Combining stock, multispecies, and ecosystem level fishery objectives within an operational management procedure: simulations to start the conversation

2016 ◽  
Vol 74 (2) ◽  
pp. 552-565 ◽  
Author(s):  
Sarah K. Gaichas ◽  
Michael Fogarty ◽  
Gavin Fay ◽  
Robert Gamble ◽  
Sean Lucey ◽  
...  
Keyword(s):  
Species Interactions ◽  
Life Histories ◽  
Single Species ◽  
Fishing Effort ◽  
Reference Points ◽  
Individual Species ◽  
Management Procedure ◽  
Trade Offs ◽  
Starting Point ◽  
Operational Management

We explored alternative status determination criteria and reference points that could simplify fisheries management using a simulated multispecies/ecosystem-based operational management procedure. There are four components to the procedure: (i) limit total removals from the ecosystem; (ii) allocate the total removals limit among aggregate species groups; (iii) maintain individual species above minimum stock size thresholds; and (iv) optimize the species mix (within aggregates) based on bio-economic portfolio analysis. In this procedure, “overfishing” criteria are applied only to aggregates of species at the ecosystem and group level, but “overfished” criteria apply at the species/stock level. Previous work using multispecies production models identified conditions where conservation and yield objectives could be balanced: aggregations of species with similar life histories, species interactions, and responses to environmental forcing supported the highest yields while minimizing risks that individual stocks dropped below biomass thresholds. Here, we use a more complex length structured multispecies, multifleet simulation model to explore management procedure steps (i)–(iii). Different species aggregation rules were applied (single species, functional groups, and full system), and yield curves were constructed for each aggregation level by sequentially increasing effort in each of the fleets (alone and simultaneously), while recruitment for each species varied stochastically around a function based on spawning stock biomass. The performance of individual species and each aggregate type was then compared with respect to yield, biomass, and economic revenue objectives under changing environmental conditions. Our results evaluate the trade-offs between these objectives for the 10 species in the simulated system. Overall we found that there are aggregate catch limits that can both maximize yield and revenue while conserving biomass. However, community composition and revenue trade-off over a range of fishing effort. We consider this a starting point for further development with scientists, managers, fishermen, and other stakeholders in the region.

scholarly journals Sustainable exploitation of temperate fish stocks

2009 ◽  
Vol 6 (1) ◽  
pp. 124-127 ◽  
Author(s):  
Henrik Sparholt ◽  
Robin M. Cook
Keyword(s):  
Species Interactions ◽  
Fishery Management ◽  
Regional Scale ◽  
Single Species ◽  
Fishing Effort ◽  
Theoretical Concept ◽  
Maximum Sustainable Yield ◽  
Production Model ◽  
The Status ◽  
Long Time

The theory of maximum sustainable yield (MSY) underpins many fishery management regimes and is applied principally as a single species concept. Using a simple dynamic biomass production model we show that MSY can be identified from a long time series of multi-stock data at a regional scale in the presence of species interactions and environmental change. It suggests that MSY is robust and calculable in a multispecies environment, offering a realistic reference point for fishery management. Furthermore, the demonstration of the existence of MSY shows that it is more than a purely theoretical concept. There has been an improvement in the status of stocks in the Northeast Atlantic, but our analysis suggests further reductions in fishing effort would improve long-term yields.

Harvesting at the Community Level

2020 ◽  
pp. 205-228
Author(s):  
Michael J. Fogarty ◽  
Jeremy S. Collie
Keyword(s):  
Single Species ◽  
Economic Incentives ◽  
Unintended Consequences ◽  
Community Context ◽  
Reference Points ◽  
Individual Species ◽  
Biological Interactions ◽  
Predator Prey ◽  
The Right ◽  
Technical Solutions

Most fisheries are not directed at individual species alone. Rather, in many instances, species within a community are caught together and are also part of competitive networks and food webs. Species that are caught together are subject to technical interactions. Species that compete or are connected through predator–prey interactions (or other types of interactions) are subject to biological interactions. Ignoring either of these forms of interaction in management can lead to unintended consequences. Technical solutions can help to avoid some species while targeting others, but a comprehensive solution requires creating the right economic incentives and some incidental catch is still inevitable. Accounting for trophic interactions means that biological reference points depend on the abundance of other taxa. Single-species approaches are invalid in a multispecies or community context where biological interactions are important. Technical interactions can make it impossible to achieve target exploitation rates even if biological interactions are relatively unimportant.

