Shoreline Vegetation on Herring Spawning Grounds in Stuart Channel, ,

C. W. Haegele and M. J. Hamey

Department of Fisheries and Oceans Fisheries and Marine Service Resource Services Branch Pacific Biological Station Nanaimo, British Columbia V9R 5K6

August 1979

Fisheries and Marine Service Manuscript Report No. 1534

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•Cover design by Christine Rusk Fisheries and Marine Service

Manuscript Report 1534

August 1979

SHORELINE VEGETATION ON HERRING SPAWNING GROUNDS IN STUART CHANNEL,

STRAIT OF GEORGIA, BRITISH COLUMBIA

by

C. W. Haegele and M. J. Hamey1

Department of Fisheries and Oceans

Fisheries and Marine Service

Resource Services Branch

Pacific Biological Station

Nanaimo, British Columbia V9R 5K6

!Address.· P • 0 • Box 34 ' Zeballos, British Columbia VOP 2AO - ii -

(c) Minister of Supply and Services Canada 1979

Cat. no. Fs 97-4/1534 ISSN 0701-7618 - iii -

ABSTRACT

Haegele,·C. W., and M. J. Harney. 1979. Shoreline vegetation on herring spawning grounds in Stuart Channel, Strait of Georgia, British Columbia. Fish. Mar. Serv. MS Rep. 1534: 29 p.

The ability to accurately record and assess herring spawnings depends to a considerable degree on a knowledge of the vegetative substrate upon which the adhesive eggs are deposited. Large format colour and colour-infrared photographs were obtained for 76 km of coastline in the northern portion of Stuart Channel on August 14, 1977. Vegetation maps were prepared from these using colour and texture keys previously developed. There were 728.1 ha of vegetation mapped with sea grasses accounting for 38%, most of the remainder being associations of red and brown algae. Vegetation was generally in excess of 100 m wide.

Key words: Marine vegetation, aerial photography, mapping.

Haegele, c. W., and M. J. Harney. 1979. Shoreline vegetation on herring spawning grounds in Stuart Channel, Strait of Georgia, British Columbia. Fish. Mar. Serv. MS Rep. 1534: 29 p.

Les possibilites de relever et d'evaluer correctement la fraye du hareng depend dans une grande mesure de la connaissance que l'on possede du substrat vegetal auquel adh~rent les oeufs deposes. On a realise des photographies de grand format en couleur et en couleur-infrarouge, le 14 aout 1977, pour 76 kilometres de ligne de cote se trouvant dans la partie nord du chenal Stuart. A partir de ces photographies ont ete preparees des cartes de la vegetation a l'aide de cles de couleur et de texture mises au point auparavant. Au total, on a cartographie 728.1 ha de vegetation, dont les plantes marines constituaient 38%, la plus grande partie du reste se composant d'associations d'algues rouges et brunes. En general, la bande de vegetation depassait 100 metres de largeur.

Mots cles: vegetation marine, photographie aerienne. cartographie. INTRODUCTION

Aerial photographs are used to map vegetation on herring spawning grounds in British Columbia (e.g. Haegele 1978). These maps are used to record and assess herring spawnings which take place mainly on rooted algae and sea grasses in the littoral and upper sub-littoral zone. These maps are not routinely field checked because of constraints of time and cost, although, fortuitously, diver surveys of herring spawnings have been conducted for most other areas mapped to date. These were used to provide field checking of vegetation maps and additional data on species composition and percent cover. No diver surveys have been conducted to date in the area covered by this report, which is the upper portion of Stuart Channel, a geographical unit referred to as the Yellow Point section in herring stock assessment.

METHODS

Vertical aerial photographs of 23 em format at a photo-scale of 1:6,000 were obtained for Dodd Narrows to Ladysmith Harbour and Thetis and Kuper Islands (Fig. 1) on August 14, 1977 with a Zeiss RMK A30/23 camera with a 305 mm focal length lens at an altitude of 1,838 m. There were 12 flight lines with 60% forward overlap between frames. Seventy-six km of coastline were photographed before predicted low tide (+0.8 m at 1026 PST) with Kodak Ektachrome MS Aerographic No. 2448 film between 0915 and 1020 PST and with Kodak Aerochrome Infrared No. 2443 film after low tide between 1025 and 1125 PST. A medium yellow (B111170) filter was used with the infrared film and a clear (HF3) filter with the colour film.

