scholarly journals Biology and population dynamics of by-catch fish species of the bottom trawl fishery in the western Mediterranean

2014 ◽  
Vol 15 (3) ◽  
pp. 613 ◽  
Author(s):  
F. ORDINES ◽  
M.T. FARRIOLS ◽  
J. LLEONART ◽  
B. GUIJARRO ◽  
A. QUETGLAS ◽  
...  
Keyword(s):  
Population Analysis ◽  
Conservation Status ◽  
Fishing Effort ◽  
Western Mediterranean ◽  
Distribution Range ◽  
Bottom Trawl ◽  
Trawl Fishery ◽  
Virtual Population ◽  
Trawl Fishing ◽  
By Catch

The teleosts Chelidonichthys cuculus, Trigloporus lastoviza, Serranus cabrilla and Trachinus draco, are important by-catch species, in terms of landed biomass and commercial value, from the continental shelf bottom trawl fishery off the Balearic Islands (western Mediterranean). The main biological parameters of these species were calculated from monthly biological samplings, and were used along with three years pseudo-cohorts (2008-2010) obtained from monitoring on-board of the bottom trawl fleet, to assess their exploitation level through Virtual Population Analysis (VPA) and Yield per Recruit (Y/R) analysis. Time series of fishery independent indicators based on MEDITS surveys data such as the evolution of the abundance and biomass, the distribution range, and the Conservation Status of Fish b (CSFb), were also analyzed. All four species analyzed showed growth overfishing. The reductions of the fishing effort required to reach the Y/RF0,1 reference point were lower, 66-73% depending on the species, to those reported for the target species M. merluccius (87%), but higher than that reported for M. surmuletus (53%), in the study area in the period 2000-2010. The abundance and biomass, and the distribution range did not show any trend for the period 2001-2011, whereas the CSFb showed signs of recovery that may be due to the displacement of the trawl fishing effort from the shelf to the slope during the last decade. Our results underline the necessary incorporation of monitoring and assessment of by-catch species to the management of fisheries as their populations can show a more pronounced overexploitation than target ones.

scholarly journals Recovery Signals of Rhodoliths Beds since Bottom Trawling Ban in the SCI Menorca Channel (Western Mediterranean)

Diversity ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 20
Author(s):  
Maria Teresa Farriols ◽  
Camille Irlinger ◽  
Francesc Ordines ◽  
Desirée Palomino ◽  
Elena Marco-Herrero ◽  
...  
Keyword(s):  
Natura 2000 ◽  
Management Plan ◽  
Fishing Effort ◽  
Western Mediterranean ◽  
Bottom Trawl ◽  
Effective Measure ◽  
Bottom Trawling ◽  
Trawl Fishing ◽  
Special Area ◽  
The Impact

One of the objectives of the LIFE IP INTEMARES project is to assess the impact of bottom trawling on the vulnerable benthic habitats of the circalittoral bottoms of the Menorca Channel (western Mediterranean), designated a Site of Community Importance (SCI) within the Natura 2000 network. The present study compares the epibenthic communities of four areas, subjected to different bottom trawl fishing intensity levels. The assignment of fishing effort levels was based on the fishing effort distribution in the area calculated from Vessel Monitoring System (VMS) data and the existence of two Fishing Protected Zones in the Menorca Channel. Biological samples were collected from 39 beam trawl stations, sampled during a scientific survey on April 2019. We compare the diversity, composition, and density of the epibenthic flora and fauna, together with the rhodoliths coverage and the morphology of the main species of rhodoliths of four areas subjected to different levels of bottom trawl fishing effort, including one that has never been impacted by trawling. Our results have shown negative impacts of bottom trawling on rhodoliths beds and the first signals of their recovery in areas recently closed to this fishery, which indicate that this is an effective measure for the conservation of this habitat of special interest and must be included in the management plan required to declare the Menorca Channel as a Special Area of Conservation.