Evaluating the influence of predator–prey interactions on stock assessment and management reference points for a large lake ecosystem

2016 ◽  
Vol 73 (9) ◽  
pp. 1372-1388 ◽  
Author(s):  
Hiroyuki Kurota ◽  
Murdoch K. McAllister ◽  
Eric A. Parkinson ◽  
N.T. Johnston
Keyword(s):  
Species Interactions ◽  
Single Species ◽  
Reference Points ◽  
Management Policy ◽  
Management Approach ◽  
Lake Ecosystem ◽  
Large Lake ◽  
Ecosystem Models ◽  
Predator Prey ◽  
Results Management

Ecosystem models are thought to offer advantages over single-species models in terms of management policy analysis. This hypothesis has proven difficult to test because of underlying system complexities, coupled with short time series and minimal contrast in environmental conditions or management policies. This paper presents a Bayesian statistical catch-at-age model to compare ecosystem models and test hypotheses about the management of a recreational fishery based on a predator–prey system using a relatively simple and data-rich ecosystem in a large lake, Kootenay Lake, British Columbia, where kokanee (Oncorhynchus nerka) are the prey and piscivorous rainbow trout (Oncorhynchus mykiss) are the predator. A model that explicitly incorporates the predator–prey interaction explained long-term data of field and fishery surveys much better than single-species models without any interactions. Minimally realistic multispecies models that treated predation identically but differed in their representation of the effects of prey abundance on predator mortality produced quite different results. Management reference points, for example, differed considerably between the models. Our study thus emphasizes that the choice of a management approach for this type of fishery will depend strongly on the model form and should take into consideration results from empirically based models that include species interactions.

scholarly journals Evaluating effectiveness of time/area closures, quotas/caps, and fleet communications to reduce fisheries bycatch

2013 ◽  
Vol 71 (5) ◽  
pp. 1286-1297 ◽  
Author(s):  
Catherine E. O'Keefe ◽  
Steven X. Cadrin ◽  
Kevin D. E. Stokesbury
Keyword(s):  
Species Interactions ◽  
Life Histories ◽  
Economic Impacts ◽  
Fishing Effort ◽  
Mitigation Measures ◽  
Fishing Gear ◽  
Target Species ◽  
Skill Sets ◽  
Gear Modification ◽  
Fishing Fleets

Abstract Designing effective bycatch mitigation programmes requires an understanding of the life histories of target and non-target species, interactions of fish and fishing gear, effects of spatial and temporal shifts in fishing effort, socio-economic impacts to the fishery, and incentives of fishery participants. The effects of mitigation measures (including fishing gear modification, time/area closures, bycatch quotas and caps, incentive programs, and fleet communication programs) have been evaluated with respect to reducing bycatch and discards. Less attention has been focused on evaluating unanticipated results related to shifts in fishing effort, changes in the size of non-target species caught, reduced catch of target species, and economic viability to fishing fleets. Time/area closures, bycatch quotas/caps, and fleet communication programmes were evaluated against a set of criteria to assess overall effectiveness in reducing bycatch without causing unintended biological and socio-economic impacts. The results suggest that wide-ranging studies of species' life histories, potential changes in fleet behaviour, and individual incentives are important for developing and implementing mitigation programmes. Combining a suite of mitigation techniques has been successful in meeting biological and socio-economic fisheries goals. Additionally, collaborative programmes that utilize the skill sets of fishers, scientists, and managers have increased effectiveness in meeting bycatch reduction objectives.

A study of the species composition and distribution of commercial penaeid prawns of Torres Strait

1987 ◽  
Vol 38 (1) ◽  
pp. 47 ◽  
Author(s):  
IF Somers ◽  
IR Poiner ◽  
AN Harris
Keyword(s):  
Species Composition ◽  
Single Species ◽  
Fishing Effort ◽  
Individual Species ◽  
Commercial Catch ◽  
Entire Area ◽  
Fine Sediments ◽  
Sediment Types ◽  
Torres Strait ◽  
Trawl Surveys

Fishermen's logbook data were used to describe the distribution of fishing effort and the composition of the commercial catches in Torres Strait. Catches consist of tiger, endeavour and king prawns. Additional information on the distribution and abundance of the individual species was obtained from four trawl surveys carried out at 3-monthly intervals during 1985. Each survey extended over the entire area of the commercial prawn fishery in Torres Strait. The species composition of the trawl surveys (48% tiger, 44% endeavour and 8% king) differed noticeably from that of the commercial catch (60% tiger, 36% endeavour, 4% king). This difference was attributed to a combination of the commercial fishery's concentration on the higher-priced tiger prawns and the different spatial and temporal distributions of the species. The tiger prawn catch consisted of two species, Penaeus esculentus (99.6%) and P. semisulcatus (0.4%). The king prawn catch comprised P. longistylus (97.5%) and P. latisulcatus (2.5%). The endeavour prawn catch was represented by a single species, Metapenaeus endeavouri. Spatial differences in the species distributions were found to be associated with the distribution of bottom sediments. Tiger prawns were most abundant on fine sediments with a mud content greater than 50%; P. semisulcatus was restricted to sediments with a mud content greater than 70%. The king prawns, unlike the tiger prawns, were most abundant on the coarse sediments with a mud content less than 20%. Endeavour prawns were the most widespread of all the species, being equally abundant on all sediment types.

