scholarly journals Round scallops and square meshes: a comparison of four codend types on the catch rates of target species and by-catch in the Queensland (Australia) saucer scallop (Amusium balloti) trawl fishery

2008 ◽  
Vol 59 (10) ◽  
pp. 849 ◽  
Author(s):  
Anthony J. Courtney ◽  
Matthew J. Campbell ◽  
Darren P. Roy ◽  
Mark L. Tonks ◽  
Keith E. Chilcott ◽  
...  
Keyword(s):  
Sea Urchins ◽  
Catch Rate ◽  
Target Species ◽  
Bivalve Molluscs ◽  
Sea Stars ◽  
Incidental Capture ◽  
Trawl Fishery ◽  
By Catch ◽  
Catch Rates ◽  
Trawl Fisheries

Concern over the amount of by-catch from benthic trawl fisheries and research into the problem have increased in recent years. The present paper demonstrated that by-catch rates in the Queensland (Australia) saucer scallop (Amusium balloti) trawl fishery can be reduced by 77% (by weight) using nets fitted with a turtle excluder device (TED) and a square-mesh codend, compared with a standard diamond-mesh codend with no TED. This large reduction was achieved with no significant effect on the legal size scallop catch rate and 39% fewer undersize scallops were caught. In total, 382 taxa were recorded in the by-catch, which was dominated by sponges, portunid crabs, small demersal and benthic fish (e.g. leatherjackets, stingerfish, bearded ghouls, nemipterids, longspine emperors, lizard fish, triggerfish, flounders and rabbitfish), elasmobranchs (e.g. mainly rays) and invertebrates (e.g. sea stars, sea urchins, sea cucumbers and bivalve molluscs). Extremely high reductions in catch rate (i.e. ≥85%) were demonstrated for several by-catch species owing to the square-mesh codend. Square-mesh codends show potential as a means of greatly reducing by-catch and lowering the incidental capture and mortality of undersize scallops and Moreton Bay bugs (Thenus australiensis) in this fishery.

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.

The influence of the type of hook on the capture of groupers and bycatch with bottom longline in the Gulf of Gabès, Tunisia

2014 ◽  
Vol 95 (1) ◽  
pp. 207-214 ◽  
Author(s):  
Khaled Echwikhi ◽  
Imed Jribi ◽  
Béchir Saidi ◽  
Mohamed Nejmeddine Bradai
Keyword(s):  
Catch Rate ◽  
Target Species ◽  
Gulf Of Gabes ◽  
Management Actions ◽  
Gulf Of Gabès ◽  
Gear Modification ◽  
Preliminary Study ◽  
By Catch ◽  
Size Limits

Members of the Epinephelinae subfamily of serranids (‘grouper’) are heavily exploited by bottom longline in the Gulf of Gabès located in the south of Tunisia. In addition to direct mortality, hook and release mortalities likely occur when fish are caught and released, due to injuries sustained from hooking as well as those associated with retrieval. During five experimental trips (29 fishing sets) conducted in August 2011 from the port of Djerba (south of the Gulf of Gabès), we evaluated the effect of hook styles (9/0 ‘J’ and 12/0 circle hook) on groupers and non-target species. A total of 340 specimens representing 10 species were captured. The higher catch rate was registered for Epinephelus aeneus. The majority of groupers captured were female mature. The circle hook increased the capture of the most common grouper E. aeneus and did not affect the catch of Epinephelus marginatus and Epinepheleus costae. The effect of the type of hook on hooking location was inconclusive. Managing of the grouper fishery using some management actions such as size limits, bag limits, and closed seasons may prevent more unnecessary losses of grouper species. From this preliminary study, a definite conclusion for or against the use of circle hook cannot be drawn. Further research on the role of gear modification and hook designs in reducing by-catch, hooking-related injury and mortality should be encouraged.

scholarly journals Reducing unwanted catches of trammel nets: experimental results of the “guarding net” in the caramote prawn, Penaeus kerathurus, small-scale fishery of the Ligurian Sea (western Mediterranean)

