An Investigation of the Feasibility of Gooseneck Barnacle Mariculture (Lepas Anatifera)
AN INVESTIGATION OF THE FEASIBILITY OF GOOSENECK BARNACLE MARICULTURE (LEPAS ANATIFERA)
by
HARRY GOLDBERG B.Sc.,University Of British Columbia,1978
A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE
in THE FACULTY OF GRADUATE STUDIES Department Of Agricultural Mechanics
We accept this thesis as conforming to the required standard
THE UNIVERSITY OF BRITISH COLUMBIA
May 1985
© Harry Goldberg, 1985 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.
Department of /fe^A^ KLCC-TCC /fr^t*ftnJ* C_S
The University of British Columbia 1956 Main Mall Van couve r, Canada V6T 1Y3
Date /IflLJL I 1 / 93
DE-6 (.3/81) i i
Abstract
Gooseneck barnacles ( Pollicipes cornucopia ) exceeding 4 cm in length are a favourite seafood in Spain. In 1978 the
British Columbia seafood industry introduced the indigenous species Pollicipes polymerus into this potentially lucrative market. Due to the problems associated with this species its export was unsuccessful.
Alternatively, to fill either the void left by Pollicipes pollymerus and/or future markets, the acquisition of seed and the subsequent suspended culture of the gooseneck barnacle,
Lepas anatifera, were investigated.
Lepas anat i fera successfully colonized the cultch (oyster shells, wooden dowelling and rubber) that was deployed at two locations off the west coast of Vancouver Island. The success of the colonization of cultch and the information obtained from a previous survey suggested that the set occurs regularly between the middle of April and the end of May off the west coast of
Vancouver Island.
The suspended culture of Lepas anatifera indicated that growth may be site specific and that areas of a high phytoplankton/zooplankton ratio may be detrimental to growth and time to sexual maturation. At the densities studied, survival seems to be proportional to density. Capitulum growth and weight gain were significantly greater for Lepas anatifera protected from predation within lantern nets than for those grown exposed on lines of oyster shells and wooden dowelling. The average total length (capitulum plus peduncle) exceeded 4cm within 17 to
23 weeks. iii
TABLE OF CONTENTS
Abstract ii List of Tables iv List of Figures v Acknowledgement ix I. INTRODUCTION 1 II. LITERATURE SURVEY 6 1. ECOLOGY 7 1. MORPHOLOGY 7 2. DISTRIBUTION 9 3. LIFE HISTORY 9 4. ADULT GROWTH 11 III. MATERIALS AND METHODS 13 1. SEED ACQUISITION 14 1. 1980 SURVEY 14 2. 1981 CULTCH DEPLOYMENT 17 2. CULTURE PHASE ' 20 1. LONGLINE SYSTEMS 20 2. SAMPLING PROGRAMME 24 3. ENVIRONMENTAL PARAMETERS 25 4. SURVIVAL 26 5. GROWTH 26 6. WEIGHT/LENGTH RELATIONSHIPS 27 7. GONADAL STATE 27 8. MAINTENANCE 27 3. STATISTICAL ANALYSIS 28 IV. RESULTS 31 1. SEED ACQUISITION 32 1. 1980 SURVEY 32 2. 1981 CULTCH DEPLOYMENT 38 2. CULTURE PHASE 38 1. ENVIRONMENTAL PARAMETERS 38 2. GONADAL STATE 44 3. SURVIVAL 47 4. GROWTH 62 5. WEIGHT/LENGTH RELATIONSHIPS 76 V. DISCUSSION 87 1. SEED ACQUISITION 87 1. 1980 SURVEY 87 2. 1981 CULTCH DEPLOYMENT 88 2. CULTURE PHASE 90 1. ENVIRONMENTAL PARAMETERS 90 2. GONADAL STATE 90 3. SURVIVAL 92 4. GROWTH 93 5. WEIGHT/LENGTH RELATIONSHIPS 95 6. TOTAL LENGTH 96 VI. CONCLUSIONS 97 VII. RECCOMENDATIONS 99 LITERATURE CITED 102 IV
List of Tables
I. A comparison of the time involved in the larval development of Lepas anatifera and Pollicipes polymerus. 1 0
II. A comparison of the growth rates of Lepas anati fera and Pollic ipes polymerus. 1 1
III Date of deployment and position of surface and subsurface buoys. 15
IV. Sampling schedule. 25
V. A comparison of the capitulum lengths of gooseneck barnacles from the top and bottom regions of the buoys (position 1,2,3,and 4). 35
VI. A comparison of the peduncle lengths of gooseneck barnacles from the top and bottom regions of the buoys (position 1,2,3,and 4). 37
VII. Chi-squared values from the Log Rank and Wilcoxin survival analysis. 54
VIII. Slope values 'B' and the corresponding chi-squared values from the Pearson's and the Likelihood ratio goodness-of- fit tests. 56
IX. Parameter values (L =°,K,to) and sample sizes (N) from the von Bertalanffy growth model for the capitulum growth of Lepas anatifera. 63
X. A comparison of the parameter values (L °°,K,to) from the von Bertalanffy growth model for the capitulum growth of gooseneck barnacles. 70 List of Figures
A drawing of the external and internal anatomy of Lepas anatifera.
Map of the north Pacific showing the location of the buoys surveyed and the cultch placement.
A schematic of the geodyne buoy showing the placement of the metal frame used for the attachment of cultch and the acquisition of Lepas anatifera (seed).
Map of the Islands of the Deer Group opposite Bamfield Inlet in Barkely Sound, indicating the study site for the culture phase.
A schematic of the longline system used for the suspended culture of Lepas anat i fera.
Plot of the mean capitulum (shell) length versus time.
Plot of the mean peduncle (stalk) length versus time.
Plot of the mean salinity versus time at the culture site.
Plot of the mean temperature versus time at the culture site.
Plot of the mean secchi depth versus time at the culture site.
Plot of the mean secchi depths versus the mean temperatures averaged over the surface and the first three meters. Plot of the percent of Lepas anatifera bearing ovigerous lamellae (egg cases) and that percent of ovigerous lamellae (egg cases) that are blue.
Plot of the percent of Lepas anatifera, of all cultch types, bearing ovigerous lamellae (egg cases) and that percent of ovigerous lamellae (egg cases) that are blue.
Plot of the accumulative percent survival versus time for Lepas anatifera from each of the lines of oyster shells (1-6).
Plot of the accumulative percent survival versus time for Lepas anatifera from each of the lines of oyster shells (7-12).
Plot of the accumulative percent survival versus time for Lepas anatifera from of each of the lines of wooden dowelling (1-3).
Plot of the accumulative percent survival versus time for Lepas anatifera within each of the lantern nets (1-2).
Plot of the accumulative percent survival versus time for Lepas anatifera totaled for each of the cultch types.
Plot of the observed and expected number of deaths for Lepas anatifera of oyster line 8.
Plot of the 'B' values (slope of the mortality) versus the mean density of Lepas anatifera per oyster shell from oyster lines 1 to 12.
Plot of the 'B' values (slope of the mortality) versus the mean density of Lepas anatifera per wooden dowelling from the wooden lines (1-3) and lantern nets (1-2).
Plot of the mean capitulum (shell) length versus time for Lepas anatifera from each of the oyster lines (1-6).
Plot of the mean capitulum (shell) VI 1
length versus time for Lepas anatifera from each of the oyster lines (7-12). 65
24. Plot of the mean capitulum (shell) length versus time for Lepas anatifera from each of the wooden lines (1-3). 66
25. Plot of the mean capitulum (shell) length versus time for Lepas anatifera from each of the lantern nets (1-2). 67
26. Plot of the mean peduncle (stalk) length versus time for Lepas anatifera from each of the oyster lines (1-6). 72
27. Plot of the mean peduncle (stalk) length versus time for Lepas anatifera from each of the oyster lines (7-12). 73
28 Plot of the mean peduncle (stalk) length versus time for Lepas anatifera from each of the wooden lines (1 -3). 74
29. Plot of the mean peduncle (stalk) length versus time for Lepas anatifera from each of the lantern nets (1-2) . 75
30. Plot of the wet weight (grams) versus capitulum (shell) length (cm.) for Lepas anatifera from the lines of oyster shells. 78
31. Plot of the wet weight (grams) versus capitulum (shell) length (cm.) for Lepas anat i fera from the lines of wooden dowelling. 79
32. Plot of the wet weight (grams) versus capitulum (shell) length (cm.) for Lepas anatifera from the lantern nets. 80
33. Plot of the log wet weight (mg.) versus capitulum (shell) length (cm.) for Lepas anatifera from each of the cultch types. 81
34. Plot of the wet weight (grams) versus peduncle (stalk) length (cm.) for Lepas anati fera from the lines of oyster shells. 83
35. Plot of the wet weight (grams) versus peduncle (stalk) length (cm.) for Lepas anati fera from the lines of wooden dowelling. 84 vi i i
36. Plot of the wet weight (grams) versus peduncle (stalk) length (cm.) for Lepas anatifera from the lantern nets. 85
37. Plot of the wet weight (grams) versus peduncle (stalk) length (cm.) for Lepas anatifera from each of the cultch types. 86 ix
Acknowledgement
I would like to acknowledge my thesis supervisor Dr. J.W.
Zaharadnik, the B.C. Science Council for the funding provided through the G.R.E.A.T. Fellowship program, and the Institute of
Ocean Science, Pat Bay, for their co-operation.
The crew and the officers of the C.F.A.V. Endeavour and the
C.S.S. Parizeau co-operated beyond the call of duty. Mr. Bob
Baden of Archipelego Marine Research was of great help. And finally, my many thanks to the entire staff of the Department of
Bio-Resource Engineering, especially Dr. R. Bulley and Mr. N.
Jackson. 1
1 I. INTRODUCTION
Revenues from the British Columbia shellfish industry have
increased in the past in response to the interest from abroad
for British Columbia's indigenous species. The geoduck ( Panope generosa ) for example was an overlooked species until the
Japanese market expressed an interest. Production in 1982 was
1115 tonnes for a landed value of 5.2 million dollars (personal communication, J. Barnes, 1983).
The Department of Fisheries and Oceans, Canada, reported
that in 1978 approximately 40 tonnes of the gooseneck barnacle,
Pollicipes polymerus, were harvested from Clayoquot Sound near
Tofino, B.C and exported to Spain (Proverbs, 1979). Testing of
this export market by the British Columbia seafood industry in
1978-1979 indicated the existence of a potential annual market
of between three and five million dollars (Proverbs, 1979). The
export market in Spain emerged because of dwindling indigenous
stocks and subsequent government restrictions upon harvesting.
Since 1970, harvesting in Spain has been prohibited from May to
October. This closure was imposed to protect the animals during
the time at which it is thought that they reproduce and the
larvae settle (personal communication, Fernandez-Pato, 1982).