scholarly journals Can economic and biological management objectives be achieved by the use of MSY-based reference points? A North Sea plaice (Pleuronectes platessa) and sole (Solea solea) case study

2008 ◽  
Vol 65 (6) ◽  
pp. 1069-1080 ◽  
Author(s):  
Graham M. Pilling ◽  
Laurence T. Kell ◽  
Trevor Hutton ◽  
Peter J. Bromley ◽  
Alex N. Tidd ◽  
...  
Keyword(s):  
North Sea ◽  
Single Species ◽  
Reference Points ◽  
Pleuronectes Platessa ◽  
Management Objectives ◽  
Employment Conditions ◽  
Trade Offs ◽  
Solea Solea ◽  
Biological Management

Abstract Pilling, G. M., Kell, L. T., Hutton, T., Bromley, P. J., Tidd, A. N., and Bolle, L. J. 2008. Can economic and biological management objectives be achieved by the use of MSY-based reference points? A North Sea plaice (Pleuronectes platessa) and sole (Solea solea) case study. – ICES Journal of Marine Science, 65: 1069–1080. We examined the biological and economic impact of changing from management based on single-species limit reference points to one based on alternative targets, using the multispecies multifleet North Sea flatfish fishery. The robustness of reference points was tested against identified changes in plaice and sole biology. Current ICES single-species limit and precautionary biomass and fishing mortality reference points were seldom consistent with each other. Although they were generally robust to biological uncertainty, fishing at Fpa for sole could lead to stock collapse under one biological scenario. Adoption of alternative targets would reduce reliance on current reference points as stocks moved to a more sustainable state. Maximum sustainable yield (MSY), maximum economic yield (MEY), and maximum employment conditions implied different effort levels in the two fleets modelled, and different profits. Ftarget could be achieved with equal effort reductions in both fleets. Changes in stock biology affected the fishing effort required to maximize employment within the fishery, whereas MSY, Fmax, and MEY targets were robust to this uncertainty. Resulting profits and yields did vary widely, however. The selection of target reference points therefore requires stakeholders to define fishery objectives explicitly, against which targets can be evaluated for the resulting trade-offs between risk to stocks, yield, employment, and other social objectives.

scholarly journals Extinction, survival or recovery of large predatory fishes

2005 ◽  
Vol 360 (1453) ◽  
pp. 13-20 ◽  
Author(s):  
Ransom A. Myers ◽  
Boris Worm
Keyword(s):  
Species Interactions ◽  
Single Species ◽  
Fishing Effort ◽  
Predatory Fish ◽  
Fishing Mortality ◽  
Sensitive Species ◽  
Marine Habitats ◽  
Effort Reduction ◽  
Predatory Fishes ◽  
Reproductive Rates

Large predatory fishes have long played an important role in marine ecosystems and fisheries. Overexploitation, however, is gradually diminishing this role. Recent estimates indicate that exploitation has depleted large predatory fish communities worldwide by at least 90% over the past 50–100 years. We demonstrate that these declines are general, independent of methodology, and even higher for sensitive species such as sharks. We also attempt to predict the future prospects of large predatory fishes. (i) An analysis of maximum reproductive rates predicts the collapse and extinction of sensitive species under current levels of fishing mortality. Sensitive species occur in marine habitats worldwide and have to be considered in most management situations. (ii) We show that to ensure the survival of sensitive species in the northwest Atlantic fishing mortality has to be reduced by 40–80%. (iii) We show that rapid recovery of community biomass and diversity usually occurs when fishing mortality is reduced. However, recovery is more variable for single species, often because of the influence of species interactions. We conclude that management of multi–species fisheries needs to be tailored to the most sensitive, rather than the more robust species. This requires reductions in fishing effort, reduction in bycatch mortality and protection of key areas to initiate recovery of severely depleted communities.

scholarly journals Using AMOEBAs to display multispecies, multifleet fisheries advice

2003 ◽  
Vol 60 (4) ◽  
pp. 709-720 ◽  
Author(s):  
Jeremy S. Collie ◽  
Henrik Gislason ◽  
Morten Vinther
Keyword(s):  
Response Surface ◽  
Single Species ◽  
Fishing Effort ◽  
Response Surface Model ◽  
Reference Points ◽  
Surface Model ◽  
Interacting Species ◽  
The North ◽  
Age Structured ◽  
Fishing Fleets

