scholarly journals Stimulating release of undersized fish through a square mesh panel in the Basque otter trawl fishery

2020 ◽  
Vol 224 ◽  
pp. 105431
Author(s):  
Elsa Cuende ◽  
Luis Arregi ◽  
Bent Herrmann ◽  
Manu Sistiaga ◽  
Iñigo Onandia
Keyword(s):  
Otter Trawl ◽  
Trawl Fishery

scholarly journals Use of avoidance behaviours to reduce the economic impacts of the EU Landing Obligation: the case study of a mixed trawl fishery

2019 ◽  
Vol 76 (6) ◽  
pp. 1554-1566
Author(s):  
Fabien Pointin ◽  
Fabienne Daurès ◽  
Marie-Joëlle Rochet
Keyword(s):  
Temporal Distribution ◽  
Grid Method ◽  
Fishing Effort ◽  
Economic Losses ◽  
Otter Trawl ◽  
Trawl Fishery ◽  
Nested Grid ◽  
Fishing Practices ◽  
The Eu

Abstract The EU Landing Obligation (LO) is designed to reduce bycatch (i.e. unwanted catch) through more selective fishing practices, such as avoidance behaviours which consist in allocating fishing effort to other species, fishing grounds or seasons. Incentives for fishers to change their behaviours depend on their economic performances as well as their ability to avoid bycatch. Changes in economic performances under the LO are evaluated based on cost and revenue equations. The nested grid method is then used to explore the spatial and temporal distribution of landings and discards, and to suggest alternative effort allocation to avoid bycatch. This article is focussed specifically on the French otter trawl fishery in the eastern English Channel and southern North Sea. Results suggest that under the LO the choke species problem will curtail fishing activities earlier in the year, leading to significant economic losses. In the absence of significant quota top-ups (at least 75%), a change in fishing practices consisting in reducing overall bycatch by 30% is insufficient to reduce losses. With a particular attention to choke species, more economically efficient avoidance strategies can be found thanks to the nested grid method.

Reflex impairment, physiological stress, and discard mortality of European plaice Pleuronectes platessa in an otter trawl fishery

2017 ◽  
Vol 74 (6) ◽  
pp. 1660-1671 ◽  
Author(s):  
Caroline Methling ◽  
Peter V. Skov ◽  
Niels Madsen
Keyword(s):  
Physiological Stress ◽  
Plasma Osmolality ◽  
Control Fish ◽  
Otter Trawl ◽  
Air Exposure ◽  
Trawl Fishery ◽  
Physiological Variables ◽  
Discard Mortality ◽  
Fisheries Policy ◽  
Short Term Mortality

Abstract The reformed European Common Fisheries Policy introduced a discard ban, with a possibility of exempting species where a high discard survival can be demonstrated. This necessitates a validation of the methods used for estimating the discard mortality of candidate species. In this study, we assess whether reflex impairment can predict short-term mortality in commercially trawled European plaice upon landing and after air exposure of up to 90 min. Sub-lethal stress was assessed by a suite of physiological variables. Over a 10-day period, mortality was monitored for a total of 199 plaice following trawl and air exposure of varying duration, and for 50 control fish scored for reflex impairment on board the vessel. Mortality was only observed in fish exposed to air for >60 min, and averaged 11.1% (95% CI = 7.1–16.3%). Reflex impairment was found to be a significant (P < 0.001) predictor of mortality in a generalized linear model, excluding other initially included variables by using a stepwise method. Plasma cortisol, haematocrit, and plasma osmolality all indicated a profound and increasing level of stress with air exposure, accompanied by a near depletion of muscle phosphocreatine and nucleotides. Fishing site had an unexpected, but significant (p < 0.05) effect on stress levels, which was also reflected in reflex impairment and mortality. Based on these findings, a possible exemption from the discard ban should include considerations on the duration of air exposure.

scholarly journals The recovery of Atlantic halibut: a large, long-lived, and exploited marine predator

2016 ◽  
Vol 73 (4) ◽  
pp. 1104-1114 ◽  
Author(s):  
M. Kurtis Trzcinski ◽  
W. Don Bowen
Keyword(s):  
Gadus Morhua ◽  
Assessment Model ◽  
Minimum Size ◽  
Otter Trawl ◽  
Atlantic Halibut ◽  
High Biomass ◽  
Total Allowable Catch ◽  
Marine Predator ◽  
Trawl Fishery ◽  
Management Actions

Abstract Atlantic halibut (Hippoglossus hippoglossus) have a long history of exploitation in the Northwest Atlantic and have gone through several periods of high biomass followed by a population crash. An assessment model using data collected on the Scotian Shelf and southern Grand Banks shows that the population peaked in 1984, then decreased sharply to a low in 1993. Several management measures were taken during the decline, including reductions in total allowable catch and a minimum size limit. Concurrently, removals by the otter trawl fishery were drastically reduced following the collapse of the cod (Gadus morhua) fishery. In 2003, recruitment increased and continued to be high for 6 years. Fishing mortality rates were moderate in the late 1990s and 2000s and the population increased. By 2009, the Atlantic halibut population was highly productive with both high biomass and high levels of recruitment. The coincidence in the timing of population recovery and management actions indicates that effective management contributed to the recovery of Atlantic halibut.