2018 ◽  
Vol 82 (S1) ◽  
pp. 131 ◽  
Author(s):  
Paolo Sartor ◽  
Daniel Li Veli ◽  
Francesco De Carlo ◽  
Alessandro Ligas ◽  
Andrea Massaro ◽  
...  
Keyword(s):  
Experimental Study ◽  
Economic Loss ◽  
Western Mediterranean ◽  
Small Scale ◽  
Target Species ◽  
Ligurian Sea ◽  
Sorting Time ◽  
Labour Costs ◽  
By Catch ◽  
Catch Rates

This study aimed to test the effectiveness of a “guarding net”, a device placed at the bottom of a trammel net, for reducing unwanted catches in the caramote prawn trammel net fishery of the Ligurian Sea. This specialized and profitable fishery is affected by unwanted catches that generate high discard rates and damage to the nets, with environmental impacts and costs for fishermen. The experimental study consisted in comparing the catches of a standard trammel net (STN) with those of two “experimental” trammel nets, e.g. STNs provided with a guarding net of 19 cm (TGN20) and 24 cm height (TGN25), respectively. The guarding net, a strip of gillnet placed at the bottom of the net, can be considered a by-catch reducer device (BRD). Some fishermen of the investigated fishery have been using this device for several years. The results of the 15 experimental fishing trials performed from June to July 2016 indicate that the guarding nets significantly reduce discards (e.g. crabs and other invertebrates); the biomass of the unwanted species caught was 75% lower than that produced by the STN. The catch rates of the target species obtained with TGN20 and TGN25 were also significantly lower than those of the STN, though of a lesser amount. Nonetheless, this economic loss can be compensated by the decrease in sorting time and material and labour costs that can be achieved using the guarding net.

Effectively managing angler satisfaction in recreational fisheries requires understanding the fish species and the anglers

2015 ◽  
Vol 72 (4) ◽  
pp. 500-513 ◽  
Author(s):  
Ben Beardmore ◽  
Len M. Hunt ◽  
Wolfgang Haider ◽  
Malte Dorow ◽  
Robert Arlinghaus
Keyword(s):  
Fish Species ◽  
Negative Influence ◽  
Catch Rate ◽  
Relative Importance ◽  
Recreational Fisheries ◽  
Northern Germany ◽  
By Catch ◽  
Catch Rates ◽  
High Catch ◽  
Important Objective

Whenever satisfied anglers are an important objective of recreational fisheries management, understanding how trip outcomes influence satisfaction reports is critical. While anglers, generally, prefer high catch rates and large fish, the relative importance of these catch outcomes for catch satisfaction has not been established across species and angler types. We examined relationships between angler specialization, trip outcomes (both catch and non-catch characteristics such as crowding), and catch satisfaction across six freshwater fish species in northern Germany. As expected, catch satisfaction was primarily determined by catch rate and fish size in all fish species; however, the relative importance of these two outcomes varied considerably across species and among angler types that differed by commitment to fishing. We found a diminishing marginal return of satisfaction for increasing catch rate for all but small-bodied cyprinid species, while increasing size of largest retained fish monotonically increased catch satisfaction in all species we examined. Non-catch outcomes (e.g., the number of other anglers seen while fishing) also had a significant negative influence on catch satisfaction, suggesting that non-catch factors are important in establishing expectations and for contextual evaluation of catch outcomes. We also determined that diversified trips made anglers more satisfied and that all else being equal, specialized anglers increased catch satisfaction from travel and fishing time. The results highlight the importance for managers to consider their particular mix of anglers as well as the fish species present when setting regulations aimed at increasing angler satisfaction.

Rigid and flexible separator panels in trawls that reduce the by-catch of small fish in the Clarence River prawn-trawl fishery, Australia

1996 ◽  
Vol 47 (8) ◽  
pp. 991 ◽  
Author(s):  
MK Broadhurst ◽  
SJ Kennelly
Keyword(s):  
Small Fish ◽  
Paired Comparisons ◽  
Target Species ◽  
Trawl Fishery ◽  
By Catch

