scholarly journals Linking Fishing Behavior and Ecosystem Dynamics Using Social and Ecological Network Models

2021 ◽  
Vol 9 ◽  
Author(s):  
Joseph J. Luczkovich ◽  
Jeffrey C. Johnson ◽  
Rebecca A. Deehr ◽  
Kevin J. Hart ◽  
Lisa Clough ◽  
...  
Keyword(s):  
Fishery Management ◽  
Fishing Effort ◽  
Ecosystem Dynamics ◽  
Ecological System ◽  
Regulatory Change ◽  
Estuarine Ecosystem ◽  
Gill Net ◽  
Affiliation Network ◽  
Multiple Species ◽  
Fishing Behavior

One goal of ecosystem-based management is studying an ecosystem and its people, the socio-ecological system, in a qualitative and quantitative modeling approach that can provide management agencies with possible outcomes of their actions using scenario forecasting. Ecosystem-based fisheries management strives to use the socio-ecological system approach, including direct and indirect impacts on multiple species including the behavioral responses of fishers after a regulatory change (a gillnet ban). Here, we link fisher behavioral networks with a mass-balanced food-web ECOPATH network model of an estuarine ecosystem and its commercial fisheries for an analysis of fishing impacts after a gillnet ban on multiple species using ECOSIM. We modeled fisher behavioral networks using reported catches of species from individual fishers along with the gear fished to create nodes in a gear/species affiliation network. Individual fishers with common gear/species use are indicative of common fishing behavior. When such fishers have high network centrality and are engaged in multiple gear/species fisheries, they can transition to other gear/species fisheries along “switching pathways” when facing a regulatory change. We used an index of joint gear participation to identify likely gear switching pathways, and we predicted changes in fishing effort after a gill net ban. We simulated the gill net ban in ECOSIM under two scenarios of fishing effort: Scenario 1, gill net fishing effort of 0%; Scenario 2, gill net fishing effort of 0% with increased effort in the alternative gear fisheries using the predicted switching pathways for the affiliation network. Scenario 1 predicted an increase in flounder (Paralichthys spp.) biomass over a decade. Under Scenario 2, fishers targeting flounders were predicted to switch from gill nets to pound nets. Scenario 2 predicted a 7% decline in flounder biomass over ten years, rather than an increase in flounders. The gillnet ban with increased effort due to switching is predicted to have the opposite effect on the conservation goal, which was to increase flounder stocks. Fishery management that incorporates a socio-ecological approach modeling both fisher behaviors and multi-species ecosystem responses can reveal single-species responses that are in the opposite direction of the anticipated management goals.

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.

Aspects of the fishery, maturation and net selectivity of the wedge sole (Dicologoglossa cuneata) off south-western Iberia: implications for fishery management

2009 ◽  
Vol 90 (7) ◽  
pp. 1465-1474 ◽  
Author(s):  
Miguel Neves Santos ◽  
Pedro Gil Lino
Keyword(s):  
Fishery Management ◽  
River Mouth ◽  
Mesh Size ◽  
Scientific Basis ◽  
Catch Per Unit Effort ◽  
Important Species ◽  
Gill Net ◽  
Catch Rates ◽  
Log Normal ◽  
First Maturity

The wedge sole (Dicologoglossa cuneata, Moreau 1881) is a commercially important species for the artisanal fleet operating off the south-western Iberian Peninsula. During 2004 and 2005 a study was undertaken aiming to provide a scientific basis for management. Data collection included information on aspects of the fishery, spawning season, size at first maturity, tangle and gill-net selectivity. Seven nominal mesh sizes were used (40, 45 and 50 mm tangle nets and 40, 50, 60 and 70 mm gill-nets). Spawning lasts from December to June, with peaks in March and May. Length at first maturity for females was estimated at 18.5 cm. Catch rates decreased sharply with increasing mesh size, with tangle nets providing the highest yields. The log-normal selectivity model provided the best fit for specimens that were wedged. The higher catch-per-unit-effort of the smaller mesh sizes and the modal length of the fitted selectivity curve being below the size-at-maturity for wedge sole, suggests that the 50 mm nominal mesh size tangle net is the most appropriate for ensuring the fishery sustainability. Nevertheless, the minimum legal size should increase to at least 18 cm and a time–area closure should be implemented off the Guadiana River mouth.

