Simulations to evaluate management trade-offs among marine mammal consumption needs, commercial fishing fleets and finfish biomass

2015 ◽  
Vol 523 ◽  
pp. 215-232 ◽  
Author(s):  
L Smith ◽  
R Gamble ◽  
S Gaichas ◽  
J Link
Keyword(s):  
Marine Mammal ◽  
Commercial Fishing ◽  
Trade Offs ◽  
Fishing Fleets

How fisher behavior can bias stock assessment: insights from an agent-based modeling approach

2020 ◽  
Vol 77 (11) ◽  
pp. 1794-1809
Author(s):  
Steven Saul ◽  
Elizabeth N. Brooks ◽  
David Die
Keyword(s):  
Stock Assessment ◽  
Fish Population ◽  
Dependent Data ◽  
Commercial Fishing ◽  
Fishing Activity ◽  
Agent Based ◽  
Dependent Observations ◽  
Sampling Protocols ◽  
Fishing Fleets ◽  
Fisher Behavior

During stock assessment, fishery-dependent observations are often used to develop indices of abundance or biomass from catch per unit of effort (CPUE) and contribute catch at size or age information. However, fisher behavior, rather than scientific sampling protocols, determines the spatial and temporal locations of fishery-dependent observations. As a result, trends from fishery-dependent data may be a function of fishing activity rather than fish population changes. This study evaluates whether data collected from commercial fishing fleets in the Gulf of Mexico are representative of trends in fish population size. A coupled bioeconomic agent-based model was developed to generate simulated fishery data, which were used to populate an age-structured stock assessment. Comparison of stock assessment results with simulated fish population dynamics showed that management advice from assessment models based on fishery-dependent data could be biased. Assessment of fish with small home ranges harvested by fishing fleets that frequent the same fishing grounds could cause overestimation of fishing mortality. Not accounting for the spatial structure of the fishers or fish can cause biased estimates of population status.

scholarly journals Do North Sea cod (Gadus morhua) fisheries maintain high catch rates at low stock size?

2008 ◽  
Vol 65 (9) ◽  
pp. 1800-1813 ◽  
Author(s):  
Anna Rindorf ◽  
Bo Sølgaard Andersen
Keyword(s):  
Spatial Distribution ◽  
North Sea ◽  
Gadus Morhua ◽  
Commercial Fishing ◽  
Stock Size ◽  
Two Factors ◽  
Cod Fisheries ◽  
Catch Rates ◽  
Fishing Fleets ◽  
The Relationship

This study presents an investigation of the relationship between stock size of North Sea cod ( Gadus morhua ) and catch rates in seven commercial fishing fleets. The shape of the relationship was estimated using a new model allowing both density-dependent changes in catchability and bias in the assessment biomass estimates. Catchability in fisheries targeting a mixed species composition either remained constant or decreased with decreasing stock size, whereas catchability in targeted cod fisheries increased with decreasing stock size. However, even in the cases where catchability increased, the change was insufficient to compensate for the decrease in stock size, and catch rates of all fleets decreased. Two factors that could lead to nonconstant catchability were investigated: (i) the presence of a decoupling between stock size and density in high-density areas and (ii) the presence of concurrent shifts in the spatial distribution of the cod stock and the cod fishery. No evidence of the former was found, but there was a northern shift in the spatial distribution of both effort and the cod stock.

Classification and analysis of VMS data in vertical line fisheries: incorporating uncertainty into spatial distributions

2017 ◽  
Vol 74 (11) ◽  
pp. 1749-1764 ◽  
Author(s):  
Nicholas D. Ducharme-Barth ◽  
Robert N.M. Ahrens
Keyword(s):  
Large Scale ◽  
Critical Role ◽  
Fishing Effort ◽  
Vertical Line ◽  
Commercial Fishing ◽  
Spatial Distributions ◽  
Fishing Pressure ◽  
Modeling Process ◽  
Fishing Fleets ◽  
Pressure Changes