Two experiments were done in the Clarence River prawn-trawl fishery that compared catches and by-catches from conventional trawls with those from modified trawls containing rigid and flexible separator panels. The modifications included (1) a soft separator panel, the 'blubber-chute' (used commercially by fishers to exclude jellyfish), (2) the standard Nordm�re grid, containing a guiding panel, and (3) a modified Nordm�re grid that had no guiding panel but included a flexible cover of mesh lying semi-attached over the escape exit. In the first experiment, simultaneous paired comparisons among these designs and their controls showed that although all three modified trawls significantly reduced the by-catch of small fish by between 75% and 90%, the standard Nordm�re grid was the only design that did not significantly reduce catches of prawns. In the second experiment, which compared this standard grid with the control during a period of flooding when the by-catch of non-target species was quite high, the standard grid significantly reduced the by-catch of juvenile bream (Acanthopagrus australis) (by 67%) with no significant reduction in catches of prawns. The potential for the Nordm�re grid to alleviate deleterious effects of prawn trawling in estuaries is discussed.

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 A simple technical measure to reduce bycatch and discard of skates and sharks in mixed-species bottom-trawl fisheries

2015 ◽  
Vol 72 (6) ◽  
pp. 1861-1868 ◽  
Author(s):  
R. J. Kynoch ◽  
R. J. Fryer ◽  
F. C. Neat
Keyword(s):  
North Atlantic ◽  
Marine Conservation ◽  
Catch Rate ◽  
Bottom Trawl ◽  
Mixed Species ◽  
Protective Measures ◽  
The North ◽  
Management Measures ◽  
Catch Rates ◽  
Trawl Fisheries

Abstract Due to global declines, skates and sharks have become a focus of marine conservation in recent years. Despite protective measures, they remain vulnerable to bycatch by fisheries, especially bottom-trawls and pose a problem for fisheries management measures that aim to eliminate discards in the future. In the mixed-species bottom-trawl fisheries of the North Atlantic catches can be increased by fitting a length of chain known as a “tickler” in front of the groundgear of the trawl. It was hypothesized that the tickler is especially effective at catching skates and rays that may otherwise escape beneath the net. A trial was undertaken with paired tows with and without the tickler chain. The trial demonstrated that the catch rate of skates and sharks can be significantly lowered by removing the tickler. A set of secondary nets (groundgear bags) attached behind the groundgear of the main net allowed the number of fish escaping under the net to be estimated and showed that the reduction of skates and sharks in the main net was accompanied by an increase in number in the groundgear bags. This suggests that prohibition of the use of tickler chains in areas that are known to be especially important to skates and sharks could have conservation benefits. The removal of the tickler chain had little effect on catch rates of haddock, whiting, and flatfish, but caused a marked decrease in the catch rate of commercially valuable anglerfish.

scholarly journals Comparison of beam trawl catch, by-catch and discard in fishing and non-fishing areas – a case study from the northern Adriatic Sea

2021 ◽  
Vol 22 (1) ◽  
pp. 108
Author(s):  
DARIA EZGETA -BALIĆ ◽  
NEDO VRGOČ ◽  
IGOR ISAJLOVIĆ ◽  
DAMIR MEDVEŠEK ◽  
ANTE VUJEVIĆ ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Beam Trawl ◽  
Northern Adriatic Sea ◽  
Important Species ◽  
Northern Adriatic ◽  
Trawl Fishery ◽  
Trawl Catch ◽  
Commercially Important ◽  
By Catch ◽  
Trawl Fisheries

Beam trawl fishery is highly important in the Croatian part of the northern Adriatic wherein 116 vessels have a licence for this type of fishing gear. A sharp decrease in the beam trawl catch observed since 2015 has raised concern about not only socio-economic issues but also ecological issues and the effect that beam trawl fisheries have had on exploited stocks. Besides the effect that beam trawl fisheries can have on targeted economically important species, intensive dredging can cause long-term changes in the benthic community. Therefore, this study aimed to detect the effect that this type of fishing gear has on target and by-catch species. Furthermore, survey data were compared with the official beam trawl fishery data gathered through Vessel Monitoring System data together with fishermen’s logbooks. Our research targeted two adjacent areas: an area where beam trawl fishing is allowed and an area where it is forbidden. The results demonstrate that the commercially important catch represented a minor share of the total beam trawl catch in both survey areas, while discard made up more than 93% of the total catch. The main beam trawl commercially important species in the Croatian part of the northern Adriatic Sea was Pecten jacobaeus, followed by Solea solea and Ostrea edulis. Our results suggest that beam trawl fisheries mostly affect target bivalve species and some non-commercial benthic species (e.g. sponges). The differences recorded between areas could suggest that beam trawl fisheries cause changes mostly in the P. jacobaeus population.

