was
1968
BCF
1970
February,
proved
months
at
the
RESTRICTED
(Colton
temperature
comparisons
U.S.A.
all
of
have
Res.Doc.70/59 anomalies
groundfish
November,
in
January,
temperature
25
ICNAF waters
in
fall
Welch
Conditions
02543,
Maine
-
Waters
1968
offshore
mean
R.
subsurface
temperatures
Positive
Maine.
Welch
in
for
W.
Mass.
annual
R.
and
Harbor,
mean
1). occurred
October
Fisheries
than
annual
Mr.
Adjacent 1970
contiguous
Fisheries the
10
Harbor,
Temperature
Hole,
Walter
by
on
and
and
1969
JUNE
1969
surface
available
Commission
and
-
(Figure
monthly greater
the
1969
Boothbay
in
68-7,
Woods
The
Jr.
or
taken
for
Maine
Commercial Atlantic at
G2 Maine
The
data
and Boothbay
MEETING available
of
of
of
offshore
higher
Cruise
1.OoC 1968. December
1968 Colton.
to
IV
made
Gulf
1969).
B. Gulf of in ANNUAL
of
and
November.
Bureau Laboratory,
International
the
and Northwest the
temperature
John observations
Laboratory,
were
temperatures index
and
than
1968)
in
by
in
Harborllwere
only B.T.
data
good
(Albatross
1968b,
September June,
Comparison
a
higher minus
Biological
Surface
The
2398
from
be
Biological These
No.
to (1969
conditions 1968a, Boothbay
except a.8°C
March,
1) are
surveys II
1950
(D.c.
Serial
~ - 2 - and Albatross IV Cruise 69-11, 8 October - 23 November 1969).
Al though there was a considerable time period reqmed to cover
the area as a whole, most 60-minute quadrangle areas were sampled at roughly the same time (! week) each year. Anomalies were computed as the difference between the 1969 and 1968 mean temperatures within
30-minute quadrangle areas at depths of 1, 50, and 100 m. During a given cruise the number of temperature observations within 30- minute quadrangle areas ranged from one to six, but in most quad rangles there were at least two observations each year. Surface temperatures (Figure 2) were higher in 1969 over the central Gulf of Maine, along the coast from Grand Manan to Portland, and east of Cape Cod. Temperatures were also higher in the South Channel area, over Georges Shoals and the southeast part of Georges Bank, and along the edge of the Continental Shelf south of Nantucket Shoals. In all other areas the temperatures were lower in 1969 than in 1968. The greatest positive anomalies
occurred over the south central Gulf of Maine and the greatest negative anomalies in the mouth of the Northeast Channel and along the southern edge of Georges Bank between Lydonia and
Veatch Canyons.
Temperatures at 50 m (Figure 3) were higher in 1969 in the
south central Gulf of Maine and off southeastern Nova Scotia
(Roseway and LaHave Banks). In all other areas temperatures were lower in 1969 than in 1968. The negative anomalies were
greatest south of Browns and Georges Banks and increased with
distance from shore. At "100 m (Figure 4) 1969 temperatures were
also h~er in the south central Gulf of Maine with the highest values occurring over the Wilkinson Basin area. In all other areas the anomalies were negative.
G3 - 3 -
Valid predictions cannot be made on a basis of such limited data for as illustrated in the 1968 and 1969 seasonal temperature curves for Boothbay Harbor, temperature conditions for a specific month are not always indicative of the annual trend. However,
Colton (1968b and 1969) has shown that the long-term warming and cooling trends of both surface and subsurface waters in the Gulf of Maine depend in large measure on the relative position and degree of mixing of coastal and oceanic water masses. Cold years occur when Slope Water is displaced or modified by Coastal Water of Labrador origin. The negative subsurface anomalies in the Northeast Channel area and along the edge of the Continental
Shelf during October - November 1969 may have been associated with a change in the composition of the subsurface water result- ing from an incursion of Labrador Coastal Water. If in fact
there was a shift in the relative position and degree of mixing of Slope Water and Labrador Coastal Water, this could be indica-
tive of a check or reversal in the upward trend in coastal and offshore sea water temperatures Which .commenced in 1968. We shall continue to monitor hydrographic conditions in critical areas along the Continental Slope to determine if the negative
temperature anomalies observed during 1969 were due to a major change in the composition of the subsurface water.
G4
d .. - 4 - Re:ferences Colton, J.B., Jr. 1968a. A comparison o:f current and long-term temperatures o:f Continental Shel:f waters, Nova Scotia to
Long Island. Intern. Comm. Northwest Atlantic Fish. Res. Bull. 5: 110-129. 1968b. Recent trends in subsur:face tempera- tures in the Gul:f o:f Maine and contiguous waters. J. Fish. Res. Bd. Canada 25: 2427-2437.
1969. T.-perature conditions in the Gul:f o:f Maine and adjacent waters during 1968. J. Fish. Res. Bd. Canada 26: 2746-2751.
18~i------'
16 "..---"-"'" 14 //
'12 ~ ~ / ::I:=: 10 I .....e h e:; 8 ~ :...... 6
4 --1968 2 " --1969
o JAN FEB MAR APR MAV JUN JUL AUG SEP OCT NOV DEC
Fig. 1. Seasonal temperature curves, Boothbay Harbor, Maine, 1968 and 1969.