Vegetation maps were prepared at the scale of photography, using enlarged Canadian Hydrographic Service navigation chart no. 3453 as a base map, with standard photogrammetric techniques. Exposed vegetation was identified from the 141 infrared diapositives employing a colour key previously developed (Haegele 1975). For vegetation submerged at the time of photography, identification was by colour and texture from the 140 colour diapositives. The vegetation was mapped by five major types identifiable on the photographs: sea grasses, rockweed, red algae, brown algae, and green algae. - 2 -

RESULTS

The vegetation in False Narrows, along the shoreline between Dodd Narrows to and including Ladysmith Harbour and Thetis and Kuper Islands, as mapped from aerial photographs, is presented on 12 maps (Fig. 2-13). Except on very steep shorelines, vegetation was generally in excess of 100 m wide and up to 300 m wide on shelving beaches. The total area of vegetation mapped was 728.1 ha, 46% of which occurred on the coast of Thetis and Kuper islands (Table 1). There were very few pure red algae (9% of total area) or pure brown algae (2%) zones mapped but mixtures of brown and red algae occupied 41% of total area. Sea grasses were mapped for 38% of total area, rockweed for 3% and green algae for 7% of total area.

ACKNOWLEDGMENTS

We would like to thank the personnel of Pacific Survey Corporation for obtaining the photographs. We are grateful to Debbie Barns, summer student at the Pacific Biological Station, for measuring the area of the vegetation. To Dr. A. S. Hourston, Herring Program Head at PBS, we remain appreciative for his continued support and encouragement of the vegetation mapping project.

REFERENCES

Haegele, C. W. 1975. Vegetation mapping of herring spawning grounds in British Columbia. Ocean 75 Record. IEEE Publication 75 ORO 995-10EC. New York, N.Y. p. 840-844.

1978. Shoreline vegetation on herring spawning grounds between Deep Bay and Dorcas Point, Strait of Georgia, B.C. Fish. Mar. Serv. MS Rep. 1485: 49 P• - 3 -

Table 1. Area of vegetation as mapped from aerial photographs in hectares (1ha=10,000 m2).

Area in ha

Brown Browns Red Green Map Grasses Rockweed algae & reds algae algae All

1. False Narrows 53.4 1.6 49.6 10.9 5.0 120.5 2. Boat Harbour 11.8 2.0 26.8 15.5 0.6 56.7 3. N. of Yellow Pt. 7.6 2.5 8.9 0.4 19.4 4. Yellow Point 32.2 6.6 32.7 3.3 74.8 5. Coffin Point 23.5 0.6 44.3 1.2 4.5 74.1 6. Ladysmith Hr.-Ent. 4.8 1.1 1.6 2.6 10.1 7. Ladysmith Hr.-Hd. 14.8 8.8 2.6 9.3 35.5 8. North Cove 32.6 1.4 18.2 8.7 60.9 9. Crescent Point 5.1 1. 8 5.1 2.8 14.8 10. Preedy Harbour 24.4 4.2 7.2 54.6 7.7 16.6 114.7 11. Clam Bay 31.5 2.3 7.1 28.8 2.7 72.4 12. Josling Point 36.7 2.5 27.6 4.6 2.8 74.2

All 278.4 23.0 14.3 300.1 64.5 47.8 728.1

- 5 -

I 2 3• 3 5 •

YELLOW POINT

Shoreline VeQetation Charts I Folse Narrows 2 Boat Harbour 3 North of Yellow Point 4 Ye II ow Po in! 5 Coffin Point 6 Ladysmith Harbour- Entrance 7 Ladysmith Harbour -Head 8 North Cove 9 Crescent Point 10 Preedy Harbour II Clam Boy 12JoslinQ Point

4 ~· 0 5 '-f---4--+-+- _:,~..L-+-----"~·-\)o--~-t-----"r------+4 •• 0 5' 0 0

I I~

12 3° 50' I 23°45'

Fig. 1. Map of study area and its division into large scale maps.