Proverbs (1979) concluded from the initial season and the
subsequent exports to Spain that the British Columbia gooseneck
barnacle industry appeared characterized by both positive and
negative aspects. The negative aspects were: 2
1) the unpredictability of the harvesting season,
2) the inaccessibility of many of the stocks,
3) the intensive and dangerous nature of the
labor,
4) the problems encountered with shipping the
product to Spain.
However, on the positive side it was suggested that:
1) the British Columbia stocks appear extensive
2) a strong demand exists in Spain,
3) the value is high
4) competing supplies on the world market are
minimal.
The negative aspects have taken their toll and as of 1982 the harvest and export from British Columbia of Pollicipes polymerus has come to a standstill.
Mariculture, specifically the suspended culture, of gooseneck barnacles was proposed since it may alleviate the problems stemming from the harvest of Pollicipes polymerus in the wild; the unpredictability of the harvesting season, the
inaccessibility of many of the stocks, and the intensive and dangerous nature of the labor. The suspended culture of molluscs
is well documented (Quayle, 1969, 1971, and 1978; Shaw,1969,
Bardach, Ryther, and McLarney, 1972, Sanders, 1973, Taguchi,
1976, and Leighton and Phleger, 1976 and 1977). Generally,
suspended culture techniques provide for: 3
1) an increase in the time food is available
2) the use of the third dimension, depth, to
enhance growth and production (Quayle, 1969).
3) a more manageable resource through husbandry
(Bardach, Ryther, and McLarney, 1972).
Furthermore, to quote Leighton and Phleger (1977)
" Shellfish which feed upon planktonic elements and which lend themselves to cultivation in relatively high densities have appeal economically and energetically to marine aquaculture, particularly true when the organism constitutes a valuable food resource "
The species chosen as a candidate for this study was not
Pollicipes polymerus but Lepas anatifera. The rapid growth of
Lepas anatifera as compared to that of Pollic ipes polymerus encouraged it's selection (Evans, 1958, Skerman, 1958a, Barnes and Reese, 1960, Hilgard, 1960, Mclntyre, 1966, and Lewis and
Chia, 1981). In addition, the meat from the peduncle (stalk) is edible and was preferred to that of Pollicipes polymerus by the
Haida people that had consumed both species (Gibbons, 1964,
Cornwall, 1970, and Ellis and Wilson, 1981).
This study centered on two main areas;
1) the acquisition of settling Lepas anatifera
(seed) from the wild
2) the success of the suspended culture of the
acquired seed. The specific objectives for each of the two areas were:
1) The Acquisition of Seed
1) to determine where, when and how
Lepas anatifera can be acquired in the
wild so future acquisitions may become a
predictable and manageable activity.
2) to obtain information on growth of
Lepas anatifera in the wild so
comparisons can be made with the
information available in the literature
and the subsequent growth observed
during the suspended culture.
2) The Suspended Culture Phase
1) to monitor the environmental
parameters salinity, temperature, and
secchi depth at the culture site and
investigate the possible effects these
parameters may have on the culture of
Lepas anatifera.
2) to determine the performance of
cultured Lepas anatifera based on its:
a) gonadal state
b) survival
c) growth
d) weight/length
relationships 5
3) to compare the performance of Lepas
anatifera grown on each of the three
cultch types; oyster shell, wooden
dowelling, and rubber, and to determine
which cultch and method optimizes
performance.
The ultimate goal of this study was to provide a foundation for the mariculture of a seafood product that may be acceptable for either the current Spanish market or latent markets that may surface in the future. 6
II. LITERATURE SURVEY
Currently there is no published literature that deals with the subject of the commercial application of maricultural techniques to gooseneck barnacles.
The available literature on Pollicipes cornucopia, the commercially utilized species in Spain, is scarce and has only covered some of the biochemical and morphological aspects of the reproductive system ( Achitav and Barnes, 1978, Klepal and
Barnes, 1977, and Klepal et al. 1977). Goldberg (1984)
investigated the feasibility of suspended culture for Pollicipes cornucopia and suggested that this species would thrive under suspended culture conditions; but the findings, though positive, were inconclusive due to the limited duration of the study.
Proverbs' (1979) report is the only document that has presented information concerning the commercial aspects of the wild harvest of Pollicipes polymerus for the British Columbia coast.
The ecology of Pollicipes polymerus and Lepas anatifera is discussed. The morphology, distribution, life history and adult growth are presented to provide the rational used in selecting
Lepas anatifera as the candidate for mariculture. 7
1. ECOLOGY
1. MORPHOLOGY
For a morphological and anatomical drawing of Lepas anatifera see figure 1.
The most apparent difference between Lepas anati fera and
Pollicipes polymerus is in the number of plates of the capitulum
(shell). In Lepas anatifera the capitulum is covered with the five original basic plates; one carina, two terga, and two scuta. In addition to these five basic plates, Pollicipes polymerus has several whorls of accessory plates at the base of the capitulum one of which, a rostral plate, comes from the anteroventral end of the capitulum (Barnes, 1974). 8
Figure 1. A drawing of the external morphology and internal anatomy of Lepas anatifera after Sherman and Sherman (1979). (A - whole animals. B - with left valve removed to reveal internal organs ) 9
2. DISTRIBUTION
Pollicipes polymerus is found in the mid-tide range of the exposed rocky Pacific coast extending from British Columbia to
Baja California (Hilgard, 1960, Cornwall, 1970 and Lewis a,b
1975). Lepas anatifera, on the other hand, is pelagic and settles on floating objects in the open ocean (Skerman,
1958a,b). Generally, Lepas anatifera is distributed world-wide.
Adults and/or larvae have been reported in the North Atlantic and North Sea (Boskel, 1975), the North-Eastern Atlantic
(Bainbridge and Roskell, 1966), the Equatorial Atlantic (II'in et al, 1981), the waters off the Islands of the French Southern and Antarctic Lands (Arnaud, 1973), the Caroline Islands of the
Western Equatorial Pacific (Newman, 1972), and the New Zealand coastal waters (Skerman, 1958a and b).
3. LIFE HISTORY
Both Lepas anatifera and Pollicipes polymerus are hermaphroditic, but cross fertilization appears obligatory
(Patel, 1959 and Hilgard, 1960). Although both species normally brood their embryos within ovigerous lamellae (egg cases) in the mantle cavity, an exception has been reported for Lepas anatifera. Salekhava (1979) observed jelly-like masses filled with eggs on the exterior of Lepas anatifera.
A summary of 'in vitro' larval development for both Lepas anatifera and Pollicipes polymerus is presented in Table I. 10
Table I - A comparison of the time involved in the
larval development of Lepas anatifera and Pollicipes
polymerus.
Lepas anatifera Pollic ipes polymerus
Naupliar Stage Day of Appearence from Fertilization
Stage One and Two 1 2th 25th
Stage Three 22th 34th
Stage Four 37th 43th
Stage Five 50th 49th
Stage Six 59th 64th
Cypr id 69th 69-79th
Note - the information presented is summarized from the
literature of Patel, 1959; Moyse, 1960 and Lewis,
1975a,b.
During larval development (stage 2-6) phytoplankton is consumed (Patel, 1959, Moyse, 1960, Moyse and Knight-Jones,
1967, and Lewis, 1975a and b). Though Pollicipes polymerus tend to brood their embryos longer than Lepas anatifera, generally the length of time from fertilization to the appearance of the settling stage (cyprid) is similiar. 11
4. ADULT GROWTH
Table II lists the required times for Lepas anatifera and
Pollicipes polymerus to attain a given capitulum length and sexual maturity.
Table II - A comparison of the growth rates of Lepas
anat i fera and Pollic ipes polymerus.
Lepas anatifera Pollicipes polymerus
Capitulum Length 2.3 cm 1.72 cm at Maturity
Age at Maturity 17 days 5 years
Capitulum Length 2.3-4.0 cm > 1.72 cm
Age 17-50 days > 5 years
Note - the information presented is summarized from the literature of Evans, 1958, Skerman, 1958a, Barnes and Reese,
1960, Hilgard, 1960, Mclntyre, 1966, and Lewis and Chia, 1981.
It is apparent that in the wild Lepas anatifera grows and matures at a much faster rate than does Pollicipes polymerus. As metamorphosed settled organisms, it is likely that Lepas anatifera and Pollicipes polymerus feed mainly on a crustacean/zooplankton diet as is indicated by the blue of their ovigerous lamellae. The blue coloring has been attributed to astaxanthin, a pigment of crustacean/zooplankton origin (Patel, 1959 and Herring,
1971).
Generally, the morphologies and life histories differ only minimally. The difference in the distributions of each of the species suggests that the acquisition of seed would be an offshore activity for Lepas anatifera and an inshore activity for Pollicipes polymerus. Ultimately, the potential for a greater growth rate for Lepas anatifera encouraged its selection as the candidate for mariculture. 13
III. MATERIALS and METHODS
Initially a survey of surface and submerged buoys (50m) was conducted offshore during late spring and early autumn of 1980 to determine where and when the cyprid larvae (seed) of Lepas anatifera settle. As well, capitulum and peduncle lengths were recorded from samples of Lepas anatifera taken during this survey to obtain information on growth in the wild. From the survey a suitable time and location were chosen for the subsequent year's acquisition of seed.
The following year different types of cultch, substrates on which seed may settle, were then deployed in the same location and during the>same time of year as the previous year's survey.
The same time frame and locations were chosen to test the regularity of seed sets and therefore determine if seed acquisition could become a predictable activity.
After the seed laden cultch were retrieved they were transported to the culture site and suspended. During the suspended culture; salinity, temperature and secchi depth were recorded. As well the 'performance parameters'; gonadal state, survival, growth and weight/length relationships were determined for Lepas anatifera grown on each of the types of cultch. These parameters from each of the types of cultch were then compared to determine the optimal cultch type and method to culture Lepas anatifera. 1 4
1 . SEED ACQUISITION
1. 1980 SURVEY
A survey of four surface buoys and three subsurface buoys
(50m) was conducted in May and September of 1980 to observe for the presence of Lepas anatifera (fig. 2). The survey was carried out onboard the C.F.A.V. Endeavour and the C.S.S. Parizeau cruises 80:13-14 in conjunction with the Institute of Ocean
Science, Pat Bay, Department of Fisheries and Oceans, Canada.
The moorings had all been deployed within the first two weeks of
May 1980 (Table III).
The surface buoy at position 3 (fig. 2) was first sampled
July 31st. 1980. Before it was redeployed approximately one third of it was cleared of organisms that had previously settled to determine if a subsequent set would occur. On September 15th.
1980 all the moorings (position 1,2,3,A,B and C) were retrieved and sampled. The samples from each of the surface buoys, which ranged in number from 36 to 77 Lepas anatifera, were obtained from two regions of the surface buoys; the top and the bottom.
