DFO- Library / MPO -Bibliotheque THE LIBRARY """,i""1"' "-^curK: biological rrA :•••• \ :,:..,:•• Research Board of ' B-c- oiuio/oo Pacific Biological Station Nanaimo, Bc Co

Circular No„ 37 July? 1955

Extent of .Herring Spawning iini Waters During 1955

Do No Outram

General

Every year since 1930, herring spawnings along the British Columbia

coastline have been reported by officers of the Federal Department of Fisherieso

Since 1937? the measurement of the size and intensity of all spawnings has been

a part of each officer"s regular duties. During the past nine years detailed

spawn surveys have been made also in southern British Columbia waters by

members of the Pacific Biological Station*

The Pacific herring (Cllupea nallasi)0 unlike the Atlantic species^

spawns in the intertidal zone0 During the spring,, eggs are deposited on veg

etation such as eelgrass and rockweed above and below the low tide line0

Spawning grounds may vary in size from a few yards to several miles9 the lengt-h

and width being largely determined by the distribution of the vegetation and

the stage of the tide at the time of spawning0 The spawning grounds are not

randomly distributed along the coast but are located in certain preferred

laces used year after year0 Maps of the northern and southern British Columbia

coastline are given in FigSo 1 and 2 and show (1) the location of the 1955

herring spawning grounds, (2) the statistical areas into which the eight sub-

districts are divided and (3) the location of place-names mentioned in the

texto

Purpose of Spawn Surveys

Conservation of this valuable fishery resource necessitates main

taining spawning stocks in the eight major herring populations of British Columbia of a size sufficient to ensure a supply of herring -to the fishery three and four years later© The relative size of the spawning stocks (i0e0 fish tfiich escaped the preceding winter fishery) is estimated by measurements

of the zones covered by spawn each year0 The data obtained from these measurements also indicates the initial strength of the new year-class0

Survey Methods

The length of each spawning area is estimated by pacing along the beach or by reference to a large-scale chart0 The width is observed visually0 The intensity of the spawning is recorded as being, in one of five broad categories (very light, light, medium, heavy or very heavy) based on the number of eggs found per linear inch of eelgrass or per square inch of other surfaces,, The information on width of the spawning zone and on intensity of spawning is applied to the length of the zone to convert the actual observed length to a comparative index of the amount of spawning is an estimate which, though not accurate within narrow limits, is believed to give a reliable indication if any major differences occurring from year to year or from place to place,,

The 195? Spawning Season In the accompanying table the results of the 1955 spawn survey based on fishery officer9s reports are given for each major population, along with data from the previous four seasons for comparison0 In the middle east coastiV lower east

coast and west coast of sub-districts the figures in parentheses represent the best estimate of the amount of spawning derived from the combined

± The average intensity for the spawnings in a statistical area is determined by weighting the extent of each individual spawning by 1,2,394* or 5 depending on the category of the intensity assigned* Converting from extent at a calculated intensity to extent at a standard intensity of 3 (medium) is accomplished by multiplying the spawning extent by the ratio of the calculated intensity to the standard intensity,, For example, 2o0 statutory miles of spawn with an estimated average intensity of 205 is equal to 196 miles at a standard intensity of 3o coverages by fisheries officers and members of the Pacific Biological Station

staffo

In 1955 the total number of statutory miles of spawn deposited (215«2) was less than that recorded in 1954 (225<,6)„ However, the spawning

extent still remained at a level that was about average for the last ten years,,

In the Queen Charlotte Island sub-district (Areas 2A(E) and 2B(E)

the spawning extent was reduced about 50 percente This resulted from heavy

exploitation in two successive years coupled with a natural decline in the ^s strengths of year-classes comprising the population,. However, the amount of

spawn deposited still remained about average for this sub-districto

In the northern sub-district (Areas 3, 4, and 5) a marked increase (40 percent) in spawn deposition was recordedo Spawn deposition in Area 4 has

declined for two years in succession but this decline has been more than com

pensated for by marked increases in Area 5o The largest individual spawning on

the in 1955 (10ol miles) occurred in Wilson Inlet (Area 5),

Although the 1954-55 catch in the northern sub-district was the lowest in the

last six years, late inshore migrations of herring schools during April were

apparently responsible for the increase in the amount of spawn deposited,.

