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Subject: Re: [!! SPAM] Re: circle hooks
From: Juan Pedro Monteagudo <[log in to unmask]>
Reply-To:Scientific forum on fish and fisheries <[log in to unmask]>
Date:Mon, 8 Dec 2008 16:41:18 +0100
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Hello David, and thanks for your info, and thanks also to the ones with 
previous posts on the issue.Actually, i didnt get such 
conclusión.Someone asked me about it, but after reading your response I 
think it was probably referring not to levels of bycatch, but rather 
increased bycatch mortality.

However, as far as i know, fishermen are reluctant to use them  as they 
claim to reduce fishing eficiency on (some) target species. Nevertheless 
, i agree with you, at least they are an approach to the problem.

JP

David Kerstetter escribió:
> Greetings from Florida, J.P.
>
> As with Mike Pol, I'm curious how you reached your conclusions about 
> the use of circle hooks with regards to bycatch.  There's actually 
> quite a bit of literature available on the use and results of circle 
> hooks, ranging from original research (for examples, see such papers 
> as Watson et al., 2005 or Kerstetter and Graves, 2006) to reviews 
> (including Cooke and Suski, 2004).  This body of work with circle 
> hooks now covers several commercial and recreational fisheries, 
> examining aspects such as catch rates and hooking location.  A free 
> "Google Scholar" (http://scholar.google.com/) search shows many of 
> these papers even have free .pdf versions available online.
>
> I would also suggest differentiating between catch rates of bycatch 
> species and bycatch mortality -- they are very different ideas, and 
> the use of circle hooks may affect these two factors differently.  For 
> example, circle hooks in multiple studies have shown a decrease in the 
> catch of pelagic stingrays, a bycatch species in the pelagic longline 
> fishery.  Circle hook studies with catch rates of sharks have shown 
> conflicting results, in part I believe because of the difficulty in 
> correctly ascribing catch rates with lost hooks, events that can occur 
> when sharks are hooked deeply or at least in such a way that they can 
> bite through the monofilament leader and thus release themselves from 
> the gear.  Catch rates of istiophorid billfishes have shown 
> conflicting results in studies with circle hooks in the pelagic 
> longline fishery, although their mortality rates are generally lower 
> with these hooks at haulback than with J-style hooks.  Assessments of 
> the post-release mortality associated with capture by different hook 
> types is yet another field of work, one generally involving the use of 
> electronic tags (e.g., Horodysky and Graves, 2006) or acoustic 
> tracking.  Please note that I've cited some pelagic fisheries work 
> only because it's most familiar to me, but much more literature exists 
> on the use of circle hooks with other marine fisheries, such as 
> serranid groupers (e.g., Bacheler and Buckel, 2004).
>
> Circle hooks are not the "silver bullet" answer to bycatch interaction 
> and bycatch mortality issues, but then again, there are very rarely 
> such solutions for any fisheries problems.  In a grossly oversimplying 
> sense, circle hooks appear to show a good deal of promise in many 
> fisheries for reducing bycatch mortality, especially for such species 
> as the istiophorid billfishes, while remaining neutral to the catch 
> rates of target species.  Not all fishes (or marine organisms, for 
> that matter) feed using the same techniques however, which would be 
> just one of many factors explaining the variations in results between 
> species and fisheries.
>
> Best regards,
>
> Dave Kerstetter
>
>
>
>
> Bacheler, N.M. and J.A. Buckel.  2004.  Does hook type influence the 
> catch rate, size, and injury of grouper in a North Carolina commercial 
> fishery?  Fisheries Research 69: 303-311.
>
> Cooke and Suski.  2004.  Are circle hooks an effective tool for 
> conserving marine and freshwater recreational catch-and-release 
> fisheries?  Aquatic Conservation: Marine and Freshwater Ecosystems 
> 14(3): 299-326.
>
> Horodysky, A.Z., and J.E. Graves.  2005. 
> <http://web.vims.edu/fish/faculty/pdfs/jeg_Horodysky_and_Graves_2005.pdf>Application 
> of pop-up satellite archival tag technology to estimate postrelease 
> survival of white marlin (Tetrapturus albidus) caught on circle and 
> straight-shank ("J") hooks in the western North Atlantic recreational 
> fishery<http://web.vims.edu/fish/faculty/pdfs/jeg_Horodysky_and_Graves_2005.pdf>. 
> Fishery Bulletin, 103:84-96.
>
> Kerstetter, D.W. and J.E. Graves.  2006. 
> <http://web.vims.edu/fish/faculty/pdfs/jeg_Kerstetter_and_Graves_2006_FO.pdf>Effects 
> of size 16/0 circle versus size 9/0 J-style hooks on target and 
> non-target species in a pelagic longline 
> fishery<http://web.vims.edu/fish/faculty/pdfs/jeg_Kerstetter_and_Graves_2006_FO.pdf>. 
> Fisheries Research 80: 239-250.
>
> Watson, J.W. et al.  2005.
>
> Fishing methods to reduce sea turtle mortality associated with pelagic 
> longlines.
>
> Canadian Journal of Fisheries and Aquatic Sciences 62(5): 965-981.
>
>
>
>
> At 01:48 AM 12/8/2008, Juan Pedro Monteagudo wrote:
>> Hi everyone, im looking for some literature on implementation of 
>> circle hooks and estimates on mitigation of bycatch, as it seems they 
>> might not be such a good alternative or even being worst at the end.
>>
>> Thanks in advance.
>>
>> JP Monteagudo
>>
>> -- 
>> Juan Pedro Monteagudo González
>> Asesoria Técnica en Pesquerías y Ciencias del Mar
>> Fisheries and Marine Sciences Consultant
>> [log in to unmask]
>> [log in to unmask]
>> +(34) 647844645
>> Skype:Dubduap
>
>
> David W. Kerstetter, Ph.D.
> Research Scientist and Adjunct Faculty
> Nova Southeastern University Oceanographic Center
> 8000 North Ocean Drive
> Dania Beach, FL 33004
> http://www.nova.edu/ocean/profiles/kerstetter/kerstetter.html
>

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