The top region was that area of the buoy at the water line and the bottom region was that area beneath the buoy. Specimens were laid along a ruler and the capitulum (shell) and peduncle
(stalk) lengths were recorded to the nearest 0.1 cm. The capitulum was measured along a line perpindicular to its base up to the tip of its apex (tergum). The peduncle was measured from its base to the base of the capitulum. Table III - Date of deployment and position of the
four surface buoys and the three subsurface buoys
used in the 1980 survey.
Surface Buoys
Date Deployed Position Latitude Longitude
May 7/1980 1 49 21.6 N 1 26 47. 1 W
May 1/1980 2 49 10.2 N 127 22. 0 W
May 7/1980 * 3 49 19.2 N 126 42. 2 W
May 1/1980 4 48 58.0 N 127 33. 0 W
Subsurface Buoys
May 5/1980 A 49 55.9 N 1 28 17. 0 W
May 8/1980 B 48 46.9 N 1 27 35. 5 W
May 9/1980 C 48 58.2 N 127 19. 7 W
-retrieved and redeployed July 31/1980) 80 KM.
128 iW 126°iw
Figure 2. Map of the north Pacific off the west coast Of Vancouver Island. (1,2,3 and 4 are locations of surface buoys - A,B, and C are locations of subsurface buoys - all buoys bore Lepas anatifera ) Positions 1 and 2 were the locations that the cultch was deployed to acquire Lepas anatifera. 17
2. 1981 CULTCH DEPLOYMENT
Cultch was deployed on April 15th 1981 at two locations, positions 1 and 2 (fig. 2). A system was designed and constructed to support cultch for the acquisition of seed (fig.
3). The system consisted of a metal ring of 5.08 cm mild steel
flat bar with galvanized eye-bolts welded to its periphery. The
ring was secured about the geodyne buoy. Sections of rubber were positioned between the metal and the geodyne buoy to protect the
buoy from abrasion.
Oyster shells ( Crassostrea gigas ), wooden dowelling and
three meter lengths of bare 2.54 cm polypropylene line were
tested as cultch. These materials were chosen since they are all
inexpensive and readily available. Holes were punched in the
oyster shells and they were then strung on three meter lengths
of 0.64 cm polypropylene line. Lengths (20 cm.) of 3.18 cm
wooden dowelling were spliced every 20 centimeters into three
meter lengths of 2.54 cm polypropylene line. A stainless steel
2.54 cm staple was driven into the dowelling about one of the
strands of the polypropylene line to hold the dowelling secure.
Twelve lines of cultch were suspended from each of the two
geodyne buoys. Two replicates of each of the three cultch types
were suspended horizontally and vertically. To suspend the lines
horizontally a given line was positioned beneath the buoy and
each end was shackled to the eye-bolts of the metal ring. To
suspended the lines vertically one end was shackled to the metal
ring and the other was tied into the eye of the apex of the
tripod which ran down from beneath the buoy. 18
The buoys were retrieved May 31st. 1981 and the number of
Lepas anatifera from each item of cultch was recorded. The seed laden cultch were held in 100 litre plastic drums. Fresh seawater was continually passed through the drums during the day the gooseneck barnacles were transported aboard the C.S.S.
Parizeau to Bamfield Marine Station, Bamfield, British Columbia.
Once at Bamfield Marine Station the seed laden cultch were suspended within one hour from the experimental longline systems. 19
SIDE VIEW
TOP VIEW
METAL RING
Figure 3. A schematic of the geodyne buoy showing the placement of the metal frame used for the attachment of cultch and the acquisition of Lepas anatifera (seed). 20
2. CULTURE PHASE
1. LONGLINE SYSTEMS
Two longline systems of similiar design and construction were deployed at McKenzie Anchorge on the foreshore lease of
Archipelego Marine Research (fig. 4 and 5).
The longline systems consisted of two five meter lengths of
2.54 cm polypropylene line strung in parallel between two 200
litre plastic drums (main floats). Four anchor lines of 1.27 cm polypropylene line ran from each of the main floats. Two lines
ran directly away from the floats and two ran perpendicularly
from the floats. At the ends of each of the four anchor lines were two 20 Kg concrete blocks held in tandem and to the ends of each of the anchor lines by a three meter length of 0.95 cm galvanized chain. The anchors were sunk in approximately ten meters of water with a 3:1 scope for the anchor lines. The
longline systems were a modification from Taguchi (1976).
Seed laden cultch was suspended from each of the two longline systems. The lines of oyster shell bearing Lepas anatifera consisted of seed laden shells spliced every 20 cm
into three meter lengths of 0.64 cm polypropylene line. The lines of wooden dowelling, as previously described, were weighted at one end with a 4.5 Kg lead cannon ball and then suspended. Sheets (approximately 800 cm.2) of rubber bearing
Lepas anatifera seed were placed into each one of the ten compartments of the lantern nets and then the lantern nets were 21
suspended. Lantern nets, a product of Culture Fisheries
Corporation, are flexible 'accordion-like' cylinders 2 meters long and 0.5 meters in diameter. The net is divided horizontally into ten 20 cm deep compartments. The main frame and compartment frames are of vinyl coated wire. The netting material is a 3 cm
UV-resistant polyethylene mesh. Each of the lines and lantern nets were buoyed with styrofoam floats to ensure that they remained suspended from the surface.
In summary then, there were two longline systems in place at the culture site. Suspended from one of the systems were six lines of oyster shells (oyster lines 1-6) and two lines of wooden dowelling (wooden lines 1-2) bearing seed, and one lantern net (lantern net 1) containing seed. Suspended from the second system were again six lines of oyster shells (oyster lines 7-12) but only one line of wooden dowelling (wooden line
3) bearing seed. As well there was one lantern net (lantern net
2) containing seed. 22
125di10W i I O I I
Figure 4. Map of the Islands of the Deer Group opposite Bamfield Inlet in Barkely Sound. Mackenzie Anchorage was the study site for the culture phase. 5M
Figure 5. A schematic of the Longline System used for the suspended culture of Lepas anatifera. (The surface floats are for the suspension of the gooseneck barnacles on the lines of oyster shells and dowelling, and within the lantern nets) 24
2. SAMPLING PROGRAMME
The environmental parameters, salinity, temperature, and secchi depth were not only measured to characterize the culture site but to determine the roles they may have played in the culture of Lepas anatifera. As well the survival of Lepas anatifera on each of the cultch types was monitored since it would provide an idea as to the production that may result from an initial set. Capitulum and peduncle lengths were recorded over time from each of the cultch types to determine which cultch type and method provided for the greatest growth rate.
Also these length measurements allowed for a comparison between
the growth of Lepas anatifera under suspended culture conditions and its growth in the wild. As well weight/length relationships were formulated to determine which cultch type and method allowed for the most robust growth. Finally, the gonadal state
of Lepas anatifera was investigated. The presence of ovigerous
lamellae was used as an indication of sexual maturity and the
occurrence of blue ovigerous lamellae was considered an index of
'good health'. The sampling programme commenced on June 15th.
1981 and continued through to October 15th. 1981 (Table IV). 25
Table IV - Sampling Schedule : Indicates the frequency,
the number of days per week, of the sampling programme
Number of Days per Week
12 3 4 5 6 7
Secchi Depth
Temperature
Salinity
Survival
Growth
Weight/Length *
Gonadal State * —
Maintenance
Note - The program was performed weekly from the 15th of
June until the end of August 1981. It was then modified
to accomodate two sampling periods, September 21st and
October 15th 1981.
(* - monthly samples)
3. ENVIRONMENTAL PARAMETERS
Salinity and temperature were recorded at four depths ; the surface and at one, two, and three meters. Salinity was recorded 26
to the nearest 0.1 ppt and temperature to the nearest 0.1 C (YSI model 33, S-C-T meter). Secchi depth was recorded to the nearest
0.1 meter with a standard 20 cm diameter secchi disc (Wetzel,
1975).
4. SURVIVAL
Initially the number of gooseneck barnacles, Lepas anatifera, per unit cultch were counted. Dead gooseneck barnacles were removed as they were recorded to prevent them from being recounted in subsequent samplings. An animal was considered dead if it had a flacid distended stalk and gaping capitulum with limp cirri drooping out.
5. GROWTH
Each line of oyster shells and wooden dowelling, and both lantern nets were subsampled. A maximum of five gooseneck barnacles were sampled from each oyster shell and wooden dowel.
Ten gooseneck barnacles were sampled from each of the compartments of the lantern nets. If there were less than the desired sample sizes present on a given substrate all the individuals were measured. Both capitulum and peduncle lengths were measured 'in situ'. The gooseneck barnacles were not removed from their given substrate. Lengths were measured to the nearest 0.1 cm. The capitulum length was measured along a line 27
perpendicular to its base up to the apex of the tergum. The peduncle was measured from its point of attachment up to the base of the capitulum.
6. WEIGHT/LENGTH RELATIONSHIPS
Monthly samples of Lepas anatifera ranging from 28 to 40 in number were removed from each of the types of cultch. The three samples were returned within one hour to the laboratory
facilities at Bamfield Marine Station and analyzed. The capitulum and peduncle lengths were first measured to the nearest 0.10 cm. Then the epizoic growth was removed, the capitulum was severed from the peduncle , the parts were blotted dry and weighed to the nearest 0.01 g. (wet weight) on a Mettler
PT320 scale.
7. GONADAL STATE
The capitulums from each of the gooseneck barnacles used in the weight/length analysis were dissected and the presence and color of ovigerous lamellae (egg cases) were recorded.
8. MAINTENANCE
Rountinely the lines and anchors of the longline systems 28
were inspected for wear. Fouling agents were removed by hand as well as possible without endangering Lepas anatifera.
3. STATISTICAL ANALYSIS
Analyses were performed with the aid of the University of
British Columbia computing facilities.
The analysis of the wild growth data from the 1980 survey consisted of comparing the capitulum and peduncle lengths from each of the surface buoys. Both the region from which the samples were taken and the time at which the samples were taken were considered. The analysis was performed with the Student's
't' test and an ANOVA test (Larkin, 1979).
The overall picture of the survival experiences of gooseneck barnacles from each of the cultch types was first
investigated. The UBC S:SLTEST (Le,l980) was used to compare the accumulative percent survival for the gooseneck barnacles from
the lines of oyster shells and wooden dowellings, and from within the lantern nets.
The nonparametric Log. Rank (Savage) and the Wilcoxin tests
(Lawless, 1982) were used to compare the survival experiences of
Lepas anatifera on each of the lines of oyster shells and dowelling and within the lantern nets. As well maximum
likelihood estimates were determined with the Newton-Raphson
iteration to obtain estimates of the slopes for the exponential parametric model used to describe survival (Lawless, 1982). 29
Where: P(T>t) = EXP (-Bt) t > 0
P(T>t) - the probability of death ocurring at time "I"
B - slope of the curve, the 'rate' at which gooseneck
barnacles die
T - Time (week)
Subsequently Pearson's chi-squared goodness-of-fit test and the likelihood ratio goodness-of-fit test were carried out to evaluate the fit of the model (Lawless, 1982). Ultimately, the
slope values were compared with the Student's 't' test (Larkin,
1979) and the likelihood ratio test (Lawless, 1982).