The by-catch of sharks in the western Mediterranean (Balearic Islands) trawl fishery

2003 ◽  
Vol 61 (1-3) ◽  
pp. 7-18 ◽  
Author(s):  
A Carbonell ◽  
F Alemany ◽  
P Merella ◽  
A Quetglas ◽  
E Román
Keyword(s):  
Western Mediterranean ◽  
Balearic Islands ◽  
Trawl Fishery ◽  
By Catch

scholarly journals Testing Nordmøre grids on the target and by-catch species of the commercial bottom trawl fishery in the Gulf of Cadiz

2015 ◽  
Vol 79 (4) ◽  
pp. 465-477 ◽  
Author(s):  
Mariángeles Gamaza ◽  
Ignacio Sobrino ◽  
Karim Erzini
Keyword(s):  
Bottom Trawl ◽  
Gulf Of Cadiz ◽  
Trawl Fishery ◽  
Gulf Of Cádiz ◽  
By Catch

scholarly journals Utilization of pop-up satellite archival transmitting tags to evaluate thorny skate (Amblyraja radiata) discard mortality in the Gulf of Maine groundfish bottom trawl fishery

2019 ◽  
Author(s):  
Ryan Knotek ◽  
Jeff Kneebone ◽  
James Sulikowski ◽  
Tobey Curtis ◽  
Joseph Jurek ◽  
...  
Keyword(s):  
New England ◽  
Fishery Management ◽  
Gulf Of Maine ◽  
Bottom Trawl ◽  
Incidental Capture ◽  
Trawl Fishery ◽  
Discard Mortality ◽  
Stock Biomass ◽  
Trawl Fishing ◽  
Fishing Practices

Abstract Thorny skate (Amblyraja radiata) remain one of the most overfished species in the Gulf of Maine (GOM) despite being designated as a prohibited (zero-possession, mandatory release) species by the New England Fishery Management Council in 2003. To better understand the extent to which discard mortality (DM) occurring after incidental capture in the GOM groundfish bottom trawl fishery may be impeding recovery, 75 individuals (55–94 cm total length, TL) were tagged with pop-up satellite archival transmitting (PSAT) tags and monitored for up to 28 days following capture under representative commercial trawl fishing practices. Data recovered from 61 PSAT-tagged skate were analysed with a longitudinal survival analysis to estimate DM and identify influential capture-related variables. DM rate was a function of TL, with larger skates (>70 cm; DM = 16.5%) experiencing lower mortality than smaller conspecifics (55–70 cm; DM = 24.5%). From our results, we estimate annual thorny skate DM in the GOM groundfish bottom trawl fishery to be 79.2 ± 0.2 mt, which accounts for <1% of the existing stock biomass in the GOM (8400 mt). This study confirms that thorny skate are relatively resilient to bottom trawl fishing practices in the GOM, and suggests that other sources of mortality may be impeding population recovery.

scholarly journals Species biology of elasmobranch by-catch in bottom-trawl fishery on the northern Patagonian shelf, Argentina

2013 ◽  
Vol 19 (3) ◽  
pp. 239-251 ◽  
Author(s):  
AC Crespi-Abril ◽  
SN Pedraza ◽  
NA García ◽  
EA Crespo
Keyword(s):  
Bottom Trawl ◽  
Trawl Fishery ◽  
Patagonian Shelf ◽  
By Catch

Changes in Catchability in a Bottom-Trawl Fishery for Cape Hake (Merluccius capensis)

1991 ◽  
Vol 48 (10) ◽  
pp. 1887-1895 ◽  
Author(s):  
Ana Gordoa ◽  
Joseph E. Hightower
Keyword(s):  
Inverse Relationship ◽  
Population Analysis ◽  
Fish Distribution ◽  
Factors Affecting ◽  
Trawl Fishery ◽  
Surplus Production ◽  
Virtual Population Analysis ◽  
Virtual Population ◽  
Average Water ◽  
Production Modeling

