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Factors affecting traffic and anchoring patterns of recreational boats in Sydney Harbour, Australia
Landscape and Urban Planning 66 (2004) 173–183
Factors affecting traffic and anchoring patterns of recreational boats in Sydney Harbour, Australia W.M. Widmer∗ , A.J. Underwood Centre for Research on Ecological Impacts of Coastal Cities, Marine Ecology Laboratories, A11, University of Sydney, Sydney, NSW 2006, Australia Received 18 December 2002; received in revised form 4 April 2003; accepted 5 April 2003
Abstract Management of recreational boating is typically based on measures of numbers of boats (e.g. marina berths, vessel registrations). Potential environmental impacts and safety aspects may, however, be a function of the number of boat movements and not of the total numbers of boats kept in a harbour. Therefore, a survey was designed to test hypotheses regarding the traffic and anchoring patterns of recreational boats in Sydney Harbour. Boat movements were visually counted for periods of 1 h in four locations in the estuary. The results indicate that recreational boating is the main component of all boat traffic, being composed chiefly by sailing yachts, with a small contribution of jet-skis. Traffic of leisure boats was more intense in summer than in winter. On weekends, there were more movements of recreational boats on sunny than on overcast/rainy conditions. Weather was not, however, a significant factor on weekdays. During the Sydney 2000 Olympic Games, the predicted increase in traffic and anchoring intensity by recreational boats was not consistent. In two out of four locations, the traffic of recreational boats during this special event was not significantly different than during baseline periods. The number of anchored boats was greater at North Harbour Aquatic Reserve (NHAR) and was positively correlated to boat traffic. Due to this observed correlation, managers can use the patterns of boat traffic to predict the patterns of anchored boats in this marine protected area. The large number of movements of sailing boats is an important issue to be considered in management of boat traffic, because this type of boat has restricted manoeuvrability and right of way over motorised recreational craft in most situations. This study quantified and identified clear patterns of recreational boat traffic. Managers can now use this information to develop strategies aiming at the improvement of boating safety and the prevention of potential environmental impacts due to the use of recreational boats in urban waterways. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Boat traffic; Estuaries; Integrated coastal management; Leisure boating; Sydney 2000 Olympic Games; Waterways
1. Introduction More than half of the world’s population presently lives in coastal areas (Vitousek et al., 1997) and the ∗ Corresponding author. Tel.: +61-2-9351-4931; fax: +61-2-9351-6713. E-mail address: [email protected] (W.M. Widmer).
0169-2046/$20.00 © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0169-2046(03)00099-9
rate of increase of coastal populations is greater than inland populations (Cicin-Sain and Knecht, 1998a). The people inhabiting coastal areas tend to group into dense aggregations. Urbanization is a major feature of coasts worldwide; several of the largest cities of the world are near the sea or at the margins of estuaries. Currently, there are 13 coastal mega-cities with more than 8 million people each (Vallega, 2001a).
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Among the plethora of human activities on the coast, recreation and tourism stand out as the most rapidly growing (Cicin-Sain and Knecht, 1998b). Coastal recreation tends to increase in association with coastal urbanization (Vallega, 2001b). As one particular type of recreational use of coastal waters, pleasure boating has increased substantially since the Second World War, due to the increase in disposable incomes in many countries and the general reduction of costs of boats with the advent of new technologies and materials (Robertson, 1995; Anderson, 1996). Traditionally, the potential environmental impacts due to recreational boating have been mainly associated with its necessary land-based infrastructure, such as marinas and related facilities. These developments have been implicated in environmental disturbances that include changes in oceanographic patterns by groynes or breakwaters and depletion of habitats by dredging and landfilling (Harvey, 1993), contamination of water and sediments due to toxic substances from fuels and antifouling paints (Rilov et al., 2000) and changes in subtidal assemblages due to introduction of artificial habitats such as pilings and floating pontoons (Glasby and Connell, 1999). These environmental issues can partially explain why many marinas are considered to be “designated developments” in the Australian state of New South Wales. As such, they require an Environmental Impact Statement (EIS) as one of the necessary procedures for the project to be granted a development consent by the planning authority, under the current New South Wales Environmental Planning and Assessment Act (Harvey, 1998). The actual use of recreational boats away from their storage facilities may, however, also have environmental consequences for coastal areas, especially on harbour and estuarine environments, where this activity is predominantly practised. According to Wolter (2001), people are highly concerned about the environmental deterioration of waterways. It is reasonable to conceive that increased levels of recreational boat traffic in coastal waters represent increased risks of environmental disturbances that include: (i) damage to seagrass meadows by propellers and anchors (Dawes et al., 1997; Creed and Amado, 1999); (ii) intentional or accidental introduction of debris (littering) by boat-users (Cahoon,
1990; Backhurst and Cole, 2000); (iii) changes of shorebird behaviour due to boat movements near roosting grounds or reproductive colonies (Bratton, 1990; Burger, 1998a); (iv) interference with marine mammals, such as changes of dolphin behaviour or injuries caused by collisions (Janik and Thompson, 1996; Buckingham et al., 1999); and (v) release of sewage from boats into estuarine waters (Strand and Gibson, 1990; Guillon-Cottard et al., 1998). Furthermore, perceptions of enjoyment of boating and its safety levels are reduced as density of boats increases in a navigable water body (Ashton and Chubb, 1972). The likelihood for conflict between recreational boating and other human uses of the waterway also increases as traffic increases, particularly near large metropolitan areas (Heatwole and West, 1982). Noise affecting foreshore residential areas is also associated with traffic of specific recreational craft such as jet-skis and power-boats. Australia is one of the most urbanized countries in the world; most people live in a few large, coastal cities. According to Yapp (1986, p. 64), “the Australian coastal zone is the nation’s prime destination for outdoor recreation”. In terms of intensity, Sydney Harbour is one of the most important areas for recreational boating in the southern hemisphere. As in other studies about recreational boating in Sydney Harbour, this activity has been typically described by the size of the recreational boating fleet. Sant (1990) used numbers of registered motor-boats and sailing vessels obtained from the then Maritime Services Board to study ways to accommodate the demand for boating in the harbour. An estimate of 36,000 recreational boats in the Sydney region was a key fact about Sydney Harbour (Department of Urban Affairs and Planning, 1999). There are approximately 7,500 recreational boats stored on Sydney Harbour, in marinas and on private moorings (Boating Industry Association of New South Wales, 2000). This is 75% of the estimate of 10,000 mooring berths from Underwood and Chapman (1999). Some 42 marinas and several sailing clubs maintain a fleet of thousands of sailing dinghies. Several public boat-ramps make the harbour available for boats stored elsewhere. One of the primary aims of integrated coastal management is to promote the ecologically sustainable development of coastal areas (Clark, 1996; Kay and
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Alder, 1999). Because humans play a significant role in the ecology of coastal ecosystems (Castilla, 1993), it is important to study the patterns of human behaviour in these systems. For instance, Underwood (1993) demonstrated that detailed information about patterns of human use of rocky shores is needed for the development of proper plans of management for these habitats. Only a fraction of the total number of boats kept in a harbour is actually in use at any given time. Therefore, information about patterns of boat traffic are necessary to provide managers with important indications about where and when certain types of potential environmental disturbances, safety risks and variations in the level of boaters’ enjoyment are most likely to occur. Furthermore, such information would be useful in the efficient allocation of resources to manage waterways. According to Adams et al. (1992, p. 113), detailed accounts of boat traffic on a waterway is an “essential prerequisite upon which to base successful management policy”. To determine the patterns of traffic in Sydney Harbour, a survey was designed to test the following hypotheses: (a) Connell and Thom (2000) pointed out that the industrial and mercantile character of the harbour has been recently replaced by recreational and residential developments. Therefore, the boat traffic in the harbour should be mainly represented by recreational vessels. For this study, mainly is considered to be more than half of all boat traffic. The proportion of recreational out of all boat traffic is predicted to be greater than 0.5. (b) As in other studies (Sowman and Fuggle, 1987; Adams et al., 1992), preliminary observations in Sydney Harbour suggested that some types of recreational boats are more intensively used than others. This is proposed to be a consistent pattern for Sydney Harbour. Therefore, if the number of sailing yachts, motor-cruisers, speed-boats and personal water-craft (PWC) are counted, it is expected that their means will be different, with greater numbers of speed-boats, consistent with other geographic areas. (c) Being an outdoor leisure activity, recreational boating tends to vary according to several factors, including time of the year, day of the week,