Commercial fishing fleets play a critical role in the population dynamics of exploited stocks. Understanding the spatial distribution of fleets allows managers to anticipate how fishing pressure on exploited stocks changes in response to fishing regulations or to large-scale perturbations. By anticipating how fishing pressure changes, managers can develop proactive responses to better protect stocks that are vulnerable to overfishing. Modern fisheries monitoring techniques, including vessel monitoring systems (VMS), have advanced this endeavor. This paper presents a framework for using VMS data to develop spatial distributions of catch, fishing effort, and catch per unit of effort (CPUE) as well as associated estimates of uncertainty in a vertical line fishery. VMS data are classified as fishing using a random forest (RF) model. Uncertainty is calculated using a two-step approach to account for uncertainty arising from the RF modeling process and the classification accuracy of the model. This framework is applied to investigate changes in the Gulf of Mexico reef fish fishery during a period of 6 years, including the 2010 Deepwater Horizon oil spill.

scholarly journals Rethinking sustainability in seafood

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Brandi McKuin ◽  
Jordan T. Watson ◽  
Stephen Stohs ◽  
J. Elliott Campbell
Keyword(s):  
Unintended Consequences ◽  
Climate Impacts ◽  
Climate Forcing ◽  
Skipjack Tuna ◽  
Fish Stocks ◽  
Trade Offs ◽  
Fisheries Conservation ◽  
Tuna Fishing ◽  
Nontarget Species ◽  
Fishing Fleets

Sustainability is a common goal and catchphrase used in conjunction with seafood, but the metrics used to determine the level of sustainability are poorly defined. Although the conservation statuses of target or nontarget fish stocks associated with fisheries have been scrutinized, the relative climate impacts of different fisheries are often overlooked. Although an increasing body of research seeks to understand and mitigate the climate forcing associated with different fisheries, little effort has sought to integrate these disparate disciplines to examine the synergies and trade-offs between conservation efforts and efforts to reduce climate impacts. We quantified the climate forcing per unit of fish protein associated with several different U.S. tuna fishing fleets, among the most important capture fisheries by both volume and value. We found that skipjack tuna caught by purse seine, a gear type that is often associated with relatively high bycatch of nontarget species, results in lower climate forcing than all other sources of proteins examined with the exception of plants. Conversely, skipjack tuna caught by trolling, a gear type that is often associated with relatively low bycatch of nontarget species, generates higher climate forcing than most other protein sources with the exception of beef. Because there is a range of selectivity and climate forcing impacts associated with fishing gears, examining the trade-offs associated with bycatch and climate forcing provides an opportunity for broadening the discourse about the sustainability of seafood. A central goal of more sustainable seafood practices is to minimize environmental impacts, thus mitigation efforts—whether they target conservation, habitat preservation, or climate impacts—should consider the unintended consequences on fisheries conservation.

scholarly journals Observation of marine mammal and bird interactions focused around a commercial fishing vessel in central Baffin Bay, Nunavut

2020 ◽  
Author(s):  
Kelsey F Johnson ◽  
Nigel Edward Hussey ◽  
Steven H. Ferguson
Keyword(s):  
Marine Mammal ◽  
Marine Ecosystem ◽  
Bird Species ◽  
The Arctic ◽  
Commercial Fishing ◽  
Physeter Macrocephalus ◽  
Fishing Vessel ◽  
Greenland Halibut ◽  
Hooded Seal ◽  
Baffin Bay

A detailed account of a variety of species foraging on Greenland halibut (Reinhardtius hippoglossoides) fisheries discards associated with a commercial fishing vessel in central Baffin Bay, Nunavut, Canada is presented. Species observed included three marine mammals; northern bottlenose whales (Hyperoodon ampullatus), sperm whales (Physeter macrocephalus), and a hooded seal (Cystophora cristata) and two marine bird species; northern fulmars (Fulmarus glacialis) and glaucous gulls (Larus hyperboreus). Inter- and intra- species interactions were observed while species were in close proximity to the stern and starboard of a commercial fishing vessel confirming anecdotal reports from boat captains. Improved understanding of marine mammal and bird interactions with fisheries in the Arctic is required to accurately assess financial and ecological (i.e., bycatch) losses, potential for entanglement and to predict the likely impact on energy flow and transport of these resource subsidies throughout the Arctic marine ecosystem.

