Threats to the Reef

[kc]

I have just been sent a really interesting document and well worth a read for anyone interested in the reef rezoning....regardless of wether you are for or against.

It is too big to post here but I am happy to send anyone a copy. Email me direct on kc@whitsunday.net.au

Might even be worthy of some good robust critiques of the document when it has been viewd by a few.

Regards

KC

[Mick]

Sent you an email kc.

[Leo_N.]

An interesting read with compelling arguments. Though like any good argument, he has only given the facts that support his argument.

The most notable exclusion from my perspective was the coral trout research that he quoted from Ayling. This research did not find large differences in fish numbers between fished and un-fished sites, but did find differences in fish size; larger fish being found in un-fished sites.

As smaller fish have a lower reproductive potential, the theory that many reefs are "seeded" from other reefs is consistent with this data, and the protection of known "source" reefs is clearly valid. The problem with this, which is also highlighted in the paper, is that we clearly don't know enough about reef reproductive and recruitment processes to make informed judgements.

Maybe the GBRMPA have cast a wide net to ensure their bases are covered in the absence of difinitive data on this topic. I think more likely is that the tourist dollar is much more important than the commercial or recreational sector, and protected areas, free of fishing boat traffic, and potentially larger fish is very attractive to tourist operators.

By the way, I have talked to several keen reef fishermen lately who all (including myself) have noticed a large increase in barramundi cod and maori wrasse (not me) catches/abundance. Though not scientific evidence, this indicates to me that the closure of these species has had a large effect on their abundance (notice that they are also pretty fish that tourists like to see).

[kc]

Interesting that a closure only 10months old would be having a noticeable impact on catch rates of adult fish?? Surely it would take a number of years before any difference was noticed?

Anyhow. Good comments Leo. Be interesting to see what others think of this document.

Regards

KC

[Leo_N.]

I thought so too at first, but they only really need to grow from just under the previous legal size to just over, as these fish were not able to be targetted previously. Because they don't need to grow from egg/larvae to this size, 10 months is quite a long time.

[Mick]

I have only managed to fit a brief skim read in but so far, it has definatley been interesting. I totaly agree with Leo, how the argument is one sided thou.

For example, the author says, anchors, walkers, divers and ships damage on average, about one ten millionth of the great barrier reef coral area and cyclones can cause thousands of hectares of damage to the reef on a yearly basis. The reef can recover from cyclones without a circus, useless remediation efforts or imposing fines. BUT, I believe if there was no legislation that gives power to issue fines, then it would be more then one ten millionth of the reef that was being damaged, or maybe thats why only such a small amount of reef gets damaged by human interference - because there are harsh penalties involved if you are caught.

I also found it interesting that the author noted that more areas closed off to fishing will not increase our catch rates but decrease them. In a way, I agree. The author goes on to say that fish that habitat a heavily fished area (like a warf or jetty) are harder to catch as they are more or less used to bait being dropped in front of them with severe consequences. On the flip side, if one was to fish a secret reef miles off shore where fish don't often see a bait being dropped in front of them, fish will charge at the first thing that they see expecting a feed. Hence, the more closed areas to fishing the denser the area allowed to be fished becomes. The more people fishing in the one spot the more switched on fish become and the less fish we catch. The author also goes on to say that fish populations on the great barrier reef are stable through out the reef when compared to areas that are closed and open to fishing.

mmmm...., interesting stuff, but like Leo said, its one side to the argument. In another way I could say that the Author is full of crap, as he says that the most heavily harvested fish on the reef (coral trout) is only lightly being harvested and there is little to no affect on the overall population. Bulldadash...., I see hundreds and thousands of live trout come into my harbour regulary. Now, we go back to grade one at primary school. Kids, what is 10 000 take away 5 000? Yes kids, the answer is 5000. If someone takes something from somewhere, that place will always be less whatever has been taken. Talking about fish, if a fish is taken by an angler then the ocean is less that one individual fish. If lots are taken then, the ocean is without lots. Sure fish recover, but its simple maths. Take and its gone.

Not realy for or against this info, but I will say its good stuff and worth a read. I will go back and read the entire document over a cuppa and let it all soak in.

Mick

(I think this is my longest post)

[Leo_N.]

The theory about fish numbers goes a litttle along the lines of resource allocation. If you take more out, it frees up more food and space for new recruits. That is why there are similar numbers, but they are smaller. This actually equates to more under-sized fish in heavily fished areas, so numbers are not the be-all and end-all of this argument. The number of fish that are available for harvest is definately affected by fishing pressure.

