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 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.

scholarly journals Actual conditions of discards of by-catch from small-scale trawl fishery in Ariake Sea

2003 ◽  
Vol 69 (3) ◽  
pp. 330-336 ◽  
Author(s):  
YOSHIO HIRAI ◽  
HIDEYUKI NISHINOKUBI
Keyword(s):  
Small Scale ◽  
Ariake Sea ◽  
Trawl Fishery ◽  
By Catch

scholarly journals Reproductive Biology of Commercially Valuable Squid, Sepioteuthis lessoniana (Lesson, 1830) Taken as By-Catch in a Tropical Trawl Fishery

2012 ◽  
Vol 4 (4) ◽  
pp. 14-19
Author(s):  
Vellathi VENKATESAN ◽  
Santhanam RAJAGOPAL
Keyword(s):  
Coastal Waters ◽  
Graphical Method ◽  
Gonadosomatic Index ◽  
Mantle Length ◽  
Trawl Fishery ◽  
Management Measures ◽  
Nidamental Gland ◽  
Commercially Important ◽  
Sepioteuthis Lessoniana ◽  
By Catch

Some aspects of the reproductive characteristics of the commercially important squid Sepioteuthis lessoniana (Lesson, 1830) in the coastal waters of Mandapam, Palk Bay was studied with a view to provide possible management measures in this region. A total of 984 individuals (508 males and 476 females) were collected between April, 2009 to March, 2010. The size of specimens ranged from 40 mm to 290 mm in mantle length. Sex ratio was not significantly different from the expected ratio of 1:1 except for months of July, October and December. Spawning season as revealed by seasonal maturity stages, gonadosomatic index of sexes and nidamental gland length (NGL) and dorsal mantle length (DML) ratio of females, lied between January to June with peak at February. Size at maturity as determined by graphical method was 83.5 for males and 112.5 for females.

Using electronic monitoring to record catches of sole (Solea solea) in a bottom trawl fishery

2017 ◽  
Vol 74 (5) ◽  
pp. 1421-1427 ◽  
Author(s):  
Aloysius T. M. van Helmond ◽  
Chun Chen ◽  
Jan Jaap Poos
Keyword(s):  
Electronic Monitoring ◽  
Single Species ◽  
Small Fish ◽  
Trawl Fishery ◽  
Video Review ◽  
Video Observations ◽  
Solea Solea ◽  
Simple Protocol ◽  
Absolute Agreement ◽  
The Individual

Electronic monitoring (EM) is often presented as a solution to document all catches through video observations under the EU landing obligation. However, identifying small fish on video in large volumes of catch is challenging. In this study, logbook records were compared with video observations for catches to test efficacy of EM for different size classes of sole (Solea solea) on board bottom trawlers. Comparisons were based on: (i) systematic differences (paired t-test), (ii) linear correlation (Pearson’s r), and (iii) absolute agreement (ICC). Results suggest that EM of small individuals in mixed fisheries is not as effective as it is for large individuals. To improve efficiency for estimating quantities of small fish, additional methods are required to enhance video review. One possible method for enhancing video review is using a protocol where crew arranged the individual fish in front of the cameras. Indeed, this study suggests that such a protocol substantially improves EM of the complete catch. However, the protocol requires an additional three minutes of processing time per haul for a single species. Given the large number of quota species under the landing obligation for this fishery, implementing the protocol thus comes with a cost for the fishing industry; the extra time needed to conduct a simple protocol probably would exceed 12 h per fishing trip.

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

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.

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