In the north central sub-district (Area 6) spawn deposition ha® been

at a low level for the past 4 years. In 1955.* spawning extent was slightly less than in 1954o In the south central sub-district (Areas 7, 8, 9 and 10) spawn ing extent was about 8 percent greater than in 1954 and was about average for recent years* While Areas 7, 8 and 9 showed increases over last year, Area 10

showed a considerable decrease,, The decreased spawn deposition in Area 10

probably reflects the greater exploitation of stocks in that area in 1954°55o The fishery in the central sub-district was characterized by a greater dependance on small "local" stocks than on the usually more important woffshore" stocks0

Abundance of all stocks in the central sub-district was low in 1954-55 as 4 ~

Sub~district and Area Statutory Miles of Spawn of Medium Intensity 1951 1952 1953 1954 1955

Islands Area 2A East ,5 0o8 3*2 1*9 Area 2B East 1002 20^2 22*1 8o0 5o4 13 o4 >2„1 llo3 Northern Area 3 (Nass) 3o2 Area 4 (Skeena) 14.5 Area 5 (Gremrille) 7c2 24o9 No^th_Centpl Area IT (Butedale) 1108

South Central Area 7 (Bella Bella) 28 ,6 17o7 29o4 28 00 2802 Area 8 (Bella Coola) 0 ,5 1.5 0o2 2o7 8e9 Area 9 (Rivers In„) 2 .1 0o8 4o2 0o4 lol Area 10( Smith In0) JLsJL 3*L 36^ 34o5 2208 43 o0 >e Upper East Coast of Vol, Area 11 (Seymour In0) 0o4 9.2 _ Area 12 (Alert Bay) uur.*mT~^r*23&T* 24o7 14o4 9o2 Middle East Coast of Volo 1292(13o8] Area 13 ^Quadra Is0) 206 6o0 5o8 3o2 Area 14 (Comox) 22 a4 24o4 23 o7 11o4 19.0(21o0J Area 15 (Powell River) 3o4 2o3 3o0 2o4 104( lo6] JtsB =4*0 Area 16 (Pender Hb„) .2JL 2sL -JL2- 31. 36ol 35o7 2U8 36o6(40(40T4) Lower East Coast of Y.I. Area 17A (Nanaimo) 1202 7o8 17o6 0o8 9o0( 9o4) Area 17B (Ladysmith) 5o8 20o4 82o4 6lo5 t6„5(28o8) Area 18 (Ganges Hb„) 0o3 2,0 2o5 1.9 1«4( 5o2) Area 19 (Victoria) a Ool 18o4 30 «3 102o5 64o2 West Coast of VQ|Io Area 23 (Barkley Sd) 4ol( 8„3) 4o8( 9o8) 7o8(13ol) 4.6(llo0 Area 24 (Clayoquot Sd) 605( 3o0) 4o9( 2o4) 7oO( 7o8) 4o2( 4o5 Area 25 (Esperanza ln0) 9o5(34ol) 208(26o6) Ilo4(36o4) 7ol(17«5 Area 26 (Kyuquot Sd) 105( loO) 0o9( lo6) 4o4( BoO) 3o2( 4o8 Area 27 ( Sd) 4o?( 5ol* l^iJ^^10^(llo|l »2( 7o3 5(513: i0.o4(76<,8T 26.3(45.1 U o So A< San Juan Is0-Boundary Bay (15.6)

GRAND TOTAL - All Areas lo?(!l94.5) 137^5(lS4^52^§g3,2) 206,8(225o6) lo9.2(215.2) & Complete coverage by fishery officer0s impossible because boat not available. - 5 - indicated by the low catch per unit of effort (31 tons per seine day) in making the smallest total catch since the -1946-47 season,, A spawning was recorded during the summer months (July 2-3) in (Area 8), This spawning was over 7 miles long and was probably the latest spawning ever re~

