scholarly journals Catch, bycatch and discards of the Galapagos Marine Reserve small-scale handline fishery

2015 ◽  
Author(s):  
Johanna S Zimmerhackel ◽  
Anna C Schuhbauer ◽  
Paolo Usseglio ◽  
Lena C Heel ◽  
Pelayo Salinas-de-León
Keyword(s):  
Marine Reserve ◽  
Marine Conservation ◽  
Economic Consequences ◽  
Small Scale ◽  
Local Market ◽  
Target Species ◽  
Fisheries Bycatch ◽  
Spatio Temporal ◽  
Catch Composition ◽  
Galapagos Marine Reserve

Fisheries bycatch is one of the most significant marine conservation issues as valuable fish are wasted and protected species harmed with potential negative ecological and socio-economic consequences. Even though there are indications that the small-scale handline fishery of the Galapagos Marine Reserve has a low selectivity, information on its bycatch never has been published. We therefore assessed the bycatch of the Galapagos handline fishery by estimating the bycatch ratio, determining species compositions of landings and bycatch, and identifying fishers’ reasons for discarding certain individuals using onboard monitoring and interview data. Moreover, we used interview surveys to reveal historical trends in the bycatch ratio. The estimated bycatch ratio of 0.40 confirmed a low selectivity of this fishery. Characterisation of the catch resulted in a total of 19 target species which were dominated by groupers, and 53 non-target species, with grunts and groupers being most prominent. Most individuals were not landed for economic motivations, either because species (77.4%) or sizes (17.7%) are not marketable and to a lesser extent for regulatory reasons (5.9%). However, sharks were after grunts with 69% the second most often mentioned bycatch taxa during interview surveys. We found that small sized individuals of some of the most exploited species suffer high bycatch mortality because they are used as bait. Moreover, over half of interviewees perceived a historical decrease in bycatch ratios that was explained by a diversification of the catch composition due to the reduction in abundance of the traditionally most important target species. As some target species show signs of overfishing and to date there are no specific regulations for the finfish fishery in place, we recommend the investigation of different gear settings such as the use of different hooks and bait species. Furthermore, we suggest the integration of faster growing species to the local market as well as spatio-temporal closures, and minimum and maximum catch sizes for overexploited species in order to improve the selectivity and sustainability of the Galapagos handline fishery.

scholarly journals Catch, bycatch and discards of the Galapagos Marine Reserve small-scale handline fishery

2015 ◽  
Author(s):  
Johanna S Zimmerhackel ◽  
Anna C Schuhbauer ◽  
Paolo Usseglio ◽  
Lena C Heel ◽  
Pelayo Salinas-de-León
Keyword(s):  
Marine Reserve ◽  
Marine Conservation ◽  
Economic Consequences ◽  
Small Scale ◽  
Local Market ◽  
Target Species ◽  
Fisheries Bycatch ◽  
Spatio Temporal ◽  
Catch Composition ◽  
Galapagos Marine Reserve

Fisheries bycatch is one of the most significant marine conservation issues as valuable fish are wasted and protected species harmed with potential negative ecological and socio-economic consequences. Even though there are indications that the small-scale handline fishery of the Galapagos Marine Reserve has a low selectivity, information on its bycatch never has been published. We therefore assessed the bycatch of the Galapagos handline fishery by estimating the bycatch ratio, determining species compositions of landings and bycatch, and identifying fishers’ reasons for discarding certain individuals using onboard monitoring and interview data. Moreover, we used interview surveys to reveal historical trends in the bycatch ratio. The estimated bycatch ratio of 0.40 confirmed a low selectivity of this fishery. Characterisation of the catch resulted in a total of 19 target species which were dominated by groupers, and 53 non-target species, with grunts and groupers being most prominent. Most individuals were not landed for economic motivations, either because species (77.4%) or sizes (17.7%) are not marketable and to a lesser extent for regulatory reasons (5.9%). However, sharks were after grunts with 69% the second most often mentioned bycatch taxa during interview surveys. We found that small sized individuals of some of the most exploited species suffer high bycatch mortality because they are used as bait. Moreover, over half of interviewees perceived a historical decrease in bycatch ratios that was explained by a diversification of the catch composition due to the reduction in abundance of the traditionally most important target species. As some target species show signs of overfishing and to date there are no specific regulations for the finfish fishery in place, we recommend the investigation of different gear settings such as the use of different hooks and bait species. Furthermore, we suggest the integration of faster growing species to the local market as well as spatio-temporal closures, and minimum and maximum catch sizes for overexploited species in order to improve the selectivity and sustainability of the Galapagos handline fishery.