Abstract In multispecies fish communities, predation levels change dynamically in response to changes in the abundance of predator and prey species, as influenced by the fisheries that exploit them. In addition to community-level metrics, it remains necessary to track the abundance of each species relative to its biological reference point. In situations with many interacting species, exploited by multiple fishing fleets, it can be complicated to illustrate how the effort of each fleet will affect the abundance of each species. We have adapted the AMOEBA approach to graph the reference levels of multiple interacting species exploited by multiple fleets. This method is illustrated with 10 species and eight fishing fleets in the North Sea. We fit a relatively simple response-surface model to the predictions of a fully age-structured multispecies model. The response-surface model links the AMOEBA for fishing effort to separate AMOEBAs for spawning stock biomass, fishing mortality, and yield. Ordination is used to give the shape of the AMOEBAs functional meaning by relating fish species to the fleets that catch them. The aim is to present the results of dynamic multispecies models in a format that can be readily understood by decision makers. Interactive versions of the AMOEBAs can be used to identify desirable combinations of effort levels and to test the compatibility of the set of single-species biological reference points.

‘[T]his world is now thy pilgrimage’: William Michael Rossetti's Cognitive Maps of France and Italy

2018 ◽  
Vol 8 (1) ◽  
pp. 84-99
Author(s):  
Eleonora Sasso
Keyword(s):  
Cognitive Linguistics ◽  
Venice Lagoon ◽  
Cognitive Map ◽  
Reference Points ◽  
Late Nineteenth Century ◽  
Mental Picture ◽  
Historical Figures ◽  
Starting Point ◽  
Cognitive Semantic ◽  
St Helena

This paper takes as its starting point the conceptual metaphor ‘life is a journey’ as defined by Lakoff and Johnson (1980) in order to advance a new reading of William Michael Rossetti's Democratic Sonnets (1907). These political verses may be defined as cognitive-semantic poems, which attest to the centrality of travel in the creation of literary and artistic meaning. Rossetti's Democratic Sonnets is not only a political manifesto against tyranny and oppression, promoting the struggle for liberalism and democracy as embodied by historical figures such as Napoleon, Mazzini, Cavour, and Garibaldi; but it also reproduces Rossetti's real and imagined journeys throughout Europe in the late nineteenth century. This essay examines these references in light of the issues they raise, especially the poet as a traveller and the journey metaphor in poetry. But its central purpose is to re-read Democratic Sonnets as a cognitive map of Rossetti's mental picture of France and Italy. A cognitive map, first theorised by Edward Tolman in the 1940s, is a very personal representation of the environment that we all experience, serving to navigate unfamiliar territory, give direction, and recall information. In terms of cognitive linguistics, Rossetti is a figure whose path is determined by French and Italian landmarks (Paris, the island of St. Helena, the Alps, the Venice Lagoon, Mount Vesuvius, and so forth), which function as reference points for orientation and are tied to the historical events of the Italian Risorgimento. Through his sonnets, Rossetti attempts to build into his work the kind of poetic revolution and sense of history which may only be achieved through encounters with other cultures.

FINDING FACTORS OF SURVIVAL THE YOUNG OF MARINE HERRING MIGRATING IN THE NORTHERN PART OF THE CASPIAN SEA

2017 ◽  
pp. 19-25
Author(s):  
Tatiana Stanislavovna Zubkova
Keyword(s):  
First Generation ◽  
Environmental Influence ◽  
Reproductive Capacity ◽  
Individual Species ◽  
Survival Ratio ◽  
The Caspian Sea ◽  
Foraging Area ◽  
Starting Point ◽  
Feeding Assessment ◽  
Predatory Fishes

The objects of research are three species of Caspian migrating herrings (Dolginsk herring ( Alosa brashnikowi ), big-eyed shad ( Alosa saposchnikowii ), Caspian shad ( Alosa caspia caspia )). The work considers two biological aspects of herring reproduction: dependence of number of underyearlings on the number of females in the end of feeding; assessment of survival rate of herring juveniles from the stage of fish egg to the stage of underyearlings. Besides fecundity of individual species, scientists take into account sex ratio in spawning populations, population fecundity, loss of reproductive capacity due to the resorption in unscreened roe. The materials obtained within 2009-2015 show that the dependence of herring underyearling number on the number of females arriving at spawning ground is extremely low. Despite a great number of females on the spawning grounds, the reasons of decreasing number of the first generation can be different: unfavorable hydrological and hydrochemical environment in foraging area, insufficient nutritive base, rescheduling of the spawning etc. The varying number of underyearlings from year to year is more pronounced with predatory fishes: the Dolginsk herring - 2.1 times, big-eyed shad - 1.7 times. The underyearling number of zoo-plankton feeder - Caspian shad is consistently high with minimal yearly variations. The young of Caspian shad have the highest survival ratio (0.0122); the young of predatory herring species the ratio is lower: Dolginsk herring is 4 times less (0.0031), big-eyed shad - 5 times less (0.0024). The data on herring survival from stage of a fish egg to an underyearling stage will become a starting point in the investigation of the environmental influence on to the new herring generations.

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