Estimating collateral mortality from towed fishing gear

Estimating collateral mortality from towed fishing gear More than 50% of the world's total marine catch (approximately 81 million tonnes) is harvested using towed fishing gears (i.e. Danish seines, dredges and otter and beam trawls). As for all methods, the total fishing mortality of these gears comprises the reported (landed) and unreported catch and other unaccounted, collateral deaths due to (i) avoiding, (ii) escaping, (iii) dropping out of the gear during fishing, (iv) discarding from the vessel, (v) ghost fishing of lost gear, (vi) habitat destruction or subsequent (vii) predation and (viii) infection from any of the above. The inherent poor selectivity of many towed gears, combined with their broad spatial deployment, means that there is considerable potential for cumulative effects of (i)–(viii) listed above on total fishing mortality, and subsequent wide‐scale negative impacts on stocks of important species. In this paper, we develop a strategy for minimizing this unwanted exploitation by reviewing all the primary literature studies that have estimated collateral, unaccounted fishing mortalities and identifying the key causal factors. We located more than 80 relevant published studies (between 1890 and early 2006) that quantified the mortalities of more than 120 species of escaping (26 papers) or discarded (62 papers) bivalves, cephalopods, crustaceans, echinoderms, elasmobranches, reptiles, teleosts and miscellaneous organisms. Seven of these studies also included the estimates of mortalities caused by dropping out of gears, predation and infection ((iii), (vii) and (viii) listed above). Owing to several key biological (physiology, size and catch volume and composition), environmental (temperature, hypoxia, sea state and availability of light) and technical (gear design, tow duration and speed) factors, catch‐and‐escape or catch‐and‐discarding mechanisms were identified to evoke cumulative negative effects on the health of most organisms. We propose that because the mortalities of discards typically are much greater than escapees, the primary focus of efforts to mitigate unaccounted fishing mortalities should concentrate on the rapid, passive, size and species selection of non‐target organisms from the anterior sections of towed gears during fishing. Once maximum selection has been achieved and demonstrated to cause few mortalities, efforts should be made to modify other operational and/or post‐capture handling procedures that address the key causal factors listed above. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Fish and Fisheries Wiley

Estimating collateral mortality from towed fishing gear

Loading next page...
 
/lp/wiley/estimating-collateral-mortality-from-towed-fishing-gear-PyllFIcsnn
Publisher
Wiley
Copyright
Copyright © 2006 Wiley Subscription Services, Inc., A Wiley Company
ISSN
1467-2960
eISSN
1467-2979
D.O.I.
10.1111/j.1467-2979.2006.00213.x
Publisher site
See Article on Publisher Site

Abstract

More than 50% of the world's total marine catch (approximately 81 million tonnes) is harvested using towed fishing gears (i.e. Danish seines, dredges and otter and beam trawls). As for all methods, the total fishing mortality of these gears comprises the reported (landed) and unreported catch and other unaccounted, collateral deaths due to (i) avoiding, (ii) escaping, (iii) dropping out of the gear during fishing, (iv) discarding from the vessel, (v) ghost fishing of lost gear, (vi) habitat destruction or subsequent (vii) predation and (viii) infection from any of the above. The inherent poor selectivity of many towed gears, combined with their broad spatial deployment, means that there is considerable potential for cumulative effects of (i)–(viii) listed above on total fishing mortality, and subsequent wide‐scale negative impacts on stocks of important species. In this paper, we develop a strategy for minimizing this unwanted exploitation by reviewing all the primary literature studies that have estimated collateral, unaccounted fishing mortalities and identifying the key causal factors. We located more than 80 relevant published studies (between 1890 and early 2006) that quantified the mortalities of more than 120 species of escaping (26 papers) or discarded (62 papers) bivalves, cephalopods, crustaceans, echinoderms, elasmobranches, reptiles, teleosts and miscellaneous organisms. Seven of these studies also included the estimates of mortalities caused by dropping out of gears, predation and infection ((iii), (vii) and (viii) listed above). Owing to several key biological (physiology, size and catch volume and composition), environmental (temperature, hypoxia, sea state and availability of light) and technical (gear design, tow duration and speed) factors, catch‐and‐escape or catch‐and‐discarding mechanisms were identified to evoke cumulative negative effects on the health of most organisms. We propose that because the mortalities of discards typically are much greater than escapees, the primary focus of efforts to mitigate unaccounted fishing mortalities should concentrate on the rapid, passive, size and species selection of non‐target organisms from the anterior sections of towed gears during fishing. Once maximum selection has been achieved and demonstrated to cause few mortalities, efforts should be made to modify other operational and/or post‐capture handling procedures that address the key causal factors listed above.