A modification of Allen's (1967) program to determine the parameter values of the von Bertalanffy growth equation (von
Bertalanffy, 1938) was provided by Dr. N.J. Wilimovsky of the
Institute of Animal Resource Ecology, University of British
Columbia. The form of the von Bertalanffy growth model is as
follows:
1 = L - *(i - EXP-K*(t - to)
where:
1 = the mean length at time 't (cm.)
L oo = the asymptotic length 'maximum length' (cm.)
K = Growth coefficient
t = time (week)
to = the time at which the length is zero if the
animal grows throughout its life as the model
describes growth 30
The Student's 't' test (Larkin, 1979) was used to compare parameter values generated from the von Bertalanffy growth equation from the lines of oyster shells and wooden dowelling bearing Lepas anatifera and the lantern nets containing Lepas anatifera. Although it is realized that the parameters are infact dependent they are treated here as independent to facilitate the comparison of growth.
The revised version of the UBC S:SLTEST (Le,l980) was used to perform the regression analysis and subsequent comparisons of regression equations in the analysis of the weight/length relat ionships.
The program ACE:GRAPH (Bonser, 1982) was used to prepare the figures and determine correlation coefficients and standard errors for the regression equations. 31
IV. RESULTS
Generally, the location and time of the setting of Lepas anatifera seed was discovered from the 1980 survey. As well information was obtained on the growth of Lepas anatifera in the wild.
Based on the 1980 survey the time frame and locations were chosen for the 1981 deployment of cultch. Settlement occurred during the same time period and at similiar locations as in the
1980 survey and the 1981 deployment of cultch. Lepas anatifera settled on both the oyster shell and wooden dowelling but did not settle on the bare polypropylene line. However, Lepas anatifera did settle serendipitously on the sections of rubber used to protect the buoy from the metal frame.
Next the seed laden cultch were transferred to the two long-line systems. Information was obtained on the growth, survival, and maturation of Lepas anatifera grown under culture conditions. The total length, capitulum plus peduncle, of Lepas anat i fera from all the cultch types exceeded the minimal harvestable size of 4 cm by the end of this study. However growth was still less than that observed in the wild. Lepas anatifera grown within the lantern nets attained the greatest lengths and were heavier for a given size than those grown on the other cultch. 32
1. SEED ACQUISITION
1 . 1980 SURVEY
The 1980 survey of buoys moored off the west coast of
Vancouver Island (fig. 2) revealed that Lepas anatifera had
settled both on surface (position 1,2,3, and 4) and subsurface
(50m) (position A,B, and C) buoys. Lepas anatifera had settled densely on the surface buoys though only sparsely on the
subsurface buoys. The settlement ocurred between the first of
May and July 31st. 1980 since no recolonization was observed
September 15th on the section of the surface buoy (position 3) cleared July 31st. 1980.
The mean capitulum (shell) lengths of gooseneck barnacles
from the surface buoys were measured on July 31st. (position 3) and September 15th. 1980 (position 1,2,3, and 4). The mean capitulum lengths of the gooseneck barnacles that were recorded
July 31st (position 3) were significantly different for the top and bottom regions of the buoy (fig. 6 and Table V). As well,
capitulum lengths that were recorded on September 15th were
greater for the bottom region than for the top (fig. 6 and Table
V).
The mean capitulum lengths of the gooseneck barnacles from
the bottom region of the buoys (position 1,2,3 and 4) when measured on September 15th were not significantly different from
each other ('F'cal df=3,l70 p=0.05 = 2.360). The mean capitulum
length of the gooseneck barnacles from the top region were
similiar for positions 1, 3, and 4. But the mean capitulum 33
length of gooseneck barnacles from the top region of position 2 was significantly shorter than those from position 1, 3 and 4
(ANOVA test 'F'cal df=3,171 p=0.05 = 35.062 and Scheffes test
'F'cal = 9.347) .
A similiar comparison of the mean stalk lengths does not show the same pattern as seen for the comparison of the capitulum lengths (fig. 7). The mean stalk lengths are significantly longer from the bottom region of the buoys
(position 1,2,3, and 4) than from the top region (Table VI).
However, the mean stalk lengths were significantly different among the four positions [ANOVA test (top region) 'F'cal df = 3,171 p=0.05 = 87.445 and ANOVA test (bottom region) 'F'cal df=3,170 p=0.05 = 12.639].
The mean capitulum lengths, from the top and bottom regions
(position 3), on September 15th were significantly longer than the mean capitulum lengths recorded on July 31st indicating growth (fig.6) (top region 't'cal df=127,p=0.05 = 11.044 and bottom region 't'cal df=108,p=0.05 = 13.862). The stalk lengths
(fig.7) were similiar from the bottom region of the buoy
(position 3) on July 31st and September 15th (bottom region
't'cal df=108,p-0.05 = 1.636). However, from the top region the stalk lengths were significantly shorter on September 15th than on July 31st (top region 't'cal df=127,p=0.05 = 7.341). 34
o —o POSITION 3 (T) N-77 N -51 H -+ POSITION 3 (B) N-68 N -41 • POSITION 1 IT) N -42 X POSITION 2 m N -46 • POSITION 4 m N -46 * POSITION 1 (B) N -48 & POSITION 2 (8) N -36 X POSITION 4 (B) N -49
31
CO Z UJ
-T- -r- - —i 1 1 1 r— -r ~i— 0.0 0.S 1.0 3.S 5.0 ts 2.0 ZS 3.0 TIME (MONTHS)
Figure 6. Plot of the mean capitulum (shell) length versus time. (T - top region of buoy and B - bottom region of buoy, N-sample size) (the standard deviations indicated are 0.5, the remaining standard deviations range from 0.3 to 0.4) Time : 0-5 - represents May 1 to October 1 1980. (for positions 1,2,3, and 4 refer to Figure aa). 35
Table V - A table of the capitulum lenghts (cm) of gooseneck barnacles from the top and bottom regions of the buoys from positions 1,2,3, and 4. The statistical results of the Student's
't' test are provided from the tests of the null hypothesis that the lengths are equal from the top and bottom regions of each buoy.
Position Region Length (cm) S.D. df p 't'cal
3 July-31 top 2.6 0.5 > 143 .05 3.75
3 July-31 bottom 2.9 0.3
1 Sept-15 top 3.5 0.3 > 88 .05 4.016 1 Sept-15 bottom 3.8 0.3 2 Sept-15 top 2.9 0.5 > 80 .05 7.125 2 Sept-15 bottom 3.7 0.4
3 Sept-15 top 3.5 0.3 > 90 .05 3.426 3 Sept-15 bottom 3.7 0.3
4 Sept-15 top 3.5 0.3 > 93 .05 4.864 4 Sept-15 bottom 3.8 0.3 36
o o POSITION 3 (T) N-77 N-51 H + POSITION 3 (B) N-68 N-41 * POSITION 1 (T) N- 42 x POSITION 2 «T) N-46 D POSITION 1 (B) N-48 uS - * POSITION 4 (T) N-46 A POSITION 2 (B) N-36 x POSITION 4 (B) N-49
i— — l
•f- I
- —i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i r O.D 0.5 tO 1.5 2.0 ZS 3.0 3.S 4.0 4,5 SJ) TIME (MONTHS)
Figure 7. Plot of the mean peduncle (stalk) length versus time. (T - top region of buoy and B bottom region of buoy, N-sample size) (the standard deviations indicated range from 1.0 to 4.0, the remaining standard deviations range from 2.3 to 2.6) Time : 0-5 - represents May 1 to October 1 1980. (for positions 1,2,3, and 4 refer to Figure aa). 37
Table VI - A table of the peduncle lengths (cm) of gooseneck barnacles from the top and bottom regions of the buoys from positions 1,2,3, and 4. The statistical results of the Student's
't' test are provided from the tests of the null hypothesis that the lengths are equal from the top and bottom regions of each buoy.
Position Region Length (cm) S.D. df p 't'cal
3 July-31 top 3.3 1.4 > 143 .05 15.591
3 July-31 bottom 8.7 2.6
1 Sept-15 top 8.5 2.3 > 88 .05 2.680 1 Sept-15 bottom 9.9 2.6 2 Sept-15 top 3.4 1.0 > 80 .05 13.838 2 Sept-15 bottom 11.8 3.9
3 Sept-15 top 5.3 1.5 > 90 .05 7.795 3 Sept-15 bottom 7.9 1.7
4 Sept-15 top 8.7 2.3 > 93 .05 2.516 4 Sept-15 bottom 9.9 2.6 38
2. 1981 CULTCH DEPLOYMENT
The system designed to acquire seed did not weather well.
The horizontal and vertical arrangement of the lines of cultch were disrupted and many of the lines were severed and the cultch was lost. Lepas anatifera settled at both position 1 and 2 (fig.
2). The oyster shells and wooden dowelling proved to be suitable substrates for the settlement of Lepas anatifera. Settlement did not occur on the bare polypropylene line. Lepas anatifera settled on the wooden dowelling mainly at the intersection of the dowelling and the polypropylene line. The rubber used to protect the geodyne buoys from the metal frame proved to be a
suitable substrate for Lepas anatifera. The average number of
Lepas anatifera that settled on each of the oyster shells, wooden dowelling and the sections of rubber (800 cm2) were 27 +
25/oyster shell, 53 + 40/dowel and 125 + 70/section of rubber.
2. CULTURE PHASE
1. ENVIRONMENTAL PARAMETERS
The salinity (fig. 8), temperature (fig. 9), and secchi depth (fig. 10) were recorded at the culture site.
The salinity varied from a low of 25 ppt to a high of 31 ppt over the three meter depth range monitored during the 39
culture phase (fig. 10).
During the first part of the culture phase (June 15 to July
31) there was a distinct range of temperatures from the surface to a depth of three meters. By the ninth week temperatures ranged from a mean low of 11.4 C at three meters to a mean high of 17.6 C at the surface. And by the eleventh week the water column had become well mixed as surface temperatures decreased.
In the final week the temperature at all depths was approximately 13.1 + 0.1 C (fig. 9). The secchi depth was around
6 meters until it rose to approximately 4.5 meters in the ninth and tenth weeks. By the final week the secchi depth was just off
the bottom at 9 meters (fig. 9).