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weather and location (Sowman and Fuggle, 1987; Adams, 1993). It is proposed that the recreational boat traffic in Sydney Harbour will also be affected by these factors. Therefore, it is predicted that there will be more traffic: (i) during summer than winter; (ii) on weekends than on working weekdays; (iii) on sunny than on overcast/rainy days; (iv) the mean amounts of recreational boat traffic from four different locations are also expected to be different. (d) Large numbers of recreational boats are anchored in some locations in Sydney Harbour (Mathews, 1997; personal observation). Because boats have to sail from their origin (marinas, private mooring-areas or public boat-ramps) to anchor at chosen sites, the numbers of boats moving (the traffic) is predicted to be related to the numbers of boats anchored in any area. (e) Previous observations suggest that recreational boating activity tends to be intensified during special events on Sydney Harbour. It is proposed that the Sydney 2000 Olympic Games was such a special event. Therefore, recreational boat traffic and the number of anchored recreational boats were expected to be greater during the 2000 Olympic Games, than during normal periods. 2. Methods 2.1. Definition of recreational boating According to the New South Wales Waterways Authority, a recreational vessel is “any vessel that is not a commercial vessel” (Waterways, 2000a, p. VI). This definition, associated with the description of types of recreational boats from Adams et al. (1992), was used to produce the definition of the categories of recreational vessels that were used in this study (Table 1). Therefore, commercial vessels, defined as boats that are “used for the carriage of persons or goods for money or any other valuable consideration, hired out or made available in the course of a business or trade or commerce” (Waterways, 2000a, p. V) were distinguished from recreational boats by means of indicative signs on the hull or rigging. From Table 1, it is worth noting the types of boats that were not included in the recreational category:
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Table 1 Recreational boatsa Motorised Speed-boat: A boat with a planing-type hull, with the capacity to exceed 20 knots and without sleeping or toilet facilities. Powered by an out-board engine. It includes rubber inflatables. Motor-cruiser: A boat bigger than a speed-boat, with a displacement hull. It has sleeping and toilet facilities and an in-board engine. Jet-ski: A small jet-propelled craft, with a high-powered and internal engine, for one or two people; also known as personal water-craft (PWC). Sailing Yacht: A boat with a mast, fixed keel, displacement hull and with sleeping and toilet facilities. It carries an auxiliary engine, that may be either in- or out-board. Bigger than a sailing dinghy. Multihulls (e.g. catamarans and trimarans), racing yachts with planing hulls and swing keel yachts were also included in this group. Dinghy: An open deck boat, with a mast and a retractable keel and without sleeping or toilet facilities. Sailboard: A surfboard for one person, powered by the wind with the aid of a sail held by the surfer’s hands. Self-powered Rowing boat: An open deck boat propelled by human power through the use of oars. It includes kayaks, Canadian canoes, traditional surf-rescue-boats and other similar boats. a Typical definitions of recreational boats used in this study, adapted from Adams et al. (1992). Not all of the characteristics described here were used for identification in the field.
water-taxis, boats selling ice-cream and other refreshments, fuel-boats, tugboats, merchant ships, professional fishing-boats, ferries, barges, charter-boats, military vessels, police-boats, rescue-boats from volunteer groups, harbour pilot boats, New South Wales Waterways Authority boats, boats from the Department of Land and Water Conservation and historic ships. In addition, rowing boats, sailing dinghies and sailboards were not included in the counts of the recreational boat traffic, because their potential environmental impacts are considered to be minimal and because their range of movement is typically confined to single coves or bays. 2.2. Measurement of boat traffic and anchored boats Previous research has used different methods to estimate boat traffic, including the use of aerial photographs (Buckingham et al., 1999), records from boat locks (Murphy and Eaton, 1983), questionnaires to boaters (Heatwole and West, 1982) and direct observation (Sowman and Fuggle, 1987). In this study, direct observation was used because it allowed the quantification of boat traffic at times and locations appropriate to the proposed hypotheses. Furthermore, being simple and inexpensive, studies using this method can be repeated more often, being also applicable to other locations where resources and technology are scarce.
Boats were counted for a period of 1 h from each of four vantage points on the harbour foreshore (Fig. 1), one in each of the four major sections of the harbour: Upper, Main, Middle and North (Stephensen, 1966; Mathews, 1997). From each vantage point, vessels that crossed an imaginary line from the point of observation to a prominent point on the other margin of the harbour were counted with the aid of a pair of binoculars. The vantage point in the northern section of the harbour was chosen to represent the recreational boat traffic within the North Harbour Aquatic Reserve (NHAR), a marine protected area in Sydney Harbour. To test the hypothesis about weather, representative samples of boat traffic under different weather conditions were required. Therefore, sampling was done on overcast/rainy and sunny conditions, chosen according to the weather forecast issued by the Australian Bureau of Meteorology on the morning of sampling. So, any day that had previously been chosen for sampling could turn out to be overcast/rainy or sunny. Once the requisite number of days of one condition were complete, sampling was only done on randomly chosen days of the other weather condition. In order to avoid variations in boat traffic at different times of day, sampling was done during the same part of the day; measurements for a given month were taken during the hour that preceded mid-afternoon, defined as at three quarters of the time span between sunrise
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Fig. 1. The four vantage points from which the recreational boat traffic and anchored recreational boats were quantified. (1) Upper Harbour, from Yumbin Point to Manns Point; (2) Main Harbour, from Point Piper to Bradleys Head; (3) Middle Harbour, from Chinamans Beach to Clontarf Point; (4) North Harbour, from Dobroyd Head to Cannae Point. Shaded areas in Middle and North Harbour indicate the locations where anchored recreational boats were counted. Dashed lines indicate the limits of the North Harbour Aquatic Reserve (NHAR).
and sunset for the 15th day of that month. The actual time of sampling therefore changed as days got longer towards summer. The same procedure was used to count the number of recreational anchored boats. At two of the four vantage points used for counting boat traffic, determining the number of anchored boats was, however, difficult due to the obstruction of the view by several coves and small bays. Previous observations suggested that there were few anchored boats at these locations. Therefore, anchored boats were only sampled at Middle and North Harbour.
2.3. Sampling design Measurements of boat traffic and anchored boats were done in two different periods of the year, low season (June to September) and high season (December to March). In each season, counts were made during weekends and weekdays, during overcast/rainy or sunny conditions, in each of the four locations (two locations for anchored boats). Two replicate samples were taken for each treatment, i.e. two independent overcast/rainy weekends, overcast/rainy weekdays, sunny weekends and sunny weekdays were sampled
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for each location in each season. This resulted in a total of 64 independent measurements (32 for anchored boats). Eight measurements of recreational boat traffic and four of the number of recreational boats anchored were taken during the Olympic Games (15 September to 1 October 2000). They were taken at the same four locations described above (two locations for anchored boats), during weekdays and weekends. Only recreational boats outside the exclusion zones were counted, in order not to include boats directly associated with the event (i.e. competitors, management, media, authorised charter-boats). These values were compared with suitable measurements taken during baseline periods and with similar characteristics in terms of season, day of the week, weather and location. 2.4. Statistical treatment For hypothesis (a), the proportion of recreational boat traffic out of the total boat traffic was calculated for the 64 measurements and the null hypothesis that the resulting mean is less than or equal to 0.5 was tested using Student’s t-test. Null hypothesis (b) of no difference among the mean numbers of sailing yachts, motor-cruisers, speed-boats and personal water-craft was tested using a single-factor analysis of variance, using counts of each type of boat in the 64 measures. The null hypotheses of no effect for hypothesis (c) was tested using analysis of variance with four factors: season (fixed, with two levels: winter and summer), day of the week (fixed, with two levels: weekdays and weekend days), weather (fixed, with two levels: overcast/rainy and sunny days) and location (fixed because only four parts of the harbour were considered, with four levels: Upper, Main, Middle and North). There were two replicate counts for each treatment. The null hypothesis of no effect for hypothesis (d) was tested by the Pearson correlation coefficient, r, using the 32 paired values of traffic and anchored boats. The null hypothesis of no difference for hypothesis (e) was tested using analysis of variance with two factors. The first factor was condition, with two levels (fixed, Olympic versus non-Olympic periods) and the second factor (fixed and orthogonal) was location, with four levels. There were two replicate values for each
treatment. For anchored boats, the factor location had two levels instead of four. For the analyses of variance, the assumptions of homogeneity of variances were tested using Cochran’s test. If necessary, transformations were done to remove heterogeneity of variances. When factors or interactions among factors were found to be statistically significant (P < 0.05), multiple comparisons (SNK tests) were used to test for differences between levels within and across factors.