Journal

Fish and FisheriesWiley

Published: Sep 1, 2006

References

  • Mortality of fish from the by‐catch of shrimp vessels in the North Sea
    Berghahn, Berghahn; Waltemath, Waltemath; Rijnsdorf, Rijnsdorf
  • Survival of decapod crustaceans discarded in the Nephrops fishery of the Clyde Sea area, Scotland
    Bergmann, Bergmann; Moore, Moore
  • Mortality of Asterias rubens and Ophiura ophiura discarded in the Nephrops fishery of the Clyde Sea area, Scotland
    Bergmann, Bergmann; Moore, Moore
  • Modifications to reduce bycatch in prawn trawls: a review and framework for development
    Broadhurst, Broadhurst
  • Importance of discards of a beam trawl fishery as input of organic matter into nursery areas within the Tagus estuary
    Cabral, Cabral; Teixeira, Teixeira; Gamito, Gamito; Costa, Costa
  • Stress induced by hooking, net towing, elevated sea water temperature and air in sablefish: lack of concordance between mortality and physiological measures of stress
    Davis, Davis; Olla, Olla; Schreck, Schreck
  • A species‐selective trawl for demersal gadoid fisheries
    Engås, Engås; Jørgensen, Jørgensen; West, West
  • The influence of dredge design on the catch of Callista chione (Linnaeus, 1758)
    Gasper, Gasper; Dias, Dias; Campos, Campos; Monteiro, Monteiro; Santos, Santos; Chicharo, Chicharo; Chicharo, Chicharo
  • On bycatches
    Hall, Hall
  • Managing by‐catch and discards: how much progress are we making and how can we do better
    Hall, Hall; Mainprize, Mainprize
  • Discarding Norway lobster ( Nephrops norvegicus L.) through low salinity layers – mortality and damage seen in simulation experiments
    Harris, Harris; Ulmestrand, Ulmestrand
  • Endurance at intermediate swimming speeds of Atlantic mackerel, Scomber scombrus L. herring, Clupea harengus L., and saithe, Pollachius virens L
    He, He; Wardle, Wardle
  • Effects of abrupt cold shock on stress responses and recovery in brown trout exhausted by swimming
    Hyvärinen, Hyvärinen; Heinimaa, Heinimaa; Rita, Rita
  • Escape mortality of cod, saithe and haddock in a Barents Sea trawl fishery
    Ingülfsson, Ingülfsson; Soldal, Soldal; Huse, Huse; Breen, Breen
  • By‐catch begone: changes in the philosophy of fishing technology
    Kennelly, Kennelly; Broadhurst, Broadhurst
  • Reducing the short‐term mortality of juvenile school prawns ( Metapenaeus macleayi ) discarded during trawling
    Macbeth, Macbeth; Broadhurst, Broadhurst; Paterson, Paterson; Wooden, Wooden
  • Effects of dredging on undersized scallops
    Maguire, Maguire; Coleman, Coleman; Jenkins, Jenkins; Burnell, Burnell
  • Fishing gear‐induced skin ulcerations in Baltic cod, Gadus morhua L
    Mellergaard, Mellergaard; Bagge, Bagge
  • Effects of simulated trawling on sablefish and walleye pollock: the role of light intensity, net velocity and towing duration
    Olla, Olla; Davis, Davis; Schreck, Schreck
  • Temperature magnified postcapture mortality in adult sablefish after simulated trawling
    Olla, Olla; Davis, Davis; Schreck, Schreck
  • Incidental capture, direct mortality and delayed mortality of sea turtles in Australia's northern prawn fishery
    Poiner, Poiner; Harris, Harris
  • Incidental capture and mortality of sea turtles in Australia's northern prawn fishery
    Poiner, Poiner; Buckworth, Buckworth; Harris, Harris
  • Damage, autotomy and arm regeneration in starfish caught by towed demersal fishing gears
    Ramsay, Ramsay; Bergmann, Bergmann; Veale, Veale; Richardson, Richardson; Kaiser, Kaiser; Vize, Vize; Feist, Feist
  • Estimated catch and mortality of sea turtles from the east coast otter trawl fishery of Queensland, Australia
    Robins, Robins
  • Reducing incidental mortality of seabirds with an underwater longline setting funnel
    Ryan, Ryan; Watkins, Watkins
  • Laboratory evidence for behavioural impairment of fish escaping trawls: a review
    Ryer, Ryer
  • Tolerance and respiration of the prawn ( Penaeus japonicus ) under cold air conditions
    Samet, Samet; Nakamura, Nakamura; Nagayama, Nagayama
  • Survival of young gadoids excluded from a shrimp trawl by a rigid deflecting grid
    Soldal, Soldal; Engås, Engås
  • Size‐related mortality of herring ( Clupea harengus L.) escaping through a rigid sorting grid and trawl codend meshes
    Suuronen, Suuronen; Perez‐Comas, Perez‐Comas; Lehtonen, Lehtonen; Tschernij, Tschernij
  • The impacts of fishing on marine birds
    Tasker, Tasker; Camphuysen, Camphuysen; Cooper, Cooper; Garthe, Garthe; Montevecchi, Montevecchi; Blaber, Blaber
  • Survival rates of sea snakes caught by demersal trawlers in northern and eastern Australia
    Wassenberg, Wassenberg; Milton, Milton; Burridge, Burridge

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off