Is this question still meaningful, with the landing obligations adopted? If yes, the question is which discard is meant...

Discard is a good indicator of showing a better fishing practices.  Simply "discard indicator" showing a low value is good for a healthy fishing stock.  Similarly higher value of this indicator is a good indicator of a bad practice.  CFP is attempting to cut down unwanted discards. 

Hi! I think "just" taking the absolute or relative discard is not enough. It really depends on the type of discard: same species, but undersized; abundant other species; rare or even threatened other species... commercially vs. non-commercially used, etc. Thus the composition really matters. And we do have the problem now under the landing obligation with discard dependent critters (like seabirds...)...

yes, i agree that the composition really matters.  I tried to answer how discard considered as an "indicator".

When thinking about this whole issue, the meanings of the word "bycatch" and "discard" become intermingled. And it depends on what You would like to assess with the indincator. An example:

You can use bycatch and discard rates to estimate the mortality that fisheries inlfict upon populations. Than You would like to know, how much bycatch/discard could be tolerated wiothout threatening thepopulation in question. With this kind of indicator, the population would be the subject of the indicator.

You could also use bycatch/discard indicators to assess how much resources a fishery is "wasting". Then the subject would be the fishery and how it is performed. I have the feeling that many NGO and the soceity would like to have such kind of information to judge whether to support a fisheries or not.

I wonder if assessing the fisheries should be adressed by the ecosystem approach or if we should focus on the first issue (impact on mortality)?

"Indicator" is something that points to or shows something.  In case of assessing ecosystem approach to fisheries, increasing bycatch/discard rates in a fishery points to the wasteful reduction of either future or current fish consumption, which is not sustainable.

within a ecosystem approach, you can include the effect of the discard/bycatch on the biological diversity of the ecosystem and the impact of this on the ocean ecosystem services (including the fishing activities)... (Worm et al. 2006 - Impacts of Biodiversity Loss on Ocean Ecosystem Services)

Hello! A very interesting topic.

I understand that regulations upon discards are mainly intended to reduce the negative impacts of commercial fisheries. This can be accomplished directly, by reducing the captures (i.e.: mortality) of non commercial species, but also inderectly, by forcing vessels to be much more selective in their activities so as to make sure that all that comes aboard is (economically) valuable. 

On the other hand, as a researcher on seabirds I can see a clear distinction between discard and bycatch. Seabirds that are accidentally caught in fishing gear are ceratinly a bycatch (although they are indeed discarded!). Conversely, many seabird populations take advantage of discards as a source of food. I am inclined to see the term bycatch as more inclusive and ecologically meaningful. The problem, whether they are discarded or not, is the bycatch.

In short, discard (we may include by-catch of seabirds also here, since these are not landed) estimates (composition and quantities) are key to know the ecosystem level effects of a given fihsery, besides the targeted species.

I think there are several perspectives for your question.

I believe bycatch and discard can be used both as indicators, for instance, I made a brief analysis of anchovy fisheries in Campeche, Mexico. This fishery was badly manage and poor understood. They used to have high percentages of bycatch/discard of very important species in juvenile stages as well certain protected species (like seahorses).

As we look at all the species that were caught through time and space during a complete season, we recommend: a) fishing gear modifications (for allowing release), b) exclusive fishing areas and depths (to diminish bycatch of certain species), c) season reduction (same as a & b), d) technical options for handling and process the main species (reduce waste), e) technical options for using discarded species.

So I think, bycatch can be more important in economic or ecological terms that the main specie(s) of the fishery, discard in terms of waste and opportunity is also important in a social and economic bases.

Wolfgang: Your question concerned the use of discard measures as indicators in the EU management system. I have no experience in the EU and cannot answer about the European details.

Globally, fisheries scientists used to have some relatively-clear definitions of terms like "discard", "landing", "bycatch" etc. but those definitions were never quite universally agreed. Once the ENGOs turned public interest towards fisheries management (in the 1990s), all of the terms and their meanings became horribly muddled. The U.S. Magnusson-Stevens Act, for example, has used "bycatch" to mean dead discards since 1996, without regard to whether the species in question was a target of the fishing effort. If someone now calls for monitoring of a "discards" indicator, there needs to be a clear definition of what is to be counted and what is not. Without such a definition, the indicator will be meaningless -- at best a political gesture.

I have, for example, seen attempts to include the weight of inanimate rocks in "discards" which seems foolish to me. But what of rocks grown over with calcareous biota?

Are fish released alive (and in condition to survive) considered "discards"?

Are individuals of protected species, seabirds, marine mammals etc. to be counted amongst the discards if released (maybe only if released dead)? What if specimens are brought ashore for scientific examination? They would not then be discards but they would be just as dead and the indicator would risk being misleading if the killing was separated from the discarding.

What of fish of no possible commercial value (the material that used to be called "trash")? Those fish are usually discarded but is it useful to combine the amount thrown away with the discards of potentially useful fish?

I would argue that the issues that need to be addressed should first be clarified and  indicators then carefully defined so that they provide meaningful information on the issues selected. Unwanted kill of protected species is clearly a negative worth monitoring. So is the wastage of undersized fish of target species, though management-driven wastage of commercially-sized fish is worse. There is a general problem when "catch" data are based on legal landings and yet used as if they reflect "removals" from the resource, ignoring discards and much else. Any or all of those (plus several other concerns) may be reasons for monitoring discards but they will need different indicators.

In the process, simplistic notions that discarding is "bad" would have to be considered more carefully. After all, if the choice is between returning unwanted fish to the marine ecosystem or bringing it ashore for dumping in a landfill, then discarding at sea must be preferable.

Consider as mortality on populations noted, but also in an energetic context for the entire system.

This echoes much of what Trevor said, but I'll use my words:  

Discard = bad right?  If you believe this equation to be true, then bycatch rates are a way to asses which fishing practices are poor performers relative to other fisheries, and impart social pressure to reduce bycatch since they are wasteful practices.

However, discard rates have nothing to do with how sustainable a fishing practice is, since it does not take into account the amounts of bycatch and more importantly how that bycatch amount relates to population status, population production, and susceptibility to over exploitation.   Consider the case where a fishery A discards only 1% of its catch at 20tons and fishery B discards 50% of its catch at 20tons.  One might conclude fishery B is worse.  However, the answer changes when I tell you that the sustainable catch cap for the species discarded in fishery A is 18 tons and  that for fishery B is 100 tons.  In this case, do you still care that the discard rate is 50% in fishery B?  Is the 1% discard rate in fishery A still 'good'?