G5 - 5 -
,- ,1\--/...... ,..., '/'f)~, "( z I , - ;" ....' ./ \
..../,:..---... .-) .... - _"""" __ .I ...." .... r' -- ~' ,..., t., f J) l) ., ....__ .... .-- :-:" /"1 -./"" n'b ,CO ,,' r , r' !' il.' ,....<.., 44· IAwlJV ' ___ ,' I l/ , / / ,,'If""'" \ "..""v " ,---" _~.__ I /- , " / ) / ( , , r" '/r;;-'-'?J~---~rJ , \)V-// F ," I / (10' --,--;/ I~//'-, i I (I ~' , " I I v .../'_ f'..... I ~ " I"rO/iI) 10.... y~"'I :,(_ 'V DO /J.-","~/ \ , / , (' .' ( I ---~ \L) ---(-// ~ //,1, - / I ,-'" ' , " ~ \. ~ ,) , ' 1, ..../ '/ .\ \ \" O 42° ~:', ,-O"~< ~ ,~ .~.'. ~/".,.. l.~' J 0 ,-;c. .. _ ,,--' J "' ",,', /,/'//" ) 1(1;:3/) - t ' " " ' " ,.,,! ~,o/~ ; " ,; ; 0"- , ... --""...... , ~'(,~0° ,/ ' " ,--,...'1° =--- .. ) : "./ ( """/ .""", 0" (0: 1 0" / ------. ' 2 ~ O ,lo61;0 ___ ,_))/<=-I .:::;:;::' 70° 6S0 66° 64° Fig. 2. Temperature anomalies at the surface during October - November 1969 relative to October - November 1968. G6 - 6 - ,- .. -,,, 9...... ~I .. ,,1\ __ -I ~jj7fl/ ..... h'\ j/ // ,.....,- --- -) /.'// ,I ,,, ,,-" ,C>_'-: ------/,/ ,-- 'Mr'.:-.--:5...'d' /;! '_--'-:i- _----_____' ,_ _u , ' ~d ' .-...... - ,if __ ~ )J< (I ~.L//-.,c.\ • /---" (h I /' .. (~,o (~'-- --~c ~~'I '-, , \ ..__"" ~ t , , ~,'r,o-'-'-" ' • ,__\ I ~" 1 '\ ')'.,1. &J ,. \-,,:._ox:~~·"/ ..' '" (3~j. " '\ ~\--2~~~y~~0 ':- Oo---)/ I yr-5 42° 0 '~ "~h/}" , _~\, \ v""--:::J : /,1 ) /4 --50 " , / ' \ " V 1"1 .J 1/1..1r. ,:;/ a ... ~ '-! -/ I ih.~W~8° , ",,_ ,~ ,,__ ,----,'- / d" A _1~i'.~L-J...... ~j:" .J~II \IOO{;"'""-'~III'I~~,=-~--t!J~~1 ,=~I , _ .... Ill/50 ... .:::::-~-I '0 .....r'il/i //~~-6 '111;--" 40° POSITIVE NEGATIVE 70° 6S0 66° 64° Fig. 3. Temperature anomalies at 50 m during October - November 1969 relative to October-November 1968. G7 - 7 - ,---"'~.....,..., - ''''-- ) .~... ) ,:~I) -- 1- \'_ - " v It' \ /' _""''''_\/,') ...'" ) 1/' #I ,. ... "'--./ , .. ' ...... _--- ~" " .. --~..-~! ... " r" ./ h " r ..,.. ...,,.... .S' "...... -;1 ,/ I "" --- ~ ./ / ' , ,- 1) :, CO'li \ /' / Ht n .~'rc,· ~t/()\ /' / 44° \ ~.-oI'!.... "'v /1 I " ) -4.[11 \"..) /- \"'1 t\ , " ( "" '~r J \ \ , " I .... - ...... /--"-- ___ ..... r i \ ,,".' ~ ,. "J 0 "':1 ---..::i' 0 '- I: i? // / 1/ /'-~ -.I-- r 10 1° ----.,._I "/\ , __ .// I ...... :,;J I " , ',-----.::...1°__ j!: / I" / / \,;" J 0 ~ / _ ~""\\ 1 :' I n - ...... -!.,....:.-'.. J's.'-""~ \.,.v 'I JI rP 1 1 /" q' " ( /) V /y ...... ---, -_/ m :,("';/ ./\ \' \ ° \_- -- /)/.. \ \ 2 -,\ ~/40 \ \ \..J - --\.._1_"__ '3° 42° //,,,--\ '=".::::-...... /',' l ...... ~ ° / / - , ( .....6 / -- /', , po. / / ,,'" I '- ...... 60 ' I / " / I' II <'_..... / \ : I ... 0 , I 3 d /' ' /" - I f... / /, / ----50M------.. :,1 ') '.'/-'"" --<" '3° " -_." ! ?-\ '40 -,'" \ /,.---/ 50 5° O/~----- /,-1 \ A\, \"--~(/\ \o~o 40° 20 3'0 ~ 0° 0° '0 2° 3 POSITIVE NEGATIVE 70° 68° 66° 64° Fig. 4. Temperature anomalies at 100 m during October - November 1969 relative to October - November 1968. G8