Incidental capture of elasmobranchs in the bottom-set gill-net fishery off the south coast of Ireland

1994 ◽  
Vol 74 (4) ◽  
pp. 837-847 ◽  
Author(s):  
S.D. Berrow
Keyword(s):  
Fishing Effort ◽  
South Coast ◽  
Fishing Gear ◽  
The South ◽  
Blue Shark ◽  
Incidental Capture ◽  
Gill Net ◽  
Total Capture ◽  
Catch Rates ◽  
Basking Shark

The incidental capture of sharks in the bottom-set gill-net fishery off the south coast of Ireland was quantified by placing observers on commercial gill-netters for the duration of a fishing trip. Forty fishing trips were sampled resulting in 1,167 km and 19,760 km h of observed fishing effort. Sixty individual sharks of seven species were reported entangled in the fishing gear. Tope, porbeagle and six-gilled sharks were the most frequently caught species, with black-mouthed dogfish, blue shark, basking shark and starry smooth hound also recorded. Total fishing effort along the south coast was calculated and total capture extrapolated from observed catch rates. An estimated 6,000 sharks were caught in this fishery during the study period.

scholarly journals Human dimensions of climate change and fisheries in a coupled system: the Atlantic surfclam case

2011 ◽  
Vol 68 (6) ◽  
pp. 1354-1367 ◽  
Author(s):  
Bonnie J. McCay ◽  
Sylvia Brandt ◽  
Carolyn F. Creed
Keyword(s):  
Climate Change ◽  
Fishery Management ◽  
Coupled System ◽  
Human Dimensions ◽  
Decision Processes ◽  
Ecological System ◽  
Economic Modelling ◽  
Cognitive Frames ◽  
Marine System ◽  
Management Council

Abstract McCay, B. J., Brandt, S., and Creed, C. F. 2011. Human dimensions of climate change and fisheries in a coupled system: the Atlantic surfclam case. – ICES Journal of Marine Science, 68: 1354–1367. Research on changes in a coupled marine system of the Mid-Atlantic Bight, focusing on Atlantic surfclams and the associated fishery and management system, is reviewed for how the human dimensions of this coupled socio-ecological system are addressed by the researchers. Our foci are on economic modelling of spatial choices, using dynamic optimization with adjustments that reflect better the natural and socio-economic realities of the fishery and on ethnographic observations of decision processes, particularly those of the regional fishery management council, with particular emphasis on cognitive frames and management communities. These are designed to be integrated with and to complement biophysical modelling of the complex coupled socio-ecological system.

Shark fisheries in Argentina

1998 ◽  
Vol 49 (7) ◽  
pp. 601 ◽  
Author(s):  
Gustavo E. Chiaramonte
Keyword(s):  
Fishing Effort ◽  
Population Trends ◽  
The South ◽  
Gill Nets ◽  
Argentine Sea ◽  
Commercial Importance ◽  
South West ◽  
Gill Net ◽  
Galeorhinus Galeus ◽  
Mustelus Schmitti

In the Argentine Sea there are about 35 species of sharks. Three species are subjected to directed fishing: the smoothhound Mustelus schmitti, the school shark Galeorhinus galeus and the copper shark Carcharhinus brachyurus. Other species of elasmobranchs with commercial importance are the angel shark Squatina spp. and several species of skates and rays. The rise in chondrichthyan declared landings registered from 1988 to 1996 is due to the increase in landings of smoothhound and rays. The most important directed shark fishery in the South-West Atlantic is the Necochea gill-net fishery for school shark, which is carried out by the coastal fleet; details are given of the ships and the gill-nets used in this area. The length frequencies of the catches by gill-nets are presented for the school shark; fishing effort (length (km) of net in the water per ship per day) and CPUE (number of sharks per fishing effort) were found not to be good indicators of population trends in the school shark fishery. Resumen. En el Mar Argentino se han registrado 35 especies de tiburones. Tres de estas especies están sometidas a una pesca dirigida; el gatuzo, Mustelus schmitti, el cazón, tiburón vitamínico o trompa de cristal, Galeorhinus galeus y la bacota, Carcharhinus brachyurus. Otras especies de elasmobranquios de importancia comercial son el pez ángel Squatina spp. y algunas especies de rayas. El incremento en los desembarcos de condríctios declarados a las autoridades pesqueras entre 1988 y 1996 es debido principalmente al incremento del desembarco de gatuzo y rayas. La pesquería dirigida a tiburón más importante en el Atlántico Sudoccidental es la pesquería costera de enmalle de Necochea para el cazón. Se describen el largo de las embarcaciones y las redes utilizadas en el área (la medida de malla, el calado y la operación del arte de pesca). Se presenta la frecuencia del largo total de las capturas de cazón en redes de enmalle. Se halló para la pesquería del cazón que el esfuerzo pesquero (estimado como km de red en el agua por embarcación por día) y la CPUE (estimada como tiburones/esfuerzo de pesca) no son buenos indicadores de la tendencia en la abundancia poblacional.