3. Results 3.1. Proportion of recreational boating The mean ratio of recreational boat traffic over total boat traffic was 0.71 (±S.E. = 0.02). This was significantly larger than 0.5 (t = 10.01, P < 0.001, d.f. = 63). 3.2. Types of boats There were significant differences among numbers of different types of recreational boats using the harbour (Table 2). Numbers of sailing yachts (almost 25± 3.5 boats h−1 ) and speed-boats (18.5 ± 1.7 boats h−1 ) did not differ significantly, but were significantly more numerous than motor-cruisers (11.5 ± 1.3 boats h−1 ). Jet-skis (4 ± 0.8 boats h−1 ) were the least numerous type of recreational craft and were significantly less abundant than the other types of recreational boats (SNK tests). 3.3. Patterns of recreational boat traffic Recreational boat traffic was significantly greater in summer, averaging 70 ± 9.5 boats h−1 , whereas in Table 2 Analysis of variance of mean numbers of different types of recreational boats present in the Sydney Harbour’s boat traffica Source of variation
d.f.
MS
F
P
Types of boats Residual
3 252
40.6 0.9
40.8
<0.001
a Data were ln(x + 1) transformed to homogenise variances, Cochan’s C = 0.34 after transformation (not significant).
W.M. Widmer, A.J. Underwood / Landscape and Urban Planning 66 (2004) 173–183 Table 3 Analysis of variance of mean numbers of recreational boat traffic in Sydney Harboura Source of variation
d.f.
MS
F
P
Season (Se) Day of the week (Da) Weather (We) Location (Lo) Se × Da Se × We Se × Lo Da × We Da × Lo We × Lo Se × Da × We Se × Da × Lo Se × We × Lo Da × We × Lo Se × Da × We × Lo Residual
1 1 1 3 1 1 3 1 3 3 1 3 3 3 3 32
8212 55755 12072 7987 213 284 994 4675 605 1233 2537 243 554 372 745 740
11 75 16 10 0.29 0.38 1.34 6.31 0.82 1.67 3.43 0.33 0.75 0.5 1
<0.01 <0.001 <0.001 <0.001 >0.5 >0.5 >0.2 <0.05 >0.4 >0.1 >0.05 >0.8 >0.5 >0.6 >0.4
a Data were not transformed, Cochan’s C = 0.16 (not significant).
winter the mean value was 47±6.8 boats h−1 (Table 3, SNK test). Traffic was particularly heavy in the Main Harbour, with a mean value of 90±14.5 boats h−1 , significantly greater than the traffic from the other three locations. Traffic in Middle Harbour (56.5±12 boats h−1 ), Upper Harbour (49±9 boats h−1 ) and North Harbour (39±9 boats h−1 ) did not differ (SNK tests). The effects of weather were dependent on the time of week (see interaction in analyses in Table 3). Weather was an important factor only during weekends. Sunny weekends had 110 ± 12 boats h−1 , significantly greater than 66 ± 7.6 boats h−1 on overcast/rainy weekends (SNK test). During the week,
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however, there was only a slight increase in recreational boat traffic on sunny days (34 ± 6.6 boats h−1 ) compared to overcast/rainy ones (24 ± 7.4 boats h−1 ), a difference that was not statistically significant. There was significantly more traffic on weekends than on weekdays, but the increase was greater during periods of sunny weather (SNK tests). 3.4. Anchoring patterns The number of recreational boats anchored in the two locations sampled (Middle and North harbour) was positively correlated with the recreational boat traffic measured at these locations (r = 0.74, P < 0.05, d.f. = 30, Fig. 2). There were, on average, more recreational boats anchored in North Harbour (26.6 ± 6.6 boats) than in Middle Harbour (14.8 ± 5 boats). 3.5. Recreational boating during the 2000 Olympic Games Differences in traffic during the Olympic Games compared to baseline levels were dependent on the location (Table 4 marked as ‘a’). In Upper and Main Harbour, the recreational boat traffic was significantly greater during the Olympic period. At Middle Harbour, there was only a slight (and not statistically significant) increase in the recreational boat traffic during the Olympic Games. At North Harbour, recreational boat traffic was reduced during the Olympic period (Fig. 3), although not significantly. The number of recreational boats anchored at Middle and North Harbour increased only slightly during the Olympic period, an increase that was not statistically significant (Table 4 marked as ‘b’).
Fig. 2. Correlation of amount of boat traffic and numbers of anchored boats in Middle and North Harbour.
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Table 4 Analysis of variance of mean amounts of traffic during the Sydney 2000 Olympic Games compared to other times Source of variation
Olympics vs. reference (O) Location (Lo) O × Lo Residual a b
Recreational boat traffica
Recreational boats anchoredb
d.f.
MS
F
P
d.f.
MS
F
P
1 3 3 8
2652 2877 2512 472
5.61 6.09 5.32
<0.05 <0.05 <0.05
1 1 1 4
120 136 15 229
0.52 0.59 0.07
>0.5 >0.4 >0.8
Data were not transformed, Cochan’s C = 0.47 (not significant). Data were not transformed, Cochan’s C = 0.36 (not significant).
Fig. 3. Mean (±S.E.) amount of recreational boat traffic at four locations, during normal (reference) conditions and during the Sydney 2000 Olympic Games; n = 2.