Trade-offs in transitions between indigenous and commercial fishing sectors: the Torres Strait tropical rock lobster fishery

2016 ◽  
Vol 23 (6) ◽  
pp. 463-477 ◽  
Author(s):  
T. Hutton ◽  
E.I. van Putten ◽  
S.D. Pascoe ◽  
R.A. Deng ◽  
É.E. Plagányi ◽  
...  
Keyword(s):  
Commercial Fishing ◽  
Rock Lobster ◽  
Trade Offs ◽  
Lobster Fishery ◽  
Torres Strait

Novel players fine-tune plant trade-offs

2015 ◽  
Vol 58 ◽  
pp. 83-100 ◽  
Author(s):  
Selena Gimenez-Ibanez ◽  
Marta Boter ◽  
Roberto Solano
Keyword(s):  
Ubiquitin Ligase ◽  
Feedback Loop ◽  
Molecular Level ◽  
26S Proteasome ◽  
Signalling Molecules ◽  
Transcriptional Reprogramming ◽  
Trade Offs ◽  
Jaz Proteins ◽  
Regulatory Feedback Loop ◽  
Fine Tune

Jasmonates (JAs) are essential signalling molecules that co-ordinate the plant response to biotic and abiotic challenges, as well as co-ordinating several developmental processes. Huge progress has been made over the last decade in understanding the components and mechanisms that govern JA perception and signalling. The bioactive form of the hormone, (+)-7-iso-jasmonyl-l-isoleucine (JA-Ile), is perceived by the COI1–JAZ co-receptor complex. JASMONATE ZIM DOMAIN (JAZ) proteins also act as direct repressors of transcriptional activators such as MYC2. In the emerging picture of JA-Ile perception and signalling, COI1 operates as an E3 ubiquitin ligase that upon binding of JA-Ile targets JAZ repressors for degradation by the 26S proteasome, thereby derepressing transcription factors such as MYC2, which in turn activate JA-Ile-dependent transcriptional reprogramming. It is noteworthy that MYCs and different spliced variants of the JAZ proteins are involved in a negative regulatory feedback loop, which suggests a model that rapidly turns the transcriptional JA-Ile responses on and off and thereby avoids a detrimental overactivation of the pathway. This chapter highlights the most recent advances in our understanding of JA-Ile signalling, focusing on the latest repertoire of new targets of JAZ proteins to control different sets of JA-Ile-mediated responses, novel mechanisms of negative regulation of JA-Ile signalling, and hormonal cross-talk at the molecular level that ultimately determines plant adaptability and survival.

Dual Goals for Speed and Accuracy on the Same Performance Task

2012 ◽  
Vol 11 (3) ◽  
pp. 118-126 ◽  
Author(s):  
Olive Emil Wetter ◽  
Jürgen Wegge ◽  
Klaus Jonas ◽  
Klaus-Helmut Schmidt
Keyword(s):  
Memory Scanning ◽  
Performance Task ◽  
Performance Tasks ◽  
Trade Off ◽  
Test Experiment ◽  
Trade Offs ◽  
New Finding ◽  
Sternberg Paradigm ◽  
Speed Accuracy ◽  
Speed And Accuracy

In most work contexts, several performance goals coexist, and conflicts between them and trade-offs can occur. Our paper is the first to contrast a dual goal for speed and accuracy with a single goal for speed on the same task. The Sternberg paradigm (Experiment 1, n = 57) and the d2 test (Experiment 2, n = 19) were used as performance tasks. Speed measures and errors revealed in both experiments that dual as well as single goals increase performance by enhancing memory scanning. However, the single speed goal triggered a speed-accuracy trade-off, favoring speed over accuracy, whereas this was not the case with the dual goal. In difficult trials, dual goals slowed down scanning processes again so that errors could be prevented. This new finding is particularly relevant for security domains, where both aspects have to be managed simultaneously.

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