scholarly journals Supporting Spatial Management of Data-Poor, Small-Scale Fisheries With a Bayesian Approach

2021 ◽  
Vol 8 ◽  
Author(s):  
Jennifer Rehren ◽  
Maria Grazia Pennino ◽  
Marta Coll ◽  
Narriman Jiddawi ◽  
Christopher Muhando
Keyword(s):  
Spatial Distribution ◽  
Marine Conservation ◽  
Environmental Drivers ◽  
Small Scale ◽  
Target Species ◽  
Short Term ◽  
Conservation Areas ◽  
Bayesian Hierarchical ◽  
Small Scale Fisheries ◽  
Spatial Management

Marine conservation areas are an important tool for the sustainable management of multispecies, small-scale fisheries. Effective spatial management requires a proper understanding of the spatial distribution of target species and the identification of its environmental drivers. Small-scale fisheries, however, often face scarcity and low-quality of data. In these situations, approaches for the prioritization of conservation areas need to deal with scattered, biased, and short-term information and ideally should quantify data- and model-specific uncertainties for a better understanding of the risks related to management interventions. We used a Bayesian hierarchical species distribution modeling approach on annual landing data of the heavily exploited, small-scale, and data-poor fishery of Chwaka Bay (Zanzibar) in the Western Indian Ocean to understand the distribution of the key target species and identify potential areas for conservation. Few commonalities were found in the set of important habitat and environmental drivers among species, but temperature, depth, and seagrass cover affected the spatial distribution of three of the six analyzed species. A comparison of our results with information from ecological studies suggests that our approach predicts the distribution of the analyzed species reasonably well. Furthermore, the two main common areas of high relative abundance identified in our study have been previously suggested by the local fisher as important areas for spatial conservation. By using short-term, catch per unit of effort data in a Bayesian hierarchical framework, we quantify the associated uncertainties while accounting for spatial dependencies. More importantly, the use of accessible and interpretable tools, such as the here created spatial maps, can frame a better understanding of spatio-temporal management for local fishers. Our approach, thus, supports the operability of spatial management in small-scale fisheries suffering from a general lack of long-term fisheries information and fisheries independent data.

scholarly journals Structure and spatio-temporal dynamics of the artisanal small-scale fisheries at the future MPA of “Taza” (Algerian coast, SW Mediterranean)

2018 ◽  
Vol 19 (3) ◽  
pp. 555 ◽  
Author(s):  
IBRAHIM BOUBEKRI ◽  
ALEX JAMES CAVEEN ◽  
ABDALLAH BORHANE DJEBAR ◽  
RACHID AMARA ◽  
HUBERT MAZUREK
Keyword(s):  
Temporal Dynamics ◽  
Field Work ◽  
Management Plan ◽  
Small Scale ◽  
Target Species ◽  
Small Scale Fisheries ◽  
The Future ◽  
Mullus Surmuletus ◽  
Spatio Temporal ◽  
Management Approaches

Artisanal Small-Scale Fisheries (SSFs) are a primordial and very diverse activity in the Mediterranean, also within Marine Protected Areas (MPAs). This diversity is explained in terms of target species, gears, and fishing strategies. The main objective of this work was to investigate the spatio-temporal dynamics of artisanal SSFs of the future MPA of “Taza” (Algeria, SW Mediterranean). Data were collected through direct assessment of daily landings and using questionnaires. They were the subject of multivariate analyses that allowed us to identify the métiers practiced by artisanal fishers. During the one year (May 2013 to April 2014) field work period, 1330 fishing trips and 1613 fishing operations in 16 fishing grounds were recorded in the Ziama fishing harbor, where 15.2 tons of total catch was assessed. Our results show that, in the study area, the boats are predominantly gillnetters and that among the five métiers characterized by target species, gear type, fishing grounds, and fishing seasons, two métiers (“Mullus surmuletus trammel net” and “Sparids monofilament gillnet”) are practiced throughout the year, while the remaining three (“Sarda sarda driftnet”, “Merluccius merluccius set gillnet”, and “Pagellus set gillnet”) are specific to a determined period of the year. The ‘Mullus surmuletus trammel net’ métier represents 40% of the total fishing operations, of which 57.5% are carried out in the coastal sector at - 25 m. This study could contribute to defining the appropriate management approaches for SSFs in the future MPA of “Taza” by providing baseline information to build a sound management plan. In Algeria, it will certainly serve as a scientific reference in terms of zoning, protection of biodiversity, and specific monitoring at particular locations and periods of the year for the sustainable management of MPAs.