4. Discussion In Sydney Harbour, recreational boating accounts for an average of 70% of the overall boat traffic, in numeric terms. This figure highlights the importance of recreational boating in the description of contemporary human uses of Sydney Harbour and sustains the idea that the harbour is currently an important venue for recreation, in addition to tourism and public/cargo transport. According to Connell (2000, p. 7), Sydney Harbour is a place where “yachts are now more evident than tugs”. More broadly, it sustains the idea proposed by Kenchington (1990) that recreation is a primary use of coastal environments. Sailing is a sport practised by generations of Sydneysiders (Stephensen, 1966) and there are many sailing vessels moored in marinas and private moorings. The life-style of a number of Sydneysiders, associated with a climate that facilitates outdoor recreation and a waterway that is the physical axis of the city (Connell and Thom, 2000) might explain why sailing yachts were the most abundant recreational boat type found
in this survey. The large number of sailing boats in a waterway is an important issue to be considered in management of boat traffic, because this type of boat has restricted manoeuvrability and right of way over motorised recreational craft in most situations. Speed-boats are less expensive and simpler to use than other boats, which may explain why they are the second most abundant type. Many of them are carried on trailers. Their abundance highlights, therefore, the great demand for public boat-ramps. Motor-cruisers, being bigger and more expensive, were expected to represent a smaller fraction of the recreational boat traffic. Although associated with conflicts among users (Roe and Benson, 2001), only a small proportion of the boat traffic was composed of jet-skis. On average, they represented 5% of the recreational boat traffic in Sydney Harbour. Nevertheless, they are perceived to be a significant source of environmental impacts in Sydney (Widmer et al., 2002) and in other parts of the world (Burger, 1998b). This is probably one of the reasons for the special restrictions applied to
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jet-skis (Waterways, 2000b) and for the more recent total ban of jet-skis on Sydney Harbour (Premier of New South Wales News Release, 28 June 2001). The number of anchored boats follows the trend shown by the traffic. Particularly noticeable is the large number of recreational boats anchored in Spring Cove (North Harbour), which is also the only aquatic reserve in Sydney Harbour. The conservation strategy of this reserve should take into account the potential environmental impacts (e.g. littering, anchor damage to seagrasses, sewage, fuel pollution) associated with this use. Due to the observed correlation, managers can use the patterns of boat traffic to predict the patterns of anchored boats in this marine protected area. Contrary to the hypothesis proposed, the increase of recreational boat traffic during the 2000 Olympic Games period was not a general pattern. It occurred in Upper and Main Harbour, but not in Middle and North Harbour. The number of anchored boats did not change significantly at any of the two locations surveyed. The large number of navigational restrictions applied during this period, such as speed-limits, no-wash, no-anchoring and exclusion zones (Waterways, 2000c) may have made Sydneysiders reluctant to go boating during this period. Although special events like the Sydney 2000 Olympic Games clearly represent an increment of recreational boat traffic, the Games did not represent an overwhelming and consistent increase in boat traffic compared to baseline conditions, probably due to the already great amount of recreational boating during normal periods. Even if boat traffic does not increase substantially, special events deserve special management because it is conceivable that unusual patterns of boaters’ behaviour (e.g. increased consumption of alcoholic beverages or reduced compliance with speed-limits), may emerge on such occasions. Recreational boat traffic is clearly predictable, with its maximum in the main section of the harbour, during sunny weekends in summer. Although these results may seem obvious at a first glance, it is only now that this predictability has been quantified and is therefore available to managers of Sydney Harbour. Patterns of boat traffic can now be fully used by managers in plans to reduce risks of damage to seagrass by propellers or boat-generated litter and sewage. Furthermore, the hypothesized effects of managerial options such as relocation of foreshore facilities, control of categories
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of boats (Jaakson, 1989) and zoning of water surface (Brown et al., 1979) can now be evaluated in relation to the patterns identified in this study. Due to the simplicity and small cost of the sampling done here, frequent surveys of boat traffic in Sydney Harbour could be done to assess longer-term trends. Estimates of recreational boat traffic may also be useful in other coastal areas where intense recreational boating occurs. In Australia, such areas include Cairns, Whitsundays archipelago and Moreton Bay in Queensland, Broken Bay and Port Hacking in New South Wales, Port Phillip Bay (Melbourne), Gulf of St. Vincent (Adelaide), River Derwent (Hobart), Perth and Darwin. Sampling boat traffic in some of these areas may, however, be logistically more difficult and therefore more expensive. The relationship between commercial and recreational boat traffic may also need managerial attention. In the port of Sydney, there are approximately 2,500 ship movements per year, with no particular pattern. There could be as many movements in a weekday as in a weekend day (Sydney Ports shipping manager, personal communication). Similarly, the schedule of arrivals and departures of commercial cruisers over a period of more than 36 months shows no pattern of movements between weekdays and weekend days. Conversely, there are more movements of commuter ferries during weekdays than during weekend days (State Transit Authority, 1998). Managers of Sydney Harbour therefore have the possibility of reducing the relative proportion of movements by commercial ships during weekends and consequently increasing the relative proportion of movements during weekdays, if measures to reduce potential conflicts between commercial and recreational boat traffic become necessary. Although more active on weekdays, there are still more than 250 ferry movements during a weekend day in Sydney Harbour (State Transit Authority, 1998). Therefore, the possibility of ferry collisions with recreational boats in routes such as Manly and Taronga Zoo should not be underestimated, due to speed and frequency of ferries across the busiest area for recreational boats (mainly sailing yachts with limited manoeuvrability). Unlike previous descriptions of the recreational boating fleet in Sydney Harbour, this study was able to quantify and identify clear patterns of recreational
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boat traffic. It also showed the magnitude of this activity, which managers can now place relative to other human uses of the harbour. These are important elements to be considered for management of boat traffic per se, in addition to the development of plans to reduce the risk of environmental impacts due to the use of recreational boats in urban waterways.
Acknowledgements We thank M. Bishop, Dr. M.G. Chapman and Dr. S. Monteiro for reviewing earlier versions of the manuscript. The final version of the manuscript was improved by useful comments from Dr. D.A. Saunders and two anonymous reviewers. We also thank Sydney Ports Corporation for providing information about movements of commercial ships. W.M. Widmer is sponsored by the Brazilian Foundation CAPES, under the scholarship no. BEX 1229/98-2. The preparation of this paper was supported by funds from the Australian Research Council through the Centre for Research on Ecological Impacts of Coastal Cities. References Adams, C.E., 1993. Environmentally sensitive predictors of boat traffic loading on inland waterways. Leisure Stud. 12, 71–79. Adams, C.E., Tippett, R., Nunn, S., Archibald, G., 1992. The utilisation of a large waterway (Loch Lomond, Scotland) by recreational craft. Scott. Geogr. Mag. 108 (2), 113–118. Anderson, J., 1996. Maritime leisure. In: Goodhead, T., Johnson, D. (Eds.), Coastal Recreation Management. E&FN Spon, London, Chapter 1, pp. 3–21. Ashton, P.G., Chubb, M., 1972. A preliminary study for evaluating the capacity of waters for recreational boating. Water Resour. Bull. 8 (3), 571–577. Backhurst, M.K., Cole, R.G., 2000. Subtidal benthic marine litter at Kawau Island, north-eastern New Zealand. J. Environ. Manage. 60, 227–237. Boating Industry Association of New South Wales, 2000. A Vision for Recreational Boating and Boat Servicing in Sydney Harbour. Boating Industry Association of New South Wales, Sydney. Bratton, S.P., 1990. Boat disturbance of ciconiiformes in Georgia estuaries. Colon. Waterbirds 13, 124–128. Brown, T.L., Finegan, E.J., Voiland, M.P., 1979. Current use of water surface zoning for recreation. Water Resour. Bull. 15, 337–344. Buckingham, C.A., Lefebvre, L.W., Shaefer, J.M., Kockman, H.I., 1999. Manatee response to boating activity in a thermal refuge. Wildl. Soc. Bull. 27, 514–522.
Burger, J., 1998a. Effects of motorboats and personal watercraft on flight behaviour over a colony of common terns. Condor 100 (3), 528–534. Burger, J., 1998b. Attitudes about recreation, environmental problems, and estuarine health along the New Jersey shore, USA. Environ. Manage. 22 (6), 869–876. Cahoon, L.B., 1990. Aluminium cans as litter in Masonboro Sound, North Carolina. J. Coastal Res. 6 (2), 479–483. Castilla, J.C., 1993. Humans: capstone strong actors in the past and present coastal ecological play. In: McDonnell, M.J., Pickett, S.T.A. (Eds.), Humans as Components of Ecosystems: The Ecology of Subtle Human Effects and Populated Areas. Springer, New York, pp. 158–162. Cicin-Sain, B., Knecht, R.W., 1998a. Integrated Coastal and Ocean Management—Concepts and Practices. Island Press, Washington, DC. Cicin-Sain, B., Knecht, R.W., 1998b. Fun at the sea: coastal tourism, recreation. Sea Technol. 37–40. Clark, J.R., 1996. Coastal Zone Management Handbook. CRC Press, Boca Raton. Connell, J., 2000. And the winner is . . . . In: Connell, J. (Ed.), Sydney: The Emergency of a World City. Oxford University Press, South Melbourne, pp. 1–18. Connell, J., Thom, B., 2000. Beyond 2000: the post-Olympic city. In: Connell, J. (Ed.), Sydney: The Emergency of a World City. Oxford University Press, South Melbourne, pp. 319–343. Creed, J.C., Amado, G.M., 1999. Disturbance and recovery of the macroflora of a seagrass (Halodule wrightii Ascherson) meadow in the Abrolhos Marine National Park, Brasil: an experimental evaluation of anchor damage. J. Exp. Mar. Biol. Ecol. 235 (2), 285–306. Dawes, C.J., Andorfer, J., Rose, C., Uranowski, C., Ehringer, N., 1997. Regrowth of the seagrass Thalassia testudinum into propeller scars. Aquat. Bot. 59, 139–155. Department of Urban Affairs and Planning, 1999. Sydney Harbour and Tributaries, Towards a Vision and Strategic Program. Discussion Paper, New South Wales Department of Urban Affairs and Planning, Sydney. Glasby, T.M., Connell, S.D., 1999. Urban structures as marine habitats. Ambio 28, 595–598. Guillon-Cottard, I., Augier, H., Console, J.J., Esmieu, O., 1998. Study of microbiological pollution of a pleasure boat harbour using mussels as bioindicators. Mar. Environ. Res. 45 (3), 239– 247. Harvey, N., 1993. Sensitivity of South Australian environments to marina construction. In: Thomas, D.S.G., Allison, R.J. (Eds.), Landscape Sensitivity. Wiley, Chichester, pp. 327–342. Harvey, N., 1998. Environmental Impact Assessment—Procedures, Practice, and Prospects in Australia. Oxford University Press, Melbourne. Heatwole, C.A., West, N.C., 1982. Recreational-boating patterns and water-surface zoning. Geogr. Rev. 72 (3), 304–314. Jaakson, R., 1989. Recreation boating spatial patterns: theory and management. Leisure Sci. 11, 85–98. Janik, V.M., Thompson, P.M., 1996. Changes in surfacing patterns of bottlenose dolphins in response to boat traffic. Mar. Mamm. Sci. 12, 567–602.