There is a negative correlation between mean secchi depths and the mean temperatures averaged over the surface and the
first three meters of the water column (fig. 11), where:
Y = 24.6 - 1.3(X)
correlation coefficient = 0.80
standard error = 0.79
The shallowest secchi depths accompany the highest temperatures and the deepest secchi depths accompany the lowest temperatures. 40
Figure 8. Plot of the mean salinity versus time at the culture site. Time : 0-20 - represents June 1 to October 31 1981 . 41
i T 1 1 1 1 1 1 1 1 1 1 T 1 1 1 1 1 1 1 1 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.9 TIME (UEEKS)
Figure 9. Plot of the mean temperature versus time at the culture site. Time : 0-20 - represents June 1 to October 31 1981. ' 42
Figure 10. Plot of the mean secchi depth versus time at the culture site. Time : 0-20 - represents June 1 to October 31 1 981 . 43
i 1 1 i 1 1 1 1 1 1 1 1—i 1 1 1 1 1 1 i I 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 TEMPERATURE ( C)
Figure 11. Plot of the mean secchi depths versus the means of the temperatures averaged over the surface and the first three meters. 44
2. GONADAL STATE
Figure 12 is a plot of the percent of those barnacles that bore ovigerous lamellae (egg cases) and that percent of the ovigerous lamellae that were blue for gooseneck barnacles from each of the cultch types versus time. Ovigerous lamellae were
first observed in Lepas anatifera of the oyster shells during
the sixth week of the culture phase. But it was not until the next sampling period of the eleventh week that ovigerous
lamellae appeared in the gooseneck barnacles on the wooden dowelling and in the lantern nets.
The incidence of egg bearing increased to 50% by the
eleventh week and decreased to 38% by the final week for the
gooseneck barnacles on the oyster shells. The incidence of egg
bearing for the gooseneck barnacles from the wooden dowelling
and lantern nets did not decrease but increased to 42% and 62%
respectively by the final week.
A time lag is very clear between that time at which
ovigerous lamallae first appeared to that at which a portion of
the ovigerous lamellae were blue. The blue ovigerous lamellae
did not appear until the ninth, eleventh, and fourteenth week
and increased to 38%, 60%, and 75% from those gooseneck
barnacles from the oyster shells, lantern nets, and wooden
dowelling respectively.
Generally, there was a time lag of six weeks from the first
appearance of ovigerous lamellae to the initial ocurrance of
blue ovigerous lamellae (fig. 13). 45
g o © BEARING BLUE EGGS (0) «, h • BEARING EGGS (0» R" «--—» SEARING BLUE EGGS (D) . x x BEARING EGGS (D;
= & Q BEARING BLUE EGGS (Nj s" * -* BEARING EGGS (N; t S- / r- /
T 1 20. D TiriE (UEEKS)
Figure 12. Plot of the percent of Lepas anatifera bearing ovigerous lamellae (egg cases) and that percent of ovigerous lamellae (egg cases) that are blue. (0 - oyster lines, D - wooden lines, and N - lantern nets) Time : 0-20 - represents June 1 to October 31 1 981 . 46
Figure 13. Plot of the percent of Lepas anatifera, of all cultch types, bearing ovigerous lamellae (egg cases) and that percent of ovigerous lamellae (egg cases) that are blue. Time : 0-20 - represents June 1 to October 31 1981 . 47
3. SURVIVAL
Figures 14 - 17 display the acummulative percent survival for gooseneck barnacles on the oyster shells, wooden dowelling, and in the lantern nets. No mortalities were observed for the first 5 weeks of the culture phase. The greatest decrease in percent survival occurred between the sixth and tenth weeks.
Percent survival levelled off during the last seven weeks of the culture phase. Differences can be observed in the shapes of the curves of each of the figures. For example the curves of figure
16 of the gooseneck barnacles on the wooden dowelling indicate that survival was different for the gooseneck barnacles from each of these lines. A difference can also be seen for the curves of the gooseneck barnacles in the lantern nets (fig. 17).
It is more difficult to discern the differences between the curves of the gooseneck barnacles of figures 14 and 15. 48
a © OYSTER CULTCH 1 •) + OYSTER CULTCH 2 —e OYSTER CULTCH 3 x x OYSTER CULTCH 4 o- CD OYSTER CULTCH 5 8- • * OYSTER CULTCH 6
erg- M >
3 o
cr UJ Q.
-1 1 1 1 1 r r —i 1 1 1 1 1 1 1 1 1 r a.o 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 TIME (UEEKS)
Figure 14. Plot of the accumulative percent survival versus time for Lepas anati fera from each of the lines of oyster shells (1-6). Time : 0-20 - represents June 1 to October 31 1981. U? —r- o o OYSTER CULICH 1 h • OYSTER CULTCH 8 o » OYSTER CULTCH 9 x x OYSTER CULTCH )0 o- o OYSTER CULTCH 11 x -—* OYSTER CULTCH 12
i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1— 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 19.0 TIflE WEEKS)
Figure 15. Plot of the accumulative percent survival, versus time for Lepas anatifera from each of the lines of oyster shells (7-12). Time : 0-20 - represents June 1 to October 31 1981 . Figure 16. Plot of the accumulative percent survival versus time for Lepas anatifera from each of the lines of wooden doweling (1-3 ) . Time : 0-20 - represents June 1 to October 31 1981 . 51
Figure 17. Plot of the accumulative percent survival versus time for Lepas anatifera within each of the lantern nets (1 -2) . Time : 0-20 - represents June 1 to October 31 1981 . 52
Generally, when the total number of deaths are considered for each of the three treatments and the percentages plotted, survival appears to be the same (fig. 1.8). A regression analysis and subsequent comparison of the regression lines fitted to the transformed percent values of weeks five through to week seventeen suggest that the curves are similiar ('F'cal = 1.14 prob=0.264). The common regression equation is :
LogY = 2.127 - 0.03275*T
where:
Y = percent surviving at time 'T'
0.03275 = slope of the curve 'mortality rate'
T = time (weeks)
This simplistic analysis of the data suggests that the mortalities follwed a simple exponential function indicating that 37.2% of the gooseneck barnacles survived the culture phase
(Fig. 18). 53
Figure 18. Plot of the accumulative percent survival versus time for Lepas anatifera totaled for each of the cultch types. Time : 0-20 - represents June 1 to October 31 1981 . 54
A more thorough investigation of the survival of the gooseneck barnacles from each of the lines and nets reinforces the initial observations that differences existed from line to line among the three treatments. The Savage Log Rank test and the Wilcoxon survival analysis concluded that there are significant differences in survival among the lines of gooseneck barnacles on oyster shells, among the lines of gooseneck barnacles on wooden dowelling, and between the gooseneck barnacles within lantern nets (Table VI).
Table VI - Chi-squared values for the Log Rank and Wilcoxin
survival analysis
Log Rank Wi lcoxin
Oyster lines 1-6 34.7 31 .8
Oyster lines 7-12 28.9 36.6
Wooden lines 1-3 1 29.8 164.2
Lantern nets 1-2 1 98.2 301 .6
(note - in all cases the probility was 0.0 that any of the
survival between the lines were similiar) 55
In order to define or describe the survival, it is possible to use the parametric model :
P(T>t) = EXP (-Bt) t > 0
where:
P(T>t) = the probability of death
occurring at time 'T'
T = Time in weeks
B = slope of the curve, the 'rate' at
which the gooseneck barnacles die
This model was fitted to the actual numbers of dead at weekly
intervals unlike the preceeding exponential model that was
fitted to the percent values.
A maximum likelihood estimate of the slope and its standard
error were obtained for each of the lines of gooseneck barnacles
on the oyster shells, the lines of gooseneck barnacles on the
wooden dowelling, and the lantern nets containing gooseneck
barnacles. Pearson's chi-squared goodness-of-fit test and the
likelihood ratio goodness-of-fit test were performed to
determine the fit of the data to the model (Table VIII). 56
Table VIII - Slope values, 'B' determined by the Newton-Raphson iteration, initiated the first (1) and the fifth week (5) and the corresponding chi-aquared values from the Pearson's and
Likelihood ratio goodness-of-fit tests
Oyster Line
'B' Values Pearson Likelihood
1 5 1 5 1 5
1 0.052 0.093 299 94 243 1 03
2 0.051 0.088 221 62 1 92 69
3 0.067 0. 1 29 263 77 217 94
4 0.065 0. 1 24 187 41 1 67 46
5 0.062 0.116 251 59 226 70
6 0.037 0.061 232 69 215 70
7 0.044 0.074 368 81 380 80
8 0.039 0.063. 94 18 106 18
9 0.045 0.075 506 1 48 477 1 42
1 0 0.047 0.082 183 58 1 55 59
1 1 0.043 0.071 500 128 509 1 37
1 2 0.032 0.050 218 54 238 54
Dowelling Line
1 0. 050 0. 087 905 222 844 235
2 0. 068 0. 1 30 1 1 68 242 1008 253
3 0. 040 0. 066 743 172 403 188
Lantern Net
1 0.064 0.120 1692 495 1419 599
2 0.037 0.059 1707 681 1976 640 57
Initially the model was fitted from the first week but the obvious independence of survival over time during the first five weeks induces a major error in the fit. The best fit, though still a poor one, was obtained from initiating the model from week five. Figure 19 is an example of a plot of the observed number of deaths and the expected number of deaths versus time generated from the model.
