[Coral-List] Sharpnose Puffer
dfenner at blueskynet.as
Sat Jan 3 01:49:45 EST 2009
In American Samoa, there are mass recruitments in most years, particularly
of the surgeonfish Ctenochaetus striatus, which is our most common adult
reef fish. They seem to come in several pulses each year, and when they
show up they are on the order of 4-5 cm long. The adults are black, but
these new recruits have thin horizontal red lines on them. Then at some
point later on, they all change to black. So you can tell when
another recruitment pulse occurs, because suddenly you have more with red
lines. There are quite a few of them that settle in most years, but in a
few years spectacular numbers settle, huge schools of perhaps hundreds of
thousands have been reported, and if they are in your transect, they can
dominate the biomass not to mention number of individuals (Ali Green
observed such schools here, including in her transects in 2002). After
pulses, the numbers seem to go down steadily, but not really rapidly I would
say, Peter Craig here has data on that. If I remember, Ali Green saw in
that huge pulse that many were in poor condition later, very thin, ragged
fins, and so on (it's all in her report). I've not seen any like that in
normal years, mind you I haven't studied it specifically.
I'd recommend a paper on the survival of new recruits in Tahiti- if I
remember, 60% were lost in the first 24 hours. They used a crest net to
measure the recruitment each night, and daytime transects to record new
recruits. They then subtracts to measure the mortality each 24 hr.
American Samoa has also had mass recruitments of two species of
rabbitfish in recent years, even though the adults here are quite uncommon.
We're not sure where they are coming from. They also recruit at roughly the
same size as the surgeons. There are also recruitment events of goatfish,
and they are even larger, maybe around 10 cm or more when they settle.
There is a
traditional Samoan fishery for the newly settled goatfish, and a traditional
basket woven as a fish trap used to collect them. They have a name specific
just for these goatfish recruits. So Samoans have known about them for a
long time, possibly for nearly the 3000 years people have been here. They
probably know a lot more useful information, too.
And like many things on coral reefs, recruitment seems to be patchy in
both space and time.
Doherty, P. J., Dufour, V., Galzin, R. Hixon, M. A., Meekan, M. G., and S.
Planes. 2004. High mortality during settlement is a population bottleneck
for a tropical surgeonfish. Ecology 85: 2422-2428
Almany, GR, Webster MS 2006. The predation gauntlet: early post-settlement
mortality in reef fishes. Coral Reefs 25: 19-22
Green, A. 2002. Status of the coral reefs on the main volcanic islands of
American Samoa: a resurvey of long term monitoring sites (benthic
communities, fish communities, and key macroinvertebrates). Report to DMWR.
Craig, P. 2005. Natural History Guide to American Samoa, 2nd Edition.
National Park of American Samoa, Dept. Marine & Wildlife Resources, and
American Samoa Community College, Pago Pago. 96 pages.
----- Original Message -----
From: "John Ogden" <jogden at marine.usf.edu>
To: "Will Welbourn" <will at bayislandsdiver.com>
Cc: <Coral-List at coral.aoml.noaa.gov>
Sent: Wednesday, December 31, 2008 4:49 AM
Subject: Re: [Coral-List] Sharpnose Puffer
> Hi Will,
> My guess is that sharpnose puffers have the same type of recruitment as
> Bill Gladfelter and I observed for balloonfish (Diodon holocanthus) many
> years ago in St. Croix. The larvae are pelagic for a long larval life,
> up to a year. During this interval; they slowly gather into huge
> schools of many thousands of individuals (about 3cm long) which then
> recruit en mass to whatever coastal region is favorable within the time
> frame of development. The area then becomes completely flooded with
> recruits which gradually disperse and are preyed upon. You could call
> this a sort of 17-year locust type of recruitment.
> It would be interesting to see if others have observed this type of
> recruitment which may be more common than we know.
> Happy New Year!
> Will Welbourn wrote:
>> I was wanting to post about the huge population increase I have noted in
>> waters of Roatan Honduras. As a full time dive instructor here for the
>> five years the last six months I have observed an increase of 300-400% in
>> the abundance of this fish.
>> Anyone know why or what it may indicate?
>> Will Welbourn, Course Director and Director of Roatan Marine Park
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