W.M. Widmer, A.J. Underwood / Landscape and Urban Planning 66 (2004) 173–183 Kay, R., Alder, J., 1999. Coastal Planning and Management. E&FN Spon, London. Kenchington, R., 1990. Managing Marine Environments. Taylor & Francis, New York. Mathews, P., 1997. The Waterways of Sydney Harbour. Phillip Mathews Book Publishers, Crowns Nest. Murphy, K.J., Eaton, J.W., 1983. Effects of pleasure-boat traffic on macrophyte growth in canals. J. Appl. Ecol. 20, 713–729. Rilov, G., Gasith, A., Evans, S.M., Benayahu, Y., 2000. Unregulated use of TBT-based antifouling paints in Israel (eastern Mediterranean): high contamination and imposex levels in two species of marine gastropods. Mar. Ecol. Prog. Ser. 192, 229–238. Robertson, R.W., 1995. Management of recreational use of waterways. In: Cardew, R., Merrick, J.R. (Eds.), Proceedings of the First International Marinas Conference, 6–10 May 1985. Graduate School of the Environment, Macquarie University, North Ryde, pp. 321–335. Roe, M., Benson, J.F., 2001. Planning for conflict resolution: jet-ski use on the Northumberland coast. Coastal Manage. 29, 19–39. Sant, M., 1990. Accommodating recreational demand: boating in Sydney Harbour, Australia. Geoforum 21 (1), 97–109. Sowman, M.R., Fuggle, R.F., 1987. Assessing recreational carrying capacity: a case study of the Kromme river estuary, South Africa. J. Shoreline Manage. 3, 53–75. State Transit Authority of New South Wales, 1998. Sydney Ferries Timetables: Neutral Bay, Taronga Zoo, Mosman, Darling Harbour, Woolwich, Rose Bay/Watsons Bay, Parramata River, Manly. State Transit Authority of New South Wales, Sydney. Stephensen, P.R., 1966. The History and Description of Sydney Harbour. Griffin Press, Adelaide.
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Strand, I.E., Gibson, G.R., 1990. The use of pump-out facilities by recreational boaters in Maryland. Estuaries 13, 282–286. Underwood, A.J., 1993. Exploitation of species on the rocky coast of New South Wales (Australia) and options for its management. Ocean Coastal Manage. 20, 41–62. Underwood, A.J., Chapman, M.G., 1999. The role of ecology in coastal zone management: perspectives from south-east Australia. In: Salomons, W., Turner, R.K., Lacerda, L.A., Ramachandran, S. (Eds.), Perspectives on Integrated Coastal Zone Management. Springer, Berlin, pp. 99–128. Vallega, A., 2001a. Urban waterfront facing integrated coastal management. Ocean Coastal Manage. 44, 379–410. Vallega, A., 2001b. Ocean governance in post-modern society—a geographical perspective. Mar. Policy 25, 399–414. Vitousek, P.M., Mooney, H.A., Lubchenco, J., Melillo, J.M., 1997. Human domination of Earth’s ecosystems. Science 227, 494– 499. Waterways, 2000a. Sewage Pollution from Vessels. Discussion Paper, New South Wales Waterways Authority, Sydney. Waterways, 2000b. NSW Safe Boating Handbook. New South Wales Waterways Authority, Sydney. Waterways, 2000c. Sydney Harbour Map—Special Olympic Edition. New South Wales Waterways Authority, Sydney. Widmer, W.M., Underwood, A.J., Chapman, M.G., 2002. Public perception of potential environmental impacts of recreational boating on Sydney Harbour. Nat. Resour. Manage. 5, 22–27. Wolter, C., 2001. Conservation of fish in navigable waterways. Landscape Urban Plann. 53, 135–144. Yapp, G.A., 1986. Aspects of population, recreation, and management of the Australian coastal zone. Coastal Zone Manage. J. 14, 47–66.
Factors affecting traffic and anchoring patterns of recreational boats in Sydney Harbour, Australia W.M. Widmer∗ , A.J. Underwood Centre for Research on Ecological Impacts of Coastal Cities, Marine Ecology Laboratories, A11, University of Sydney, Sydney, NSW 2006, Australia Received 18 December 2002; received in revised form 4 April 2003; accepted 5 April 2003
Abstract Management of recreational boating is typically based on measures of numbers of boats (e.g. marina berths, vessel registrations). Potential environmental impacts and safety aspects may, however, be a function of the number of boat movements and not of the total numbers of boats kept in a harbour. Therefore, a survey was designed to test hypotheses regarding the traffic and anchoring patterns of recreational boats in Sydney Harbour. Boat movements were visually counted for periods of 1 h in four locations in the estuary. The results indicate that recreational boating is the main component of all boat traffic, being composed chiefly by sailing yachts, with a small contribution of jet-skis. Traffic of leisure boats was more intense in summer than in winter. On weekends, there were more movements of recreational boats on sunny than on overcast/rainy conditions. Weather was not, however, a significant factor on weekdays. During the Sydney 2000 Olympic Games, the predicted increase in traffic and anchoring intensity by recreational boats was not consistent. In two out of four locations, the traffic of recreational boats during this special event was not significantly different than during baseline periods. The number of anchored boats was greater at North Harbour Aquatic Reserve (NHAR) and was positively correlated to boat traffic. Due to this observed correlation, managers can use the patterns of boat traffic to predict the patterns of anchored boats in this marine protected area. The large number of movements of sailing boats is an important issue to be considered in management of boat traffic, because this type of boat has restricted manoeuvrability and right of way over motorised recreational craft in most situations. This study quantified and identified clear patterns of recreational boat traffic. Managers can now use this information to develop strategies aiming at the improvement of boating safety and the prevention of potential environmental impacts due to the use of recreational boats in urban waterways. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Boat traffic; Estuaries; Integrated coastal management; Leisure boating; Sydney 2000 Olympic Games; Waterways
1. Introduction More than half of the world’s population presently lives in coastal areas (Vitousek et al., 1997) and the ∗ Corresponding author. Tel.: +61-2-9351-4931; fax: +61-2-9351-6713. E-mail address: [email protected] (W.M. Widmer).
0169-2046/$20.00 © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0169-2046(03)00099-9
rate of increase of coastal populations is greater than inland populations (Cicin-Sain and Knecht, 1998a). The people inhabiting coastal areas tend to group into dense aggregations. Urbanization is a major feature of coasts worldwide; several of the largest cities of the world are near the sea or at the margins of estuaries. Currently, there are 13 coastal mega-cities with more than 8 million people each (Vallega, 2001a).