[nonibbles]

Is this the same article that can be downloaded on the sunfish site - "threats to the Great Barrier Reef" By Dr Walter Stark? From all previous posts it does sound like what he has written. It is a very interesting article indeed but as stated earlier only points to one side of arguments. Fortunately he seeks to provide data that refutes gbrmpa's claims.
I think the days are long gone where a balanced argument is going to be published. It sure would be nice to freely get hold of significant amounts of credible info on BOTH sides of the fence though.

[kc]

When you are re-reading Mick see if you can look into Dr Aylings trout studies...might just change your mind about trout numbers.

If you can't find them drop me a line and I will ping them off to you. No doubt the good doctor is just putting one side of the augument....but!! GBRMPA & various green lobbies have always just put the other side.

This , by any measure, an interesting read and given I have been waya for a month may have already done the rounds but I only got hold of it this morning.

KC

[nulla]

Leo_N

Regarding Coral Trout - I mentioned CRC report 52 in a previous post and I repeat it here as a similar debate has arisen:


"It is important to note that the status of coral trout populations in areas open to fishing remained relatively robust under all strategies we considered. For example, even under the most ‘adverse’ scenario of maximum effort constrained to the smallest fishable area, spawning biomass (in the open areas) remained above 50% of virgin spawning biomass and biomass available for harvest (i.e., above the minimum legal size limit) remained above 30% of virgin available biomass. These statistics generally would be considered acceptable for a harvested stock. In large part, this is likely to be the consequence of the biologically precautionary minimum legal size limit on harvest of common coral trout, which ensures that most fish can spawn in at least one year before reaching harvestable size."

This is the known science relating to coral trout at least. I have trouble reading into this the need for closures. If you catch some fish there will be less left. So what. The key issue is "is the take sustainable".? This report seems it indicate it is. Size limits are there to ensure fish have an opportunity to spawn so the fact that the average fish may be smaller, so long as the spawning biomass is sustainable is not of great concern.

As for barramundi cod and maori wrasse - you mention an increase in abundance not size - not the same thing - and then claim catch bans have increased abundance in 10 months - I have trouble following this.

The report mentioned by KC - written by Dr Walter Starck can be accessed at

http://ipa.org.au/files/IPABackgrounder17-1.pdf



Nulla

[Leo_N.]

Yeah, good points there nulla.

Yes, most fish can spawn before reaching legal size but fecundity is related to size, so the larger females have a higher reproductive potential. This was my point.

Fair enough, spawning biomass might be above 30% of virgin biomass now, but what is the effect of sustained pressure at current rates. If GBRMPA make a mistake on the conservative side , they can still look proactive in protecting the reef (even if there is nothing wrong now). However if they err to the side of non-protection and effects of fishing pressure has been underestimated they get roasted for not protecting the reef.

However as I have mentioned, I don't really think that the sustainability of the fishery is a major decision point for reef protection. Rather, it is the tourist dollar that counts, which is much higher than recreational and commercial fishing combined. More big fish is what tourists want to see (and, yes pretty ones as well).

And sorry for again not explaining the barra cod and maori wrasse thing well enough. These species (at least from my experience and others that I have talked to) do not appear to be caught by the line fishery at a small size. I have never caught either species below 1/2 kg, and maori wrasse not until much larger. When you think about it there must be heaps more of those little guys out there than big ones, as some must die on the way. Therefore I think that the abundance caught has increased due to them entering the catch at some size, and I am noticing an increase, because there are more larger fish out there that can be caught by my 6/0 to 8/0 hooks. Maybe I am cluthing at straws to explain what I and others seem to have observed as ther is no data to support this.

[nonibbles]

With regard to barramundi cod, word of mouth is that they were a common live trouters bycatch. The word of mouth is that they were often dispatched and sent over the side. If this is true then the trouters moving on from some areas would also contribute to a resumption of these fish taking up residence.

[Leo_N.]

author=nonibbleslink=board=General;num=1118198819; start=10#11date=06/09/05at15:40:04 The word of mouth is that they were often dispatched and sent over the side.

???Why would they kill them and leave them when they go for $80 - $100/kg live on the Hong Kong markets ??? #From what I have seen, they were taken by pro trout fishermen live, and were a most welcome "by-catch". #

[kc]

Agree with Leo, I saw about 100 of them live at a trout exporter in Bowen just before they became no-take. Apparently destined for a fish farming experiment.

KC

[nonibbles]

So the live trouters were allowed to take a no take species ??? or did they just do it anyway?

[kc]

No,

Once they were no take, this was for everyone. Pre this the trout boats used to take both Barra Cod & Wrasse.

KC