E = N[ EXP (-Bt) - EXP (-B(t + 1)]
t > 0 (0 represents the fifth week)
E = expected number of deaths
N = initial number of gooseneck barnacles
B = slope 'mortality rate' 58
in _. o OBSERVED VALUES
in + EXPECTED VALUES
-
tn © r~" - + o 15. 0 0 DEATH S 12. 5 o O F : R m + E p + Z + o + o + in _ p* ~ o o o »w— in i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i i I 0.0 2.0 4.0 6.0 6.0 10.0 12.0 14.0 16.0 18.0 20.0 TIME WEEKS) Figure 19. Plot of the observed and expected number of deaths for Lepas anatifera of oyster line 8. Time : 0-20 - represents June 1 to October 31 1 981 . 59 Although the model fitted poorly it allowed for a further comparison of survival. Log likelihood estimates indicate that slopes (ie 'B' values) differed for each of the lines of gooseneck barnacles on oyster shells (chi-squared=134.5 for oyster lines 1-6 and chi-squared=32.4 for oyster lines 7-12) and for each of the lines of gooseneck barnacles on wooden dowelling (chi-squared=223.3 for wooden lines 1-3). A Student's 't' test indicated that the slopes differed for the gooseneck barnacles within each of the lantern nets ('t'calculated=12.8). Although survival differed between lines, an explanation may now be found. A plot of the mean densities of each substrate type (oyster shells, wooden dowelling, and rubber within the lantern nets) from each of the lines and nets versus the slopes of the exponential model (ie the 'B' values) suggests that survival was density dependent. Generally an inverse relationship between mortality and density is seen (fig. 20-21). This inverse relationship, where greater mortality rates are associated with lower densities, may account for the differences observed. 60 o OYSTER LINES 1-6 • OYSTER LINES 7-12 o o to LU _J d > O O • I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I ' 0.0 10.0 2Q.0 30.0 40.0 SO.O 60.0 70.0 60.0 SCO 100.0 MEAN DENSITIES Figure 20. Plot of the 'B' values (slope of the mortality) versus the mean density of Lepas anatifera per oyster shell from oyster lines 1 to 12. 61 o UOODEN LINES 1-3 • LANTERN NETS 1-2 o in ui _J o m o + 0.0 25.0 50.0 75.0 100.0 12S.0 150.0 175.0 200.0 225.0 2S0.O MEAN DENSITIES Figure 21. Plot of the 'B' values (slope of the mortality) versus the mean density of Lepas anatifera per wooden doweling from the wooden lines (1-3) and lantern nets (1-2). 62 4. GROWTH Capitulum Growth The von Bertalanffy growth model ( von Bertalanffy, 1938) was fitted to the mean capitulum lengths of each of the lines of gooseneck barnacles on oyster shells, each of the lines of gooseneck barnacles on wooden dowelling, and each of the lantern nets containing gooseneck barnacles (fig. 22-25). The form of the von Bertalanffy growth model is as follows: 1 = L oo *0-EXP-K*(t -to) ) where: 1 = the mean length at time 't' (cm.) L oo = the asymptotic length 'maximum length' K = Growth coefficient t = time (weeks) to = the time at which the length is zero if the animal grows throughout its life as the model describes growth Figures 22 - 25 display the mean capitulum lengths versus time. The parameters 'L » 'K', and 'to' for each of the curves can be found in Table IX. 63 Table IX - A list of the parameter values (L °° -cm, K,to -weeks) and sample sizes (N) from the von Bertalanffy growth model for the capitulum growth of gooseneck barnacles. Parameter Values L 00 K to N Oyster Line 1 3.1 0.11 -3.9 483 2 3.0 0.10 -3.1 509 3 2.9 0.12 -2.3 483 4 3.0 0. 12 -3. 1 521 5 2.8 0.14 -2.9 522 6 3.0 0.11 -3.7 530 7 3.1 0.10 -5.4 540 8 2.8 0.15 -3.2 530 9 2.8 0.14 -5.5 535 10 2.8 0. 15 -2.7 582 1 1 3.1 0.10 -3.9 483 1 2 2.9 0.14 -3.9 647 Dowelling Line 1 3.1 0.11 -3.2 788 2 3.3 0.09 -2.3 854 3 3.0 0.13 -2.2 1 023 Lantern Net 1 6.9 0.02 -8.8 1051 2 4.0 0.05 -7.5 1235 64 V> 1 o o OYSTER LINE 1 H • OYSTER LINE 2 »- « » OYSTER LINE 3 . x x OYSTER LINE 4 o- o OYSTER LINE 5 3- ». * OYSTER LINE 6 H 1 1 I I 1 1 1 1 I 1 I I 1 I 1 1 1 1 1 I O.D 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 16.0 20.0 TIME (IVEEKS) Figure 22. Plot of the mean capitulum (shell) length versus time for Lepas anatifera from each of the oyster lines (1-6). (standard deviations for each mean value range from 0.2 to 0.4) Time : 0-20 - represents June 1 to October 31 1981 . 65 0 © OYSTER LINE 7 1 + OYSTER LINE 8 « t> OYSTER LINE 9 x x OYSTER LINE 10 o- a OYSTER LINE 11 * * OYSTER LINE 12 UJ c CO x-' i •nr- —r- -1— I— "T -1— 0.0 18.0 20.0 2.0 4.0 6.0 8.0 10.00 12.0 14.0 16.0 TIME (UEEKS) Figure 23. Plot of the mean capitulum (shell) length versus time for Lepas anatifera from each of the oyster lines (7-12). (standard deviations for each mean value range from 0.2 to 0.4) Time : 0-20 - represents June 1 to October 31 1981 . 66 o UOODEN LINE 1 --+ UOODEN• LINE 2 » UOODEN LINE 3 Figure 24. Plot of the mean capitulum (shell) length versus time for Lepas anatifera from each of the wooden lines ( 1 -3) . (standard deviations for each mean value range from 0.2 to 0.3) Time : 0-20 - represents June 1 to October 31 1981 . 67 Figure 25. Plot of the mean capitulum (shell) length versus time for Lepas anatifera from each of the lantern nets (1-2). (standard deviations for each mean value range from 0.2 to 0.3) Time : 0-20 - represents June 1 to October 31 1981. 68 An initial overview indicates that the gooseneck barnacles on the lines of oyster shells (fig. 22 and 23, Table IX) and wooden dowellings (fig. 24 and Table IX) have asymptotic lengths (L o° ) ranging from 2.80 to 3.80 cm and 'K' values ranging from 0.09 to 0.15. The gooseneck barnacles from the lantern nets have asymptotic lengths (L °° ) ranging from 4.0 to 6.9 cm and 'K' values ranging from 0.02 to 0.05 (fig. 25 and Table IX). Generally the ' L °° ' values for those gooseneck barnacles within the lantern nets are double those from the lines of oyster shells and wooden dowelling. As well the 'K' values for the gooseneck barnacles from the lantern nets are one third of those for the gooseneck barnacles on the lines of oyster shells and wooden dowelling. In summary the gooseneck barnacles of the lantern nets attained a larger asymptotic length at a slower rate than the gooseneck barnacles on the lines of oyster shells and wooden dowelling. The curves of capitulum growth of the gooseneck barnacles on the lines of oyster shells 1-6 and the lines of oyster shells 7-12 were compared for similiar 'L °> ' 'K' and 'to' mean values. The level of significance was chosen at p=0.02 since the standard deviations for the mean asymptotic lengths (L °°) were less than or just greater than the precision involved in measuring the lengths. For example the mean ' L °° ' for the gooseneck barnacles of the lines of oyster shells 1-6 and 7-12 were 3.00 + 0.09 and 2.91 + 0.14. Therefore it was decided that to be able to reject the null hypothesis that 'L =° ' was equal, the probability must be equal to or more extreme than p=0.02. Subsequently this level of significance was used throughout the 69 comparisons of mean parameter values of each cultch type. The mean parameter values were similiar for both the gooseneck barnacles on the lines of oyster shells 1-6 and 7-12 (Table X). Next the mean parameter values for the gooseneck barnacles on the lines of oyster shells 1-12 were compared to the gooseneck barnacles on the lines of wooden dowelling 1-3. Again there was no significant difference (Table X). Therefore the capitulum growth of those gooseneck barnacles on the lines of oyster shells and wooden dowelling appear to be similiar. The parameters ' L °= ', 'K', and 'to' from the von Bertalanffy growth equation for the gooseneck barnacles of each of the lantern nets were compared. The parameters 'K' and 'to' were significantly different. However, because of the heterogeniety of the variances, the ' L °= ' values could not be compared but in spite of this the values do appear to be different (Table X). Although the capitulum growth of Lepas anati fera was different for the two lantern nets , Lepas anatifera exposed on the lines of oyster shells and wooden dowelling attained a shorter asymptotic length (L °° ) more rapidly (ie a greater 'K' value) than Lepas anatifera contained in both the lantern nets. 70 Table X - A comparison of the parameter values (L °°-cm,K,to- weeks) generated from the von Bertalanffy growth model for the capitulum growth of gooseneck barnacles. Cultch lines Parameter S .D. df P ' t'cal Oyster lines 1- 6 L »-3.0 0 . 1 > 10 .02 1 .308 Oyster 1 ines 7 -12 L °°-2.9 0 . 1 Oyster lines 1- 6 K-0.11 0 .015 > 10 .02 1 .308 Oyster lines 7 -12 K-0. 13 0 .024 Oyster lines 1- 6 to-3.2 0 .6 > 10 .02 1 .739 Oyster lines 7 -12 to-4.1 0 .5 Oyster lines 1 -12 L »-2.9 0 . 1 > 13 .02 2.203 Wooden lines 1- 3 L °°-3. 1 0 . 1 Oyster lines 1 -12 K-0.12 0 .020 > 1 3 .02 1.319 Wooden lines 1- 3 K-0.11 0 .020 Oyster lines 1-1 2 to-3.6 1 .0 > 1 3 .02 2.227 Wooden lines 1- 3 to-2.6 0 .55 Lantern net 1 L =°- 6.9 0 .4 > Lantern net 2 L °°- 4.0 0 . 1 Lantern net 1 K-0.002 0 .0017 > OO .02 397.4 Lantern net 2 K-0.050 0 .0017 Lantern net 1 to-8.8 0 .2 > oo .02 178.7 Lantern net 2 to-7.5 0 .2 (* - heterogeniety of variance - 'F'cal,df=2,» p=0.025,= 5.007) 71 Peduncle Growth The mean stalk lengths measured at weekly intervals from June 15 to October 15 1981 are shown in figures 26 - 29. Unlike the figures for the mean capitulum growth no clear pattern is observable. Generally the curves are characterized by an initial fluctuation of stalk lengths during the first eight weeks, followed by a more stable behaviour for the remainder of the culture phase. Another feature of the figures of stalk length is that the gooseneck barnacles of the lantern nets appear to attain greater stalk lengths than the gooseneck barnacles on the lines of wooden dowelling followed by the gooseneck barnacles on the lines of oyster shells. An analysis of the final mean stalk lengths indicates a significant difference between those gooseneck barnacles from the lines of oyster shells, lines of wooden dowelling and the lantern nets (ANOVA test, 'F'cal df = 2,°°,p=0.025 =5.0067). 72 o o OYSTER LINE 1 4 • OYSTER LINE 2 « e OYSTER LINE 3 . x x OYSTER LINE 4 o- a OYSTER LINE 5 °" » * OYSTER LINE 6 in _ in -i 1 1 r~—i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 TIME (UEEKS) Figure 26. Plot of the mean peduncle (stalk) length versus time for Lepas anatifera from each of the oyster lines (1-6). (standard deviations indicated on figure). Time : 0-20 - represents June 1 to October 31 1981. 73 o o OYSTER LINE 7 H • OYSTER LINE 8 » OYSTER LINE 9 x k OYSTER LINE 10 B- a OYSTER LINE 11 * « OYSTER LINE 12 x _J tX t— to ~i 1 r —i 1 1 1 1 1 1 1 1 1 1 1 1 1 i r 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 16.0 20.0 TIME (WEEKS) Figure 27. Plot of the mean peduncle (stalk) length versus time for Lepas anati fera from each of the oyster lines (7-12). (standard deviations indicated on figure). Time : 0-20 - represents June 1 to October 31 1981 . 74 o o DOULING LINE 1 A • DOULING LINE 2 V"* <» • DOULING LINE 3 0_ _ in p> ~ I - V »n ^ >*- - -4w ooj ^—7-* \/ — i / \ U | __ —-- •— »i /* \ STflL J / J / / i in _j , , 1 1 1 1 1 1—I 1 1 1 1 1 1 1 1 1 I 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 TIHE (UEEKS) Figure 28. Plot of the mean peduncle (stalk) length versus time for Lepas anatifera from each of the wooden lines (1-3). (standard deviations indicated on figure). Time : 0-20 - represents June 1 to October 31 1981 . 