Where’s the Science?

The article has a lot to say about how many members each group has, but were is the evidence that the kelp is in “serious decline”?

Smeehee,

Thanks for your comment.

This content is from Environment Tasmania Inc and Humane Society International about their nomination.

I think you’ll find more information, including details on peer-reviewed references, here:

http://www.geol.utas.edu.au/kelpwatch/facts_d.html

For example:

“Following surveys of M.pyrifera in south-eastern and eastern Tasmania (eg. Cribb 1954, Olsen 1966, Sanderson 1987), it is clear that the size and number of beds of M.pyrifera has dramatically declined over the past 30 years, to perhaps only 5% of the original area (Edgar 1997).

Beds have declined from approximately 120 km2 in 1954 (Cribb 1954), to 8 km2 in 1986 (Sanderson 1987), to approximately 0.5 km2 in 1988/89 (SeaCare, pers.comm.). Possibly the greatest loss occurred on the east coast, with a greater than 90% decline occurring during 1978-81 (Edgar pers.comm.)”

Thomas Moore - Editor

Kapow! nice one Skip

Cheers thanks Skip, Very interesting reading.

The scary thing is that that site was last updated in December 2004.. One wonders what happened to the Kelp steering committee and such.

There is certainly no doubt that kelp forest has declined significantly on the east coast, with the over fishing of lobster having caused an explosions in population of the long spinned sea urchin, this urchin eats the small kelp plants preventing the forest from growing back after a big storm events.

Overfishing combined with the strengthening of the east Australian current bring warm nutrient poor water down the coast has caused the once prolific kelp forest to decline to it current sad state.  It is essential that the overfishing of lobster is halted on the east coast to give the kelp forest every chance of coming back.

It is interesting how overfishing is blamed again, when commercial and recreational fishing is conducted within a regulatory framework based on scientific adivce provided to managers and politicians.

Given Macrocystis spores can lie senescent for a number of years it is therefore surprising it has not re-established within the boundaries of marine reserves at Bicheno and Maria Island if overfishing were the sole culprit.

A much more likely scenario is that the species is stressed for a number of reasons, but that increasingly strong incursions of nutrient poor EAC are to blame for the decline in macro. This is primarily because (uniquely for algae) macrocystis had trumpet cells which are required to transport photosynthate around the plant. Low nutrient levels, in particular nitrogen, cause this system to falter and hey presto - declining macrocystis.

As evidence, look at the remaining stands of giant kelp, they are either in predominantly cooler areas less effected by the EAC and consequently accessing cool nutrient rich water, OR they are in areas with high current flow and can access more nutrients, OR they are near a nutrient source (sewage outfall, seal colony etc)

sorry guys, overfishing is pretty tenuous on this one im afraid.

As above thanks for good reading. can some one help me ,why at present time 11/06/09 is the kelp as thick if not, thicker than ever in block 13E DPIWE identification block (Actaeon Island).For the last 20+ years it has come and gone,some say seven year cycle . not sure! The fish on the btm. are better than ever (sise and juvenile) Sorry it isnt over fishing in this area!

Hey Smeehee,

the giant kelp steering committe was formed to help review all the available information on giant kelp in Tasmania and assess it against the threatened species guidelines.

The guidelines for listing a threatened species were not written with GK in mind and therefore do not really address the inter and intra annual fluctuations it can experience - even in good times.

No-one can dispute the long term decline in GK on the Tasmanian east coast, and many (myself included) see this as a concern for a number of reasons. Despite this, the evidence does not show this species to be ‘threatened’, ‘critically endangered’ or ‘extinct’. It is already protected under the LMRPA.

For an in depth and wholistic understanding of the issues involved here (and believe me there are some crackers) you should contact Dr Craig Sanderson at utas. He has dedicated years to studying this species in both paid, voluntary and community positions and is rightly considered the primary authority on macrocystis in Tasmania

Hi, I would like to suggest a push to stop scallop dredging, I believe this is the reason giant kelp is washing up on the shores of our east coastal beaches.  I have been seeing this damage for the past 7 years, the stenched caused by the rotting seaweed and other wild life is disgusting, don’t believe me? have a look for yourself, go to ‘the gardens’ or ‘Beerbarrel Beach’
I really hope the raping of our natural resource by multi conglomerate comanies will stop before it’s too late.  Who can afford scallops anyway?
Cheers, Lea9

G’day Lea9,

Thanks for your comments.

