedke
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Feedback Loop ◽  
Environmental Changes ◽  
Biodiversity Loss ◽  
Trophic Levels ◽  
Nutrient Pulse ◽  
Trade Offs ◽  
Food Web Model

Biodiversity decline causes a loss of functional diversity, which threatens ecosystems through a dangerous feedback loop: this loss may hamper ecosystems' ability to buffer environmental changes, leading to further biodiversity losses. In this context, the increasing frequency of climate and human-induced excessive loading of nutrients causes major problems in aquatic systems. Previous studies investigating how functional diversity influences the response of food webs to disturbances have mainly considered systems with at most two functionally diverse trophic levels. Here, we investigate the effects of a nutrient pulse on the resistance, resilience and elasticity of a tritrophic---and thus more realistic---plankton food web model depending on its functional diversity. We compare a non-adaptive food chain with no diversity to a highly diverse food web with three adaptive trophic levels. The species fitness differences are balanced through trade-offs between defense/growth rate for prey and selectivity/half-saturation constant for predators. We showed that the resistance, resilience and elasticity of tritrophic food webs decreased with larger perturbation sizes and depended on the state of the system when the perturbation occured. Importantly, we found that a more diverse food web was generally more resistant, resilient, and elastic. Particularly, functional diversity dampened the probability of a regime shift towards a non-desirable alternative state. In addition, despite the complex influence of the shape and type of the dynamical attractors, the basal-intermediate interaction determined the robustness against a nutrient pulse. This relationship was strongly influenced by the diversity present and the third trophic level. Overall, using a food web model of realistic complexity, this study confirms the destructive potential of the positive feedback loop between biodiversity loss and robustness, by uncovering mechanisms leading to a decrease in resistance, resilience and elasticity as functional diversity declines.

scholarly journals Decoupled taxonomic and ecological recoveries from the Permo-Triassic extinction

2018 ◽  
Vol 4 (10) ◽  
pp. eaat5091 ◽  
Author(s):  
Haijun Song ◽  
Paul B. Wignall ◽  
Alexander M. Dunhill
Keyword(s):  
Time Scales ◽  
Carrying Capacity ◽  
Mass Extinction ◽  
Marine Species ◽  
Taxonomic Diversity ◽  
Marine Ecosystems ◽  
Trophic Levels ◽  
Ecosystem Structure ◽  
Top Down ◽  
Structure Building

The Permian-Triassic mass extinction was the worst crisis faced by life; it killed >90% of marine species in less than 0.1 million years (Ma). However, knowledge of its macroecological impact over prolonged time scales is limited. We show that marine ecosystems dominated by non-motile animals shifted to ones dominated by nektonic groups after the extinction. In Triassic oceans, animals at high trophic levels recovered faster than those at lower levels. The top-down rebuilding of marine ecosystems was still underway in the latest Triassic, ~50 Ma after the extinction, and contrasts with the ~5-Ma recovery required for taxonomic diversity. The decoupling between taxonomic and ecological recoveries suggests that a process of vacant niche filling before reaching the maximum environmental carrying capacity is independent of ecosystem structure building.

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