75 o © LANTERN NET 1 •« • LANTERN NET 2 Figure 29. Plot of the mean peduncle (stalk) length versus time for Lepas anatifera from each of the lantern nets (.1 -2) . (standard deviations indicated on figure). Time : 0-20 - represents June 1 to October 31 1981 . 76 5. WEIGHT/LENGTH RELATIONSHIPS Capitulum The relationships of capitulum wet weight versus length are shown in figures 30 - 32. Regression lines have been fitted to each of the monthly capitulum measurements. The regression coefficients range between 0.85 to 0.97 except for the one low value of 0.61 for the October sample from the lines of wooden dowelling. Generally the gooseneck barnacles of the lantern nets and the lines of oyster shells (fig. 30 and fig. 32) display a pattern of an increasing slope accompanying subsequent samples. This same pattern is not apparent for the gooseneck barnacles on the lines of wooden dowelling (fig. 31). The regression lines for the July, August, and September measurements appear to be similiar. This is most likely a result of the samples containing a similiar size range of capitulums. When the data are viewed as a whole the expected exponential relationship is apparent. The logarithmic transformation of the weight data (Log mg.) and the subsequent comparison of regression equations revealed that the curves for the oyster cultch, wooden dowelling, and lantern nets differed (fig.33) ('F'cal = 14.67 prob=0). It was expected that the regression equations would be similiar in the absence of any inhibitions to growth. To explore for a possible cause of the observed difference the data were again compared excluding the June samples. The June samples were excluded since they preceded the start of the observed mortalities. A comparison of the regression equations including the July to October data indicated that the curves for the gooseneck barnacles on the lines of oyster shells and wooden dowelling were similiar (Scheffes test, 'F'cal = 0.11 prob=0.73733) , where: Log. Y = 0.2293 + 0.5388 * X and that the curve for the gooseneck barncles from the lantern nets differed, where: Log.Y = 0.3892 + 0.6016 * X. 78 N Regression Eauation r S. E. o © JUNE 40 Y - -0.57 • 0.61(X) 0.90 0.08 •i + JULY 38 T - -1.30 • 1.03(X) 0.87 0.14 « • RUGUST 39 T - -1.96 • 1.33(X) 0.89 0.18 x k SEPTEMBER 30 T - -2.60 • 1.56 Of S 0/ 8 . Is- UJ i— I I "I T T —i— I 3.6 4.0 0.0 0.4 0.8 12 1.6 2.0 2.4 2.8 3.2 SHELL LENGTH (CM.) Figure 30. Plot of the wet weight (grams) versus capitulum (shell) length (cm.) for Lepas anatifera from the lines of oyster shells. 79 N Reqression Eouation r S. E. o e JUNE 40 Y - -0.44 • 0.52U) 0.97 0.04 -• • JULY 40 y - -i.22 • 1.00(X) 0.93 0.09 • » AUGUST 39 y - -i.52 • 1.09U) 0.92 0.09 * x SEPTEMBER 28 Y - -1.29 • 1.00(X) 0.86 0.15 O- CD OCTOBER 39 y - -i.i2 • i.iKz) 0.61 0.26 • • 8 O o / CD Q -O ° 5 3 j ° a/ o _ J 3 ~ i 1 1 1 r 1.6 2.0 2.4 SHELL LENGTH (CM.) Figure 31. Plot ot the wet weight (grams) versus capitulum (shell) length (cm.) for Lepas anatifera from the lines of wooden doweling. N Regression Eauation r S. E. o o JUNE 36 Y • -0.54 • 0.62U) 0.93 0.08 •• + JULY 40 Y - -0.87 • 0.76U) 0.92 0.08 * • AUGUST 38 Y - -1.84 + 1.29(X) 0.90 0.13 x x SEPTEMBER 29 Y » -2.83 • 1.64(2) 0.84 0.22 B- D OCTOBER 30 Y - -3.42 + 1.98U) 0.87 0.24 3S. 3 _ I— I "T" i—i—i— -1— 0.0 0.4 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0 SHELL LENGTH (CrU Figure 32. Plot of the wet weight (grams) versus capitulum (shell) length (cm.) for Lepas anatifera from the lantern nets. 81 Figure 33. Plot of the log wet weight (mg.) versus capitulum (shell) length (cm.) for Lepas anatifera from each of the cultch types. 82 Peduncle The regression lines are fitted to the data of peduncle (stalk) wet weight vs length (fig. 34-36). Unlike the regression analysis for the capitulums, the coefficients are generally lower and more varied, ranging from 0.22 to 0.81. Neither is the same clear exponential pattern present as it was for the capi tulums. A comparison of the three regression equations for the gooseneck barnacles from the oyster cultch, the wooden cultch and within the lantern nets indicated significant differences ( 'F'cal =5.20 prob=0.00579). 83 N Regression Equation r S. E. o e JUNE 40 T - -0.4.0 + 0.18(X) 0.84 0.07 H + JULY 36 ? - -0.23 + 0.34(X) 0.90 0.22 » AUGUST " 39 T « -0.25 + 0.45 r l 1 1 1 1 1 1 1 1 1 1 r i 1 1 1 r 1Q.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 STALK LENGTH (CM.) Figure 34. Plot of the wet weight (grams) versus peduncle (stalk) length (cm.) for Lepas anatifera from the lines of oyster shells. 84 N Regression Equation r S. E. o o JUNE 40 T - -0.06 • 0.17U) 0.36 0.02 * • JULY 40 . T • -0.13 • 0.25U) 0.79 0.18 03 *.U J.U V.u STALK LENGTH (CM.) Figure 35. Plot of the wet weight (grams) versus peduncle (stalk) length (cm.) for Lepas anatifera from the lines of wooden doweling. 85 N Reqression Equation r S. E. o o JUNE 36 T • -0.07 • 0.18(X) 0.81 0.08 4 • JULY 40 Y - -0.28 + 0.26(X) 0.77 0.16 « » flUCUST 38 Y » -0.25 • 0.32(X) 0.76 0.28 x x SEPTEMBER 29 Y - 0.11 + 0.3KX) 0.76 0.39 o- a OCTOBER 30 Y - 0.29 + 0.31(X) 0.82 0.23 CD 3 . »' x 1-1 ^ UJ 3 . UJ °/>i>/'x a a CV *''2«.x .-^V* J' • T 1 1 1 1 1 r 1.0 2.0 3.0 4.0 S.0 STALK LENGTH (CM.) Figure 36. Plot of the wet weight (grams) versus peduncle (stalk) length (cm.) for Lepas anatifera from the lantern nets. 86 Figure 37. Plot of the wet weight (grams) versus peduncle (stalk) length (cm.) for Lepas anatifera from each of the cultch types. 87 V. DISCUSSION 1. SEED ACQUISITION 1 . 1 980 SURVEY Skerman (1958a) reported that Lepas anatifera had attained capitulum lengths of 2.15 to 2.90 cm within 39 to 63 days off the east coast of New Zealand. As well Skerman (1958b) observed that this set off the east coast of New Zealand occurred within a fortnight covering a 32 km front approximately 50 km from shore. From the set observed during the 1980 survey on the surface buoys, Lepas anatifera colonized a region that extended 80 km south west off Estevan Point, Vancouver Island. As well, it is suggested from the capitulum lengths recorded during the survey that this set occurred within a short time frame. The difference noted between the mean capitulum lengths of Lepas anatifera from the top and bottom region of the buoys suggests that continual submergence leads to increased growth. The increased growth may be a result of the greater amount of time available for feeding. Therefore the proposed suspended culture should provide better growth than a regime of tidal exposure, as has been reported for molluscan suspended culture (Quayle, 1969, 1971, and 1978; Shaw,1969, Bardach, Ryther, and McLarney, 1972, Sanders, 1973, Taguchi, 1976, and Leighton and Phleger, 1976 and 1977). The dense colonization of the surface buoys is typical of 88 the gregarious nature of both the pedunculate and balanoid barnacles (Knight-Jones and Stephenson, 1950). The sparse settlement of the subsurface buoys was probably due to their depth (50 m.) and their coating of anti-fouling paint. In conclusion, a dense settlement may occur regularly in the spring in that area covered in the 1980 survey. 2. 1981 CULTCH DEPLOYMENT The destruction of the arrangement of the lines of cultch was most likely a result of the violent motion associated with the geodyne buoys during periods of heavy seas. The oyster shells, while abrading the polypropylene lines, probably severed them. As well it is likely that the abrasion of any of the lines by the metal and/or the 'legs' below the buoy ultimately severed them. This suggests that future attempts at the acquisition of seed must take into account the potential sea conditions. Oyster shells provide a suitable substrate because they offer a very rough and irregular surface to cyprid larvae. The rugophilic behaviour of cyprids is documented for balanoids (Crisp and Barnes 1954 ) and pedunculates (Skerman 1958). The denser settlement at the intersection of the wooden dowelling and the polypropylene line was probably due to the shading provided there. Negative phototropism was obseved by Skerman (1958b) for Lepas anati fera. Furthermore, the attractive qualities of the rubber were most likely the shade beneath the buoy and its dark color. Both features are attractive to the 89 settling cyprid larvae of barnacles (Visscher,1927 and Pomerat and Reiner, 1942). Finally, the failure of the polypropylene line to provide an attractive substrate may have been due to some quality of its 'newness' because Lepas anatifera has been observed settled on older more weathered polypropylene line (personal observation). The acquisition of seed ocurred sometime between April 15th and May 30th 1981 at the same locations (positions 1 and 2) as the previous year's set. These similiar times and locations of the settlements of Lepas anatifera for 1980 and 1981 suggests that both location and time of settlement are predictable. These predictive qualities are encouraging for the possible future acquisition of large amounts of seed. As well, the success of the cultch types in attracting sets of Lepas anatifera seed suggests that this proceedure need not require expensive nor difficult to obtain materials. Generally, the acquisition of large amounts of seed may be accomplished inexpensively and easily if one respects the potential force of the sea. 90 2. CULTURE PHASE 1. ENVIRONMENTAL PARAMETERS Little can be concluded from the measurements of salinity other than that it did not vary greatly from the salinity expected in the area of the acquisition of Lepas anatifera, The negative correlation of secchi depth and temperature showed that the shallowest secchi depths ocurred during the highest mean temperatures of the water column. Although the phytoplankton biomass was not measured it may be possible to obtain an indication of its abundance if we assume that the turbidity was proportional to the abundance of phytoplankton. Then it can be said that the number of phytoplankton 'bloomed' when temperatures increased and subsequently the numbers decreased when temperatures fell. Therefore during the first period of the culture phase phytoplankton was believed to be more abundant than in the second cooler period of September and October. The importance of this becomes clearer when gonadal state, mortality, and growth are considered. 