Management of the Cape hake (Merluccius capensis) stock off the coasts of Angola and Namibia has been based on surplus production modeling, which incorporates an assumption of constant catchability. Results of least-squares catch-at-age analysis and virtual population analysis were used to estimate catchability from 1968 to 1986. Estimated catchability was either relatively constant or gradually increasing from 1968 to 1978, but fluctuated considerably between about 1979 and 1983. The fluctuations may have been due to an inverse relationship between catchability and abundance or to environmental factors affecting fish distribution. The period of highest estimated catchability corresponded to the period of lowest estimated abundance and below-average water temperatures. If management is based on the assumption of constant catchability but catchability is inversely related to abundance, the risk of overfishing will be greatest when the stock is at the lowest levels. Future assessments should place increased reliance on survey data or incorporate an appropriate model of catchability changes.

scholarly journals Combining in-trawl video with observer coverage improves understanding of protected and vulnerable species by-catch in trawl fisheries

2014 ◽  
Vol 65 (9) ◽  
pp. 830 ◽  
Author(s):  
Vanessa F. Jaiteh ◽  
Simon J. Allen ◽  
Jessica J. Meeuwig ◽  
Neil R. Loneragan
Keyword(s):  
Video Camera ◽  
Fishing Effort ◽  
Vulnerable Species ◽  
Independent Observer ◽  
Video Footage ◽  
Trawl Fishery ◽  
Scalloped Hammerhead ◽  
Sea Snakes ◽  
By Catch ◽  
Trawl Fisheries

Assessments of incidental wildlife mortality resulting from fishing rarely account for unobserved by-catch. We assessed by-catch of protected and vulnerable wildlife species in an Australian trawl fishery by comparing in-trawl video footage with data collected by an on-board observer. Data were obtained from 44 commercial trawls with two different by-catch reduction devices (BRDs). Eighty-six individuals from six major taxa (dolphins, sharks, rays, sea snakes, turtles and sygnathids) were documented from video analysis, including the endangered scalloped hammerhead shark (Sphyrna lewini) and the critically endangered green sawfish (Pristis zijsron). On the basis of the 2008–2009 fishing effort of 4149 trawls and scaling from these results, we estimated the annual catch of protected and vulnerable species (± 1 s.e.) at 8109 ± 910 individuals. Only 34% of by-catch was expelled through the BRDs. Independent observer data for the 44 trawls showed that 77% of the landed by-catch from these taxa were dead when discarded. The results indicate that unaccounted by-catch in trawl fisheries can be substantial, and that current methods of recording by-catch on-board vessels are likely to underestimate total fishing mortality. We recommend gear modifications and their validation through dedicated observer coverage, combined with in-trawl video camera deployments to improve current approaches to by-catch mitigation.

scholarly journals Standardized catch rate of cockfish, Callorhinchus callorynchus, in a bottom trawl fishery of Patagonia: Is it possible its use as a predictor of abundance trend?

2015 ◽  
Vol 63 (2) ◽  
pp. 147-160 ◽  
Author(s):  
Juan F. Bernasconi ◽  
María Raquel Perier ◽  
Edgardo E. Di Giácomo
Keyword(s):  
Linear Models ◽  
Fishing Effort ◽  
Catch Rate ◽  
Bottom Trawl ◽  
General Linear ◽  
Homogeneous Distribution ◽  
Annual Trend ◽  
Trawl Fishery ◽  
Total Variability ◽  
Best Fit

Abstract The catch per unit of effort (CPUE) data of cockfish, Callorhinchus callorynchus, during 1986-2011 was evaluated for the bottom trawl fishery of the San Matías gulf (Patagonia, Argentina). The objective of this work was to detect what are the factors related to fishery dynamic that affect catch rate of cockfish and to assess standardized CPUE by General linear models (GLMs) and General linear mixed models (GLMMs) as a relative abundance index. The annual trend of the catch rate indicated an increase during the evaluated period. The nominal CPUE and the indices standardized by the Delta-GLM and Delta-GLMM showed the same annual trend, with increases of 57%, 61.1% and 60.7%, respectively. The LogNormal models have the best-fit model and explained 23.5% of the total variability. The factors year, month, depth and hake CPUE explained the highest variability. The analysis of the models indicated that the catch rate of cockfish is subject to the lack of an homogeneous distribution of the fishing effort during different years, months and vessels. This was related to the fleet dynamic searching the targets species. The increasing trend of CPUE and landings would be indicating an increase in effort directionality to the cockfish in the last decade.

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