Can you provide any details on the links you claim you’ve been seeing for the past 7 years between scallop fishing and the loss of Giant Kelp?

Are scallops found and fished in areas where kelp forests grow?

I’m fairly certain that scallops are sold to both a domestic and export market - and it is customers in those markets that afford the fish.  Maybe someone else can comment on the size of the domestic and export markets?  I’m sure these sales are important to the fishermen involved?

Thomas Moore
Editor

There is certainly no connection at all between kelp forest loss and scallop dredging, scallops are found on soft sediment, and kelp forest on hard reef. You will find kelp washed up on east coast beaches after a big easterly blow.

Hi Thomas Moore, Thank you for your response, I didn’t expect any less???  Like I said take a look for yourself take a trip over to see instead of discrediting everything I said.  I watch the dredging and I see the aftermath the next day, you say a strong easterly…And you would know because…?
I am a witness not a backseat observer like others I need not mention.  Regards, Lea9

Hi Jim, Since you need proof of where scallops are found eg: Amongst grassy sea beds… Here is a link to a video live footage (http://www.youtube.com/watch?v=6N-XfjVfG0w&feature=fvw).
Regards, Lea

PS: None so blind as those who will not see

Thanks for the info long time interested, very interesting stuff how the Kelp hasn’t flourished in areas were there has been a ban on fishing.

Interesting Vid Lea9, I shouldn’t be surprised that there wasn’t any Tasmanian Giant Kelp (Macrocystus pyrifera) since the vid was from America, but thanks none the less for posting the vid to show that the Scallops live in grassy sea beds.

Lea9, JIM I am not looking argument what depth are the com. scallops taken from?what is the max depth GK grows on east coast.Personally as a recreational scallop diver the only place i found scallops near hard btm. was in dover bay. The scallops doughboy and queens not commercial.this was 30 years ago Now days they dont send down rubber sounders (human). They have videos atached to dredges to make sure the are cathing fish not rock. A modern sounder will tell the fishers what type of btm. they are on. Rocky btm. that will hold GK will damage dredges,They do have a replacment leading edge on dredges in case .

Lea9,

There’s no need for attitude or personal attacks.

You can expect that if you make very strong accusatory comments, using loaded words, that others may question or ask for more details.  It is a discussion.

I may be wrong in specific cases, but I think you’ll find that in general seagrass = soft substrate and not the rocky reef habitat that I’m pretty sure you’ll find is needed for Giant Kelp.  It is my understanding, possibly in error in some cases, that scallop dredgers avoid areas that could support Giant Kelp.  As I asked previously - can you provide any details?  Have you seen scallop dredging in kelp beds?

What you will certainly find is that across the readership that visits CoastView there is significant real world experience, people out there everyday involved with the marine environment through scientific research, industry, conservation, and recreation - “frontseat” observers that are part of Tasmania’s coastal community.

Thomas Moore
Editor

Lea9, I am certainly not some back seat casual observer, I spend a number of days out on the water fishing or diving each month, and am paying close attention to the changes we are currently experiencing in the marine environment on the east coast.

The video you posted has nothing to do with the plight of giant kelp forest, sea grass is a plant and is found on soft sediment where scallops are found. The destruction of sea grass beds is another issue totally separate and not to be confused (as you seem to be) with the decline of giant kelp forest.

I would have to agree that loss of giant kelp is unlikely to have any link with dredging. Rocky bottoms will damage dredges, and it is not the habitat scallops are found in. Probably the place scallop dredging has caused most significant damage to ecosystems in the past is the d’Entrecasteaux channel.

After a large easterlie, masses of giant kelp can be found washed up all the way down the east coast to past EHN.