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Bycatch - or Searching an Ethics for the Oceans

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One method to avoid killing Dolphins in this form of fishery is the so called ìBackdown procedureî where divers are utilized to release the Dolphins by simply lowering the net to open escape routes. Other technological adjustments such as rescue platforms also were added to the catching routine[x].

At the same tome the unfortunate Tuna despite being magnificent creatures never had such a positive image and may well be hunted to near extinction.

2.1.2 Long Lining some approaches for improvements

Often there is not one single technological answer to a single technological question, and solving the bycatch issue in long-line fisheries is such a case. However, there are a number of promising developments that in combination may well reduce bycatch to tolerable levels at least in terms of commerce and population biology. Such approaches include (See Kibel, 2007):

--> Circle hooks (reducing turtle and sea bird bycatch significantly)

--> Pingers (as deterrents for marine mammals)


--> Applying weights to lures to quickly lower lines beyond levels where they can be reached by birds, or use heavier frozen baits)

--> Deep setting (also adding significant weights to the line to create a deep bow out of reach of birds

--> Automatic release bait pods (a new high-tech approach using a closed bait pod that opens via pressure control at a pre-set depth)

2.1.3 Trawling and excluder devices

One of the few effective technological measures that reduce bycatch in trawling has been the introduction of exclusion devices in the nets. Those basically are rigid grids or similar structures that separate any big animals from the main catch and divert them to a special exit of the net while the main catch is directed to the cod end by the water stream. There are a variety of exclude devices and respective net designs of varying effectiveness, however, their effectiveness all in all must be considered as ìbetter than nothingî, especially since the problem of catch and discard of juvenile specimens of other species remains unresolved. This issue will most likely be addressed, since there again are commercial incentives at play because many of the destroyed juvenile animals would be commercially relevant when larger. Some further improvements of trawling methods are required. The current methods can be broadly categorized into[xi]

--> those that separate species by differences in behaviour

--> those that mechanically exclude unwanted organisms according toothier size (see above).

Excluder devices also do not guarantee that the excluded animals actually are safe they may well be dead or heavily injured from the impact on the device, which would make the damage invisible, but not undone. Among the work that still needs to be done are:

--> Thorough Quantification of bycatches and accumulation of fishery-related information

--> Long-term examination and re-evaluation of modifications

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http://thiesen.webnode.com/

Stefan Thiesen is a Germany, UK and USA educated earth and space scientist and science writer. He is an expert in marine science, climatology and planetary sciences, author of several popular science books in German and English as well as a novel (more...)
 
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Policy makers around the globe are increasingly fa... by Stefan Thiesen on Thursday, Jul 1, 2010 at 12:17:02 PM
Greed has put many men to sleep and buried the con... by Donald on Thursday, Jul 1, 2010 at 12:53:40 PM
What you write, Donald, reminds me of Haruki Murak... by Stefan Thiesen on Sunday, Jul 4, 2010 at 4:47:23 AM
I heard about grazing- harvesting recently outside... by Ursula Siebert on Saturday, Jul 3, 2010 at 12:23:30 PM
I was remotely involved with some research regardi... by Stefan Thiesen on Sunday, Jul 4, 2010 at 4:40:52 AM