Change of relative fishing power index from technological development in the otter trawl fishery

2020 ◽  
Vol 56 (1) ◽  
pp. 26-36
Author(s):  
Hyun-Su JO ◽  
Young-Il SEO ◽  
Taeg-Yun OH ◽  
Young-Su AN ◽  
Byung-Yeob KIM ◽  
...  
Keyword(s):  
Power Index ◽  
Technological Development ◽  
Otter Trawl ◽  
Trawl Fishery

scholarly journals Trawling disturbance on megabenthos and sediment in the Barents Sea: chronic effects on density, diversity, and composition

2015 ◽  
Vol 73 (suppl_1) ◽  
pp. i98-i114 ◽  
Author(s):  
Lene Buhl-Mortensen ◽  
Kari E. Ellingsen ◽  
Pål Buhl-Mortensen ◽  
Kristian L. Skaar ◽  
Genoveva Gonzalez-Mirelis
Keyword(s):  
Biological Diversity ◽  
Barents Sea ◽  
Otter Trawl ◽  
Positive Trend ◽  
Trawl Fishery ◽  
Chronic Effects ◽  
Wide Range ◽  
History Of ◽  
Ecological Importance ◽  
Physical Impact

Abstract Bottom-trawl fisheries are expanding into deeper habitats and higher latitudes, but our understanding of their effects in these areas is limited. The ecological importance of habitat-forming megabenthos and their vulnerability to trawling is acknowledged, but studies on effects are few. Our objective was to investigate chronic effects of otter trawl fishery on substratum and megabenthos on the shelf (50–400 m) and slope (400–2000 m) in the southern Barents Sea. The study area represents a wide range in the history of fishing intensity (FI). Physical impact of trawling, density of trawl marks (TMs), was quantified on 250 video transects from shelf and slope, and megabenthos (>2 cm) composition was studied on 149 video transects from the shelf. The number of satellite-recorded vessels within grid cells 5 × 5 km was used as a proxy for FI in the TM analysis and for the megabenthos records within a 2-km radius around the transects. The effects of using different search area sizes were tested. Patterns in the density of TMs and megabenthos composition were compared with FI using linear regression and correspondence analysis. Occurrence of TMs was not directly related to FI but to bottom type, whereas megabenthos density and diversity showed a negative relation. For 79 of the 97 most common taxa, density was negatively correlated with FI. The sponges Craniella zetlandica and Phakellia / Axinella were particularly vulnerable, but also Flabellum macandrewi (Scleractinia), Ditrupa arietina (Polychaeta), Funiculina quadrangularis (Pennatulacea), and Spatangus purpureus (Echinoidea) were negatively correlated with FI, whereas asteroids, lamp shells, and small sponges showed a positive trend. Our results are an important step towards the understanding of chronic effects of bottom trawling and are discussed in relation to the descriptors “Biological diversity” and “Seafloor integrity” in the EU Marine strategic framework directive.

scholarly journals Seasonal and temporal trends in metrics of fish community for otter-trawl discards in a Mediterranean ecosystem

2008 ◽  
Vol 65 (4) ◽  
pp. 539-550 ◽  
Author(s):  
K. Tsagarakis ◽  
A. Machias ◽  
M. Giannoulaki ◽  
S. Somarakis ◽  
I. Karakassis
Keyword(s):  
Fish Community ◽  
Eastern Mediterranean ◽  
Temporal Trends ◽  
Demersal Fish ◽  
Trophic Levels ◽  
Otter Trawl ◽  
Mediterranean Ecosystem ◽  
Taxonomic Distinctness ◽  
Fishing Season ◽  
Trawl Fishery

Abstract Tsagarakis, K., Machias, A., Giannoulaki, M., Somarakis, S., and Karakassis, I. 2008. Seasonal and temporal trends in metrics of fish community for otter-trawl discards in a Mediterranean ecosystem. – ICES Journal of Marine Science, 65: 539–550. Trends in discard to marketed ratios, size spectra, diversities, and trophic levels of the demersal fish community were examined using data from a seasonally closed commercial trawl fishery in the eastern Mediterranean Sea (Ionian Sea), over a period of about 10 years. Trends were also examined for the artificial fractions derived from the discarding process (the marketed, the discarded, and the non-marketed clusters of the catch), as well as for the “big” and “small” fractions (defined by the size at which 50% of all specimens were discarded). The ratio of the discarded/marketed catch fluctuated greatly. Two commercial (Merluccius merluccius, and Mullus barbatus) and two non-marketed species (Lepidotrigla cavillone, and Argentina sphyraena) were the characteristic species of the fractions. A declining trend with time was observed for the examined time-series for species richness (S), Margalef’s d, and average taxonomic distinctness (Δ+), whereas the variation in taxonomic distinctness (Λ+) increased. The composition and/or trophic level of discards in relation to the marketed catch seemed to be indicative of the exploitation state of the demersal community: differences between the discarded and marketed fractions were high at the beginning of the fishing season (autumn), but the values of the indices converged at the end of the fishing season (spring). These changes could be attributed to alternative discarding strategies for certain species in response to increased cumulative fishing mortality towards the end of the period.

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