" \'
JUL..'
L'IlTRODUC'fICfll
During the
hired SOUBA
SllrnlOO:<'
11 dbrer"
of 1961.
II
seafood dealer at Charleston, Oragon
to J;,arvest clams in subtidal area", with hydraulic
by considerable pUblicity.
t,nemselves
pumps and motors and
of
This
and
to
to a
out~
is
on
and
the low tide le',,,,1 in area", bordering known intertidal clam beds.
IT
Self-contained ~ter breathing apparatuso
The
of
harvest was conducted from a 22.cfoot boat equipped with an air compressor.
for the diverts
air~line,
and a 2-inch gasoline powered pump nozzled down to
One diver found and "staked" clam holes and the other diver pro~
3/4 inch.
ceeded to wash out the clams previously located.
The two divers ware taking
about 100 pounds of clams per hour at that time.
Many small cla\ll.s were inci-
dentally washed out.
On August 15. 1962, a
personal~use
clam harvester was obser'lfed in
Coos Bay using hydraulic equipment to harvest clams.
inch pump powered ..lith a 2~ h.p. gasoline mot;or.
This man was using a
311.-
While lL"lder observation. he
harvilsted 20 large gaper clams and 19 small gaper clams ranging in size from 1
to
Ii
inches in lengUI.
L'1formed
~i;,hat
These clams ,1/ere left, exposed.
i'lhen thhl man 'Was
he was ilxceedL'lg the bag limit. he :i.nformed the observers that
he was ha:rn.resting the excess for friends.
~riment.!!1 .Qllil.eI'1J''!.ti,~
On May 22. 1963, shellfish pI~jeot pereolL~el. equipped with a l~-inch
pump and motor. e.xpetimentIt11l;y dug gaper clams in Yaquina Bay.
technique employed reduced the main-line from a
~-inch garden hose attached.
in
2~inch
The
outlet to 1 inch with a
This equiilment permitted removal of gaper clams
seconds from a depth of 12-18 inches.
The effect upon the bottom from
the equipment was to leave a 24-30 inch circle
washings 1.'1 the area where
the clam was removed end a hole 6 inches in diameter
~~d
12-18 inches
•
Sand clams. bent-nose clams. and one rasorclam were exposed for possible predation by this method.
Though not many people utilize the
firs'~
two species
they are edible and it ie not deemed desirable to destroy them needlessly.
The
second technique employee! involved the rlilllloval of the reducer and the !-inch
garden Ilose.
Tha 2-incll main-line then was used to wash out clams.
By this
method nina square feet of clam bed was washed out cco a depth of 18 inches in
l~ minutes.
This operation exposed all sizes and speoies of clams, and in
general cllused heavy damage to plants and animals alike,
Digging clams with a. shovel also displaces smaller cl/l.llls but they are
usually covered. hence not exposed to predation.
When the
is used these
pUl11p
clams float out and are exposed to predation by gulla. crabs. or starfish.
DISCUSSION
The ability to take clams with hydraulic equipment has been knowa by
the ehellfish staff for several years, and 1..1'1 i'act has been employed
clams for marldng stu.dies.
'&0
obtain
Only within the last ttl/O years has this method of
harvMting claJll8 become a serious problem.
With the attendant publicity in
the Coos Bay area it is expected that the use ot this equipment probably will
spread to other estuarie::l.
The states of Washington and CalifoI""nia prohibit
is quite detriDrental to clam beds sinoe it regrades the bottom
Our experiments inrlicate that this
equi~nent.
basis, is probably no more destro,ctive than a shovel.
or other species to predation.
In, Coos
~atarisls
and
when used on a limited
HO'>'6ver. large pumps
obse:rvations, it was recorded
tr~t
fellt,are of til:!.;; equipment. and probably the greatest potential danger ·to the
displaying slow growth, and if sub,iected to intenlile digging pressure can very
readily be reduced in abundance.
Accompanying this reduction in ab11l1dance is
a reduction in the' «"el'B,g6 size of individual animals han'ested.
effect, reduces the potontial yield of the resource.
'Ihill. in
4.
The cOllll.lleroia1 clam har4J'est in Coos Bay
the period July through
December, 1962, amounted to 46,626 pounds compared to 7,406 pounds in 1960,
and 13,690 pounds in 1961.
Of the 1,6,626 pounds landed in 1962, 46,173 pounds
are known to !la'"..e been gaper clams harvested with llydrau,1ic equipnent.
tio
breakdo'Wu by species is available for the years 1960 and 1961 because f.he clams
were reported mostly as "bay clams".
Two divers working ,11th SCUBA gear in
1962 were harvesting as llluch as 2,000 pounds of gaper clams per day and averaging
728 pound6 per landing.
It can be argued that the divers are
haF~esting S
resource that is
untouched by most clam diggers, but all subt.idal harvest to date is taking
place on the outer perimeter of Knorrrl intertidal clam beds.
It has always
been the opinion of the shellfish staff that these an:'lJllsls seFV"ed as a seed
reserve for restocking intert.:'l,dal areas in case of intertidal de<::i.mation.
Also,
if the subtidal area becomes depleted there is nothing to stop divers from
working the intertidal are1l, during high tide.
this.
No regulations ai;
pl~esent
Even :If i t were lllegl!,l. policing would be virt;nally imposa:lble.
theae a.reas were to be han'ested on both law and high
prevent
If
'lie would soon be
without gaper clams.
As information on t.hJ.s typs of equipment eprellde more and more commercial diggers will un,doubtedly 6tar'G ueing it.
who become discontented with the present
Also,
porsonal~uee
dig£ore
lixnite when taking clams ie eo
easy will either exceed their bag limits or buy oommen:;ial li,censl'ls so they
oan harvest more cla."lls.
Thus, the dlggi.ng pressure on this species may increase
to an uwjesirable level.
CONCLUSIONS ArID RECO}l}1ENDATION
Observations indicate that if
p~'operly
employed, hydraulio hsrvesti.ng
of gaper clams is probably no more harmful than diggir!g by shovel.
If improperly
employed it is very detrimental to associated speciea and bottom conditions.
'1h", gaper clam is a slow-growing animal and can l'eadily be reduced in abundance.
The efficiency of this equipment constitutes a thrllat to the abundance of
gaper clams in Cooe Bay and other areas where it might be employed.
Subtidal
clam beda, because of channel dredging and other factors, are limited to
narr~~
bands adjacent to irltertidal beds.
fol:'!ll
seed stock reserve for intertidal areas and COngiltitute
III
It is believed that these beds
against overdigging within the intel·tidal area.
Ii
major safeguard
Hydraulic eqllipmant, by its
washing and floating action, exposes many small clams, both gaper and other
speoies. to predation by galls. crabs, fi.sh, and starfish.
While digging with
shovels alao dislooates clams. the animals are not exposed as readily as when
hydraulic equipment is used.
In view of the foregoing, it
olam digging be limited to
the reoommendation of the staff that
hand-pm~erad
opsrated suotion pipes, or the
tools such as shovals, rakes, hand-
"plUl1l.ber~s
friend".
As an alternative to oomplete outlawing of h;Ydraulic ha!'Vest or clams,
a pemi.t system could be
inltia·~ed.
issued on a seasonal basis, each
Pel:'lllits for specific operators eould be
per~t
tailQrsd to a specifie ares. hydraulic
device. operator, a.nd ehellfi.sh cO!1lll!Ullity,
i'ie belisve such a permit system
be impoasibly difficult to enforce.
C. Dale Sn01~
Oregon Fish CO'mtdssion
Shellfish Investigationll
July 17. 1963