How useful is the ratio of fish density outside versus inside no-take marine reserves as a metric for fishery management control rules?

2011 ◽  
Vol 68 (2) ◽  
pp. 343-359 ◽  
Author(s):  
Elizabeth A. Babcock ◽  
Alec D. MacCall
Keyword(s):  
Fishery Management ◽  
Spatial Scales ◽  
Marine Reserves ◽  
Density Ratio ◽  
Relative Weight ◽  
Fishing Effort ◽  
Management Control ◽  
Fish Density ◽  
Control Rules ◽  
Stock Depletion

A management strategy evaluation (based on five species in the California, USA, nearshore fishery) of control rules that reduce relative fishing effort as a function of the ratio of fish density outside versus inside no-take marine reserves (as a measure of depletion) showed that although the control rules allowed effort to increase at first, in the long term, they were effective at maintaining spawning stock biomass and yield for all simulated species, including depleted ones. Scenarios with fish movement, illegal fishing in the reserve, or post-dispersal density dependence in recruitment required higher density ratio targets, such as 60% of mature fish or 80% of all fish, to avoid stock depletion. The effort allowed by multispecies density-ratio control rules depended on the relative weight given to more or less depleted species. High variability in recruitment or in monitoring data caused the allowable effort to fluctuate. Density-ratio control rules have the advantages that they require no historical data, they can be used at local spatial scales, and they adjust to changing environmental conditions.

Preliminary results of a study into the incidental mortality of sharks in Gill-nets in two Tasmanian Shark Nursery Areas

1992 ◽  
Vol 43 (1) ◽  
pp. 237 ◽  
Author(s):  
H Williams ◽  
AH Schaap
Keyword(s):  
Relative Abundance ◽  
Fishing Effort ◽  
Shark Species ◽  
Nursery Areas ◽  
Preliminary Results ◽  
Gill Net ◽  
Galeorhinus Galeus ◽  
Potential Rate ◽  
Incidental Mortality ◽  
Gill Netting

Since the early 1960s, certain sheltered bays and estuaries around Tasmania have been designated shark nursery areas, where the taking of either the school shark (Galeorhinus galeus) or the gummy shark (Mustelus antarcticus) has been prohibited. Recent assessments of Australian stocks of school and gummy sharks indicate that they are close to collapse, and the management of the fishery has come under review. With respect to shark nursery areas, concern has focused on the potential rate of incidental mortality of sharks caused by recreational gill-net fishing and poaching. In 1990, a study was begun in Frederick Henry Bay and Norfolk Bay, the largest proclaimed shark nursery areas in Tasmania, to estimate recreational net-fishing effort and incidental captures of sharks. School sharks were caught in waters deeper than 5 m; gummy sharks and dogfish were caught at all depths. The diversity and relative abundance of shark species increased with depth, whereas the diversity of teleosts decreased with depth. Most captured school and gummy sharks were between 1+ and 3+ years of age. Preliminary estimates of potential incidental mortality demonstrate that gill-netting in depths greater than 5 m may be a significant source of mortality for both species.

KAPASITAS PENANGKAPAN IKAN PELAGIS KECIL DI PERAIRAN PANTAI BARAT SULAWESI SELATAN (FISHING CAPACITY OF SMALL PELAGIC FISH IN OF WEST COAST OF SOUTH SULAWESI)

2016 ◽  
Vol 1 (2) ◽  
pp. 117 ◽  
Author(s):  
Alfa Nelwan
Keyword(s):  
West Coast ◽  
Fishing Effort ◽  
Pelagic Fish ◽  
Production Data ◽  
Fish Production ◽  
Beach Seine ◽  
Small Pelagic Fish ◽  
South Sulawesi ◽  
Gill Net ◽  
Development Analysis