scholarly journals Catch, bycatch and discards of the Galapagos Marine Reserve small-scale handline fishery

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e995 ◽  
Author(s):  
Johanna S. Zimmerhackel ◽  
Anna C. Schuhbauer ◽  
Paolo Usseglio ◽  
Lena C. Heel ◽  
Pelayo Salinas-de-León
Keyword(s):  
Marine Reserve ◽  
Small Scale ◽  
Galapagos Marine Reserve

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.

scholarly journals Changes in the catch composition of artisanal fisheries attributable to dolphin depredation in a Mediterranean marine reserve

2009 ◽  
Vol 66 (4) ◽  
pp. 699-707 ◽  
Author(s):  
Delphine Rocklin ◽  
Marie-Catherine Santoni ◽  
Jean-Michel Culioli ◽  
Jean-Antoine Tomasini ◽  
Dominique Pelletier ◽  
...  
Keyword(s):  
Marine Reserve ◽  
Bottlenose Dolphins ◽  
Artisanal Fisheries ◽  
Catch Per Unit Effort ◽  
Natural Reserve ◽  
Catch Composition ◽  
The Impact ◽  
High Fish ◽  
Fishing Area ◽  
Fish Avoidance

AbstractRocklin, D., Santoni, M-C., Culioli, J-M., Tomasini, J-A., Pelletier, D., and Mouillot, D. 2009. Changes in the catch composition of artisanal fisheries attributable to dolphin depredation in a Mediterranean marine reserve. – ICES Journal of Marine Science, 66: 699–707. There is increasing evidence from previous studies, and from fishers’ observations, that coastal dolphins use fishing nets as an easily accessible feeding source, damaging or depredating fish caught in the nets. This study investigates the impact of dolphin depredation on artisanal trammelnets by analysing the catch composition of 614 artisanal fishing operations in the Bonifacio Strait Natural Reserve (France). Common bottlenose dolphins (Tursiops truncatus) attacked, on average, 12.4% of the nets and damaged 8.3% of the catch. However, attacked nets were characterized by statistically significantly higher catch per unit effort than unattacked ones. Catch composition also differed significantly after dolphin attacks; bentho-pelagic fish were more represented and reef-associated fish less represented. Our results suggest that (i) dolphins are attracted by high fish densities in the fishing area and/or nets, and (ii) their attacks induce specific fish-avoidance behaviour, according to the fish position in the water column. Although dolphins depredate a small part of the catch, damage to nets, not yet assessed in this area, could weaken the benefits that reserves can provide to artisanal fisheries.

scholarly journals Small-scale spatio-temporal characteristics of accumulation rates in western Dronning Maud Land, Antarctica

2008 ◽  
Vol 54 (185) ◽  
pp. 315-323 ◽  
Author(s):  
Helgard Anschütz ◽  
Daniel Steinhage ◽  
Olaf Eisen ◽  
Hans Oerter ◽  
Martin Horwath ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Temporal Variations ◽  
Spatial Variations ◽  
Small Scale ◽  
Accumulation Rates ◽  
Order Of Magnitude ◽  
Dronning Maud Land ◽  
Spatio Temporal ◽  
Ground Penetrating ◽  
Firn Core

AbstractSpatio-temporal variations of the recently determined accumulation rate are investigated using ground-penetrating radar (GPR) measurements and firn-core studies. The study area is located on Ritscherflya in western Dronning Maud Land, Antarctica, at an elevation range 1400–1560 m. Accumulation rates are derived from internal reflection horizons (IRHs), tracked with GPR, which are connected to a dated firn core. GPR-derived internal layer depths show small relief along a 22 km profile on an ice flowline. Average accumulation rates are about 190 kg m−2 a−1 (1980–2005) with spatial variability (1σ) of 5% along the GPR profile. The interannual variability obtained from four dated firn cores is one order of magnitude higher, showing 1σ standard deviations around 30%. Mean temporal variations of GPRderived accumulation rates are of the same magnitude or even higher than spatial variations. Temporal differences between 1980–90 and 1990–2005, obtained from two dated IRHs along the GPR profile, indicate temporally non-stationary processes, linked to spatial variations. Comparison with similarly obtained accumulation data from another coastal area in central Dronning Maud Land confirms this observation. Our results contribute to understanding spatio-temporal variations of the accumulation processes, necessary for the validation of satellite data (e.g. altimetry studies and gravity missions such as Gravity Recovery and Climate Experiment (GRACE)).

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