scholarly journals A trap with a twist: evaluating a bycatch reduction device to prevent rockfish capture in crustacean traps

2012 ◽  
Vol 70 (1) ◽  
pp. 114-122 ◽  
Author(s):  
Brett Favaro ◽  
Stefanie D. Duff ◽  
Isabelle M. Côté
Keyword(s):  
Fish Species ◽  
Target Species ◽  
Important Species ◽  
Incidental Capture ◽  
Bycatch Reduction ◽  
Target Fish ◽  
Commercially Important ◽  
Catch Rates ◽  
Novel Devices

Abstract Favaro, B., Duff, S. D., and Côté, I. M. 2013. A trap with a twist: evaluating a bycatch reduction device to prevent rockfish capture in crustacean traps. – ICES Journal of Marine Science, 70:114–122. Bycatch, or the incidental capture of non-target species, occurs in fisheries around the world, with often detrimental ecological consequences. Bycatch reduction devices (BRDs) that increase catch specificity have been used successfully in some fisheries, and the development of such devices remains an important component of the global effort to reduce bycatch rates. We tested novel devices designed to exclude juvenile rockfish (Sebastes spp.) from traps used to catch spot prawns (Pandalus platyceros), a commercially important species in British Columbia, Canada. The devices included reductions in trap opening sizes and novel bent-tunnel openings. Reducing trap opening size did not affect bycatch rates of rockfish or other non-target fish species. In contrast, bent-tunnel BRDs eliminated rockfish bycatch, and two of the bent-tunnel variants also excluded other fish species. However, prawn catch rates were reduced in all modified gear, and large prawns were often excluded more than small prawns. Videos recorded in situ revealed that prawn attempts to enter traps took longer and were more likely to fail in BRD-equipped than in unmodified traps. We conclude that bent-tunnel BRDs have the potential to be useful, but improvements are needed to increase prawn catch to levels similar to that of unmodified traps.

scholarly journals FLEXSELECT: counter-herding device to reduce bycatch in crustacean trawl fisheries

2018 ◽  
Vol 75 (6) ◽  
pp. 850-860 ◽  
Author(s):  
Valentina Melli ◽  
Junita D. Karlsen ◽  
Jordan P. Feekings ◽  
Bent Herrmann ◽  
Ludvig A. Krag
Keyword(s):  
Gadus Morhua ◽  
Melanogrammus Aeglefinus ◽  
Target Species ◽  
Merluccius Merluccius ◽  
Flexible Tool ◽  
Flatfish Species ◽  
Trawl Fishery ◽  
Merlangius Merlangus ◽  
Trawl Fisheries ◽  
Haddock Melanogrammus Aeglefinus

FLEXSELECT is a simple counter-herding device that aims at reducing the bycatch of fish by scaring them away from the trawl path without affecting the catches of the target species. FLEXSELECT was tested in the Norway lobster (Nephrops norvegicus) directed trawl fishery, as this includes bycatch of both roundfish and flatfish. Length-based data were collected for Nephrops, four roundfish species (cod (Gadus morhua), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), and hake (Merluccius merluccius)), and two flatfish species (plaice (Pleuronectes platessa) and lemon sole (Microstomus kitt)), and length-based catch comparisons were performed. No significant effect on the target species, Nephrops, was detected, whereas a reduction of 39% (CI: 29%–46%) was obtained for the overall number of fish. Catches of all the six fish species examined were significantly reduced by FLEXSELECT, with the efficiency varying considerably among species and over length classes. No significant diel differences were found for either roundfish or flatfish species. FLEXSELECT prevents bycatch species from interacting with the trawl, thus most likely enhancing their survival and fitness. Moreover, its fast attachment system makes FLEXSELECT a flexible tool, adaptable to different fisheries and catch goals.

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