2. GONADAL STATE The appearance of ovigerous lamellae (egg cases) by the ninth week of the culture phase corresponds to a nine to fifteen 91 week period since Lepas anatifera had settled. Lepas anatifera may become egg bearing in as little as two and a half weeks to eight weeks (Skerman, 1958a, Patel, 1959, and Mclntyre, 1966). The difference between the period reported in the literature and the period observed in this study may or may not be significant. If the difference is significant, then it can be assumed, that conditions may not have been optimal at the culture site. In addition blue colored ovigerous lamellae were not observed until the eleventh week. Blue is the normal color of ovigerous lamellae of Lepas anatifera and is an indication of the presence of astaxanthin (Herring, 1971). The ocurrence of blue ovigerous lamellae and the proportional increase of blue ovigerous lamellae corresponds with the time during which the secchi depth increased. The increase in secchi depth, which if as proposed earlier is an indication of the abundance of phytoplankton, suggests that indeed the biomass of phytoplankton fell as the temperatures fell. And as the phytoplankton biomas fell perhaps the proportion of zooplanktonrphytoplankton increased. Therefore the retarded appearance of ovigerous lamellae may have been due in part to an inadequate diet available to the gooseneck barnacles. This may account for the difference between the period of time observed at the culture site and that reported in the literature for the age at which Lepas anatifera may be found bearing eggs. 92 3. SURVIVAL Generally the figures of percent survival indicated that the first five weeks were free of mortalities, followed by a rapid increase and then a levelling off by the tenth and eleventh weeks. The results suggested that mortality was inversely proportional to density. Fouling of the substrates may be responsible for this phenomenon. It may have taken the fouling organisms (algae, balanoid barnacles and Mytilus edulis ) the first five weeks to establish themselves before survival was adversely affected. A lower density of gooseneck barnacles would increase the space available for fouling organisms. The balanoid barnacels and Mytilus edulis would compete for food. The algae would interfere with the circulation of water about the gooseneck barnacles. The impedence of water circulation may have inhibited feeding and the removal of toxic waste products. The levelling off of mortalities after the eleventh week may have been the result of two factors, the fouling algae had begun to die back and a richer zooplankton diet may have become available as is assumed by the appearance of blue ovigerous lamellae. The die off of • the algae would have increased the circulation of water amidst the gooseneck barnacles and allowed for increased feeding efficiency and removal of toxic waste products. The availabilty of a richer diet of zooplankton would have improved the health of the surviving gooseneck barnacles. Predation is another factor that may have accounted for mortalities. Pile perch ( Rhacochilus vacca ) were observed 93 feeding on the cirri of Lepas anatifera. Only the cirri were observed to be eaten. Whether the loss of cirri would be responsible for deaths is not known but the loss would definitely interfere with the efficiency of feeding. This effect appears to become more evident when the growth and the weight/length relationships are considered. Generally, survival and therefore production may be optimized if only that cultch that initially has the greatest density of seed is used in the suspended culture. Control of fouling and predation will inturn increase production. 4. GROWTH Capitulum Growth The results indicated that gooseneck barnacles from the lantern nets had greater capitulum growth than the gooseneck barnacles on the lines of oyster shells and wooden dowelling. A lower asymptotic length was attained more rapidly for the gooseneck barnacles on the lines of oyster shells and wooden dowelling than for the gooseneck barnacles within the lantern nets. A reason for this difference may have been differential predation. The gooseneck barnacles within the lantern nets were protected from the predacious pile perch which were observed nibbling the cirri of the gooseneck barnacles exposed on the 94 lines of oyster shells and wooden dowelling. The subsequent shortening of the cirri would tend to decrease the efficiency of feeding and therefore inhibit growth. The gooseneck barnacles affected by predation would have been less likely able to obtain sufficient nourishment for optimal growth and therefore would have attained lower asymptotic lengths (L °° ) than those not affected by predation. Therefore seed laden cultch protected within lantern nets is probably the best method to culture Lepas anatifera. If it is assumed that Lepas anatifera from the 1981 culture study and the 1980 survey had initially settled the same time in each year, a comparison of growth can be made between the culture study and the wild. By the middle of September 1980 the mean capitulum length for gooseneck barnacles from all four surface bouys was 3.56 + 0.31 cm. The mean capitulum lengths of the gooseneck barnacles averaged over the mean capitulum lengths from each of the lines of oyster shells and wooden dowelling, and the mean capitulum length averaged from the two lantern nets were 2.57 + 0.03 and 2.66 + 0.04 cm respectively. Growth was clearly less under suspended culture conditions at the study site than for Lepas anat i fera observed in the wild. The difference is most probably due to those factors previously discussed; fouling agents, predation and the initially poor diet at the culture site. Peduncle Growth The stalk length varies proportionately with density and varies depending on its degree of contraction. Although greater 95 stalk lengths were attained in the wild than at the culture site it is difficult to actually make this comparison considering the variable nature of the stalk. Unlike the capitulum the stalk is a poor indication of growth (Skerman 1958b ). Although stalk length is a poor indication of growth it is the stalk which is the edible part of the gooseneck barnacle. Perhaps then, the best way to maximize its growth would be to utilize only the most densely settled cultch. This should not only maximize stalk length but as previously suggested will optimize survival and therefore production. 5. WEIGHT/LENGTH RELATIONSHIPS Generally the stalk wet weight/length relationship is not as clear as that observed for the logarithmic weight/length relationship of the capitulum. This is due to the variable nature of the stalk, its elasticity and density dependency (Skerman 1958a ). The most striking feature to arise from the analysis of the weight/length relationship was the difference observed for the capitulum of the gooseneck barnacles exposed to predation and those protected within the lantern nets. The capitulum of the gooseneck barnacles within the lanterns were heavier for a given length than the gooseneck barnacles from the lines of oyster shells and wooden dowelling. Again the advantages of the lantern nets are apparent. 96 6. TOTAL LENGTH Generally the combined mean average total length (capitulum plus stalk) of Lepas anatifera ranged from 4.2 to 6.3 cm by the end of the culture period. This range of mean values exceeds the minimal mean harvestable size of 4 cm for the gooseneck barnacle Pollic ipes cornucopia commercially utilized in Spain (Goldberg, 1984 ). If Pollic ipes cornucopia is assumed to grow at a similiar rate as Pollicipes polymerus, which is indigenous to the west coast of North America, a comparable size would not be attained in the wild for several years. Pollicipes polymerus, the species that the British Columbia seafood industry exported to Spain, does not attain sexual maturity and capitulum lengths of 1.72 cm for five years, nor is it expected to attain full growth in less than twenty years (Barnes and Reese, 1960, Hilgard, 1960, Mclntyre, 1966, and Lewis and Chia, 1981). Lepas anatifera, from the time of the acquisition of seed to the end of the culture phase, attained sexual maturity within nine to fifteen weeks and total lengths exceeding 4 cm within 17 to 23 weeks. Although growth was still less than that observed in the wild, Lepas anatifera grew enough under culture conditions to exceed the minimal harvestable size set in Spain. 97 V CONCLUSIONS 1. SEED ACQUISITION 1. Lepas anatifera settles densely in the spring, from the middle of April until the end of May, off the west coast of Vancouver Island. The predictability of both the time and the location of setting is encouraging for future acquisitions of seed. A reliable source of seed is neccessary for a successful mariculture venture. 2. Oyster shells, lengths of wooden dowelling and sheets of rubber are suitable cultch, but 'new' polypropylene is not. The success of these inexpensive and easily obtained materials suggests that the acquisition of seed need not be a costly proposition. 3. The factor that may prove to be the most difficult to deal with is the potential devastating force of the sea. Equipment must be rigged to withstand violent storms. 2. CULTURE PHASE 1. Growth rate may be site specific. Growth appears to have been less under suspended culture conditions at this study site than for Lepas anatifera observed in the wild. Areas of a high phytoplankton/zooplankton ratio may be a detriment to growth and 98 time to sexual maturation. Therefore a more exposed site may be more beneficial to growth. However a mariculture operation located at a protected site is more easiliy managed and maintained because of its accessibility and the reduction of damage caused by adverse weather. 3. At the densities studied, survival seems to be directly proportional to the number of Lepas anatifera per unit of cultch. This suggests that to optimize production only that cultch that is most densely colonized should be transferred to the culture phase. 4. Capitulum growth and weight gain were significantly greater for Lepas anatifera protected from predation within the lantern nets than for those grown exposed on lines. Although the lantern nets increase costs their use appears to be the most successful means of culturing Lepas anatifera . 5. The mean total length (capitulum plus peduncle) exceeded, within 17 to 23 weeks, the average minimal harvestable size of 4 cm for the gooseneck barnacle Pollicipes cornucopia, which is consumed in Spain. It is encouraging that a commercially acceptable size can be reached in such a short time. This suggests that a marketable sized product could be available annually by late fall from sets obtained in early spring. 99 VI. RECOMMENDATIONS 1. SEED ACQUISITION 1. The time and location of set should be further investigated to accurately establish the time frame during which Lepas anatifera settle. In addition locations should be sought which emphasize proximity both to the shore and to potential culture sites. 2. Cultch types and orientation should be optimized stressing practical and inexpensive methods to deploy and retrieve equipment. 3. Hatchery techniques should be developed to avoid the dependence and limitations that may arise from a reliance on natural sets. 2. CULTURE PHASE 1. Site specificity needs to be investigated. Particularly, an investigation of protected versus exposed sites is warranted. 2. The effect of phytoplankton versus zooplankton rich media should be investigated if, as proposed from this study, a rich phytoplankton medium is detrimental to growth and sexual 100 maturity. 3. The maximum depth at which Lepas anatifera can be optimally grown should be investigated to perhaps avoid some of the problems associated with fouling. 4. The optimum density at which Lepas anatifera can be cultured should be investigated under controlled conditions to determine if the relationship between survival and density observed in this study is valid or merely an artifact. 3. GENERAL CONSIDERATIONS 1. The marketability of Lepas anatifera should be verified before further biological or engineering studies are initiated. 2. Perhaps the most important concern that needs to be addressed is not one specific to the mariculture of Lepas anatifera but one that focuses on the growth of the industry as a whole in British Columbia. The essence of this concern for British Columbia can best be found in a liberal paraphrasing of Larkin's (1982) views and his presentation of Nash's (1979) views; Mariculture in British Columbia, aside from the Salmon Enhancement Programme, is a cottage industry which depends for it's development on the initiatives of many individuals. 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