corded in that area. In the upper east coast of Vancouver Island sub-district (Areas 11 and 12) a sharp reduction (36 percent) in the amount of spawn occurred in 1955. The catch (9*200 tons) in this sub-district, the largest since 1941* was probably responsible for a reduced abundance of the spawning stocks. The absence of a regular spawning in (Area 12) lowered the total number of miles of spawn found in this sub-district0 In the middle east coast of Vancouver Island sub-district (Areas 13, 14* 15 and 16) spawning extent was above average, about 68 percent greater than in the previous year0 There was apparently an increased abundance of fish in this sub-district during the 1954-55 season since the catch of 24,650 tons was the largest ever recorded,, Large spawning^ along the Parksville - Deep Bay shoreline (Area 14) and at the head of (Area 13) accounted for the increased spawn deposition in this sub-district„ In the lower east coast of Vancouver Island sub-district (Areas 17A, 17B, 18 and 19) the combined figures from both fishery officers and Pacific Biological Station personnel are presented. While spawn deposition in 1955 was still above average, a reduction of 32 percent from the 1954 level occurred* The lack of recurrent spawnings in the Yellow Point region (Area 17B) was largely responsible for the decrease» However, the re-appearance of a large spawning (807 miles) at (Area 17A) after a disappointing showing in 1954 should be noted. The spawning population in 1955 was apparently less than that of the previous year,, It is interesting to note that another unusually late spawning occurred, this time at Boat Harbour (Area 1?B)0 This is the first spawning ever recorded as late as May in the Strait of Georgia0

In the west coast of Vancouver Island 3ub=district (Areas 23, 24, 25s 26 and 27) the 1955 spawnings were comparable with those of the previous season and

(Area 27). A survey of the - San Juan Island region by members of the Pacific Biological Station revealed the presence of several previously unreported spawning grounds in the „ An exceptionally large spawning, partly in Canadian waters and partly in American waters, was found near Point Roberts on February 19th0 This spawning ground measured over one million square yards, making it one of the largest individual herring spawnings on the Pacific eoasto The other spawnings in the San Juan Islands, however, were small in extent and of light intensity, suggesting that this region may not be an important spawning area,, An examination of the spawning dates shows that there is a tendency for spawnings to occur later in the season towards the north (see Figo 3). In the west coast of Vancouver Island sub-district (north of UB° 45°) 92 percent of the spawnings occurred before the end of March while in the Queen Charlotte

Island and northern ^-districts (north of 52° 10B) the first spawnings did not

occur until the end of March, with 86 percent of them taking place during

Aprilo Tae period of spawning appears to be shorter in the north than in the

southo

Discussion

The herring industry in 1954-55 experienced itls poorest season

since 1946-47. While fishing in the Queen Charlotte Island sub-district and

in sub-districts along the east coast of Vancouver Island was good, fishing

was poor in the west coast of Vancouver Island, the northern and the central

sub-districtSo Some alarm was felt by fishermen after the season that these

sub-districts had been "overfished" and that the spawning stock might have been reduced to a level that would endanger future production* The 1955 spawn survey showed that in these regions sufficient fish either escaped the fishery or moved into spawn after the close of the season to maintain spawn deposition at an

approximately average level0

The results of the experiment on the west coast of Vancouver Island from 1946-47 to 1953-54 showed that in spite of the more intensive fishery resulting from the lack of quota restrictions, spawn deposition was never reduced to a critical level4 Good year-classes resulted as often as average or poor year-classes from small spawnings and poor or average year-classes occurred as often as good year-classes from large spawnings,, The fluctuations in abundance on the west coast are better explained by other factors affecting year-class strength than by the effect of fishing on spawningo It would seem probable that the same situation exists in other regions, that is, that the fluctuations in abundance result not from the intensive fishery but from naturally occurring fluctuations in year-class strength,, Figo lo Map of northern British Columbia showing the location of the 1955 herring spawning grounds (heavy black zones) by statistical areaso Also shown are place-naaes mentioned in the terto t 0 3 *™"

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U lS h- A R •SPAWNINGS IN NORTHERN B.C. WATERS Y (AJtEAS 2AE, 2BE, 3,4, AND 3).

SPAWNINGS IN SOUTHERN B.C. WATERS (AREAS 23, 24, 2 5, 26 AND setA , J. I 4 3 2 10 12 3 4 HERRING SPAWNING EXTENT IN MILES (STAT.) Fig, 5o Symmetrychartshowinga coaparisonof thetimesof herringspawningin northernand southernBritishColumbia.Thesizeof individualspawnings(instatutorymiles)is shownby horizontallinesalignedto extendequallyto the leftandrightof the centre axis. \