Kapasitas penangkapan adalah ukuran kemampuan yang dikerahkan oleh berbagai jenis unit penangkapan ikan yang tergabung sebagai suatu armada penangkapan ikan untuk memperoleh hasil tangkapan. Penelitian ini menganalisis trend dan kapasitas penangkapan ikan pelagis kecil di perairan pantai barat Sulawesi Selatan. Delapan jenis alat penangkap yang signifikan di Selat Makassar, perairan barat Provinsi Sulawesi Selatan adalah payang, pukat pantai, pukat cincin, jaring insang hanyut, jaring lingkar, jaring insang tetap, bagan perahu dan bagan tancap.  Produksi dari 8 unit penangkapan berdasarkan 6 jenis ikan pelagis kecil, yaitu (1) kembung (Rastrelliger sp), (2) layang (Decapterus sp), (3) lemuru (Sardinella longiceps), (4) selar (Selaroides spp), (5) tembang (Sardinella  fimbriata), (6) teri (Stolephorus spp). Total upaya penangkapan ikan tahunan dari kedelapan jenis unit penangkapan ikan tersebut dihitung untuk kurun waktu selama 20 tahun (1987-2006) dengan menerapkan standardisasi berdasarkan kemampuan setiap jenis unit penangkapan ikan.  Analisis dilakukan untuk mengidentifikasi trend CPUE dan kapasitas penangkapan ikan pelagis kecil menggunakan metode Peak to Peak Analysis di tiga zona perairan pantai, yaitu perairan laut dangkal  (zona A), perairan bentuk teluk (zona B) dan perairan laut dalam (zona C), Tren CPUE di ketiga zona menunjukkan cenderung menurun dalam kurun waktu 30 tahun, dimana tren menurun CPUE di zona C menunjukkan lebih besar dibandingkan zona lainnya.  Kapasitas penangkapan di zona A, perlu mereduksi jumlah unit penangkapan sebesar 6%, sedangkan di zona B sebesar 5% dan zona C sebesar 11% untuk mencapai produksi optimal.Fishing capacity can be regarded as a total mobilized capability made by fishing fleet to produce catch. This research analyze trend and fishing capacities of small pelagic fish in off west coast of South Sulawesi. There are 8 significant fishing unit operated in off west coast of South Sulawesi ; these are  payang, beach seine, purse seine, drift gill net, encircling gillnet, fixed gill net, boat liftnet, fixed liftnet.  The fish production data cover 6 types of fish, i.e. Indian mackerel, anchovy, sardines, scads, and trevally caught by 8 types fishing unit. Annual fishing effort and CPUE over a period of 30 years (1977-2006) were calculated after a standardization considering variability in capture capability and fisheries development.  Analysis was conducted for identifyng CPUE trend and fishing capacities of small pelagic fish using Peak to Peak Analysis. The study area was divided into three regions, i.e, around Spermonde Island  (zone A), off Polman and Pinrang district (zone B) and off Majene dan Mamuju district (zone C).  CPUE trend in three water zone showed to decrease for 30 year of period, where decreasing CPUE trend at zone C was higher than other zones.  Fishing capacities in zone A need to be reduced of fishing effort for  6%, whereas in zone B was 5% and zone C was 11%.

scholarly journals Predicting the effects of area closures and fishing effort restrictions on the production, biomass, and species richness of benthic invertebrate communities

2006 ◽  
Vol 63 (5) ◽  
pp. 822-830 ◽  
Author(s):  
J.G. Hiddink ◽  
T. Hutton ◽  
S. Jennings ◽  
M.J. Kaiser
Keyword(s):  
Species Richness ◽  
North Sea ◽  
Fishery Management ◽  
Benthic Communities ◽  
Fishing Effort ◽  
Management Actions ◽  
The North ◽  
The North Sea ◽  
Effort Reduction ◽  
Positive Effect

AbstractTo effectively implement an Ecosystem Approach to Fisheries (EAF), managers need to consider the effects of management actions on the fishery and the ecosystem. Methods for assessing the effects on target stocks are generally well developed, but methods for assessing the effects on other components and attributes of the ecosystem are not. Area closures and effort controls are widely used fishery management tools that affect the distribution of fishing effort and may therefore have consequences for a range of species and habitats. An approach is developed to predict the effects of area closures and effort control on the biomass, production, and species richness of benthic communities in the North Sea. The redistribution of beam trawling effort as a result of management action was modelled with a random utility model, assuming that fishers selected fishing grounds on the basis of their knowledge of past catch rates. The effects of trawling on benthic invertebrates were predicted using a size-based model that accounted for differences in habitat among fishing grounds. Our simulations demonstrated that closures of different sizes and in different locations could have positive or negative effects on benthic communities. These predicted effects resulted from the trade-off between recovery in the closed areas and additional trawling effects in the open areas that arose from displaced fishing activity. In the absence of effort controls, closure of lightly fished areas had the strongest positive effect on benthic communities. Effort reduction also had a positive effect. Therefore, area closures in lightly fished areas, coupled with effort reduction, are expected to minimize the effects of fishing on benthic communities. As it was not possible to access full international data for the North Sea beam trawl fleet, the results of the analyses are illustrative rather than complete. Nevertheless, what is demonstrated is an effective approach for assessing the environmental consequences of fishery management action that can be used to inform management decision-making as part of an EAF.

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