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Among the plethora of human activities on the coast, recreation and tourism stand out as the most rapidly growing (Cicin-Sain and Knecht, 1998b). Coastal recreation tends to increase in association with coastal urbanization (Vallega, 2001b). As one particular type of recreational use of coastal waters, pleasure boating has increased substantially since the Second World War, due to the increase in disposable incomes in many countries and the general reduction of costs of boats with the advent of new technologies and materials (Robertson, 1995; Anderson, 1996). Traditionally, the potential environmental impacts due to recreational boating have been mainly associated with its necessary land-based infrastructure, such as marinas and related facilities. These developments have been implicated in environmental disturbances that include changes in oceanographic patterns by groynes or breakwaters and depletion of habitats by dredging and landfilling (Harvey, 1993), contamination of water and sediments due to toxic substances from fuels and antifouling paints (Rilov et al., 2000) and changes in subtidal assemblages due to introduction of artificial habitats such as pilings and floating pontoons (Glasby and Connell, 1999). These environmental issues can partially explain why many marinas are considered to be “designated developments” in the Australian state of New South Wales. As such, they require an Environmental Impact Statement (EIS) as one of the necessary procedures for the project to be granted a development consent by the planning authority, under the current New South Wales Environmental Planning and Assessment Act (Harvey, 1998). The actual use of recreational boats away from their storage facilities may, however, also have environmental consequences for coastal areas, especially on harbour and estuarine environments, where this activity is predominantly practised. According to Wolter (2001), people are highly concerned about the environmental deterioration of waterways. It is reasonable to conceive that increased levels of recreational boat traffic in coastal waters represent increased risks of environmental disturbances that include: (i) damage to seagrass meadows by propellers and anchors (Dawes et al., 1997; Creed and Amado, 1999); (ii) intentional or accidental introduction of debris (littering) by boat-users (Cahoon,
1990; Backhurst and Cole, 2000); (iii) changes of shorebird behaviour due to boat movements near roosting grounds or reproductive colonies (Bratton, 1990; Burger, 1998a); (iv) interference with marine mammals, such as changes of dolphin behaviour or injuries caused by collisions (Janik and Thompson, 1996; Buckingham et al., 1999); and (v) release of sewage from boats into estuarine waters (Strand and Gibson, 1990; Guillon-Cottard et al., 1998). Furthermore, perceptions of enjoyment of boating and its safety levels are reduced as density of boats increases in a navigable water body (Ashton and Chubb, 1972). The likelihood for conflict between recreational boating and other human uses of the waterway also increases as traffic increases, particularly near large metropolitan areas (Heatwole and West, 1982). Noise affecting foreshore residential areas is also associated with traffic of specific recreational craft such as jet-skis and power-boats. Australia is one of the most urbanized countries in the world; most people live in a few large, coastal cities. According to Yapp (1986, p. 64), “the Australian coastal zone is the nation’s prime destination for outdoor recreation”. In terms of intensity, Sydney Harbour is one of the most important areas for recreational boating in the southern hemisphere. As in other studies about recreational boating in Sydney Harbour, this activity has been typically described by the size of the recreational boating fleet. Sant (1990) used numbers of registered motor-boats and sailing vessels obtained from the then Maritime Services Board to study ways to accommodate the demand for boating in the harbour. An estimate of 36,000 recreational boats in the Sydney region was a key fact about Sydney Harbour (Department of Urban Affairs and Planning, 1999). There are approximately 7,500 recreational boats stored on Sydney Harbour, in marinas and on private moorings (Boating Industry Association of New South Wales, 2000). This is 75% of the estimate of 10,000 mooring berths from Underwood and Chapman (1999). Some 42 marinas and several sailing clubs maintain a fleet of thousands of sailing dinghies. Several public boat-ramps make the harbour available for boats stored elsewhere. One of the primary aims of integrated coastal management is to promote the ecologically sustainable development of coastal areas (Clark, 1996; Kay and
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Alder, 1999). Because humans play a significant role in the ecology of coastal ecosystems (Castilla, 1993), it is important to study the patterns of human behaviour in these systems. For instance, Underwood (1993) demonstrated that detailed information about patterns of human use of rocky shores is needed for the development of proper plans of management for these habitats. Only a fraction of the total number of boats kept in a harbour is actually in use at any given time. Therefore, information about patterns of boat traffic are necessary to provide managers with important indications about where and when certain types of potential environmental disturbances, safety risks and variations in the level of boaters’ enjoyment are most likely to occur. Furthermore, such information would be useful in the efficient allocation of resources to manage waterways. According to Adams et al. (1992, p. 113), detailed accounts of boat traffic on a waterway is an “essential prerequisite upon which to base successful management policy”. To determine the patterns of traffic in Sydney Harbour, a survey was designed to test the following hypotheses: (a) Connell and Thom (2000) pointed out that the industrial and mercantile character of the harbour has been recently replaced by recreational and residential developments. Therefore, the boat traffic in the harbour should be mainly represented by recreational vessels. For this study, mainly is considered to be more than half of all boat traffic. The proportion of recreational out of all boat traffic is predicted to be greater than 0.5. (b) As in other studies (Sowman and Fuggle, 1987; Adams et al., 1992), preliminary observations in Sydney Harbour suggested that some types of recreational boats are more intensively used than others. This is proposed to be a consistent pattern for Sydney Harbour. Therefore, if the number of sailing yachts, motor-cruisers, speed-boats and personal water-craft (PWC) are counted, it is expected that their means will be different, with greater numbers of speed-boats, consistent with other geographic areas. (c) Being an outdoor leisure activity, recreational boating tends to vary according to several factors, including time of the year, day of the week,
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weather and location (Sowman and Fuggle, 1987; Adams, 1993). It is proposed that the recreational boat traffic in Sydney Harbour will also be affected by these factors. Therefore, it is predicted that there will be more traffic: (i) during summer than winter; (ii) on weekends than on working weekdays; (iii) on sunny than on overcast/rainy days; (iv) the mean amounts of recreational boat traffic from four different locations are also expected to be different. (d) Large numbers of recreational boats are anchored in some locations in Sydney Harbour (Mathews, 1997; personal observation). Because boats have to sail from their origin (marinas, private mooring-areas or public boat-ramps) to anchor at chosen sites, the numbers of boats moving (the traffic) is predicted to be related to the numbers of boats anchored in any area. (e) Previous observations suggest that recreational boating activity tends to be intensified during special events on Sydney Harbour. It is proposed that the Sydney 2000 Olympic Games was such a special event. Therefore, recreational boat traffic and the number of anchored recreational boats were expected to be greater during the 2000 Olympic Games, than during normal periods. 2. Methods 2.1. Definition of recreational boating According to the New South Wales Waterways Authority, a recreational vessel is “any vessel that is not a commercial vessel” (Waterways, 2000a, p. VI). This definition, associated with the description of types of recreational boats from Adams et al. (1992), was used to produce the definition of the categories of recreational vessels that were used in this study (Table 1). Therefore, commercial vessels, defined as boats that are “used for the carriage of persons or goods for money or any other valuable consideration, hired out or made available in the course of a business or trade or commerce” (Waterways, 2000a, p. V) were distinguished from recreational boats by means of indicative signs on the hull or rigging. From Table 1, it is worth noting the types of boats that were not included in the recreational category:
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Table 1 Recreational boatsa Motorised Speed-boat: A boat with a planing-type hull, with the capacity to exceed 20 knots and without sleeping or toilet facilities. Powered by an out-board engine. It includes rubber inflatables. Motor-cruiser: A boat bigger than a speed-boat, with a displacement hull. It has sleeping and toilet facilities and an in-board engine. Jet-ski: A small jet-propelled craft, with a high-powered and internal engine, for one or two people; also known as personal water-craft (PWC). Sailing Yacht: A boat with a mast, fixed keel, displacement hull and with sleeping and toilet facilities. It carries an auxiliary engine, that may be either in- or out-board. Bigger than a sailing dinghy. Multihulls (e.g. catamarans and trimarans), racing yachts with planing hulls and swing keel yachts were also included in this group. Dinghy: An open deck boat, with a mast and a retractable keel and without sleeping or toilet facilities. Sailboard: A surfboard for one person, powered by the wind with the aid of a sail held by the surfer’s hands. Self-powered Rowing boat: An open deck boat propelled by human power through the use of oars. It includes kayaks, Canadian canoes, traditional surf-rescue-boats and other similar boats. a Typical definitions of recreational boats used in this study, adapted from Adams et al. (1992). Not all of the characteristics described here were used for identification in the field.
water-taxis, boats selling ice-cream and other refreshments, fuel-boats, tugboats, merchant ships, professional fishing-boats, ferries, barges, charter-boats, military vessels, police-boats, rescue-boats from volunteer groups, harbour pilot boats, New South Wales Waterways Authority boats, boats from the Department of Land and Water Conservation and historic ships. In addition, rowing boats, sailing dinghies and sailboards were not included in the counts of the recreational boat traffic, because their potential environmental impacts are considered to be minimal and because their range of movement is typically confined to single coves or bays. 2.2. Measurement of boat traffic and anchored boats Previous research has used different methods to estimate boat traffic, including the use of aerial photographs (Buckingham et al., 1999), records from boat locks (Murphy and Eaton, 1983), questionnaires to boaters (Heatwole and West, 1982) and direct observation (Sowman and Fuggle, 1987). In this study, direct observation was used because it allowed the quantification of boat traffic at times and locations appropriate to the proposed hypotheses. Furthermore, being simple and inexpensive, studies using this method can be repeated more often, being also applicable to other locations where resources and technology are scarce.