---~00 ...... -~!,(1

. --~.po:""

--~.0 --- ......

'. ·.- .' ..... '

...... , NARROWS

ISLAND ;I /"" - SEA GRASSES '· Ill ROCKWEED ~ RED ALGAE ~ BROWN ALGAE oo 0 GREEN ALGAE

YARDS 0 100 500 1000 E'e:"""*"e--=t:" ;;;;;;!$=' ;;;$"' i!!$$1 I 0 100 500 1000 METERS . -.

Fig. 2. Shoreline vegetation from aerial photographs for False Narrows (map 1 in Fig. 1).

- 9

ISLAND

\ '

51 on 51 on 101M. '. BOAT . - .

HARBOUR

_,. .- .:

-·

SEA GRASSES ROCK WEED Ill YAROS ~ RED ALGAE 0 100 500 1000 r...:--- e-o¢*" ;;;;;;::s=- E$5"' ii$Z!3 I ~ BROWN ALGAE 0 100 500 1000 00 METERS 0 GREEN ALGAE

Fig. 3. Shoreline vegetation from aerial photographs for Boat Harbour (map 2 in Fig. 1).

- 11

TO I BOAT

... ~ .· .'~!.', .. .

,' ,' •• • #' , I I . .. ; '

...... ;

N 0 R T H OF

tot... , ' YELLOW P 0 IN T IOioo . ...

' I ' ...... ""' .- · I I

SEA GRASSES .. Ill ROCKWEED ~ RED ALGAE lo 0 I ~ BROWN ALGAE oo ·' 0 GREEN ALGAE

, YA liDS . 0 100 500 1000 F'L..!!++3 ~ ;;;.s:- #$P 1!$$1 I oToo =-- 5oo 1000 METE liS

Fig. 4. Shoreline vegetation from aerial photographs for north of Yellow Point (map 3 in Fig. 1}.

.. ' .---~· SEA GRASSES Ill ROCK WEED ·--~ '<1.~ .. " ~ REO ALGAE

BROWN ALGAE .. :.:;··,..)"~ ·. ', I. ·, .. .I ~ ·- :: -. . . oo - 0 GREEN ALGAE

YELLOW PO ~--._

I N D I A N RESERVE ~· '. 1-' w

' . - . ""' -. KULLEET - : 10101 B A Y -· -.

'. . - 201.,'

...... , ..

. ·· YAROS 0 100 500 100 0 h;;;....-&3 ...... ___,...... F+3 ~ j#!¢1' I 0 100 500 1000 II ETERS

Fig. 5. Shoreline vegetation from aerial photographs for Yellow Point (map 4 in Fig. 1).

- 15

SEA GRASSES Ill ROCKWEED ~ RED ALGAE )'/ BROWN ALGAE

0 0 ° GREEN ALGAE N 0 I A N ~ fm 10 fm 20fm I

RESERVE

'.

COFFIN

·,- ~ -f::j-

' SHARPE POINT (

YA A OS D 100 500 1000 f"' ....------...... =--' ;:;;;:g-: ;;;g:::c e::::g 0 100 50 0 1000 METE AS

Fig. 6. Shoreline vegetation from aerial photographs for Coffin Point (map 5 in Fig. 1).

N D A N RESERVE

SEA GRASSES Ill ROCKWEED ~ RED ALGAE ~ BROWN ALGAE - ----I oo I 0 GREEN ALGAE I

,..... --- ...... ------

' ' 5fm DUNSMUIR

LADYSMITH HARBOUR

~ ENTRANCE YARDS ~- 0 100 500 IODO ~.,' ... ..' P 0 I NT ~ 0 100 500 1000 ·' METERS 1

Fig. 7. Shoreline vegetation from aerial photographs for the entrance of Ladysmith Harbour (map 6 in Fig. 1).

