Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study Finds Circle Hooks Lower Catch Rate For Offshore Anglers

29.03.2012
Anglers are required to use circle hooks in some fishing tournaments because they are less likely to cause lethal injuries in billfish, such as marlin.

However, research from North Carolina State University shows that broadening circle hook requirements could adversely impact charter and recreational fishing, since they make it more difficult to catch non-billfish.

“We wanted to know whether circle hooks are effective as conventional J hooks when angling for non-billfish – such as yellowfin tuna – in North Carolina waters,” says Paul Rudershausen, a research assistant in NC State’s biology department and lead author of a paper describing the research.

The NC State team worked with charter boat captains and mates who were experienced with use of circle hooks to look at the efficacy of circle hooks versus J hooks when trolling offshore with rod and reel. The findings are relevant for similar fishing efforts in other waters where these same species occur.

A “circle hook” is defined as a circular hook in which the point of the hook is perpendicular to – and aligned with – the shank of the hook. This differs from a J hook, which is shaped like the letter J.

Studies have found that circle hooks are less likely to mortally wound billfish during recreational or charter fishing. As a result, the National Marine Fisheries Service instituted regulations requiring anglers in Atlantic billfish tournaments to use circle hooks when using natural baits. J hooks are still permitted if an angler is using purely artificial bait.

Anglers and fishing industry observers have speculated about the possibility that circle hook regulations may be expanded to fishing outside of billfish tournaments – even when anglers are not fishing for billfish – to protect billfish species that may be caught inadvertently.

This speculation led NC State researchers to determine whether circle hooks would be as effective as J hooks when fishing for non-billfish species. The answer is no.

The researchers looked at the relative effectiveness of circle and J hooks for three popular sporting fish: dolphinfish (often called mahi mahi in the Pacific), yellowfin tuna and wahoo. “Circle hooks were roughly 60 to 70 percent as effective at catching these three species as J hooks,” Rudershausen says.

The researchers found that the fish would still strike at the bait, but that the hook was significantly less likely to set in the mouth of the fish. However, when the hook did set, anglers were just as likely to be able to get the fish to the boat.

“The charter ocean fishing industry is economically significant in North Carolina,” Rudershausen says, “receiving approximately $65 million in for-hire fees in 2009. The concern is that circle hooks would drive down catch rates – which could result in fewer clientele for North Carolina’s offshore charter fishing industry.”

The researchers hope to work with economists to better capture the potential economic impact of any expansion of circle hook regulations.

The paper, “A comparison between circle hook and J hook performance in the troll fisheries off North Carolina,” was co-authored by Dr. Jeffrey Buckel, associate professor of biology at NC State; Greg Bolton, laboratory research specialist in NC State’s Department of Food, Bioprocessing & Nutrition Sciences, Tyler Averett, a former technician at NC State; Randy Gregory of the North Carolina Division of Marine Fisheries; and Paul Conn of the National Marine Fisheries Service. The paper was published this month in Fishery Bulletin. The cooperating charter boat captains were Dale Britt on the F/V Sensation and Pete Zook on the F/V Energizer. The research was supported by North Carolina’s Fishery Resource Grant program which is administered by NC Sea Grant.

-shipman-

Note to Editors: The study abstract follows.

“A comparison between circle hook and J hook performance in the troll fisheries off North Carolina”

Authors: Paul J. Rudershausen, Jeffrey A. Buckel, Greg E. Bolton, Tyler W. Averett, North Carolina State University; Randy Gregory, North Carolina Division of Marine Fisheries; Paul Conn, National Marine Fisheries Service

Published: March 2012 in Fishery Bulletin

Abstract: We compared numbers of strikes, proportions of fish that hooked up after strikes, proportion of fish that stayed on hook (retained) after hook up, and numbers of fish caught between circle and J hooks rigged with dead natural fish bait (ballyhoo) and trolled for three oceanic predator species: dolphinfish (Coryphaena hippurus), yellowfin tuna (Thunnus albacares), and wahoo (Acanthocybium solandri). Interactions were compared between circle and J hooks fished on 75 trips by two user groups (charter and recreational fishermen). Hooks were affixed to three species-specific leader types most commonly fished in this region: monofilament (dolphinfish), f luorocarbon (tuna), and wire (wahoo). Numbers of fish caught per trip and three potential mechanisms that might inf luence numbers caught (i.e., number of strikes, proportion of fish hooked, and proportion retained) were modeled with generalized linear models that considered hook type, leader type, species, user (fishing) group, and wave height as main effects. Hook type was a main effect at the catch level; generally, more fish were caught on J hooks than on circle hooks. The effect of hook type on strike rates was equivocal. However, J hooks had a greater proportion of hook-ups than did circle hooks. Finally, the proportion of fish retained once hooked was generally equal between hook types. We found similar results when data from additional species were pooled as a “tuna” group and a “mackerel” group. We conclude that J hooks are more effective than circle hooks at the hook-up level and result in greater numbers of troll-caught dolphinfish, tunas, and mackerels.

Matt Shipman | EurekAlert!
Further information:
http://www.ncsu.edu

More articles from Studies and Analyses:

nachricht Real-time feedback helps save energy and water
08.02.2017 | Otto-Friedrich-Universität Bamberg

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>