Boats were counted for a period of 1 h from each of four vantage points on the harbour foreshore (Fig. 1), one in each of the four major sections of the harbour: Upper, Main, Middle and North (Stephensen, 1966; Mathews, 1997). From each vantage point, vessels that crossed an imaginary line from the point of observation to a prominent point on the other margin of the harbour were counted with the aid of a pair of binoculars. The vantage point in the northern section of the harbour was chosen to represent the recreational boat traffic within the North Harbour Aquatic Reserve (NHAR), a marine protected area in Sydney Harbour. To test the hypothesis about weather, representative samples of boat traffic under different weather conditions were required. Therefore, sampling was done on overcast/rainy and sunny conditions, chosen according to the weather forecast issued by the Australian Bureau of Meteorology on the morning of sampling. So, any day that had previously been chosen for sampling could turn out to be overcast/rainy or sunny. Once the requisite number of days of one condition were complete, sampling was only done on randomly chosen days of the other weather condition. In order to avoid variations in boat traffic at different times of day, sampling was done during the same part of the day; measurements for a given month were taken during the hour that preceded mid-afternoon, defined as at three quarters of the time span between sunrise
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Fig. 1. The four vantage points from which the recreational boat traffic and anchored recreational boats were quantified. (1) Upper Harbour, from Yumbin Point to Manns Point; (2) Main Harbour, from Point Piper to Bradleys Head; (3) Middle Harbour, from Chinamans Beach to Clontarf Point; (4) North Harbour, from Dobroyd Head to Cannae Point. Shaded areas in Middle and North Harbour indicate the locations where anchored recreational boats were counted. Dashed lines indicate the limits of the North Harbour Aquatic Reserve (NHAR).
and sunset for the 15th day of that month. The actual time of sampling therefore changed as days got longer towards summer. The same procedure was used to count the number of recreational anchored boats. At two of the four vantage points used for counting boat traffic, determining the number of anchored boats was, however, difficult due to the obstruction of the view by several coves and small bays. Previous observations suggested that there were few anchored boats at these locations. Therefore, anchored boats were only sampled at Middle and North Harbour.
2.3. Sampling design Measurements of boat traffic and anchored boats were done in two different periods of the year, low season (June to September) and high season (December to March). In each season, counts were made during weekends and weekdays, during overcast/rainy or sunny conditions, in each of the four locations (two locations for anchored boats). Two replicate samples were taken for each treatment, i.e. two independent overcast/rainy weekends, overcast/rainy weekdays, sunny weekends and sunny weekdays were sampled
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for each location in each season. This resulted in a total of 64 independent measurements (32 for anchored boats). Eight measurements of recreational boat traffic and four of the number of recreational boats anchored were taken during the Olympic Games (15 September to 1 October 2000). They were taken at the same four locations described above (two locations for anchored boats), during weekdays and weekends. Only recreational boats outside the exclusion zones were counted, in order not to include boats directly associated with the event (i.e. competitors, management, media, authorised charter-boats). These values were compared with suitable measurements taken during baseline periods and with similar characteristics in terms of season, day of the week, weather and location. 2.4. Statistical treatment For hypothesis (a), the proportion of recreational boat traffic out of the total boat traffic was calculated for the 64 measurements and the null hypothesis that the resulting mean is less than or equal to 0.5 was tested using Student’s t-test. Null hypothesis (b) of no difference among the mean numbers of sailing yachts, motor-cruisers, speed-boats and personal water-craft was tested using a single-factor analysis of variance, using counts of each type of boat in the 64 measures. The null hypotheses of no effect for hypothesis (c) was tested using analysis of variance with four factors: season (fixed, with two levels: winter and summer), day of the week (fixed, with two levels: weekdays and weekend days), weather (fixed, with two levels: overcast/rainy and sunny days) and location (fixed because only four parts of the harbour were considered, with four levels: Upper, Main, Middle and North). There were two replicate counts for each treatment. The null hypothesis of no effect for hypothesis (d) was tested by the Pearson correlation coefficient, r, using the 32 paired values of traffic and anchored boats. The null hypothesis of no difference for hypothesis (e) was tested using analysis of variance with two factors. The first factor was condition, with two levels (fixed, Olympic versus non-Olympic periods) and the second factor (fixed and orthogonal) was location, with four levels. There were two replicate values for each
treatment. For anchored boats, the factor location had two levels instead of four. For the analyses of variance, the assumptions of homogeneity of variances were tested using Cochran’s test. If necessary, transformations were done to remove heterogeneity of variances. When factors or interactions among factors were found to be statistically significant (P < 0.05), multiple comparisons (SNK tests) were used to test for differences between levels within and across factors.
3. Results 3.1. Proportion of recreational boating The mean ratio of recreational boat traffic over total boat traffic was 0.71 (±S.E. = 0.02). This was significantly larger than 0.5 (t = 10.01, P < 0.001, d.f. = 63). 3.2. Types of boats There were significant differences among numbers of different types of recreational boats using the harbour (Table 2). Numbers of sailing yachts (almost 25± 3.5 boats h−1 ) and speed-boats (18.5 ± 1.7 boats h−1 ) did not differ significantly, but were significantly more numerous than motor-cruisers (11.5 ± 1.3 boats h−1 ). Jet-skis (4 ± 0.8 boats h−1 ) were the least numerous type of recreational craft and were significantly less abundant than the other types of recreational boats (SNK tests). 3.3. Patterns of recreational boat traffic Recreational boat traffic was significantly greater in summer, averaging 70 ± 9.5 boats h−1 , whereas in Table 2 Analysis of variance of mean numbers of different types of recreational boats present in the Sydney Harbour’s boat traffica Source of variation
d.f.
MS
F
P
Types of boats Residual
3 252
40.6 0.9
40.8
<0.001
a Data were ln(x + 1) transformed to homogenise variances, Cochan’s C = 0.34 after transformation (not significant).
W.M. Widmer, A.J. Underwood / Landscape and Urban Planning 66 (2004) 173–183 Table 3 Analysis of variance of mean numbers of recreational boat traffic in Sydney Harboura Source of variation
d.f.
MS
F
P
Season (Se) Day of the week (Da) Weather (We) Location (Lo) Se × Da Se × We Se × Lo Da × We Da × Lo We × Lo Se × Da × We Se × Da × Lo Se × We × Lo Da × We × Lo Se × Da × We × Lo Residual
1 1 1 3 1 1 3 1 3 3 1 3 3 3 3 32
8212 55755 12072 7987 213 284 994 4675 605 1233 2537 243 554 372 745 740
11 75 16 10 0.29 0.38 1.34 6.31 0.82 1.67 3.43 0.33 0.75 0.5 1
<0.01 <0.001 <0.001 <0.001 >0.5 >0.5 >0.2 <0.05 >0.4 >0.1 >0.05 >0.8 >0.5 >0.6 >0.4
a Data were not transformed, Cochan’s C = 0.16 (not significant).