I I I

I I TH HARBOUR H E A D I I I I ------1---- 1

I N D I A N I RESERVE I I I

I 1-' ·I· \.0 ------_.._,

·. } ·~ I

SEA GRASSES Ill ROCKWEED ~ RED ALGAE YAROS PUBLIC ~ BROWN ALGAE 0 100 500 1000 oo 0 GREEN ALGAE 0 100 500 1000 METERS

Fig. 8. Shoreline vegetation from aerial photographs for the head of Ladysmith Harbour (map 7 in Fig. 1).

.. · ...•.... -

·--~-· ...•.. ..-~--- ·~· ' ' ..: ~- . - : - - .· .· ~MIAMI ISLET SEA GRASSES RAGGED ISLET - Ill ROCK WEED ' ~ RED ALGAE . . .. - . :.·, ... '\ ~ ,. ... ·. I , 1 BROWN ALGAE \ ...... ·. - ~ ... . . ', .. - . oo - 0 GREEN ALGAE ., . . .· .- .. - . . . . ~.... ·. .·

..·_., ...

- '' . N ' ' ' ......

..-~*~ '' •. POINT

COVE

~ ZOfm 10101 -f':i-

I 1 ,· \ YAROS ·. 0 100 500 1000 -. . 0 100 500 1000 .. . . , .. . METERS ·-

Fig. 9. Shoreline vegetation from aerial photographs for North Cove (map 8 in Fig. 1).

THETIS ISLAND

..... ·· ' ·· .... CRESCENT

-. PREEDY 10110

·-' HARBOUR •' N w ZOI10- - ·· ....

- SEA GRASSES Ill ROCK WEED ~ RED ALGAE /'/ BROWN ALGAE oo 0 GREEN ALGAE

YAROS ~ 0 100 800 1000 re-..-...e------;:;;:.;g=iJ$$t' i!!$$jl 1 0 IOO 800 1000 METERS \

Fig. 10. Shoreline vegetation from aerial photographs for Crescent Point (map 9 in Fig. 1).

THETIS ISLAND KUPER ISLAND

TELEGRAPH

.51•' ,101• - SEA GRASSES Ill ROCK WEED N ~ RED ALGAE I U1 ~ BROWN ALGAE oo GREEN ALGAE --- 201•.- 0 '. '·

POINT -. - '.

'·- -. . '

PREEOY HARBOUR ~ -t=:~- - YARDS 500 1000 0 100 ·- 0 100 500 1000 \ METERS

Fig. 11. Shoreline vegetation from aerial photographs for Preedy Harbour (map 10 in Fig. 1).

.... , - SEA GRASSES Ill ROCK WEED ~ RED ALGAE ~ BROWN ALGAE oo -. 0 GREEN ALGAE -.... -... .. ,' -~.... -

I.

CLAM BAY THETIS -- N ---~ .__, ROCKET' ISLAND SHOAL ~~ \

K U PER ISLAND

I N DIAN RESERVE YARDS 0 100 500 1000

~~o ~ ""'";;o -----a = 10~0 METERS

Fig. 12. Shoreline vegetation from aerial photographs for Clam Bay (map 11 in Fig. 1).

I NO IAN • ~ I ... - - SEA GRASSES - ' "~ Ill ROCKWEEO RESERVE R~ ' - ~ RED ALGAE ' /'/ BROWN ALGAE oo 0 GREEN ALGAE

KUPER ISLAND

------N \.0

Sf"', 'IOfM -....- 201M ... -....

·-· ·, .. ~-·.... ·-:· ' LAMALCH I -_-... · .. . 0 '•, - BAY ~ ~.·,~J ~ -

YAROS 0 100 500 1000 Fe-...... e-=--" ;;;;;&=' ;;;.g::r ;g::"l I 0 100 500 1000 \ - NORTH METERS REEF ·~ --- ·- --­

Fig. 13. Shoreline vegetation from aerial photographs for Josling Point (map 12 in Fig. 1).