winter the mean value was 47±6.8 boats h−1 (Table 3, SNK test). Traffic was particularly heavy in the Main Harbour, with a mean value of 90±14.5 boats h−1 , significantly greater than the traffic from the other three locations. Traffic in Middle Harbour (56.5±12 boats h−1 ), Upper Harbour (49±9 boats h−1 ) and North Harbour (39±9 boats h−1 ) did not differ (SNK tests). The effects of weather were dependent on the time of week (see interaction in analyses in Table 3). Weather was an important factor only during weekends. Sunny weekends had 110 ± 12 boats h−1 , significantly greater than 66 ± 7.6 boats h−1 on overcast/rainy weekends (SNK test). During the week,
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however, there was only a slight increase in recreational boat traffic on sunny days (34 ± 6.6 boats h−1 ) compared to overcast/rainy ones (24 ± 7.4 boats h−1 ), a difference that was not statistically significant. There was significantly more traffic on weekends than on weekdays, but the increase was greater during periods of sunny weather (SNK tests). 3.4. Anchoring patterns The number of recreational boats anchored in the two locations sampled (Middle and North harbour) was positively correlated with the recreational boat traffic measured at these locations (r = 0.74, P < 0.05, d.f. = 30, Fig. 2). There were, on average, more recreational boats anchored in North Harbour (26.6 ± 6.6 boats) than in Middle Harbour (14.8 ± 5 boats). 3.5. Recreational boating during the 2000 Olympic Games Differences in traffic during the Olympic Games compared to baseline levels were dependent on the location (Table 4 marked as ‘a’). In Upper and Main Harbour, the recreational boat traffic was significantly greater during the Olympic period. At Middle Harbour, there was only a slight (and not statistically significant) increase in the recreational boat traffic during the Olympic Games. At North Harbour, recreational boat traffic was reduced during the Olympic period (Fig. 3), although not significantly. The number of recreational boats anchored at Middle and North Harbour increased only slightly during the Olympic period, an increase that was not statistically significant (Table 4 marked as ‘b’).
Fig. 2. Correlation of amount of boat traffic and numbers of anchored boats in Middle and North Harbour.
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Table 4 Analysis of variance of mean amounts of traffic during the Sydney 2000 Olympic Games compared to other times Source of variation
Olympics vs. reference (O) Location (Lo) O × Lo Residual a b
Recreational boat traffica
Recreational boats anchoredb
d.f.
MS
F
P
d.f.
MS
F
P
1 3 3 8
2652 2877 2512 472
5.61 6.09 5.32
<0.05 <0.05 <0.05
1 1 1 4
120 136 15 229
0.52 0.59 0.07
>0.5 >0.4 >0.8
Data were not transformed, Cochan’s C = 0.47 (not significant). Data were not transformed, Cochan’s C = 0.36 (not significant).
Fig. 3. Mean (±S.E.) amount of recreational boat traffic at four locations, during normal (reference) conditions and during the Sydney 2000 Olympic Games; n = 2.
4. Discussion In Sydney Harbour, recreational boating accounts for an average of 70% of the overall boat traffic, in numeric terms. This figure highlights the importance of recreational boating in the description of contemporary human uses of Sydney Harbour and sustains the idea that the harbour is currently an important venue for recreation, in addition to tourism and public/cargo transport. According to Connell (2000, p. 7), Sydney Harbour is a place where “yachts are now more evident than tugs”. More broadly, it sustains the idea proposed by Kenchington (1990) that recreation is a primary use of coastal environments. Sailing is a sport practised by generations of Sydneysiders (Stephensen, 1966) and there are many sailing vessels moored in marinas and private moorings. The life-style of a number of Sydneysiders, associated with a climate that facilitates outdoor recreation and a waterway that is the physical axis of the city (Connell and Thom, 2000) might explain why sailing yachts were the most abundant recreational boat type found
in this survey. The large number of sailing boats in a waterway is an important issue to be considered in management of boat traffic, because this type of boat has restricted manoeuvrability and right of way over motorised recreational craft in most situations. Speed-boats are less expensive and simpler to use than other boats, which may explain why they are the second most abundant type. Many of them are carried on trailers. Their abundance highlights, therefore, the great demand for public boat-ramps. Motor-cruisers, being bigger and more expensive, were expected to represent a smaller fraction of the recreational boat traffic. Although associated with conflicts among users (Roe and Benson, 2001), only a small proportion of the boat traffic was composed of jet-skis. On average, they represented 5% of the recreational boat traffic in Sydney Harbour. Nevertheless, they are perceived to be a significant source of environmental impacts in Sydney (Widmer et al., 2002) and in other parts of the world (Burger, 1998b). This is probably one of the reasons for the special restrictions applied to
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jet-skis (Waterways, 2000b) and for the more recent total ban of jet-skis on Sydney Harbour (Premier of New South Wales News Release, 28 June 2001). The number of anchored boats follows the trend shown by the traffic. Particularly noticeable is the large number of recreational boats anchored in Spring Cove (North Harbour), which is also the only aquatic reserve in Sydney Harbour. The conservation strategy of this reserve should take into account the potential environmental impacts (e.g. littering, anchor damage to seagrasses, sewage, fuel pollution) associated with this use. Due to the observed correlation, managers can use the patterns of boat traffic to predict the patterns of anchored boats in this marine protected area. Contrary to the hypothesis proposed, the increase of recreational boat traffic during the 2000 Olympic Games period was not a general pattern. It occurred in Upper and Main Harbour, but not in Middle and North Harbour. The number of anchored boats did not change significantly at any of the two locations surveyed. The large number of navigational restrictions applied during this period, such as speed-limits, no-wash, no-anchoring and exclusion zones (Waterways, 2000c) may have made Sydneysiders reluctant to go boating during this period. Although special events like the Sydney 2000 Olympic Games clearly represent an increment of recreational boat traffic, the Games did not represent an overwhelming and consistent increase in boat traffic compared to baseline conditions, probably due to the already great amount of recreational boating during normal periods. Even if boat traffic does not increase substantially, special events deserve special management because it is conceivable that unusual patterns of boaters’ behaviour (e.g. increased consumption of alcoholic beverages or reduced compliance with speed-limits), may emerge on such occasions. Recreational boat traffic is clearly predictable, with its maximum in the main section of the harbour, during sunny weekends in summer. Although these results may seem obvious at a first glance, it is only now that this predictability has been quantified and is therefore available to managers of Sydney Harbour. Patterns of boat traffic can now be fully used by managers in plans to reduce risks of damage to seagrass by propellers or boat-generated litter and sewage. Furthermore, the hypothesized effects of managerial options such as relocation of foreshore facilities, control of categories
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of boats (Jaakson, 1989) and zoning of water surface (Brown et al., 1979) can now be evaluated in relation to the patterns identified in this study. Due to the simplicity and small cost of the sampling done here, frequent surveys of boat traffic in Sydney Harbour could be done to assess longer-term trends. Estimates of recreational boat traffic may also be useful in other coastal areas where intense recreational boating occurs. In Australia, such areas include Cairns, Whitsundays archipelago and Moreton Bay in Queensland, Broken Bay and Port Hacking in New South Wales, Port Phillip Bay (Melbourne), Gulf of St. Vincent (Adelaide), River Derwent (Hobart), Perth and Darwin. Sampling boat traffic in some of these areas may, however, be logistically more difficult and therefore more expensive. The relationship between commercial and recreational boat traffic may also need managerial attention. In the port of Sydney, there are approximately 2,500 ship movements per year, with no particular pattern. There could be as many movements in a weekday as in a weekend day (Sydney Ports shipping manager, personal communication). Similarly, the schedule of arrivals and departures of commercial cruisers over a period of more than 36 months shows no pattern of movements between weekdays and weekend days. Conversely, there are more movements of commuter ferries during weekdays than during weekend days (State Transit Authority, 1998). Managers of Sydney Harbour therefore have the possibility of reducing the relative proportion of movements by commercial ships during weekends and consequently increasing the relative proportion of movements during weekdays, if measures to reduce potential conflicts between commercial and recreational boat traffic become necessary. Although more active on weekdays, there are still more than 250 ferry movements during a weekend day in Sydney Harbour (State Transit Authority, 1998). Therefore, the possibility of ferry collisions with recreational boats in routes such as Manly and Taronga Zoo should not be underestimated, due to speed and frequency of ferries across the busiest area for recreational boats (mainly sailing yachts with limited manoeuvrability). Unlike previous descriptions of the recreational boating fleet in Sydney Harbour, this study was able to quantify and identify clear patterns of recreational
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boat traffic. It also showed the magnitude of this activity, which managers can now place relative to other human uses of the harbour. These are important elements to be considered for management of boat traffic per se, in addition to the development of plans to reduce the risk of environmental impacts due to the use of recreational boats in urban waterways.
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